Patent Application
20160209285
This application claims benefit of Japanese Applications JP 2015-008246, filed on Jan. 20, 2015 and JP 2015-008360, filed on Jan. 20, 2015. The disclosures of the prior applications are hereby incorporated by reference herein in their entirety.
1. Technical Field
The present invention relates to a pressure sensor, a method of manufacturing the pressure sensor, an altimeter, an electronic apparatus, and a moving object.
2. Related Art
There has be known a pressure sensor including a sensor chip that detects pressure and generates an electric signal corresponding to a detection value of the pressure, a package that houses the sensor chip, and inert liquid that surrounds the sensor chip in the package and propagates the pressure to the sensor chip (see, for example, JP-A-9-126920 (Patent Literature 1)). In the pressure sensor, the sensor chip includes a diaphragm that bends with received pressure and a pressure reference chamber provided on the diaphragm. The pressure outside the package acts on the diaphragm via the inert liquid. The pressure applied to the pressure sensor is detected from a deflection amount of the diaphragm due to the application of the pressure to the diaphragm.
However, in the pressure sensor having such a configuration, for example, air bubbles easily occur when the inert liquid is filled in the package. If the air bubbles come into contact with a pressure receiving surface of the diaphragm, pressure detection accuracy is deteriorated.
An advantage of some aspects of the invention is to provide a pressure sensor in which air bubbles do not easily come into contact with a pressure receiving surface of the diaphragm and deterioration in pressure detection accuracy can be reduced, a method of manufacturing the pressure sensor, and an altimeter, an electronic apparatus, and a moving object including the pressure sensor.
The invention can be implemented as the following application examples.
A pressure sensor according to this application example includes: a pressure sensor element having a pressure receiving surface; and a resin section disposed around the pressure sensor element and formed of curable resin. The resin section includes a first portion disposed at least on the pressure receiving surface and a second portion separate from the first portion. A curing rate of the first portion is higher than a curing rate of the second portion.
With this configuration, it is possible to obtain the pressure sensor in which air bubbles less easily come into contact with the pressure receiving surface and deterioration in pressure detection accuracy can be reduced.
In the pressure sensor according to this application example, it is preferable that the first portion and the second portion respectively contain resin materials of the same kind.
With this configuration, it is easy to adjust the curing rates (hardness levels) of the first portion and the second portion.
In the pressure sensor according to this application example, it is preferable that the pressure sensor element includes a recess, the bottom surface of which is the pressure receiving surface, and the first portion is disposed to be connected to an inner side surface joined to the bottom surface in the recess.
With this configuration, air bubbles much less easily come into contact with the pressure receiving surface.
In the pressure sensor according to this application example, it is preferable that the curable resin is cured by heat.
With this configuration, it is possible to easily perform curing of the curable resin.
In the pressure sensor according to this application example, it is preferable that the curable resin is cured by light.
With this configuration, it is possible to easily perform curing of the curable resin.
In the pressure sensor according to this application example, it is preferable that the pressure sensor further includes a package configured to house the pressure sensor element and the resin section.
With this configuration, it is possible to protect the pressure sensor element and store the curable resin in the package.
In the pressure sensor according to this application example, it is preferable that the package has an opening, and the pressure sensor element is disposed with the pressure receiving surface directed to a direction different from the direction of the opening.
With this configuration, it is possible to protect the pressure receiving surface.
In the pressure sensor according to this application example, it is preferable that the first portion is subjected to defoaming treatment.
With this configuration, air bubbles much less easily come into contact with the pressure receiving surface.
In the pressure sensor according to this application example, it is preferable that the pressure sensor element includes a diaphragm having the pressure receiving surface and a pressure reference chamber disposed on the opposite side of the pressure receiving surface with respect to the diaphragm, the resin section further includes at least a third portion disposed on the opposite side of the diaphragm with respect to the pressure reference chamber, the second portion is disposed around the first portion and the third portion, and a curing rate of the first portion and a curing rate of the third portion are higher than a curing rate of the second portion.
With this configuration, it is possible to obtain the pressure sensor in which air bubbles less easily come into contact with the pressure receiving surface of the diaphragm, a stress balance on both sides (the diaphragm side and the opposite side of the diaphragm) of the pressure reference chamber less easily changes, and deterioration in pressure detection accuracy can be reduced.
In the pressure sensor according to this application example, it is preferable that a difference between the curing rate of the first portion and the curing rate of the third portion is smaller than a difference between the curing rate of the first portion and the curing rate of the second portion and a difference between the curing rate of the third portion and the curing rate of the second portion.
With this configuration, the stress balance on both the side (the diaphragm side and the opposite side of the diaphragm) of the pressure reference chamber is more stabilized.
In the pressure sensor according to this application example, it is preferable that the first portion, the second portion, and the third portion respectively contain resin materials of the same kind.
