Patent Application
20070247507
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
An embodiment of the present invention will now be described with reference to
In the following description, directions +X, +Y, +Z are indicated by corresponding arrows in drawings. The negative directions −X, −Y, −Z are the directions opposite to directions +X, +Y, +Z, respectively. The plainly expressed directions X, Y, Z correspond to directions ±X, ±Y, ±Z, respectively.
As shown in
The LTCC multilevel substrate 2 has a plurality of sheet-like low temperature co-fired ceramic substrates (hereinafter, referred to simply as insulating layers 4), which are stacked together. Each of the insulating layers 4 is a baked body of glass ceramic material and the thickness of the insulating layer 4 is several hundreds of micrometers. The glass ceramic material is, for example, a mixture of a glass element such as alkali oxide of borosilicic acid and a ceramic element such as alumina.
Various types of circuit elements 5 such as a resistance element, a capacity element, a coil element, and a plurality of internal traces 6, or metal traces electrically connecting the circuit elements 5 together, are provided between each adjacent pair of the insulating layers 4. The circuit elements 5 and the internal traces 6 are baked bodies of metal particles such as silver or silver alloy particles and formed using a droplet ejection apparatus 10 of the present invention. Via traces 7 having a stacked via structure or a thermal via structure are formed in each of the insulating layers 4. The via traces 7 electrically connect the circuit elements 5 and the internal traces 6 together throughout the insulating layers 4. Each of the via traces 7 is a baked body of metal particles such as silver or silver alloy particles, like the circuit elements 5 and the internal traces 6.
A method for manufacturing the above-described LTCC multilevel substrate 2 will hereafter be explained with reference to
Referring to
Specifically, droplets Fb of the metal ink F are ejected onto an area (hereinafter, referred to simply as a trace forming area) on the trace forming surface 4Sa in which the circuit elements 5 and the internal traces 6 are to be provided. The droplets Fb are then dried in the trace forming area. Such ejection and drying are repeated to form a corresponding element trace 5F and a corresponding conducting trace 6F in the trace forming area. The droplets Fb received in the trace forming area are dried by radiating incident light Le (see
After forming the element traces 5F, the conducting traces 6F, and the via traces 7F in the green sheets 4S, the green sheets 4S are stacked altogether. Then, the portions corresponding to the LTCC multilevel substrates 2 are cut out and baked as a stacked body 4B. In other words, the green sheets 4S, the element traces 5F, the traces 6F, and the via traces 7F are stacked altogether and baked simultaneously. In this manner, the LTTC substrates 2 each having the insulating layers 4, the circuit elements 5, the internal traces 6, and the via traces 7 are obtained.
With reference to
As shown in
A gate-like guide member 16 projects from opposing sides of the base 11 in direction X perpendicular to the scanning direction in such a manner as to straddle the base 11. An ink tank 17, which extends in direction X, is arranged on the guide member 16. The ink tank 17 retains the metal ink F and supplies the metal ink F to a droplet ejection head 21, which is provided below the ink tank 17, under a predetermined level of pressure.
A pair of upper and lower guide rails 18 extending in direction X are formed substantially along the entire width of the guide member 16 in direction X and located in direction −Y with respect to the guide member 16. A carriage 20 is secured to the guide rails 18 and moves along the guide rails 18 and in the directions ±Y. An ejection head 21 is arranged at a bottom surface 20a of the carriage 20.
As shown in
Referring to
In the illustrated embodiment, a position located on the trace forming surface 4Sa in correspondence with each of the nozzles N in direction −Z, or a position at which a droplet Fb is received by the trace forming surface 4Sa, is defined as a droplet receiving position P. An end of the liquid surface FLa located in the direction opposite to the scanning direction, or in direction −Y, is defined as an incident position Pe. The distance between the droplet receiving position P and the incident position Pe is defined as a standby distance WF.
Referring to
The semiconductor module LDM includes a semiconductor laser LD and an optical element PS forming an optical radiation system. The semiconductor laser LD radiates a belt-like collimated laser beam, which spreads substantially along the entire width of the light exit hole H in direction X, downward. The wavelength of the laser beam radiated by the semiconductor laser LD is set in the range of the absorption wavelength of the metal ink F (in the illustrated embodiment, 808 nm). The optical element PS includes a retarder. The optical element PS converts the polarized state of the laser beam from the semiconductor laser LD to a prescribed state of linearly polarized light, which is, in the illustrated embodiment, to the state of a polarized light with 100% of p-polarized light components. The optical element PS then radiates the polarized light downward.
