Patent Application
20140022718
The present invention relates to a vacuum sealed package that vacuum seals an electronic device, and a method for manufacturing the vacuum sealed package.
In recent years, there has been a demand for miniaturization, increased performance, and cost reductions for packages and devices in which an electronic device such as an infrared ray sensor, gyro sensor (angular velocity sensor), temperature sensor, pressure sensor, and acceleration sensor is vacuum-encapsulated therein. In particular, in a package or device that implements an infrared ray sensor (infrared ray receiving element) for use in a surveillance camera for night-time security or in thermography that calculates and displays temperature distribution, the inside thereof is required to be sealed with a high vacuum.
In general, infrared ray receiving elements are divided into a quantum type and a thermal type. Among these, although the thermal type has a lower level of tracking capability compared to that of the quantum type, since it is of a form that detects relative thermal quantity, it may be made in a non-cooling form and the structure thereof may be simplified. For that reason, it is possible to keep the manufacturing cost low with the thermal type.
In a package or device having this thermal-type infrared ray sensor mounted therein, an infrared ray which has been transmitted through a window is absorbed by the light-receiving portion of the detecting element, and thereby the temperature of the vicinity of the light-receiving portion changes. Further, resistance change associated with this temperature change is detected as a signal.
In order to detect a signal with a high level of sensitivity, it is necessary to thermally insulate the light receiving portion. For that reason, conventionally this thermal insulation property has been ensured by adopting a structure in which the light receiving portion is floated in an empty space, or by arranging the detecting element itself in a vacuum container.
However, once an electronic device has been sealed in a vacuum in order to ensure this thermal insulation property, there occurs a phenomenon in which gas molecules (H2O, O2, N2, and the like) that have been adsorbed on surfaces inside the vacuum sealed package body are slowly released into the space in the package body over time, and the level of vacuum within the package body is reduced. As a result, the problem arises of the performance of the electronic device decreasing (for example, in an infrared ray sensor, the sensitivity of the output signal drops).
Therefore, in order to remedy such issues in a conventional vacuum sealed package, a material called a “getter” is mounted in the interior of the package, and so even in the case where outgassing occurs inside of the package body as described above, a drop in the vacuum level is prevented by absorbing the gas molecules with the getter.
As the material of the getter, for example, zirconium, vanadium, iron, or an alloy of these materials is used. However, when left in the atmosphere, gas molecules end up being adsorbed on the surface thereof, resulting in a saturated state in which the no more gas can be adsorbed. Therefore, prior to mounting a getter in a vacuum sealed package and vacuum encapsulating it, it is necessary to carry out a so-called “activation” process on the getter, and having completed the activation process, the getter needs to be encapsulated in the vacuum atmosphere. In the “activation” process, the getter is heated to 400° C. to 900° C. to discharge the molecules on the surface.
Patent Document 1 for example discloses art of a thermal-type non-cooling infrared ray sensor device having a getter mounted therein and a method for manufacturing the same.
Also, Patent Document 1 discloses as another technique in which the getter 105 is bonded to the inner surface of the metal cap 102 as shown in
Note that the device shown in
In addition to Patent Document 1, Patent Documents 2 and 3 also disclose thermal-type non-cooling infrared radiation sensor devices having a getter mounted therein and methods of manufacturing them.
As for the art that is disclosed in Patent Document 2, as shown in
As for the art that is disclosed in Patent Document 3, as shown in
Also, in addition to the Patent Documents 1 to 3 mentioned above, there is also a vacuum package technique that is disclosed in Patent Document 4. In this vacuum package, as shown in
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2003-139616
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. H11-326037
[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2006-10405
[Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2007-073721
However, the conventional vacuum sealed packages shown in
For example, in the vacuum sealed package shown in
Also, in the manufacturing method for the vacuum sealed package shown in
Also, in the manufacturing method for the vacuum sealed package shown in
Also, although the vacuum package shown in
Also, a vacuum sealed package in which an infrared ray sensor is installed as an electronic device is given as a representative example of a vacuum sealed package, with reference to Patent Documents 1 to 4. However, of course, even in the case of using a device other than an infrared ray sensor as the electronic device, the issues as described above are still present.
The present invention has been conceived in view of the above circumstances, and has as its object to provide a vacuum sealed package that can perform vacuum sealing of a package main body portion with a simple system and without using an expensive vacuum apparatus such as one in which a movable machine component or a robot handling mechanism or the like is provided therein in a package of a type that performs sealing of the package main body portion in a state of the interior being vacuumed beforehand, and a manufacturing method therefor. Also, it has as its object to provide a vacuum sealed package with excellent productivity that is capable of easily maintaining the vacuum state after sealing, and a method of manufacturing therefor.
In order to solve the aforementioned issues, the present invention provides the following means.
That is, the present invention provides a vacuum sealed package that includes a package main body portion in which a first main body portion and a second main body portion are bonded via a hollow portion, and a getter material and an electronic device that are provided within the hollow portion of the package main body portion, and the inside of the package main body portion is sealed in the state of the hollow portion being evacuated via a through-hole that brings the inside of the hollow portion and the outside of the package main body portion into communication, in which the first main body portion includes a wiring substrate, the getter material and the electronic device are respectively connected to a first conductor pad and a second conductor pad that are positioned in the hollow portion and formed on the wiring substrate, the first conductor pad is connected via a thermally conductive material with a third conductor pad that is positioned outside of the hollow portion and formed on the wiring substrate, and the second conductor pad is electrically connected with a fourth conductor pad that is positioned outside of the hollow portion and formed on the wiring substrate.
Also, the present invention provides a vacuum sealed package that includes a package main body portion in which a first main body portion and a second main body portion are bonded via a hollow portion, and a getter material and an electronic device that are provided within the hollow portion of the package main body portion, and that in the state of the hollow portion being evacuated via a through-hole that brings the inside of the hollow portion and the outside of the package main body portion into communication, the through-hole is sealed with a sealing member, in which the sealing member is formed by partially heating the vicinity of the through-hole of the package main body portion so as to melt the vicinity of the through-hole is melted.
According to the present invention, since the third conductor pad is positioned outside of the hollow portion of the package main body portion and is connected via a thermally conductive material with the first conductor pad that is formed on the wiring substrate that is positioned in the hollow portion of the package main body portion, after evacuating and sealing the hollow portion of the package main body portion, if for example a laser beam or the like is emitted onto the third conductor pad, the first conductor pad and a getter material on the first conductor pad are heated via the thermally conductive material. Thereby, it is possible to cause gas molecules in the hollow portion of the package main body portion to adsorb to the getter material. That is, in the present invention, after evacuating and sealing the hollow portion of the package main body portion, it is possible to heat the getter material on the first conductor pad in the hollow portion of the package main body portion via the thermally conductive material. Accordingly, in a package employing a system in which sealing of the package main body portion is performed in a state of the interior being evacuated in advance, it is possible to maintain the vacuum state after sealing of the package main body portion, and possible to significantly improve the productivity of the package with a simple system.
Also, in the present invention, since the sealing member that seals the through-hole with the inside and outside of the hollow portion of the package main body portion is constituted by partially heating the vicinity of the through-hole, and the constituent material of the package main body portion being melted, for example by making the sealing member a material with a lower melting point than the package main body portion, it is possible to perform sealing of the through-hole with a low-power laser device, and as a result it is possible to lower the manufacturing cost.