With this configuration, it is easy to adjust curing rates (hardness levels) of the first portion, the second portion, and the third portion.
A method of manufacturing a pressure sensor according to this application example includes: preparing a pressure sensor element having a pressure receiving surface, a package, first curable resin, and second curable resin including a component same as a component of the first curable resin; disposing the first curable resin on the pressure receiving surface; curing the first curable resin; disposing the pressure sensor element in the package; disposing the second curable resin in the package to surround the pressure sensor element and the first curable resin; and curing the first curable resin and the second curable resin disposed in the package.
With this configuration, it is possible to obtain the pressure sensor in which air bubbles less easily come into contact with the pressure receiving surface and deterioration in pressure detection accuracy can be reduced.
A method of manufacturing a pressure sensor according to this application example includes: preparing a pressure sensor element including a diaphragm having a pressure receiving surface and a pressure reference chamber disposed on the opposite side of the pressure receiving surface with respect to the diaphragm, a package, and first curable resin, second curable resin, and third curable resin including the same component one another; disposing the first curable resin on the pressure receiving surface and disposing the third curable resin on the opposite side of the diaphragm with respect to the pressure reference chamber; curing the first curable resin and the third curable resin; disposing the pressure sensor element in the package; disposing the second curable resin in the package to surround the pressure sensor element, the first curable resin, and the third curable resin; and curing the first curable resin, the second curable resin, and the third curable resin disposed in the package.
With this configuration, it is possible to obtain the pressure sensor in which air bubbles less easily come into contact with the pressure receiving surface of the diaphragm, a stress balance on both sides (the diaphragm side and the opposite side of the diaphragm) of the pressure reference chamber less easily changes, and deterioration in pressure detection accuracy can be reduced.
In the method of manufacturing the pressure sensor according to this application example, it is preferable that the manufacturing method further includes defoaming the first curable resin disposed on the pressure receiving surface before the curing the first curable resin.
With this configuration, since air bubbles in the first curable resin can be removed, it is possible to effectively reduce contact of the pressure receiving surface and the air bubbles.
An altimeter according to this application example includes the pressure sensor according to the application example.
With this configuration, it is possible to obtain the altimeter having high reliability.
An electronic apparatus according to this application example includes the pressure sensor according to the application example.
With this configuration, it is possible to obtain the electronic apparatus having high reliability.
A moving object according to this application example includes the pressure sensor according to the application example.
With this configuration, it is possible to obtain the moving object having high reliability.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
A pressure sensor, a method of manufacturing the pressure sensor, an altimeter, an electronic apparatus, and a moving object according to the invention are explained in detail below with reference to embodiments shown in the accompanying drawings.
First, a pressure sensor according to a first embodiment of the invention is explained.
The pressure sensor 1 shown in
The package 2 has a function of housing the pressure sensor element 3 in an internal space 28 formed on the inside thereof and fixing the pressure sensor element 3. The pressure sensor element 3 is protected by the package 2. The filler 9 is easily disposed around the pressure sensor element 3.
As shown in
The base 21 configures the bottom surface of the package 2 and is formed in a box shape. A constituent material of the base 21 is not particularly limited. Examples of the constituent material include various ceramics like oxide ceramics such as alumina, silica, titania, and zirconia and nitride ceramics such as silicon nitride, aluminum nitride, and titanium nitride and insulative materials such as various resin materials like polyethylene, polyamide, polyimide, polycarbonate, acrylic resin, ABS resin, and epoxy resin. One kind of these materials can be used or two or more kinds of these materials can be used in combination. Among these materials, the constituent material is desirably the various ceramics. Consequently, it is possible to obtain the package 2 having excellent mechanical strength. Note that, besides, a plan view shape of the base 21 may be, for example, a circular shape, a rectangular shape, or a polygonal shape having five or more corners.
The housing 22 configures a lid section of the package 2. In this embodiment, the entire shape of the housing 22 is formed in a cylindrical shape. The housing 22 includes a first part, the outer diameter and the inner diameter of which gradually decrease from the lower end toward the upper end up to height halfway in package height, and a second part, the outer diameter and the inner diameter of which are substantially fixed from the halfway height toward the upper end. As a constituent material of the housing 22, materials same as the materials described above as the examples of the constituent materials of the base 21 can be used. Note that the shape of the housing 22 is not particularly limited.
The flexible wiring board 25 is located between the base 21 and the housing 22. The flexible wiring board 25 has a function of supporting the pressure sensor element 3 and the IC chip 4 in the package 2 and extracting electric signals of the pressure sensor element 3 and the IC chip 4 to the outside of the package 2. The flexible wiring board 25 is configured by a base material 23 having flexibility and a wire 24 formed on the upper surface side of the base material 23.