A cylindrical lens 25 forming the optical radiation system is arranged in the light exit hole H. The lens 25 is a lens having curvature only in direction Y. The width of the lens 25 in direction X is equal to the width of the ejection head 21 in direction X. After receiving the laser beam from the semiconductor laser module LDM, the lens 25 converges only components of the laser beam in direction +Y (or direction −Y) and radiates the elements downwardly as incident light Le.
A mirror stage 26 extending downward from the carriage 20 and a reflective mirror 27 pivotally supported by the mirror stage 26 are provided below the light exit hole H. The reflective mirror 27 forms the optical radiation system. The mirror stage 26 supports the reflective mirror 27 pivotally about a pivotal axis extending along direction X. The reflective mirror 27 is a galvanic mirror and has a reflective surface 27m located at the side facing the cylindrical lens 25. The width of the mirror 27 in direction X is equal to the width of the ejection head 21 in direction X. The reflective mirror 27 receives the incident light Le from the lens 25 by the reflective surface 27m and reflects the incident light Le substantially along the tangential direction of the trace forming surface 4Sa. In the illustrated embodiment, the angle between a normal line of the liquid surface FLa (the trace forming surface 4Sa) and the incident light Le that has been reflected is defined as the incident angle θe and set to 88°.
After having been reflected by the reflective mirror 27, the incident light Le is introduced through the gap between the ejection head 21 and the green sheet 4S and the area of the incident light Le corresponding to the beam waist reaches the incident position Pe on the liquid surface FLa. Some of the incident light Le received at the incident position Pe is transmitted through and absorbed by the liquid film FL. Specifically, when the green sheet 4S is moved in the scanning direction, or direction +Y, some of the incident light Le reflected by the reflective mirror 27 sequentially dries the liquid film FL in the vicinity of the incident position Pe. In this manner, a layer trace FP extending in the scanning direction is provided.
Some of the incident light Le that has reached the incident position Pe is not transmitted through the liquid film FL and reflected in the direction opposite to the scanning direction as reflected light Lr. In the illustrated embodiment, a plane (a Y-Z plane) defined by the reflected incident light Le and the reflected light Lr corresponding to the reflected incident light Le is defined as the incident plane.
The reflectance of the incident light Le with respect to the liquid film FL changes in correspondence with the polarized state of the incident light Le. Specifically, the reflectance Rp of the polarized light (the p-polarized light) in which the direction of the electric field vector E is parallel with the incident plane and the reflectance Rs of the polarized light (the S polarized light) in which the direction of the electric field vector E is perpendicular to the incident plane are obtained by the following equations in which N1 represents the refraction factor of the air and N2 represents the refraction factor of the liquid film FL. The reflectance Rp of the p-polarized light is lower than the reflectance Rs of the s-polarized light at a given incident angle θe.
According to the equations, the following equation is satisfied.
φ=sin−1{(N1/N2)cos(π/2−θe)}
For example, if the refraction factor of the air is 1, the refraction factor of the liquid film FL is 1.3, and the incident angle θe is 88°, the reflectance Rp of the p-polarized light and the reflectance Rs of the s-polarized light are 75.2% and 84.5%, respectively. In other words, the amount of the p-polarized incident light Le transmitted through and absorbed by the liquid film FL after reaching the incident position Pe is approximately 10% greater than the corresponding amount of the incident light Le of the s-polarized light.
In the droplet ejection apparatus 10 of the illustrated embodiment, the optical element PS of the semiconductor laser module LDM converts the laser beam radiated by the semiconductor laser LD to the p-polarized light and radiates the p-polarized incident light Le. In the illustrated embodiment, the p-polarized light is a linearly polarized light with an electric field vector oscillating parallel with the incident plane, which contains substantially no other components, or a polarized light with 100% of p-polarized components.