Also, in an exemplary embodiment of the present invention, the low-melting-point portion that includes a low-melting-point metal material with a lower melting point than the package main body portion is provided in the vicinity of the through-hole, and the sealing member is formed that plugs the through-hole by heating and melting the low-melting-point portion. In a conventional structure, since there is no low-melting-point metal film in the interior of the through-hole, and the main material itself of the package main body portion is exposed, a wetting defect occurs, and so more time is required in the case of plugging the interior of the through-hole. In contrast, in the exemplary embodiment of the present invention, by heating the low-melting-point portion, the low-melting-point portion wetly spreads well in the interior of the through-hole, and so there is the advantage of being able to reliably plug the through-hole. That is, in a package employing a system in which sealing of the package main body portion is performed in a state of the interior being evacuated in advance, it is possible to perform sealing of the package main body portion, and possible to significantly improve the productivity of the package with a simple system.
Hereinbelow, a vacuum sealed package in a first exemplary embodiment of the present invention shall be described with reference to
First, in these figures,
In these figures, a vacuum sealed package P includes a package main body portion 4 in which a first main body portion 1 with a wiring substrate 10 (described below) integrated on the upper surface thereof and a second main body portion 2 that serves as a lid member are joined with a hollow portion 3 interposed therebetween, and a getter material G and an electronic device E that are provided in the hollow portion 3 within this package main body portion 4.
A through-hole 5 that brings the hollow portion 3 and the outside of the package main body 4 into communication is formed in the package main body portion 4, and the inside of the hollow portion 3 is evacuated by a vacuum exhaust tube 6 (
The wiring substrate 10 is positioned in the hollow portion 3 of the package main body portion 4 and provided on the upper surface of the first main body portion 1. The getter material G that serves as an adsorbent material for gas molecules (H2O, O2, N2, and the like) and the electronic device E are provided on the wiring substrate 10.
The getter material G and the electronic device E are respectively connected to a first conductor pad 11 and a second conductor pad 12 that are formed on the wiring substrate 10. The first conductor pad 11 is connected via a thermally conductive material 13 to a third conductor pad 14 that is positioned on the outside of the hollow portion 3 and formed on the wiring substrate 10. The second conductor pad 12 is electrically connected via a wire 16 to a fourth conductor pad 15 that is positioned on the outside of the hollow portion 3 of the package main body portion 4 and formed on the wiring substrate 10.
The getter material G is positioned on the same surface as the main surface of the wiring substrate 10 (the surface on which the electronic device E is mounted), and is mounted or is directly formed on the first conductor pad 11 that is formed in the hollow portion 3. The getter material G is provided in order to prevent a minute amount of gas molecules (H2O, N2, O2, Ar and the like) that had adsorbed on the inner surfaces of the vacuum sealed package main body portion 4 (the inner surfaces of the first main body portion 1 or the second main body portion 2), after manufacture of the vacuum sealed package P, being released into the package hollow portion 3 and the degree of the vacuum being reduced. Prior to performing vacuum sealing, the inside of the package main body portion 4 is sufficiently evacuated, and the gas molecules that are adsorbed onto the inner surfaces of the package main body portion 4 are as much as possible removed by baking. However, even still there is a possibility of gas molecules that could not be fully removed being emitted within the hollow portion 3 over a long period, but the getter material G adsorbs them, and thereby prevents a reduction in the level of vacuum in the package main body 4.
There are no particular restrictions on the getter material G, and for example it is possible to use zirconium, titanium, vanadium, iron or an alloy that includes these.
Moreover, the first conductor pad 11 that the getter material G is mounted on is provided on the principal surface of the wiring substrate 10 and the same surface as the surface on which the electronic device E and the getter material G are mounted. The first conductor pad 11 is connected with the third conductor pad 14 that is formed on the outside of the package hollow portion 3 via a thermally conductive material 13.
As the thermally conductive material 13, it is preferable to use a metallic material that has Cu, Al, Au, Ag, Pd, or Pt, for example, as a major component. It is preferable that the perimeter of this thermally conductive material 13 be surrounded with an insulating material such as glass ceramics, alumina, and glass. Generally a metallic material that has Cu, Al, Au, Ag, Pd, Pt, or the like as a major component has high thermal conductivity, while an insulating material such as glass ceramics, alumina, and glass generally has low thermal conductivity. For this reason, in the case of heating the third conductor pad 14 that is positioned on the outside of the package main body portion 4, heat can be efficiently transmitted to the getter material G on the first conductor pad 11 via the thermal conductive material 13, and so it is possible to indirectly heat the getter material G.
Also, by using the circuit substrate 10 that uses glass ceramics, alumina, and glass as the insulating material in this way, it is possible to realize a package that is highly reliable over a long period. The reason for this is that the coefficient of linear expansion of the aforementioned insulating material is small (approximately 3 to 4 ppm), and so the difference of the coefficient of linear expansion between the wiring substrate 10 and the electronic device E (in which a circuit is generally formed with Si serving as a base substrate) is small.
When using the aforementioned insulating material, compared to the case of using a resin material, outgassing that occurs from the insulating material is less, and so there is the advantage of being able to prevent a worsening of the vacuum after manufacturing the vacuum sealed package.
As the method of heating the third conductor pad 14, it is possible to use a method that directly emits a laser beam 21 from a laser light source 20 onto the third conductor pad 14 (
Since the metallic material having Cu, Al, Au, Ag, Pd, or Pt as its main component that is used as the thermally conductive material 13, and the insulating material such as glass ceramics, alumina, and glass have high upper temperature limits, even if exposed at the temperature and time required for activating the getter material G (approximately 400° C. to 900° C. and approximately 10 seconds to 10 minutes), no deformation or alternation occurs.
The electronic device E generally has a rectangular plate shape, and is provided on the principal surface of the first main body portion 1, which is inside the hollow portion 3 of the package main body portion 4. The electronic device E is fixed to the principal surface of the first main body portion 1 via a bonding material such as an epoxy resin-based adhesive film and metallic solder material (omitted in the drawing).
When fixing the electronic device E and the wiring substrate 10 via an adhesive or bonding material, a metal material 17 such as for example Cu, Ni, Au, Al, Pd or the like is formed on the surface of the wiring substrate 10. This is in order to raise the adhesive strength between the insulating material used for the wiring substrate 10 and the adhesive or bonding material. Depending on what kind of material is used for the insulating material that is used for the wiring substrate 10, since the adhesive strength with the adhesive or bonding material differs, there are cases in which it is acceptable to not form the metal material 17 depending on the selection conditions of the materials.
Also, the electronic device E is electrically connected with the second conductor pad 12 that is formed on the principal surface of the wiring substrate 10 that is positioned in the hollow portion 3 and on the same surface as the surface on which the electronic device E is mounted. For example, in the example shown in
It is also possible to use a TAB tape connection method, or a method that connects with metal bumps such as solder bumps or Au bumps, using a flip-chip mounting that mounts the circuit formation surface E1 of the electronic device E so as to face the wiring substrate 10.
The second conductor pad 12 is electrically connected with the fourth conductor pad 15 that is formed on the wiring substrate 10 and positioned outside of the hollow portion 3. Using this fourth conductor pad, the connection of the vacuum sealed package and a motherboard substrate, or a module substrate is performed. This electronic device E is not particularly restricted, and it is possible to use for example a memory element (memory) such as DRAM or flash memory, various types of arithmetic processing devices (processor), a power supply element, a sensor element (infrared ray sensor, gyro sensor (angular velocity sensor), temperature sensor, pressure sensor, acceleration sensor, and oil pressure sensor), or the like.