As shown in
The wire 24 has electric conductivity. As shown in
In the four wiring sections 241, end portions on the pressure sensor element 3 side are respectively flying leads 241a. Similarly, end portions on the IC chip 4 side are flying leads 241b. The four flying leads 241a are provided such that the distal end sides thereof project into the opening section 233. In distal end portions, the flying leads 241a are electrically connected to the pressure sensor element 3 via conductive fixed members 14. The pressure sensor element 3 is separated from the frame section 231 and supported by the flying leads 241a. Similarly, the four flying leads 241b are provided such that the distal end sides thereof project into the opening section 233. In distal end portions, the flying leads 241b are electrically connected to the IC chip 4 via conductive fixed members 15. By adopting the configuration explained above, the pressure sensor element 3 and the IC chip 4 are electrically connected via the four wiring sections 241. Communication can be performed between the pressure sensor element 3 and the IC chip 4. Note that the fixed members 14 and 15 are not particularly limited as long as the fixed members 14 and 15 have electric conductivity. For example, a metal brazing material such as solder, a metal bump such as a gold bump, and a conductive adhesive can be used.
On the other hand, in the four wiring sections 245, proximal end sides are provided in the belt body 232 and the distal end sides are provided in the frame section 231. Distal end portions of the four wiring sections 245 are flying leads 245a. The four flying leads 245a are provided such that the distal end sides thereof project into the opening section 233. In distal end portions, the flying leads 245a are electrically connected to the IC chip 4 via the conductive fixed members 15. The IC chip 4 is separated from the frame section 231 and supported by the flying leads 245a and the flying leads 241b.
With the package 2 having such a configuration, for example, by electrically connecting a motherboard or the like of an electronic apparatus or a moving object explained below to the end portions of the wiring sections 245, it is possible to extract electric signals of the pressure sensor element 3 and the IC chip 4 to the outside of the package 2.
Note that the number of wiring sections included in the wire 24 is not particularly limited and only has to be set as appropriate according to the number of connection terminals 743 explained below provided in the pressure sensor element 3 and the number of connection terminals 42 explained below provided in the IC chip 4. A constituent material of the wire 24 is not particularly limited as long as the constituent material has electric conductivity. Examples of the constituent material include metal such as Ni, Pt, Li, Mg, Sr, Ag, Cu, Co, and Al, alloys such as MgAg, AlLi, and CuLi containing these kinds of metal, and oxides such as ITO and SnO2. One kind of these materials can be used or two or more kinds of these materials can be used in combination.
As shown in
The substrate 5 is formed in a plate shape and configured by stacking, in written order, a semiconductor substrate 51 configured by an SOI substrate (a substrate in which a first Si layer 511, an SiO2 layer 512, and a second Si layer 513 are stacked in this order), a first insulating film 52 configured by a silicon oxide film (SiO2 film) on the semiconductor substrate 51, and a second insulating film 53 configured by a silicon nitride film (SiN film). However, the semiconductor substrate 51 is not limited to the SOI substrate. For example, a silicon substrate can be used.
In the semiconductor substrate 51, a diaphragm 54 thinner than a peripheral portion and deflectively deformed by received pressure is provided. The diaphragm 54 is formed by providing a bottomed recess 55 in the lower surface of the semiconductor substrate 51. The lower surface (the bottom surface of the recess 55) is a pressure receiving surface 541.
A not-shown semiconductor circuit (a circuit) is fabricated on and above the semiconductor substrate 51. The semiconductor circuit includes an active element such as a MOS transistor and circuit elements such as a capacitor, an inductor, a resistor, a diode, and a wire formed according to necessity.
The pressure sensor section 6 includes, as shown in
The element peripheral structure 7 is formed to define the hollow section 8. The element peripheral structure 7 includes, as shown in
The interlayer insulating films 71 and 73 are not particularly limited. For example, an insulating film such as a silicon oxide film (SiO2 film) can be used. The wiring layers 72 and 74 are not particularly limited. For example, a metal film such as an aluminum film can be used. The sealing layer 76 is not particularly limited. Metal films of Al, Cu, W, Ti, TiN, and the like can be used. The surface protection film 75 is not particularly limited. Films having resistance for protecting an element from moisture, dust, scratches, and the like such as a silicon oxide film, a silicon nitride film, a polyimide film, and an epoxy resin film can be used.
The hollow section 8 defined by the substrate 5 and the element peripheral structure 7 is a closed space and functions as a pressure reference chamber for providing a reference value of pressure detected by the pressure sensor element 3. The hollow section 8 is located on the opposite side of the pressure receiving surface 541 of the diaphragm 54 and disposed to overlap the diaphragm 54 in plan view of the pressure sensor element 3. The hollow section 8 is in a vacuum state (e.g., 10 Pa or less). Consequently, the pressure sensor element 3 can be used as a so-called “absolute pressure sensor element” that detects pressure with reference to the vacuum state. However, the hollow section 8 does not have to be in the vacuum state. For example, the hollow section 8 may be in an atmospheric pressure state, may be in a decompressed state in which air pressure is lower than the atmospheric pressure, or may be a pressurized state in which air pressure is higher than the atmospheric pressure.