Therefore, since the polarized state of the incident light Le has been converted into the state of the p-polarized light, a correspondingly great amount of incident light Le is transmitted through and absorbed by the liquid film FL. Such improved absorption rate of the incident light Le allows the incident light Le to reliably dry the liquid film FL, forming the layer trace FP that is sufficiently dry. Then, multiple layer traces FP are sequentially stacked together to form the conducting trace 6F (see
Next, the electric configuration of the droplet ejection apparatus 10, which has the above-described structure, will be described with reference to
As illustrated in
An input device 41 having manipulation switches such as a start switch and a stop switch is connected to the controller 40. The input device 41 provides information regarding the position coordinates of the trace forming area (the layer trace FP) with respect to a trace forming plane (the trace forming surface 4Sa) to the controller 40 as a prescribed form of trace forming information Ia. The controller 40 generates bit map data BMD based on the trace forming information Ia sent from the input device 41.
In correspondence with each of the bit values (0 or 1), the bit map data BMD instructs whether to turn on or off the corresponding one of the piezoelectric elements PZ. That is, the bit map data BMD instructs whether to eject a droplet Fb onto each of positions on the trace forming plane (the trace forming surface 4Sa) above which the ejection head 21 is moved. In other words, in accordance with the bit map data BMD, droplets Fb are ejected onto corresponding target positions defined on the trace forming area.
The controller 40 is connected to an X-axis motor driver circuit 42 and provides a corresponding drive signal to the X-axis motor driver circuit 42. In response to the drive signal from the controller 40, the X-axis motor driver circuit 42 rotates an X-axis motor MX in a forward or reverse direction to move the carriage 20. The X-axis motor driver circuit 42 is connected to an X-axis encoder XE and receives a detection signal from the X-axis encoder XE. The X-axis motor driver circuit 42 generates a signal regarding the movement direction and the movement amount of the carriage 20 (each of the droplet receiving positions P) with respect to the trace forming surface 4Sa in correspondence with the detection signal from the X-axis encoder XE. The X-axis motor driver circuit 42 then sends the signal to the controller 40.
The controller 40 is connected to a Y-axis motor driver circuit 43 and provides a corresponding drive signal to the Y-axis motor driver circuit 43. In response to the drive signal from the controller 40, the Y-axis motor driver circuit 43 rotates a Y-axis motor MY in a forward or reverse direction to move the stage 13. The Y-axis motor driver circuit 43 is connected to a Y-axis encoder YE and receives a detection signal from the Y-axis encoder YE. The Y-axis motor driver circuit 43 generates a signal regarding the movement direction and the movement amount of the stage 13 (the trace forming surface 4Sa) in correspondence with the detection signal from the Y-axis encoder YE. The Y-axis motor driver circuit 43 then sends the signal to the controller 40. In correspondence with the signal from the Y-axis motor driver circuit 43, the controller 40 calculates the position of each droplet receiving position P relative to the trace forming surface 4Sa. The controller 40 outputs an ejection timing signal LP each time the droplet receiving positions P reach the corresponding target positions.
The controller 40 is connected to a semiconductor laser driver circuit 44. The controller 40 outputs a trace forming start signal S1 to the semiconductor laser driver circuit 44 to start trace forming and a trace forming end signal S2 to end the trace forming. In response to the trace forming start signal S1, the semiconductor laser driver circuit 44 operates the semiconductor laser module LDM to radiate the p-polarized incident light Le. In response to the trace forming end signal S2, the semiconductor laser driver circuit 44 operates the semiconductor laser module LDM to end radiation of the incident light Le. That is, in trace forming, the controller 40 controls operation of the semiconductor laser module LDM through the semiconductor laser driver circuit 44 to radiate the p-polarized incident light Le.
The controller 40 is connected to an ejection head driver circuit 45 and provides piezoelectric element drive voltage COM for driving the piezoelectric elements PZ to the ejection head driver circuit 45 synchronously with the ejection timing signal LP. Further, in accordance with the bit map data BMD, the controller 40 generates ejection control signals SI synchronized with prescribed clock signals and serially transfers the ejection control signals SI to the ejection head driver circuit 45. The ejection head driver circuit 45 sequentially converts the ejection control signals SI of the controller 40, which are in serial forms, into parallel forms in correspondence with the piezoelectric elements PZ. Further, each time the ejection head driver circuit 45 receives the ejection timing signal LP from the controller 40, the ejection head driver circuit 45 latches the ejection control signals SI, which have been converted into the parallel forms. The ejection head driver circuit 45 then supplies the piezoelectric element drive voltage COM to those of the piezoelectric elements PZ that are selected in accordance with the ejection control signals SI.