The material of the first main body portion 1 and the second main body portion 2 that constitute the vacuum sealed package main body portion 4 is not particularly limited, but it is preferable that it be a material that hinders the discharge of gas after being vacuum sealed. Specifically, it is preferable that the first main body portion 1 and the second main body portion 2 be a semiconductor material such as Si or Ge, a metal such as Ni, Fe, Co, Cr, Ti, Au, Ag, Cu, Al, Pd, Pt or the like, an alloy material that has these as a primary component thereof, or a glass or ceramics material such as SiO2 or Al2O3 or the like. It is preferable to avoid use of a resin material for the material of the main body portions 1 and 2. This is because a resin material easily absorbs moisture, and the water molecules can easily be discharged into the package main body portion 4 after being vacuum sealed.
Also, it is preferable that the package main body portion 4, in particular the second main body portion 2 be manufactured from an alloy material (such as kovar and alloy 42 or the like) that contains at least Ni. Since an alloy material such as kovar and alloy 42 that contains at least Ni has a low coefficient of linear expansion (approximately 3 to 4 ppm), it is possible to realize a package with a high level of long-term reliability. Moreover, since an alloy material such as kovar and alloy 42 is a magnetic body, it has a magnetic shielding effect. As a result, no electromagnetic interference from another electronic device mounted outside the structure that encapsulates the electronic device E is received, and so there is the advantage that stable operation can be realized. Conversely, in the case of the electronic device E that is encapsulated in the structure emitting a strong electromagnetic wave, there is also the advantage of being able to prevent electromagnetic interference to other electronic devices that are mounted outside of the package main body portion 4. Moreover, since these materials are metallic materials and are electric conductors, in the case where a metallic layer (metallic film) of a different type than those materials, needs to be formed on the surface, there is the advantage of being able to use an electro (electrolytic) plating method that can form a thick metallic layer in a shorter period of time and at a lower cost compared to those of the sputtering method and vapor deposition method.
The first main body portion 1 and the second main body portion 2 may be bonded via a solder material such as Sn, Pb, SnPb, SnAg, SnCu, SnAgCu, SnIn, SnZn, SnBi, SnZnBi, Bi, In, InAg or the like. In this case, it is preferable to form in advance, on the surface of the portion where the first main body portion 1 and the second main body portion 2 are bonded with each other, by means of a sputtering method, a vapor deposition method, or a plating method Ni, NiP, Au, Cu, Ag, Fe, Co, Pd, Ti, Cr, Pt, which prevents solder diffusion or promotes solder wettability, or an alloy with any of these materials serving as a primary component thereof. The aforementioned solder material is supplied between these metallic films, and it is heated and melted using a reflow furnace, a hot plate, or the like, to thereby connect the first main body portion 1 and the second main body portion 2.
There are also several other methods of connecting the first main body portion 1 and the second main body portion 2 that do not use the aforementioned solder material. For example, in the case of the combination of materials constituting the first main body portion 1 and the second main body portion 2 being Si—Si, SiO2—SiO2, Si-glass, glass-glass or the like, they may be directly bonded by anodic bonding or the like. Also, in the case of Si—Si, glass-glass, metal-metal or the like, surface activated bonding may also be employed. Also, in the case of a metal-metal combination, in addition to surface activated bonding, bonding may be conducted by means of a thermal compression bonding method or a welding method. Also, by forming an Au film on the surfaces of the first main body portion 1 and the second main body portion 2, the first main body portion 1 and the second main body portion 2 may be bonded in a process of an Au-Au thermal compression bonding, an ultrasonic bonding, a surface activated bonding, or the like.
The through-hole 5 for evacuation is formed in the second main body portion 2 as described above.
This vacuum exhaust tube 6 evacuates the inside of the package main body portion 4 by being connected with a vacuum pump 24 (described below) via a pipe 23, in the state of being connected to the through-hole 5 of the second main body portion 2.
It is preferable that the vacuum exhaust tube 6 be made of a metallic material that has Cu, Al or the like as a main component, and be joined in an air-tight manner by welding with the second main body portion 2.
After evacuation, the vacuum exhaust tube 6 is left connected with the vacuum pump 24, and by metal press sealing a portion of the vacuum exhaust tube 6 by a crimping method or the like, a seal member 7 is formed, whereby the vacuum seal package P is manufactured.
Note that the reference symbol 50 in the aforementioned first exemplary embodiment denotes a conductor pattern, but this shall be described in third exemplary embodiment below.
Next, the manufacturing method of the vacuum sealed package in the present exemplary embodiment constituted in this way shall be described.
First, as shown in
Next, the getter material G that for example has zirconium, vanadium, iron, or an alloy thereof as a main component is mounted on the first conductor pad 11 on the wiring substrate 10 using a conductive material such as an electroconductive adhesive or the like (omitted in
In
Next, as shown in
Next, as shown in
In the case of using an infrared ray sensor (infrared ray receiving element) for the electronic device E, since a high vacuum of approximately 10−6 Ton to 10−7 Torr (104 Pa to 10−5 Pa) or less is generally required or preferred as the level of vacuum directly after vacuum sealing, it is preferable to prepare a vacuum pump by combining a rotary pump and a cryopump, or combining a rotary pump and a turbo-molecular pump.
Also, after the achieved level of vacuum has entered the range of approximately 104 Pa, in order to discharge chiefly water molecules that adhere to the surface of the hollow portion 3 of the package main body portion 4 and perform evacuation, it is preferable to also incorporate a baking step that heats the package main body portion 4 to approximately 100° C. to 200° C. or more. Also, this baking step may also be performed after the getter activation step described below.
Next, as shown in
Moreover, as shown in
Generally it is necessary to heat the getter material G to about 400° C. to 900° C. Accordingly, in the indirect heating method that uses the laser beam 21 as shown in
Next, the vacuum exhaust tube 6 is crimped using a crimping tool 25 as shown in
As described in detail above, according to the vacuum sealed package P in the first exemplary embodiment of the present invention, the third conductor pad 14 is outside of the hollow portion 3 of the package main body portion 4, and is connected via the thermally conductive material 13 with the first conductor pad 11 that is formed on the wiring substrate inside of the hollow portion 3 of the package main body portion 4. After vacuuming and sealing the hollow portion 3 of the package main body portion 4, for example if the laser beam 21 is emitted onto the third conductor pad 14, the first conductor pad 11 will be heated through the thermally conductive material 13, and the getter material G on the first conductor pad 11 will be heated. Thereby, it is possible to cause gas molecules in the hollow portion 3 of the package main body portion 4 to adsorb to the getter material G, and it is possible to prevent a reduction in the level of vacuum in the hollow portion 3.
That is, since it is possible to heat via the thermally conductive material 13 the getter material G on the first conductor pad 11 in the hollow portion 3 of the package main body portion 4 after vacuuming and sealing the hollow portion 3 of the package main body portion 4 in the aforementioned vacuum sealed package P, in a package of a type that performs sealing of the package main body portion 4 in a state of the interior being vacuumed in advance, it is possible to maintain the vacuum state after sealing of the package main body portion 4 and possible to significantly improve the productivity of the package with a simple system that does not use an expensive vacuum apparatus, such as disclosed in Patent Documents 1 to 3 (a vacuum apparatus with a mechanism that moves a machine component provided therein, or a robot handling mechanism or the like provided therein).