As shown in
The IC chip 4 includes, for example, a driving circuit for supplying a voltage to the bridge circuit 60, a temperature compensation circuit for performing temperature compensation of an output from the bridge circuit 60, a pressure detection circuit that calculates applied pressure from an output from the temperature compensation circuit, and an output circuit that converts an output from the pressure detection circuit into a predetermined output form (CMOS, LV-PECL, LVDS, etc.) and outputs the pressure. The IC chip 4 includes connection terminals 42 connected to the circuits. The connection terminals 42 are electrically connected to the flying leads 245a via the fixed members 15 (see
As shown in
The filler 9 contains curable resin as a main component. That is, the filler 9 is a resin section mainly formed of the curable resin. The curable resin is particularly desirably thermosetting resin or photocurable resin (in particular, ultraviolet curable resin). Consequently, it is possible to more easily perform curing of the curable resin.
The filler 9 only has to be a substance having curability and softer than the pressure sensor element 3, the IC chip 4, and the package 2 and is, for example, in a liquid state or a gel state. As a specific example of the filler 9, for example, silicone oil, fluorine-based oil, and silicone gel can be used. Note that various fillers may be mixed in the filler 9, for example, for the purpose of improving thermal conductivity and the purpose of adjusting viscosity.
The filler 9 includes two portions (regions) having different curing rates (resin curing rates). Specifically, the filler 9 includes a first portion 91 that is in contact with the pressure receiving surface 541 of the pressure sensor element 3 and an inner side surface joined to the periphery of the pressure receiving surface 541 in the recess 55 and is disposed to fill the recess 55 and a second portion 92 located around the first portion 91 and surrounding the first portion 91 and the pressure sensor element 3. A curing rate of the first portion 91 is higher than a curing rate of the second portion 92. That is, the first portion 91 is harder (has lower penetration) than the second portion 92. Note that the first portion 91 and the second portion 92 contain resin materials of the same kind as main components. Only the curing rates (hardness levels) of the first portion 91 and the second portion 92 are substantially different.
By adopting such a configuration, air bubbles less easily come into contact with the pressure receiving surface 541. It is possible to reduce fluctuation and deterioration in pressure detection accuracy. Therefore, the pressure sensor 1 can show excellent pressure detection accuracy. Specifically, air bubbles sometimes occur in the filler 9 when the filler 9 is filled in the internal space 28. If the air bubbles move in the filler 9 and come into contact with the pressure receiving surface 541, the air bubbles act like a cushion. Pressure is not appropriately transmitted to the pressure receiving surface 541 in a portion where the air bubbles come into contact with the pressure receiving surface 541. Therefore, if the air bubbles come into contact with the pressure receiving surface 541, fluctuation and deterioration in pressure detection accuracy occur.
On the other hand, in the pressure sensor 1 in this embodiment, since the curing rate of the first portion 91 that covers the pressure receiving surface 541 is higher than the curing rate of the second portion 92. Therefore, for example, intrusion of air bubbles into the first portion 91 from the second portion 92 and movement of the air bubbles in the first portion 91 are effectively suppressed. Therefore, the air bubbles less easily come into contact with the pressure receiving surface 541. It is possible to reduce fluctuation and deterioration in pressure detection accuracy.
The curing rates of the first portion 91 and the second portion 92 are not particularly limited as long as the curing rate of the first portion 91 is higher than the curing rate of the second portion 92. Depending on materials, for example, the curing rate of the first portion 91 is desirably within a range of 40% or more and 90% or less and more desirably within a range of 50% or more and 80% or less. The curing rate of the second portion 92 is desirably within a range of 10% or more and 60% or less and more desirably within a range of 20% or more and 40% or less. By setting the curing rates of the first portion 91 and the second portion 92 in such a range, it is possible to set the second portion 92 to viscosity of a degree for not allowing the second portion 92 to flow out from the opening of the package 2. It is possible to set the first portion 91 to viscosity of a degree for not allowing air bubbles to move on the inside of the first portion 91.
The viscosities of the first portion 91 and the second portion 92 are not particularly limited as long as the viscosity of the first portion 91 is higher than the viscosity of the second portion 92. However, for example, the penetration of the first portion 91 is desirably within a range of 50 or more and 200 or less and is more desirably within a range of 150 or more and 200 or less. The penetration of the second portion 92 is desirably within a range of 100 or more and 250 or less and more desirably within a range of 200 or more and 250 or less. Consequently, it is possible to sufficiently soften the filler 9. Pressure applied to the pressure sensor 1 efficiently acts on the pressure receiving surface 541. It is possible to effectively suppress movement of air bubbles on the inside of the first portion 91. Note that measurement of a curing rate can be performed by measurement by an FT-IR, fluorescence measurement, and the like. Penetration can be measured by a method conforming to a test method specified by JIS K 2207.
