JP2008135601A - Circuit board and formation method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a circuit board, capable of forming a pattern formed on a substrate at a target position with accuracy while heating the substrate, and to provide the circuit board. <P>SOLUTION: The temperature of a green sheet 4G at via hole 7 formation is set to a temperature condition, equal to the temperature of the green sheet 4G, when the pattern of internal wiring is formed for formation. As a result, when the pattern of the internal wiring is formed, the green sheet 4G has the same degree of expansion as that of the green sheet 4G at via hole formation, and hence, the pattern of the internal wiring is not arranged deviated from the via hole 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a circuit board forming method and a circuit board.

In recent years, in order to form a wiring pattern on a substrate, a functional material is dissolved or dispersed in a solvent such as acetone, processed into a liquid material, and then formed into fine droplets (ink) on the substrate for patterning. A so-called droplet discharge method (inkjet method) is known (for example, see Patent Document 1).

In this type of droplet discharge method (inkjet method), by sequentially discharging droplets (ink) while heating the substrate, the drying speed of the droplets (ink) disposed on the substrate is increased. A technique for improving the patterning speed has been proposed.
JP 2004-306372 A

However, in particular, when a known aqueous solvent is used as the solvent, it is necessary to heat the substrate to about 46 ° C. in order to reliably evaporate the solvent. As a result, although depending on the constituent material of the substrate, the substrate normally expands during heating. For example, when an LTCC substrate (green sheet) is used as the substrate, when the substrate is heated from room temperature (26 ° C.) to 46 ° C., the substrate lengthens by about 80 μm.

As a result, when the pattern is formed while the substrate is heated, droplets are disposed on the expanded substrate, and thus there is a problem that the pattern cannot be formed at a desired position. For example, in the case where a pattern is formed so as to be connected to the via wiring on an LTCC substrate (green sheet) on which via wiring or the like has been formed in advance, the position of the liquid droplet is arranged by thermal expansion of the LTCC substrate (green sheet). Will shift greatly. For this reason, the formed pattern is not connected to the via wiring, and a substrate having desired characteristics is not manufactured.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a circuit board forming method capable of accurately forming a pattern formed on a substrate at a target position while heating the substrate. It is to provide a circuit board.

The circuit board forming method of the present invention includes a first step of forming a via hole in a substrate, a second step of injecting a wiring material into the via hole, and a functional material by a droplet discharge head based on bitmap data. In the circuit substrate forming method comprising the third step of sequentially discharging functional liquid droplets to the heated substrate, the substrate temperature at the time of forming the via hole and the substrate temperature at the time of discharging the droplet are made equal. .

According to this, the substrate when the via hole is formed expands or contracts by the same amount as the substrate when the droplet is discharged. Therefore, the pattern formed by the droplets of the functional liquid disposed on the substrate is formed in a state in which the pattern is expanded (expanded) as much as the degree of expansion (expansion) of the substrate at the time of forming the via hole. It is arranged at a position where it is electrically connected without being displaced.

In this circuit board forming method, the via hole may be formed by laser processing or punching.
According to this, the via hole is formed with high accuracy. In addition, a minute via hole can be formed.

In this pattern forming method, the substrate is a porous substrate and is a low-temperature firing sheet composed of ceramic particles and a resin, and the functional liquid is a liquid material in which a metal material is dispersed as the functional material. It may be.

According to this, a pattern made of a metal film can be formed neatly and in a short time on the porous substrate.
The circuit board of the present invention is a circuit board having wiring formed by the above-described circuit forming method.

  According to this, it becomes a circuit board which can raise productivity more.

Hereinafter, an embodiment of a pattern method embodying the present invention will be described with reference to the drawings.
First, the circuit module 1 of the present invention will be described.
In FIG. 1, a circuit module 1 includes an LTCC multilayer substrate 2 formed in a plate shape, and a semiconductor chip 3 connected to the upper side of the LTCC multilayer substrate 2 by wire bonding.

The LTCC multilayer substrate 2 is a laminate of a plurality of circuit boards formed in a sheet shape and an LTCC substrate 4 as a low-temperature firing sheet. Each LTCC substrate 4 is a glass ceramic material (for example, a sintered body of a glass component such as borosilicate alkali oxide and a ceramic component such as alumina) (porous substrate), and has a thickness of several hundred μm. It is. In the following description, for convenience of explanation, it is assumed that the LTCC substrate 4 has a square shape in which the length of one side is Lo (see FIG. 9A).