Next, a second exemplary embodiment of the present invention shall be described with reference to
In this second exemplary embodiment, the through-hole 5 for evacuation is formed in advance in the second main body portion 2 that serves as the lid member of the package main body portion 4. The method of plugging this through-hole 5 differs from the first exemplary embodiment. The number of through-holes 5 may be one, but it is preferable that a plurality be formed in order to raise the evacuation efficiency. It is preferable to design the optimal number of through-holes 5 from the standpoint of the formation cost of the through-holes 5 and the process cost related to evacuation time.
The through-hole 5 is formed by a method such as anisotropic etching, isotropic etching, dry etching, drilling, sand blasting, ultrasonic machining, and wire-electrical discharge. In the case of the substrate in which the through-hole 5 is formed being Si, it is possible to form the through-hole 5 by anisotropic etching or isotropic etching. That is to say, the through-holes 5 may be formed such that a mask or an alkali-resistant resist that is comprised of SiO2, SiN, SiON or a metallic material is formed at a portion where the through-holes 5 are not formed, and then etching is performed by KOH, TMAH (tetra methyl ammonium hydroxide), hydrazine, EPW (ethylenediamine-pyrocatechol-water), or the like. Furthermore, in the case of the substrate being a metallic material instead of Si, a photoresist may be used as the mask material, and an acid or alkali may be used as the etching liquid. The method of forming the through-holes 5 is also common among the exemplary embodiments described later.
The through-hole 5 is plugged by a sealing member 30 that consists of the material that constitutes the second main body portion 2, or a material with a lower melting point than the material that constitutes the second main body portion 2 that is formed in the vicinity of the through-hole 5 or over the entire surface of the second main body portion 2.
Also, although not shown in
By using for example a laser beam apparatus to conduct local heat application on the perimeter of the through-hole 5 to a temperature equal to or above the melting point of the material, the sealing member 30 is melted and fixed in a state of blocking the through-hole 5, whereby the through-hole 5 is plugged. At this time, the location where the through-hole 5 is plugged becomes the sealing member 30. In the case of the material that constitutes the second main body portion 2 being metal or Si, generally the melting point is approximately 1000° C. or higher, so by forming in advance for example Sn or an Sn-containing alloy material (Sn, SnPb, SnAg, SnAgCu, SnCu, SnIn, SnZn, SnBi, SnZnBi or the like, the melting point of which is approximately 100° C. to 300° C.) on the surface of the second main body portion 2 (in the vicinity of the through-hole 5, or over the entire surface of the second main body portion 2), and performing local heating of this solder material with a laser, this through-hole 5 is sealed with the solder material. This method can further reduce the power of the laser device, and can lower the manufacturing cost. This kind of solder material is formed for example by an electrolytic plating method, a nonelectrolytic plating method, a sputtering method, a vacuum deposition method, or the like. If the second main body portion 2 is an electric conductor such as metal, it is preferable to manufacture with an electrolytic plating method from the aspect of manufacturing cost. Also, since these solder materials have a high energy absorption rate for a laser beam, from the aspect of heat absorption efficiency as well it is possible to cause them to melt using a lower power laser apparatus when performing local heat application using a laser beam, and so it is possible to lower the equipment investment cost for the manufacturing installation. As a result, it is possible to shorten the laser irradiation time, and possible to lower the process cost.
The low-melting-point solder material may be formed on the entire surface of the second main body portion 2 (including the inside of the through-hole 5), and may be formed only at the periphery of the through-hole 5 and the inside of the through-hole 5. From the aspect of manufacturing cost, it is more preferable to form a film-like low-melting-point portion (denoted by reference number 31) consisting of a low-melting-point metal material on the entire surface of the second main body portion 2 since the cost of masking is eliminated and therefore this can be conducted inexpensively. That is to say, by forming the film-like low-melting-point portion 31 over the entire surface of the second main body portion 2 including the through-hole 5, the process using a mask is eliminated compared to a structure having the low-melting-point structure formed partly thereon, and so it is possible to realize an inexpensive vacuum sealed package.
As shown in
Also, as shown in
Moreover, in the case of a structure in which the low-melting-point portion 31 is not formed on the entire surface of the second main body portion 2 or the perimeter of the through-hole 5 including the interior thereof, the size of the through-hole 5 needs to be a small size of approximately 100 μm or less in order to reliably plug the through-hole 5 (when the hole is large, plugging it is difficult). However, taking into consideration the strength of drill teeth, it is difficult to form a through-hole 5 of 100 μm or less by a machining process.
On the other hand, in the case of a structure in which the low-melting-point portion 31 is formed on the entire surface of the second main body portion 2 or the perimeter of the through-hole 5 including the interior thereof, the through-hole 5 is made to have a diameter of approximately 200 μm, which can be easily formed in a machining process, and thereafter if the low-melting-point portion 31 is formed with a thickness of 70 μm on the surface of the second main body portion 2 including the interior of the through-hole 5, it is possible to easily form a hole with a diameter of 60 μm. Further, if the hole diameter is 60 μm, it is possible to easily plug the through-hole 5 by melting the low-melting-point portion 31.
There is no particular restriction as to the dimension of the through-hole 5, but it is preferable for it to be as small as possible. The reason for this is that when the through-hole 5 is large, then the amount of time required for plugging the through-hole 5 will become long, and the power of a laser apparatus for plugging the through-holes 5 will need to be high, consequently making the manufacturing cost high. On the other hand, when the size of the through-hole is too small, the problem arises of vacuuming taking a long time, and so it is preferable to determine the size of the through-holes 5 in terms of the cost of the total process.
As shown in
Hereinbelow, the method for manufacturing the second exemplary embodiment of the present invention shall be described. The initial steps of the manufacturing process are the same as the second exemplary embodiment of the present invention, and so shall be omitted. The description shall commence from the step of performing evacuation.
In the state prior to plugging the through-hole 5 as shown in
Next, as shown in
Subsequently, as shown in
The method of emitting the laser beam 21 to heat only the third conductor pad 14, and the method of heating only the perimeter of the through-hole 5 do not expose the electronic device E to a high temperature, and so do not degrade the characteristics of the electronic device E. Moreover, since the locations where the second main body portion 2 and the wiring substrate 10 are bonded and the locations where the electronic device E and the wiring substrate 10 are bonded are not made to exfoliate by the heat, there are significant advantages in terms of manufacturing.
Also, since it is possible to emit the laser beam 21 on the perimeter of the through-hole 5 (prior to plugging the through-hole 5) of the package installed in the vacuum chamber 40, even if the laser device is not arranged in a vacuum, it is possible to realize a more compact vacuum chamber 40, and it is possible to achieve a more inexpensive vacuum chamber 40. As a result, it is possible to manufacture a vacuum sealed package at a more inexpensive manufacturing cost.
Furthermore, although there is no particular restriction, the diameter of the laser beam 21 is preferably greater than the diameter of the through-hole 5. If the diameter of the laser beam 21 is smaller than the diameter of the through-hole 5, then there will be employed a method in which the laser beam 21 is irradiated so as to serially trace the outer periphery of the through-hole 5 to gradually plug the through-hole 5. Consequently, in this method the time required for plugging the through-hole 5 becomes longer, and so there is a tendency for the manufacturing process cost to increase.
On the other hand, if the diameter of a laser beam 21 is greater than that of the through-hole 5, the center of the spot diameter of the laser beam 21 can be made to align with the center of the through-hole 5. Thereby, it is possible to shorten the time of plugging the through-hole 5 since it is possible to emit the laser beam 21 on the perimeter of the through-hole 5 in one stroke, without the need to emit the laser beam 21 serially on the outer periphery of the through-hole 5.