In particular, in this embodiment, the first portion 91 and the second portion 92 are formed of materials of the same kind (the same resin materials). Therefore, the filler 9 has a simpler configuration. It is easier to adjust the curing rates of the first portion 91 and the second portion 92. In this embodiment, since the first portion 91 is disposed to fill the entire region of the recess 55, it is possible to set the second portion 92 sufficiently away from the pressure receiving surface 541. Therefore, the air bubbles much less easily come into contact with the pressure receiving surface 541. It is possible to further reduce the fluctuation and deterioration in the pressure detection accuracy. In this embodiment, since the first portion 91 is kept at a minimum enough for filling the entire region of the recess 55 (as shown in
The first portion 91 is desirably subjected to defoaming treatment. Consequently, it is possible to remove air bubbles in the first portion 91. Therefore, it is possible to effectively prevent the air bubbles in the first portion 91 from coming into contact with the pressure receiving surface 541. Note that the defoaming treatment is not particularly limited. Examples of the deforming treatment include a method of performing evacuation explained in a manufacturing method below.
The configuration of the pressure sensor 1 is explained above.
A method of manufacturing the pressure sensor 1 is explained.
The method of manufacturing the pressure sensor 1 includes a step of preparing the pressure sensor element 3, the package 2, a first curable resin 91A, and a second curable resin 92A, a step of disposing the first curable resin 91A on the pressure receiving surface 541 of the pressure sensor 1, a step of curing (semi-curing) the first curable resin 91A, a step of disposing the pressure sensor element 3 in the package 2, a step of disposing the second curable resin 92A in the package 2 to surround the pressure sensor element 3 and the first curable resin 91A, and a step of curing (semi-curing) the first curable resin 91A and the second curable resin 92A disposed in the package 2.
The manufacturing method is explained below in detail. However, for convenience of explanation, the same thermosetting resin is used as the first curable resin 91A and the second curable resin 92A. The curing rates of the first curable resin 91A and the second curable resin 92A before being served for manufacturing are equal.
First, as shown in
Subsequently, as shown in
Subsequently, as shown in
Subsequently, as shown in
Subsequently, heat is applied to the first curable resin 91A and the second curable resin 92A under the same condition to semi-cure the first curable resin 91A and the second curable resin 92A. When the first curable resin 91A and the second curable resin 92A are silicone oil, the first curable resin 91A and the second curable resin 92A are semi-cured, for example, under a condition of 150°×30 minutes. The curing rate of the first curable resin 91A is not particularly limited. The curing rate is, for example, approximately 40% or more and 90% or less. The curing rate of the second curable resin 92A is, for example, approximately 10% or more and 60% or less. Note that, since the first curable resin 91A and the second curable resin 92A are the resin materials of the same kind, the first curable resin 91A, for which a curing time is long (curing is performed twice), has a higher curing rate than the second curable resin 92A, for which a curing time is short (curing is performed only once). Consequently, the filler 9 including the first portion 91 formed of the first curable resin 91A and the second portion 92 formed of the second curable resin 92A is obtained.
Consequently, the pressure sensor 1 is manufactured as shown in
According to the manufacturing method explained above, it is possible to manufacture the pressure sensor 1 with a relatively simple method. In particular, the manufacturing method includes the step of defoaming the first curable resin 91A before curing the first curable resin 91A. Therefore, air bubbles in the first portion 91 are removed and the pressure sensor 1 having higher pressure detection accuracy is obtained. Note that, in the manufacturing method explained above, the defoaming of the second curable resin 92A may be performed prior to the curing of the first curable resin 91A and the second curable resin 92A. Consequently, it is possible to sufficiently reduce the air bubbles in the filler 9.
Note that, in this embodiment, the thermosetting resin is used as the first curable resin 91A and the second curable resin 92A. However, photocurable resin may be used as the first curable resin 91A and the second curable resin 92A. In this case, the first curable resin 91A and the second curable resin 92A can be cured by radiating light (e.g., ultraviolet ray) thereon instead of heat.
In the embodiment explained above, the curable resin is described as “being cured” even if the curing rate of the curable resin is less than 100% (e.g., the curable resin is semi-cured).
The pressure sensor according to the second embodiment is explained below. Differences from the first embodiment are mainly explained. Explanation of similarities is omitted.
The pressure sensor 1 in the second embodiment is the same as the pressure sensor 1 in the first embodiment except that the direction of a pressure sensor element in a package is different.
As shown in
According to the second embodiment, it is possible to exhibit effects same as the effects of the first embodiment.
The pressure sensor in the third embodiment is explained below. Differences from the embodiments explained above are mainly explained. Explanation of similarities is omitted.