Each LTCC substrate 4 includes various circuit elements 5 such as a resistance element, a capacitive element, and a coil element, internal wiring 6 that electrically connects each circuit element 5, and a predetermined hole diameter that exhibits a stack via structure and a thermal via structure. A plurality of via holes 7 having a diameter (for example, 30 μm) and via wirings 8 filled in the via holes 7 are formed. The internal wiring 6 is connected to a predetermined via wiring 8 to electrically connect the circuit elements 5 to each other. Each internal wiring 6 is a sintered body obtained by sintering fine particles of silver (Ag) as a functional material and a metal material, and is formed using a droplet discharge device (inkjet device).

Next, a droplet discharge device 20 for manufacturing the LTCC multilayer substrate 2 will be described with reference to FIGS.
It explains according to. FIG. 2 is an overall perspective view illustrating the droplet discharge device 20. 3 and 4 are diagrams for explaining the droplet discharge head 30. FIG.

In FIG. 2, the droplet discharge device 20 has a base 21 formed in a rectangular parallelepiped shape.
A pair of guide grooves 22 extending along the longitudinal direction (Y arrow direction) is formed on the upper surface of the base 21. Above the guide groove 22, a stage 23 is provided that moves along the guide groove 22 in the Y arrow direction and the counter-Y arrow direction. A placement portion 24 is formed on the upper surface of the stage 23 to place the LTCC substrate 4 (hereinafter referred to as “green sheet 4G”) before firing. The placement unit 24 positions and fixes the placed green sheet 4G with respect to the stage 23, and conveys the green sheet 4G in the Y arrow direction and the counter-Y arrow direction. A rubber heater H is embedded in the upper surface of the stage 23. Green sheet 4G placed on the placement unit 24
Is heated to a predetermined temperature by a rubber heater H. In this embodiment, 4
It is heated to 6 ° C.

The base 21 has a gate-shaped guide member 2 straddling the direction (X arrow direction) orthogonal to the conveying direction.
5 is erected. On the upper side of the guide member 25 is an ink tank 26 extending in the direction of the arrow X.
Is arranged. The ink tank 26 stores the metal ink F as the functional liquid and supplies the stored metal ink F to the droplet discharge head 30 at a predetermined pressure.

As the metal ink F, for example, an aqueous metal ink in which fine particles of silver (Ag) having a particle diameter of several nm to several tens of nm are dispersed in an aqueous solvent can be used. Liquid droplet Fb of metal ink F (see FIG. 4)
When heated, a part of the solvent or the dispersion medium evaporates to thicken the outer shape of the surface. The droplet Fb of the metal ink F whose outer edge is thickened stops and stops its own wetting and spreading along the surface direction of the green sheet 4G.

The guide member 25 is formed with a pair of upper and lower guide rails 28 extending in the X arrow direction over substantially the entire width in the X arrow direction. A pair of upper and lower guide rails 28 includes a carriage 29.
Is attached. The carriage 29 is guided by the guide rail 28 and moves in the X arrow direction and the counter X arrow direction. A droplet discharge head (hereinafter simply referred to as “discharge head”) 30 is disposed in the carriage 29.

3 is a view of the discharge head 30 as viewed from the green sheet 4G side (lower side).
4 is a cross-sectional view of a main part for explaining the internal configuration of the ejection head 30. In the present embodiment, for the sake of convenience of explanation, the description will be made assuming that one ejection head 30 is provided on the carriage 29, but actually, a plurality of ejection heads 30 are provided side by side.

As shown in FIGS. 3 and 4, nozzle plates 31 are respectively disposed below the ejection head 30.
Is provided. A nozzle forming surface 31a substantially parallel to the green sheet 4G is formed on one side surface of the nozzle plate 31 opposite to the green sheet 4G. When the green sheet 4G is positioned immediately below the ejection head 30, the nozzle forming surface 31a has a distance (platen gap) between the nozzle forming surface 31a and the green sheet 4G held at a predetermined distance (for example, 500 μm). Yes.

In FIG. 3, the nozzle plate 31 includes a plurality of nozzles N arranged along the direction of the arrow Y.
A pair of nozzle rows NL is formed. In the pair of nozzle rows NL, 180 nozzles N are formed per inch. In FIG. 3, for convenience of explanation, only 10 nozzles N are shown per row.

In the pair of nozzle rows NL, each nozzle N of one nozzle row NL interpolates between the nozzles N of the other nozzle row NL. That is, the ejection head 30 has 180 × 2 = 360 nozzles N per inch in the Y arrow direction (the maximum resolution is 360 dpi).