In the case of emitting the laser beam 21 with the center of the spot diameter of the laser beam 21 aligned with the center of the through-hole 5, since the laser beam 21 passes through the center of the through-hole 5, the position of the through-hole 5 needs to be designed in advance so that the laser beam 21 does not come into contact with the electronic device E, the wire 22, the wiring, and so forth.
A YAG laser is suitable as the laser, however in addition to this another type of laser may be used provided it has the capability of melting the material to be melted, such as a ruby laser, an excimer laser, a carbon dioxide gas laser, a liquid laser, a semiconductor laser, and a free electron laser. The requirements of the laser are the same for all the exemplary embodiments of the present specification.
Furthermore, in the case of the exemplary embodiment of the present invention, as shown in
B is taken as the diameter of the through-hole 5 after formation of the low-melting-point portion 31, C is taken as the thickness of the second main body portion 2 or the wiring substrate 10 in which the through-hole 5 has been formed, and D is taken as the spot diameter of the laser beam 21.
CB
2/(D2−B2)≦A
B<D
The above inequations shall be described in detail below with reference to
A, B, C, and D are respectively the thickness of the low-melting-point portion 31, the diameter of the through-hole 5 after formation of the low-melting-point portion 31, the thickness of the second main body portion 2 or the wiring substrate 10 having the through-hole 5 formed therein, and the spot diameter of the laser beam 21.
Assuming that the portion where the laser beam 21 and the low-melting-point portion 31 make contact with each other is a circle with a diameter D, the following formula (1) denotes a volume 31 (VD-B) of the low-melting-point portion 31 that is irradiated by the laser beam 21, heated to a temperature greater than or equal to the melting point, and is melted to plug the through-hole 5.
V
D-B
=πA(D2−B2)/4 (1)
Moreover, the following formula (2) denotes a volume 32 (VB) of the through-hole 5 that is plugged by the low-melting-point portion 31.
V
B
=πCB
2/4 (2)
Here, in order to completely fill the through-hole 5 with the low-melting-point portion 31, the following formula (3) needs to be satisfied.
VB≦VD-B (3)
For that reason, by substituting formulas (1) and (2) for the values of the formula (3) and rearranging yields the following formula (4).
CB
2/(D2−B2)≦A (4)
Since the spot diameter D of the laser beam 21 needs to be greater than the diameter B of the through-hole 5 in order to heat the low-melting portion 31 on the periphery of the through hole 5, it is necessary to satisfy the condition denoted by the following formula (5).
B<D (5)
That is to say, the thickness A of the low-melting portion 31 is set so that the volume (VD-B) of the low-melting portion 31 to be melted may become greater than the volume (VB) of the through-hole 5, and the spot diameter D of the laser beam 21 is set so as to be greater than the diameter B of the through-hole 5.
As described above, by preliminarily designing the thickness A of the low-melting portion 31, the diameter B of the through-hole 5 after the low-melting portion 31 has been formed, the thickness C of the second main body portion 2 or the wiring substrate 10 having the through-hole 5 formed therein, and the spot diameter D of the laser beam 21 so as to satisfy the formulas (4) and (5), it is possible to reliably plug the through-hole 5 with the low-melting portion 31, and it is possible to realize a package with a high manufacturing yield.
Moreover, the above-mentioned method is a method that can best shorten the emission time of the laser beam 21, and plug the through-hole 5. However, in the case of wanting to manufacture a package using existing equipment, but there being no equipment specification that can satisfy formula (5), such that the spot diameter D of the laser beam 21 is smaller than the diameter B of the through-hole 5 (B>D), it is possible to emit the laser beam 21 so as to draw a circle along the periphery of the entrance opening of the through-hole 5, and plug the though-hole 5. In this method, the shot number of the laser beam 21 increases in order to draw a circle, and so the time for plugging the through-hole 5 becomes longer than the aforementioned method.
Moreover, according to the vacuum sealed package in this exemplary embodiment, since the through-hole 5 is plugged by directly melting the constituent material at the through-hole 5 perimeter by conducting local heat application such as laser beam irradiation, it is possible to eliminate the process of placing on the through-hole 5 a third fixing material for plugging the through-hole 5, and possible to cut the manufacturing cost.
In the first exemplary embodiment of the present invention shown in
For example,
Here, the infrared ray receiving element 44 which is an infrared ray sensor shall be explained in detail. There are two types of infrared ray receiving elements 44, namely, “quantum type” and “thermal type”. Since the “thermal type” has a simpler structure and the manufacturing cost is lower, it is preferable to use a thermal-type infrared ray receiving element 44 from the point of manufacturing cost. Moreover, in order to increase the sensitivity of the thermal-type infrared ray receiving element 44, it is necessary to increase the thermal insulation property in order to enlarge temperature changes in the infrared detecting element by ensuring that the heat generated in the infrared detecting element is retained as much as possible when infrared radiation is emitted on the infrared ray receiving element 44. Consequently, in order for the thermal-type infrared ray receiving element 44 to exhibit the minimum performance, generally a vacuum state of 10-2 Torr or lower is required as a surrounding environment. That is to say, a vacuum environment in which there are almost no gas molecules inside the package main body portion 4 is needed. Also, in order to maintain the stability of the device over a prolonged period of time, it is additionally preferable to further increase the level of vacuum immediately after vacuum sealing. Further, it is preferable that the through-hole 5 be sealed with a high degree of airtightness after evacuating the inside of the package main body portion 4 preferably to 10-6 Torr or less. Even if referred to as vacuum sealing, it is nevertheless highly unlikely for the level of vacuum of the inside not do drop after sealing, and so it always has a leak rate that is a finite value. The higher the level of vacuum just after vacuum sealing, the longer the time required for the level of vacuum to deteriorate to 10-2 Ton at which minimum performance can be still exhibited even at the same leak rate, and so ultimately it is possible to realize a package in which an infrared ray receiving element 44 having a high level of long-term reliability is mounted.
In the vacuum sealed package in the present exemplary embodiment that includes the infrared ray receiving element 44, a rectangular opening 2A is provided at a portion positioned directly above (a portion opposed to) the light receiving portion of the infrared ray receiving element 44 of the second main body portion 2, and an infrared ray transmissive window 45 that is comprised of an infrared ray transmissive window material (a material that allows infrared radiation to pass) is bonded so as to block that infrared ray transmissive hole 35.
Although the infrared ray receiving element 44 is mounted in the package body portion 4 that has been vacuum sealed, since infrared rays need to be transmitted from the outside of the package into the package main body portion 4, as the material of the infrared ray transmissive window 45, in addition to Si, Ge, ZnS, ZnSe, Al2O3, SiO2 or the like, materials including an alkali halide-based material or alkali earth halide-based material such as LiF, NaCl, KBr, CsI, CaF2, BaF2, MgF2 or the like, and a chalcogenide-based glass that has Ge, As, Se, Te, Sb or the like as the main component thereof, are preferable in order to be able to transmit infrared rays.
According to this constitution, the infrared ray receiving element 44 is sealed within a vacuum, and the infrared ray transmissive window 45 is mounted at a position directly above the light receiving portion of the infrared ray receiving element 44. Therefore, the infrared radiation passes from the outside of the sealed package through the infrared ray transmissive window 45, and it reaches the light receiving portion of the infrared ray receiving element 44. For that reason, it is possible to realize an infrared ray sensor package with a high level of sensitivity. Also, although not illustrated in the present exemplary embodiment, an antireflection film is formed in advance on the surface of the infrared ray transmissive window 45. Furthermore, while Torr is used as the unit of pressure in the present specification, it is possible to convert it to an SI unit at 1 Ton=133.3 Pa.