Next, a method for forming the element traces 5F and the conducting traces 6F using the droplet ejection apparatus 10 will be explained.
First, as illustrated in
In this state, the trace forming information Ia is input to the controller 40 through the input device 41. In accordance with the trace forming information Ia, the controller 40 produces the bit map data BMD and stores the bit map data BMD. Then, the controller 40 operates the X-axis motor driver circuit 42 to arrange the carriage 20 (the ejection head 21) at a predetermined position in such a manner that, when the green sheet 4S is moved, the target positions pass the corresponding droplet receiving positions P. After arranging the carriage 20 at the predetermined position, the controller 40 operates the Y-axis motor driver circuit 43 to start transport of the green sheet 4S.
The controller 40 then outputs the trace forming start signal SI to the semiconductor laser driver circuit 44 and operates the semiconductor laser module LDM to radiate the p-polarized incident light Le. The incident light Le is reflected by the reflective mirror 27 substantially in a tangential direction of the green sheet 4S and reaches the trace forming surface 4Sa at the incident angle θe.
Also, after the transport of the green sheet 4S is started, the controller 40 outputs the ejection control signals SI, which have been generated based on the bit map data BMD, to the ejection head driver circuit 45.
Further, in response to the start of the transport of the green sheet 4S, the controller 40 outputs the ejection timing signal LP to the ejection head driver circuit 45 each time the target positions reach the corresponding droplet receiving positions P. In other words, the controller 40 selects the nozzles N that are to eject the droplets Fb in correspondence with the ejection control signals SI. The controller 40 operates the nozzles N to eject the droplets Fb onto the target positions each time the droplet receiving positions P corresponding to the selected nozzles N reach the target positions.
The ejected droplets Fb reach the corresponding target positions defined on the trace forming surface 4Sa. After having been moved by a standby distance WF, each of the droplets Fb that have reached the target positions is joined with the corresponding one of the precedingly ejected droplets Fb. This forms the liquid film FL, which spreads in the trace forming area. The p-polarized incident light Le is radiated onto the incident position Le on the liquid film FL.
Since the polarized state of the incident light Le that has reached the incident position Pe corresponds to the state of the p-polarized light, the incident light Le is transmitted through and absorbed by the liquid film FL by a correspondingly greater amount. This forms a sufficiently dry layer trace FP. Afterwards, by sequentially stacking layer traces FP together in similar manners, the element trace 5F and the conducting trace 6F are formed. This suppresses defects in formation of the element traces 5F and the conducting traces 6F.
The illustrated embodiment, which is constructed as above-described, has the following advantages.
The semiconductor laser module LDM having the semiconductor laser LD and the optical element PS is mounted in the carriage 20 in which the ejection head 21 is provided. The ejection head 21 forms the liquid film FL through joining of the droplets Fb ejected onto the green sheets 4S. The semiconductor laser module LDM radiates the p-polarized incident light Le onto the liquid surface FLa of the liquid film FL.
Since the polarized state of the incident light Le has been converted into the state of the p-polarized light, the amount of the incident light Le reflected by the liquid surface FLa is decreased and the amount of the incident light Le transmitted through the liquid film FL is increased. This enhances the absorption rate of the incident light Le by the liquid film FL, thus improving efficiency of drying the liquid film FL. In this manner, defects in formation of the element traces 5F and the conducting traces 6F, or the circuit element 5 and the internal traces 6, are suppressed.
The carriage 20 includes the ejection head 21, the semiconductor laser module LDM, and the reflective mirror 27. The position of the incident light Le relative to each of the received droplets Fb is thus maintained. This allows the p-polarized incident light Le to be radiated onto the incident position Pe on the liquid surface FLa with increased reproducibility. The dry states of the element traces 5F and the conducting traces 6F are thus stabilized, further suppressing defects in formation of the circuit elements 5 and the internal traces 6.
Since the light source of the incident light Le is formed by the semiconductor laser LD, the droplet ejection apparatus 10 is reduced in size and weight.