In FIG. 4, a supply tube 30 </ b> T is connected to the upper side of the discharge head 30. The supply tube 30T is disposed so as to extend in the Z arrow direction, and supplies the metal ink F from the ink tank 26 to the ejection head 30.

On the upper side of the nozzle N, a cavity 32 communicating with the supply tube 30T is formed. The cavity 32 accommodates the metal ink F from the supply tube 30T and supplies the metal ink F to the corresponding nozzle N. On the upper side of the cavity 32, a vibration plate 33 is attached, which vibrates in the vertical direction and expands and contracts the volume in the cavity 32. A piezoelectric element PZ corresponding to the nozzle N is disposed on the upper side of the vibration plate 33. The piezoelectric element PZ contracts and expands in the vertical direction to vibrate the diaphragm 33 in the vertical direction. Diaphragm 33 that vibrates vertically
Forms metallic ink F into droplets Fb of a predetermined size and ejects them from the corresponding nozzles N. The ejected droplets Fb fly in the direction of the opposite Z arrow of the corresponding nozzle N, land on the upper surface (ejection surface 4Ga) of the green sheet 4G, and localize. And the droplet discharge apparatus 2 of this embodiment
0 is sequentially discharged so that a plurality of droplets Fb are connected in series on the green sheet 4G before firing. In this way, the internal wiring 6 formed in a line shape on the green sheet 4G
Pattern (wiring pattern) is formed.

Next, the electrical configuration of the droplet discharge device 20 will be described with reference to FIG.
As shown in FIG. 5, the control device 50 includes a CPU 50A, a ROM 50B, a RAM 50C, and the like. The control device 50 follows the stored various data and various control programs.
A reciprocating process of the stage 23 and the carriage 29, a heating control process of the rubber heater H, a drive control process of the piezoelectric element PZ, and the like are executed.

An input / output device 51 having various operation switches and a display is connected to the control device 50. The input / output device 51 displays the processing status of various processes executed by the droplet discharge device 20. Further, the input / output device 51 inputs bitmap data BD for forming the internal wiring 6 to the control device 50.

Specifically, the bitmap data BD is data that defines ON or OFF of each piezoelectric element PZ according to the value of each bit (“0” (L level) or “1” (H level)). That is, the bitmap data BD is data defining whether or not the surface of the green sheet 4G is divided into a plurality of regions and the droplets Fb are arranged in the divided regions. The bitmap data BD is based on the assumption that the green sheet 4G is at a high temperature (46 ° C.), and is data that takes into account the expansion of the green sheet 4G due to heating.

An X-axis motor drive circuit 52 is connected to the control device 50. The control device 50 outputs a drive control signal to the X-axis motor drive circuit 52. In response to the drive control signal from the control device 50, the X-axis motor drive circuit 52 rotates the X-axis motor MX for moving the carriage 29 forward or backward.

Further, a Y-axis motor drive circuit 53 is connected to the control device 50. Control device 50
Outputs a drive control signal to the Y-axis motor drive circuit 53. In response to the drive control signal from the control device 50, the Y-axis motor drive circuit 53 rotates the Y-axis motor MY for moving the stage 23 forward or backward.

Furthermore, a head drive circuit 54 is connected to the control device 50. Control device 50
Outputs a discharge timing signal LT synchronized with a predetermined discharge frequency to the head drive circuit 54. The control device 50 outputs a drive signal COM for driving each piezoelectric element PZ to the head drive circuit 54 in synchronization with the ejection frequency. The control device 50 uses the bitmap data BD
Is used to generate a discharge control signal SI synchronized with a predetermined frequency, and the discharge control signal SI is serially transferred to the head drive circuit 54. The head drive circuit 54 serially / parallel converts the ejection control signal SI from the control device 50 in correspondence with each piezoelectric element PZ. Further, every time the head driving circuit 54 receives the ejection timing signal LT from the control device 50, the head driving circuit 54 latches the serial / parallel converted ejection control signal SI, and drives the piezoelectric element PZ selected by the ejection control signal SI. COM is supplied.

The control device 50 is connected to a rubber heater drive circuit 55. The control device 50 outputs a drive control signal to the rubber heater drive circuit 55. The rubber heater drive circuit 55 drives the rubber heater H in response to a drive control signal from the control device 50, and controls the green sheet 4G placed on the stage 23 to have a predetermined temperature. In the present embodiment, the temperature of the green sheet 4G is equal to or higher than the temperature of the metal ink F when ejected from the ejection head 30 and less than the boiling point of the functional material included in the metal ink F (the lowest boiling temperature in the liquid composition). Temperature) of 46 ° C. in this embodiment.