According to the vacuum sealed package P in the second exemplary embodiment of the present invention as described in detail above, after evacuating and sealing the inside of the hollow portion 3 of the package main body portion 4, by heating the getter material G via the thermally conductive material 13 that couples the first and third conductor pads 14 that are respectively inside and outside of the hollow portion 3 of the package body portion 4, it is possible to maintain the vacuum state inside the hollow portion 3 of the package body portion 4. Therefore, in a package of a type that performs sealing of the package main body portion 4 in the state of the interior being vacuumed in advance, it is possible to maintain the vacuum state after sealing of the package main body portion 4 with a simple system that does not use an expensive vacuum apparatus such as disclosed in Patent Documents 1 to 3 (one with a movable machine component provided therein, or a robot handling mechanism or the like provided therein), and so it is possible to significantly improve the productivity of the package.
In the vacuum sealed package P in the second exemplary embodiment, the sealing member 30 that seals the through-hole 5 to the inside of the hollow portion 3 of the package body portion 4 and the outside is constituted by partially heating the vicinity of the through-hole 5 such that a constituent material of the package main body portion 4 is melted. Therefore, by for example making the sealing member 30 a low-melting point material with melting point lower than the package main body portion 4, it is possible to perform sealing of the through-hole 5 with a low-power laser device, and as a result it is possible to lower the manufacturing cost.
In the present exemplary embodiment, the low-melting-point portion 31, which is comprised of a low-melting point metal material having a lower melting point than the package main body portion 4, is provided in the vicinity of the through-hole 5, and the low-melting-point portion 31 is heated and melted, thereby forming a portion or all of the sealing member 30 that plugs the through-hole 5.
In a conventional structure in which the main material itself of the package main body portion 4 is exposed without a film of a low-melting-point metal on the interior of the through-hole 5, time is required for plugging the interior of the through-hole 5 due to the occurrence of a wetting defect. In contrast, in the present exemplary embodiment, by heating the low-melting-point portion 31, the low-melting-point portion 31 has good wet-spreading also in the interior of the through-hole 5, and so there is the advantage of being able to reliably plug the through-hole 5. That is to say, in a package of a type that performs sealing of the package main body portion 4 in the state of the interior being evacuated in advance, it is possible to perform sealing of the package main body portion 4 with a simple system, and possible to significantly improve the productivity thereof.
Next, a third exemplary embodiment shall be described with reference to
A width 51 of a conductor pattern 50 that surrounds the periphery of an electronic device E that is formed on the wiring substrate 10, which is a characteristic of the third exemplary embodiment of the present invention, shall be described.
In the case of using the wiring substrate 10 in the first main body portion 1 of the package as with the first exemplary embodiment and the second exemplary embodiment of the present invention, a continuous conductor pattern 50 is formed that surrounds the periphery of the electronic device E on the surface of the wiring substrate 10. As shown in
By using this kind of structure, the continuous conductor pattern 50 that is formed on the surface of the wiring substrate 10 so as to surround the periphery of the electronic device E and the second main body portion 2 are bonded, with the width 51 of the conductor pattern 50 wider than the bonding width 52 of the second main body portion 2. Accordingly, it is possible to sufficiently cover the periphery of the second main body portion 2 via a bonding portion 53 that is formed by a bonding material that bonds the second main body portion 2 and the wiring substrate 10 (for example, a low-melting-point metal film), and it is possible to realize a package with a higher level or reliability.
Although not shown in
In the vacuum sealed package P, after sealing the package main body portion 4, it is necessary to avoid the occurrence of outgassing, which can invite a drop in the long-term reliability of the electronic device E and cause degradation of the performance due to a drop in the vacuum. For that reason, the bonding of the second main body portion 2 and the circuit substrate 13 is preferably performed by a process that does not employ flux. In a process that does not use flux, oxidation of the bonding portion section impedes airtight bonding. Therefore, in order to prevent such oxidization, it is preferable that Au be formed in advance on at least any one surface of the surface of the conductor pattern 50 and the surfaces of the conductor pads 11, 12, 14, and 15.
According to this constitution, it is possible to prevent oxidation of the surface of the conductor pattern 50 and the conductor pads 11, 12, 14 and 15, and it is possible to achieve a superior solder wettability. Also, there is the advantage of being able to perform wire bonding using a wire that has a metal such as Au or Al as the main component, and it is possible to achieve a package with a high manufacturing yield and a high design flexibility.
Next, a fourth exemplary embodiment of the present invention shall be described with reference to
The through-hole 5 in the fourth exemplary embodiment is formed with a tapered shape so that the hole diameter gradually becomes smaller from the outermost surface of one surface of the second main body portion 2 or the wiring substrate 10 to the surface on the opposite side.
When the diameter of the through-hole 5 is formed with a tapered shape such that the hole diameter gradually becomes smaller from the outermost surface of one surface of the second main body portion 2 or the wiring substrate 10 to the surface on the opposite side, it is possible to directly emit the laser beam 21 not only on the outermost surface of one surface of the second main body portion 2 or the wiring substrate 10 (the place where the hole diameter is greatest), but also on the surface of the interior of the through-hole 5. For that reason, since the material on the interior of the through-hole 5 is also heated and can be melted. As a result, it is possible to more easily plug the through-hole 5, and it is possible to achieve a package with a high manufacturing yield.
One of the methods of forming the through-hole 5 having such a tapered shape is an etching method. In particular, when anisotropic etching is used, it is possible to obtain the through-hole 5 having various types of tapered shapes. The shape of the through-hole 5 may be appropriately changed.
For example, as shown in
As shown in
In
Next, a fifth exemplary embodiment of the present invention shall be described with reference to
As shown in
The through-hole 5 for evacuation, which brings the hollow portion 3 and the outside of the package main body portion 4 into communication, is formed in the package main body portion 4, and the inside of the hollow portion 3 is vacuumed via the through-hole 5, and the sealing member 30 that is plugged by the low-melting-point portion 31 with the vacuum state maintained is provided in the through-hole 5 (a figure showing the sealed state is omitted).
It is preferable that the first main body portion 1 be a wiring substrate, for example. The getter material G and the electronic device E (including the infrared ray receiving element 44) are within the hollow portion 3 and respectively connected to the first conductor pad 11 and the second conductor pad 12 that are formed on the wiring substrate 10. The second conductor pad 12 is electrically connected with the fourth conductor pad 15 that is positioned on the outside of the hollow portion 3 of the package main body portion 4 and formed on the wiring substrate 10.
The getter material G is mounted on a position where contact is possible with the laser beam 21 that is emitted from outside of the package main body portion 4, passes through the infrared ray transmissive window 45, and reaches the inside of the hollow portion 3.
As shown in
In this way, while performing vacuum evacuation, after the getter material G is heated and activated, the laser beam 21 is emitted from the outside of the vacuum chamber 40 through the infrared ray transmissive window 45 onto the low-melting-point portion 31 that is formed on the surface around the through-hole 5 as shown in
Next, a sixth exemplary embodiment of the present invention shall be described with reference to
The sixth exemplary embodiment differs from the fifth exemplary embodiment on the point of the getter material G being mounted or formed within the hollow portion 3 of the package main body portion 4 and on the inner surface of the infrared ray transmissive window 45. There are no particular limitations on the mounting method or formation method of the getter material G. However, it is preferable for it to be welded to the surface of the infrared ray transmissive window 45 that is comprised for example of Ge or Si and the like, or be film-formed on the surface of the infrared ray transmissive window 45 using a thin-film formation technique such as a sputtering method or a vapor deposition method.