The pressure sensor 1 in the third embodiment is the same as the pressure sensor 1 in the first embodiment except that disposition of a pressure sensor element and an IC chip in a package is different.
As shown in
According to the third embodiment, it is possible to exhibit effects same as the effects of the first embodiment.
The pressure sensor in the fourth embodiment is explained below. Differences from the embodiments explained above are mainly explained. Explanation of similarities is omitted.
The pressure sensor 1 in the fourth embodiment is the same as the pressure sensor 1 in the first embodiment except that the filler 9 includes the first portion 91 disposed on the pressure receiving surface 541 of the pressure sensor element 3, a third portion 93 disposed on the opposite side of the diaphragm 54 with respect to the hollow section 8 (the pressure reference chamber), and the second portion 92 located around the first portion 91 and the third portion 93 and surrounding the first portion 91, the third portion 93, and the pressure sensor element 3. That is, in the pressure sensor 1 in the fourth embodiment, the filler 9 includes the third portion 93 in addition to the first portion 91 and the second portion 92 (see
In this embodiment, as shown in
As a constituent material of the filler 9 (the resin section), a material same as the constituent material of the filler 9 in the first embodiment can be used.
In other words, a difference between the curing rate of the first portion 91 and the curing rate of the third portion 93 can also be considered to be smaller than a difference between the curing rate of the first portion 91 and the curing rate of the second portion 92 and a difference between the curing rate of the third portion 93 and the curing rate of the second portion 92.
By adopting such a configuration, first, air bubbles less easily come into contact with the pressure receiving surface 541. It is possible to reduce fluctuation and deterioration in pressure detection accuracy. Therefore, the pressure sensor 1 can show excellent pressure detection accuracy. Specifically, air bubbles sometimes occur in the filler 9 when the filler 9 is filled in the internal space 28. If the air bubbles move in the filler 9 and come into contact with the pressure receiving surface 541, the air bubbles act like a cushion. Pressure is not appropriately transmitted to the pressure receiving surface 541 in a portion where the air bubbles come into contact with the pressure receiving surface 541. Therefore, if the air bubbles come into contact with the pressure receiving surface 541, fluctuation and deterioration in pressure detection accuracy occur.
On the other hand, in the pressure sensor 1 in this embodiment, since the curing rate of the first portion 91 that covers the pressure receiving surface 541 is higher than the curing rate of the second portion 92. Therefore, for example, intrusion of air bubbles into the first portion 91 from the second portion 92 and movement of the air bubbles in the first portion 91 are effectively suppressed. Therefore, the air bubbles less easily come into contact with the pressure receiving surface 541. It is possible to reduce fluctuation and deterioration in pressure detection accuracy.
Second, a stress balance applied to the hollow section 8 less easily changes. It is possible to reduce deterioration in pressure detection accuracy with time. Specifically, on the lower side (the pressure receiving surface 541 side) of the hollow section 8, the first portion 91 is disposed on the pressure receiving surface 541. On the upper side (the ceiling section 81 side), the third portion 93 is disposed on the ceiling section 81. Since the first portion 91 and the third portion 93 have high curing rates (curing of the first portion 91 and the third portion 93 is advanced) compared with the second portion 92, a change in the curing rate (a hardness degree) with time after that is less compared with the second portion 92. Therefore, a stress balance on both sides (the upper side and the lower side in
The curing rates of the first portion 91, the second portion 92, and the third portion 93 are not particularly limited as long as the curing rates of the first portion 91 and the third portion 93 are higher than the curing rate of the second portion 92. The curing rates of the first portion 91, the second portion 92, and the third portion 93 are different depending on materials. For example, the curing rates of the first portion 91 and the third portion 93 are desirably within a range of 40% or more and 90% or less and more desirably within a range of 50% or more and 80% or less. The curing rate of the second portion 92 is desirably within a range of 10% or more and 60% or less and more desirably within a range of 20% or more and 40% or less. By setting the curing rates of the first portion 91, the second portion 92, and the third portion 93 respectively in the ranges, it is possible to set the second portion 92 to viscosity of a degree for not allowing the second portion 92 to flow out from the opening of the package 2. It is possible to set the first portion 91 to viscosity of a degree for not allowing air bubbles to move on the inside of the first portion 91. The stress balance on both the sides across the hollow section 8 much less easily changes.
The viscosities of the first portion 91, the second portion 92, and the third portion 93 are not particularly limited as long as the viscosities of the first portion 91 and the third portion 93 are higher than the viscosity of the second portion 92. For example, the penetrations of the first portion 91 and the third portion 93 are desirably within a range of 50 or more and 200 or less and more desirably within a range of 150 or more and 200 or less. The penetration of the second portion 92 is desirably within a range of 100 or more and 250 or less and more desirably within a range of 200 or more and 250 or less. Consequently, it is possible to sufficiently soften the filler 9. Pressure applied to the pressure sensor 1 efficiently acts on the pressure receiving surface 541. It is possible to effectively suppress movement of air bubbles on the inside of the first portion 91. The first portion 91 and the third portion 93 have more appropriate hardness levels. The stress balance on both the sides across the hollow section 8 much less easily changes. Note that measurement of a curing rate can be performed by measurement by an FT-IR, fluorescent measurement, and the like. Penetration can be measured by a method conforming to a test method specified in JIS K 2207.