The reflective mirror 27 reflects the incident light Le from the semiconductor laser module LDM substantially along the tangential direction of the green sheet 4S and sends the incident light Le to the liquid surface FLa opposed to the ejection head 21. This allows drying of the droplets Fb immediately after the droplets Fb have been received by the green sheet 4S or joined together. As a result, the shapes and the sizes of the element traces 5F and the conducting traces 6F can be selected from a wider range.
The optical element PS changes the polarized state of the laser beam radiated by the semiconductor laser LD and radiates the p-polarized incident light Le. The laser beam of the p-polarized light is thus constantly received by the liquid surface FLa regardless of the polarized state of the laser beam of the semiconductor laser LD. This further reliably suppresses defects in trace forming.
The illustrated embodiment may be modified in the following forms.
The p-polarized incident light Le may be radiated onto the separate droplets Fb, instead of the liquid film FL in which the droplets Fb are joined together. In other words, as long as the polarized state of the laser beam radiated onto the droplets Fb is the state of the p-polarized light, the present invention is applicable regardless of the shapes of the droplets Fb, which are radiation targets of the laser beams.
The p-polarized incident light Le may be radiated in a direction other than a direction at the incident angle θe, which extends substantially along the tangential direction of the green sheet 4S. For example, the p-polarized incident light Le may be sent at the incident angle θe substantially along a normal direction of the green sheet 4S.
The laser beam radiated by the semiconductor laser LD, or the incident light Le, is not restricted to the polarized light with 100% of p-polarized components but may be a polarized light with at least 80% to 100% of p-polarized components.
Although the liquid film FL is dried by a common incident light Le, the incident light Le from the semiconductor laser module LDM may be divided in correspondence with the nozzles N. Each of the divided rays of the incident light Le is then radiated onto the corresponding portion of the liquid film FL. Alternatively, semiconductor laser modules LDM may be provided by the number equal to the number of the nozzles N. In this case, the incident light Le from each of the semiconductor laser modules LDM is radiated onto the corresponding portion of the liquid film FL.
In these cases, it is preferred that radiation of the incident light Le be performed selectively in correspondence with the ejection control signals SI for selecting the nozzles N. In other words, it is preferred that radiation of the incident light Le be carried out solely in correspondence with the nozzles N that eject the droplets Fb. In this manner, the incident light Le is solely radiated onto the liquid film FL, improving efficiency of using the incident light Le.
The p-polarized incident light Le may not only dry the droplets Fb or the liquid film FL, but also bake the dried droplets Fb or liquid film FL. In this case, the incident light Le, which is locally radiated, suppresses insufficient baking of the element trace 5F and the conducting trace 6F.
Instead of generating the bit map data BMD by the controller 40 in accordance with the trace forming information Ia, the bit map data BMD may be generated in advance by an external device and sent from the input device 41 to the controller 40.
The reflective mirror 27 does not necessarily have to be the galvanic mirror but may be a prism mirror. Alternatively, the reflective mirror 27 may be omitted and the incident light Le may be radiated from the cylindrical lens 25 directly onto the droplets Fb.
The droplet ejection head is not restricted to the droplet ejection head 21, which is a piezoelectric element driven type, but may be an ejection head of a resistance heating type or an electrostatically driven type.
All of the circuit elements 5 and all of the internal traces 6 do not have to be formed by an inkjet method. That is, only comparatively small circuit elements 5 or internal traces 6 may be provided by the inkjet method.
The trace forming material is not restricted to the metal ink but may be a liquid in which insulating film forming material or organic material is dispersed. In other words, the trace forming material may be any suitable material as long as the material is dried by the laser beam and forms traces of solid phase.
The traces are not restricted to the element traces 5F and the conducting traces 6F. The traces may be embodied as various types of metal traces used in liquid crystal displays, organic electroluminescence displays, or electric field effect type displays (FEDs or SEDs) including flat electron release elements. The term traces in this specification, among other types of deposits, include any linear deposits forming a pattern and dots forming an identification code. In other words, traces may be embodied as any suitable form as long as the traces are solid and formed by dried droplets.
The present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006119563 | Apr 2006 | JP | national |
| 2007023389 | Feb 2007 | JP | national |