In this sixth exemplary embodiment, as shown in
In this way, while performing vacuum evacuation, after the getter material G is heated and activated, the laser beam 21 is emitted from the outside of the vacuum chamber 40 through the infrared ray transmissive window 45 onto the low-melting-point portion 31 that has been formed on the surface of the second main body portion 2 around the through-hole 5 as shown in
Also,
In the modification of the sixth exemplary embodiment, as shown in
In another modification of the sixth exemplary embodiment, as shown in
When continuing to emit the laser beam 21 onto the getter material G in the present process, a portion of the energy of the laser beam 21 is absorbed by the infrared ray transmissive window 45. As a result, a portion of the infrared ray transmissive window 45 that comes into contact with the laser beam 21 is heated, and the heat, as shown by the arrow A (
Since the emission position of the laser beam 21 need not be changed, it is possible to shorten the series of process times of heating and activating the getter material G and plugging the through-hole 5.
Next, a seventh exemplary embodiment of the present invention shall be described with reference to
In the seventh exemplary embodiment, the getter material G is mounted or formed within the hollow portion 3 of the package main body portion 4 and on the inner surface of the second main body portion 2. More specifically, as shown in
As shown in
Although there are no particular limitations on the mounting method or formation method of the getter material G, it is preferable to weld it to the surface of the second main body portion 2 having for example kovar and alloy 42 or the like as the main material, or film-form it on the surface of the second main body portion 2 using a film-formation technique such as a sputtering method or a vacuum deposition method.
As shown in
While performing this vacuum evacuation, after the getter material G is heated and activated, the laser beam 21 is emitted from outside of the vacuum chamber 40 through the infrared ray transmissive window 45 onto the lid surface of the periphery of the through-hole 5 as shown in
As shown in
Thereafter, although not depicted in the figure, while performing vacuum evacuation in this manner the getter material G is heated and activated. Subsequently, the laser beam 21 is emitted from outside of the vacuum chamber 40 through the infrared ray transmissive window 45 onto the lid surface of the periphery of the through-hole 5 similarly to the seventh exemplary embodiment as shown in
In the modification of the seventh exemplary embodiment of the present invention shown in
By adopting the structure shown in
In the modification of the seventh exemplary embodiment shown in
Next, an eighth exemplary embodiment of the present invention shall be described with reference to
In the vacuum sealed package P in the present eighth exemplary embodiment, the second main body portion 2 that is a lid member that encompasses the infrared ray receiving element 44 is constituted by joining a frame member 60 (shown in
Here, the ring-shaped frame member 60 and plate member 61 are joined by the low-melting-point portion 31 having a lower melting point than the material that constitutes the respective structures that is formed in advance on their respective surfaces.
In general, it is not easy to manufacture a second main body portion 2 that has a hollow portion capable of containing the infrared ray receiving element 44. While there is for example a means that forms a hollow portion 3 that can contain the infrared ray receiving element 44 by etching, it is difficult to form the shape of a space with dimensional accuracy. In contrast, according to the vacuum sealed package P of the present exemplary embodiment, the frame member 60, which has the opening 60A formed in the center thereof and has the size and thickness capable of containing the infrared ray receiving element 44 inside of the opening 60A, is bonded with the plate member 61 to thereby manufacture the second main body portion 2. Therefore, it is possible to easily manufacture the second main body portion 2 at a low cost.
In the case of this low-melting-point portion 31 being absent on the surface in the first place, for example a fixing material such as solder or the like is subsequently formed on the surface of the ring-shaped frame member 60 and the plate-shaped member 61, and they are fused together. Alternatively, if they are the same material, they are both bonded by a bonding means such as surface activated bonding, thermal compression bonding, ultrasonic bonding, anode bonding, and the like.
In the aforementioned exemplary embodiment, the example was described of the infrared ray receiving element 44 being vacuum sealed, but in the case of using an electronic device E other than the infrared ray receiving element 44, the infrared ray transmissive window 45 shown in
Next, a ninth exemplary embodiment of the present invention shall be described with reference to
The aforedescribed first exemplary embodiment to eighth exemplary embodiment showed examples of the electronic device E (including the infrared ray receiving element 44) being mounted in the first package main body portion 4 or on the wiring substrate 10 via a bonding material. In the vacuum sealed package P in the ninth exemplary embodiment of the present invention shown in
In the case of the present exemplary embodiment, since the integrated circuit of the electronic device E (including the infrared ray receiving element 44) that is formed on the first package main body portion 4 has a thin thickness (several 10 μm), there is the advantage in that the vacuum sealed package P can be made thin, and since there is no need to use a bonding material, there is the advantage in that gas release inside the package is unlikely after it has been vacuum sealed.
Next, a tenth exemplary embodiment of the present invention shall be described.
In the exemplary embodiments 1 to 9 of the present invention described hitherto, the fourth conductor pad 15 that serves as the external terminal of the package main body portion 4 is formed on the same surface side as the surface on which the electronic device E (including the infrared ray receiving element 44) is mounted or formed, in the main body portion 1 that includes the wiring substrate 10 of the package main body portion 4. In the tenth exemplary embodiment, the fourth conductor pad 15 (the pad serving as the external terminal of the package main body portion 4) is formed on the reverse-opposite side of the surface on which the electronic device E (the infrared ray receiving element 44 in
According to this constitution, since there is no need to provide the fourth conductor pad 15 further to the outside than the second main body portion 2 that serves as the lid member of the package main body portion 4, it can be made smaller than the first to ninth exemplary embodiments of the present invention. Also, in the present exemplary embodiment shown in
Next, an eleventh exemplary embodiment of the present invention shall be described.
The eleventh exemplary embodiment is similar to the tenth exemplary embodiment, with the fourth conductor pad 15 being formed on the reverse-opposite side of the surface on which the electronic device E (including the infrared ray receiving element 44) is mounted or formed. It differs slightly from the tenth exemplary embodiment by the second conductor pad 12 being electrically connected with the fourth conductor pad 15 via a pin-shaped conductor 65. The pin-shaped conductor 65 penetrates the first main body portion 1 of the package main body portion 4, and extends from the inside of the hollow portion 3 to the outside of the package main body portion 4. The first main body portion 1 of the package main body portion 4 and the pin-shaped conductor 65 are bonded in close contact by welding or the like.
According to this constitution, since there is no need to provide the fourth conductor pad 15 further to the outside than the second main body portion 2 similarly to the tenth exemplary embodiment of the present invention, it can be made smaller than the first to ninth exemplary embodiments of the present invention.
Next, a twelfth exemplary embodiment of the present invention shall be described.
In the twelfth exemplary embodiment, only the method of plugging the through-hole 5 differs from the other exemplary embodiments. That is, the package main body portion 4 is placed in a vacuum chamber, and a spherical low-melting-point metal material 70 such as a solder alloy ball that includes for example Sn is placed on the through-hole 5, and vacuum evacuation is performed from the clearance between the spherical low-melting-point metal material 70 and the through-hole 5. Subsequently, after activating the getter 6 by the same method as the first exemplary embodiment or the second exemplary embodiment, the laser beam 21 is emitted on the spherical low-melting-point metal material 70 on top of the through-hole 5 by the same method, and the through-hole 5 is plugged by melting the spherical low-melting-point metal material 70.
Next, a thirteenth exemplary embodiment of the present invention shall be described.