In particular, in this embodiment, the first portion 91, the second portion 92, and the third portion 93 are formed of the materials of the same kind (the same resin materials). Therefore, the filler 9 has a simpler configuration. It is easier to adjust the curing rates of the first portion 91, the second portion 92, and the third portion 93. In this embodiment, since the first portion 91 is disposed to fill the entire region of the recess 55, it is possible to set the second portion 92 sufficiently away from the pressure receiving surface 541. Therefore, the air bubbles much less easily come into contact with the pressure receiving surface 541. It is possible to further reduce the fluctuation and deterioration in the pressure detection accuracy. In this embodiment, since the first portion 91 is kept at a minimum enough for filling the entire region of the recess 55 (as shown in
In this embodiment, the third portion 93 has the curing rate substantially the same as the curing rate of the first portion 91. Therefore, the stress balance on both the sides across the hollow section 8 is further stabilized. In particular, in this embodiment, since the third portion 93 is disposed to include the ceiling section 81 (the hollow section 8) in plan view, the effects explained above are more conspicuous. However, the curing rate of the third portion 93 may be different from the curing rate of the first portion 91 as long as the curing rate of the third portion 93 is higher than the curing rate of the second portion 92. A part (e.g., an edge portion) of the ceiling section 81 may protrude from the third portion 93.
The first portion 91 is desirably subjected to defoaming treatment. Consequently, it is possible to remove air bubbles in the first portion 91. Therefore, it is possible to effectively prevent the air bubbles in the first portion 91 from coming into contact with the pressure receiving surface 541. Note that the defoaming treatment is not particularly limited. Examples of the defoaming treatment include a method of performing evacuation explained in a manufacturing method below.
Note that, in this embodiment, the first portion 91 and the third portion 93 are formed as separate bodies and are separated from each other. However, for example, the first portion 91 and the third portion 93 may be joined (integrated). The pressure sensor element 3 may be covered with the first portion 91 and the third portion 93.
A method of manufacturing the pressure sensor 1 in this embodiment is explained.
The method of manufacturing the pressure sensor 1 includes a step of preparing the pressure sensor element 3, the first curable resin 91A, the second curable resin 92A, a third curable resin 93A, a step of disposing the first curable resin 91A on the pressure receiving surface 541 of the pressure sensor element 3 and disposing the third curable resin 93A in the ceiling section 81, a step of curing (semi-curing) the first curable resin 91A and the third curable resin 93A, a step of disposing the pressure sensor element 3 in the package 2, and a step of disposing the second curable resin 92A in the package 2 to surround the pressure sensor element 3, the first curable resin 91A, and the third curable resin 93A and curing (semi-curing) the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A disposed in the package 2.
The manufacturing method is explained in detail below. For convenience of explanation, as the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A, the same thermosetting resin is used. Curing rates of the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A before being served for manufacturing are equal to one another.
First, as shown in
Subsequently, as shown in
Subsequently, in a state in which the pressure receiving surface 541 (the opening of the recess 55) is directed to the upper side in the vertical direction, the pressure sensor element 3 is disposed in a vacuum chamber and evacuated to defoam the first curable resin 91A. Consequently, air bubbles are removed from the first curable resin 91A. Heat is applied to the first curable resin 91A and the third curable resin 93A under the same condition to semi-cure the first curable resin 91A and the third curable resin 93A. For example, when the first curable resin 91A and the third curable resin 93A are silicone oil (having a curable rate of 0%), the first curable resin 91A and the third curable resin 93A are desirably semi-cured, for example, under a condition of 150°×30 minutes. Curing rates of the first curable resin 91A and the third curable resin 93A at this point are not particularly limited. The curable rates are desirably set to, for example, approximately 20% or more and 40% or less.
Subsequently, as shown in
Subsequently, as shown in
Subsequently, heat is applied to the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A under the same condition to semi-cure the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A. When the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A are silicone oil, the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A are desirably semi-cured, for example, under a condition of 150°×30 minutes. The curing rates of the first curable resin 91A and the third curable resin 93A are not particularly limited. For example, the curing rates are desirably, for example, approximately 40% or more and 90% or less. The curing rate of the second curable resin 92A is desirably, for example, approximately 10% or more and 60% or less. Note that, since the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A are the resin materials of the same kind, the first curable resin 91A and the third curable resin 93A having an equal curing time have substantially equal curing rates. The first curable resin 91A and the third curable resin 93A, for which a curing time is long (curing is performed twice), have higher curing rates than the second curable resin 92A, for which a curing time is short (curing is performed only once). Consequently, the filler 9 including the first portion 91 formed of the first curable resin 91A, the second portion 92 formed of the second curable resin 92A, and the third portion 93 formed of the third curable resin 93A is obtained.