The present exemplary embodiment is one that is constituted as a printed circuit board 80 with the vacuum sealed package P mounted thereon. That is to say, the printed circuit board 80 includes a vacuum sealed package P that uses an electronic device E (including the infrared ray receiving element 44).
As the vacuum sealed package P, it is possible to apply any of the vacuum sealed packages P in the exemplary embodiments described above. Also, as shown in
Note that it is possible to assemble an electronic device using the vacuum sealed package P in the above-described twelfth exemplary embodiment, or the printed circuit board 80 in the above-described thirteenth exemplary embodiment. That is to say, it is possible to constitute an electronic device including the above-described vacuum sealed package P or the printed circuit board 80, and according this electronic device, manufacturing cost can be lowered compared to that of the conventional practice. Examples of electronic devices to which this may be applied include, for example, an infrared camera in which is mounted the vacuum sealed package P of the infrared ray receiving element (infrared ray sensor) 44 or a module substrate (printed circuit board) having the vacuum sealed package P, or a thermography that enables the temperature distribution of an object to be visualized. Moreover, even when the electronic device E is a device other than the infrared ray receiving element (infrared ray sensor) 44, for example, it is still suitable for vehicle onboard electronic devices in which malfunctioning is not permitted even in high temperature or high humidity environments (car navigation, car audio, electronic toll collection (ETC) device, and the like), and for electronic devices for use in the water in which water ingress is not tolerated (underwater camera, underwater sonar device, and the like) are suitable. Hereinabove, a plurality of exemplary embodiments have been described, but the present invention should not be considered as being limited to the above-described exemplary embodiments provided it does not exceed the scope thereof.
As a fourteenth exemplary embodiment of the present invention, a vacuum sealed package P that uses the infrared ray receiving element (infrared ray sensor) 44 shall be described with reference to
First, an Si substrate measuring 10 mm×13 mm and having a thickness of 0.2 mm was prepared as the infrared ray transmissive window 45 (
Next, there were prepared a plate member 61 having an outer diameter of 15 mm×15 mm, an inner diameter of 8 mm×11 mm (the diameter of the opening of the opening portion 2A), and a thickness of 0.2 mm as shown in
The materials shown in
A wiring substrate with an outer diameter of 18 mm×18 mm and a thickness of 0.5 mm, the insulative base material of which consisting of glass ceramics, was used as the first main body portion 1 shown in
Next, the electronic device E (infrared ray receiving element 44 in the present exemplary embodiment) was adhesively fixed to the first main body portion 21 that includes the wiring substrate 10 by a bonding material, and then, the infrared ray receiving element 44 and the second conductor pad 12 on the wiring substrate 10 were bonded with the wire 22 that has Al as its material.
Subsequently, the conductor pattern 50 on the wiring substrate 10, the ring-shaped frame member 60, the plate member 61, and the infrared ray transmissive window 45 were position-aligned and laminated, and they were then collectively bonded using a nitrogen reflow furnace, whereby the package main body portion 4 shown in
Next, the package main body portion 4 prior to vacuum sealing shown in
Thereafter, the laser beam 21 was emitted from the laser apparatus 20 installed outside of the vacuum chamber 40, passing through the infrared ray transmissive window 45 on the package main body portion 4 onto the getter material G (placed inside the package main body portion 4 and on the surface of the infrared ray transmissive window 45), and the getter material G was heated to approximately 800° C. and activated for several 10 s of seconds. The laser beam 21 was emitted from above the getter material G.
Thereafter, the laser beam 21 emission portion of the laser apparatus 20 was moved to be positioned approximately directly over the through-hole 5 provided in the package main body portion 4, and the laser beam 21 was emitted from the laser apparatus 20 through the glass transmissive window 43 onto the periphery of the through-hole 5 of the package, and the SnAg film that serves as the low-melting-point portion 31 formed at the periphery of the through-hole 5 was melted to plug the through-hole 5, whereby the vacuum sealed package was manufactured.
Here, the spot diameter of the laser beam 21 was 0.4 mm. The dimensions A, B, C, and D are preferably CB2/(D2−B2)≦A and B<D, in the case where the thickness of the SnAg film is A (0.05 mm), the diameter of the through-hole 5 after the SnAg film has been formed is B (maximum value of 0.1 mm), the thickness of the structure having the through-hole 5 formed therein is C (0.2 mm), and the spot diameter of the laser beam 21 is D (0.4 mm). By putting the dimensions of A, B, C, and D in the range defined by the aforementioned formulas, it was possible to reliably plug the through-hole 5 with the SnAg material.
When the present vacuum sealed package P was mounted in an infrared camera, acquisition of the required image was confirmed. Moreover, after manufacturing this vacuum sealed package P, it could be confirmed that the required image was obtained in the same manner after one year.
In the fourteenth exemplary embodiment of the present invention as described in detail above, since it is possible to heat the getter material G on the first conductor pad 11 in the hollow portion 3 of the package main body portion 4 via the thermally conductive material 13 after evacuating the interior of the hollow portion 3 of the package main body portion 4 and sealing it, in a package of a type that performs sealing of the package main body portion 4 in a state of the interior being evacuated in advance, it is possible to maintain the vacuum state after sealing of the package main body portion 4 and possible to significantly improve the productivity of the package with a simple system that does not use a costly vacuum apparatus such as disclosed in Patent Documents 1 to 3 (one with a movable machine component provided therein, or a robot handling mechanism or the like provided therein).
In the exemplary embodiment of the present invention, the low-melting-point portion 31, which is comprised of a low-melting point metal material having a lower melting point than the package main body portion 4, is provided in the vicinity of the through-hole 5, and the low-melting-point portion 31 is heated and melted, thereby forming a portion or all of the sealing member 30 that plugs the through-hole 5. Thereby, in a conventional structure in which the main material itself of the package main body portion 4 is exposed without a low-melting-point metal film on the interior of the through-hole 5, time is required for plugging the interior of the through-hole 5 due to the occurrence of a wetting defect. In contrast, in the present exemplary embodiment, by heating the low-melting-point portion 31, the low-melting-point portion 31 has good wet-spreading also in the interior of the through-hole 5, and so there is the advantage of being able to reliably plug the through-hole 5. That is, in a package of a type that performs sealing of the package main body portion 4 in the state of the interior being evacuated in advance, it is possible to perform sealing of the package main body portion 4 with a simple system, and possible to significantly improve the productivity thereof.
Hereinabove, the exemplary embodiments of the present invention were described in detail with reference to the drawings, but specific constitutions are not restricted to these exemplary embodiments, and various design modifications are included without departing from the scope of the present invention.
Priority is claimed on Japanese Patent Application No. 2009-36511, filed Feb. 19, 2009, the content of which is incorporated herein by reference.
The present invention can be applied to a vacuum sealed package of an electronic device such as an infrared light detector (infrared ray sensor), gyro sensor (angular velocity sensor), temperature sensor, pressure sensor, and acceleration sensor that are used in thermography, car navigation, car audio, ETC devices, underwater cameras, underwater sonar devices, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-036511 | Feb 2009 | JP | national |
This present application is a Divisional application of Ser. 13/148,524 filed on Aug. 9, 2011, which is a National Stage Entry of international application PCT/JP2010/000451, filed on Jan. 27, 2010, which claims the benefit of priority from Japanese Patent Application 2009-036511, filed on Feb. 19, 2009, the disclosures of all of which are incorporated in their entirety by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13148524 | Aug 2011 | US |
| Child | 14033672 | US |