Consequently, the pressure sensor 1 is manufactured as shown in
According to the manufacturing method explained above, it is possible to manufacture the pressure sensor 1 with a relatively simple method. In particular, the manufacturing method includes the step of defoaming the first curable resin 91A before curing the first curable resin 91A. Therefore, air bubbles in the first portion 91 are removed and the pressure sensor 1 having higher pressure detection accuracy is obtained. Note that, in the manufacturing method explained above, the defoaming of the second curable resin 92A may be performed prior to the curing of the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A. Consequently, it is possible to sufficiently reduce the air bubbles in the second portion 92.
Note that, in this embodiment, the thermosetting resin is used as the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A. However, photocurable resin may be used as the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A. In this case, the first curable resin 91A, the second curable resin 92A, and the third curable resin 93A can be cured by radiating light (e.g., ultraviolet ray) thereon instead of heat.
In the embodiment explained above, the curable resin is described as “being cured” even if the curing rate of the curable resin is less than 100% (e.g., the curable resin is semi-cured).
According to the fourth embodiment explained above, it is possible to exhibit effects same as the effects of the first embodiment.
The pressure sensor according to the second embodiment is explained below. Differences from the first embodiment are mainly explained. Explanation of similarities is omitted.
The pressure sensor 1 in the fifth embodiment is the same as the pressure sensor 1 in the fourth embodiment except that the direction of a pressure sensor element in a package is different.
As shown in
According to the fifth embodiment, it is possible to exhibit effects same as the effects of the fourth embodiment.
The pressure sensor according to the sixth embodiment is explained below. Differences from the above-mentioned embodiment are mainly explained. Explanation of similarities is omitted.
The pressure sensor 1 in the sixth embodiment is the same as the pressure sensor 1 in the fourth embodiment except that disposition of a pressure sensor element and an IC chip in a package is different.
As shown in
According to the sixth embodiment, it is possible to exhibit effects same as the effects of the fourth embodiment.
An example of an altimeter including a pressure sensor according to the invention is explained.
As shown in
A navigation system applied with an electronic apparatus including the pressure sensor according to the invention is explained.
As shown in
With the navigation system, it is possible to acquire altitude information in addition to the acquired position information. For example, when a vehicle travels on a high-level road, a position on which is substantially the same as the position on a general road in the position information, if the navigation system does not have the altitude information, the navigation system cannot determine whether the vehicle is traveling on the general road or traveling on the high-level road. The navigation system provides a user with information concerning the general road as priority information. Therefore, in the navigation system 300 according to this embodiment, the altitude information can be acquired by the pressure sensor 1. It is possible to detect an altitude change due to entrance into the high-level road from the general road and provide the user with navigation information in a traveling state on the high-level road.
Note that the electronic apparatus including the pressure sensor according to the invention is not limited to the electronic apparatus explained above. The electronic apparatus can be applied to, for example, a personal computer, a cellular phone, medical apparatuses (e.g., an electronic thermometer, a blood manometer, a blood sugar meter, an electrocardiogram apparatus, an ultrasonic diagnostic apparatus, and an electronic endoscope), various measuring devices, meters (e.g., meters for a vehicle, an airplane, and a ship), and a flight simulator.
A moving object including the pressure sensor according to the invention is explained.
As shown in
The pressure sensor, the method of manufacturing the pressure sensor, the altimeter, the electronic apparatus, and the moving object according to the invention are explained above with reference to the embodiments shown in the figures. However, the invention is not limited to pressure sensor, the method of manufacturing the pressure sensor, the altimeter, the electronic apparatus, and the moving object. For example, the components of the sections can be replaced with any components having the same functions. Any other components and steps may be added. The embodiments may be combined as appropriate.
In the embodiments, the pressure sensor including the piezoelectric resistance elements is explained as the pressure sensor section. However, the pressure sensor section is not limited to the pressure sensor. For example, a component including a flap-type vibrator, other MEMS vibrators such as an inter digital transducer, and vibration elements such as a quartz vibrator can also be used.
In the embodiments, the wiring sections, the pressure sensor element, and the IC chip are connected by the flying leads. However, a method of connecting the wiring sections, the pressure sensor element, and the IC chip is not limited to the connection by the flying leads. The pressure sensor element and the IC chip may be connected via, for example, a bonding wire.
In the embodiments, the pressure sensor includes the IC chip. However, the IC chip may be omitted.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-008246 | Jan 2015 | JP | national |
| 2015-008360 | Jan 2015 | JP | national |