Next, a via hole forming apparatus 60 for forming the via hole 7 in the green sheet 4G will be described with reference to FIGS. FIG. 6 is an overall perspective view illustrating the via hole forming apparatus 60. FIG. 7 is a schematic diagram of a laser device.

In FIG. 6, the via hole forming device 60 has a configuration similar to that of the droplet discharge device 20 described above. That is, the via hole forming device 60 has a base 61 formed in a rectangular parallelepiped shape. A pair of guide grooves 62 extending along the longitudinal direction (Y arrow direction) is formed on the upper surface of the base 61. Above the guide groove 62, a stage 63 is provided that moves along the guide groove 62 in the Y arrow direction and in the anti-Y arrow direction. On the upper surface of the stage 63, a placement portion 64 is formed to place the green sheet 4G. The placement unit 64 positions and fixes the placed green sheet 4G with respect to the stage 63, and places the green sheet 4G in the Y direction.
It is conveyed in the arrow direction and the anti-Y arrow direction. A rubber heater H <b> 1 is embedded in the upper surface of the stage 63. The green sheet 4G placed on the placement unit 64 is heated to a predetermined temperature by the rubber heater H1. In this embodiment, it is heated to 46 ° C.

The base 61 has a gate-shaped guide member 6 straddling the direction (X arrow direction) orthogonal to the conveying direction.
5 is erected. The guide member 65 is formed with a pair of upper and lower guide rails 68 extending in the X arrow direction over substantially the entire width in the X arrow direction. A carriage 69 is attached to the pair of upper and lower guide rails 68. X guided by a pair of upper and lower guide rails 68
Move in the arrow direction and anti-X arrow direction. A laser device 70 is disposed on the carriage 69.

As shown in FIG. 7, the laser device 70 includes a laser emission port 70a on its lower surface, and irradiates a laser beam LZ from the laser emission port 70a toward the upper surface of the green sheet 4G. In the green sheet 4G, a through hole (via hole 7) is formed by the energy of the laser beam LZ. The via hole 7 of this embodiment has a diameter of about 30 nm.

Next, the electrical configuration of the via hole forming apparatus 60 will be described with reference to FIG. FIG.
These are electrical circuit diagrams for explaining the electrical configuration of the via hole forming apparatus 60.
As shown in FIG. 8, the control device 80 includes a CPU 80A, a ROM 80B, a RAM 80C, and the like. The control device 80 executes the reciprocating motion of the stage 63 and the carriage 69, the heating control processing of the rubber heater H1, the drive control processing of the laser device 70, and the like according to the stored various data and various control programs.

The control device 80 is connected to an input / output device 81 having various operation switches and a display. The input / output device 81 displays the processing status of various processes executed by the via hole forming device 60. Further, the input / output device 81 inputs bitmap data BD1 for forming a via hole in the green sheet 4G to the control device 80.

Specifically, the bitmap data BD1 is data that defines on / off of the laser device 70 corresponding to the value of each bit (“0” (L level) or “1” (H level)). That is, similar to the bitmap data BD, the data defines whether or not the surface of the green sheet 4G is divided into a plurality of areas and each of the divided areas is irradiated with the laser beam LZ.

The bitmap data BD1 is based on the assumption that the green sheet 4G is at a high temperature (46 ° C.), and is data that takes into account the expansion of the green sheet 4G due to heating.

The control device 80 is connected to an X-axis motor drive circuit 82. The control device 80
A drive control signal is output to the X-axis motor drive circuit 82. The X axis motor drive circuit 82 is an X axis motor for moving the carriage 69 in response to a drive control signal from the control device 80 for moving the carriage 69 in response to a drive control signal from the control device 80. Turn MX1 forward or reverse.

Further, a Y-axis motor drive circuit 83 is connected to the control device 80. Control device 80
Outputs a drive control signal to the Y-axis motor drive circuit 83. In response to the drive control signal from the control device 80, the Y-axis motor drive circuit 83 rotates the Y-axis motor MY1 for moving the stage 63 forward and backward.

Furthermore, a laser device drive circuit 84 is connected to the control device 80. The control device 80 outputs an irradiation timing signal LT1 synchronized with a predetermined ejection frequency to the laser device driving circuit 84. The control device 80 drives a drive control signal CO for driving the laser device 70.
M1 is output to the laser device drive circuit 84 in synchronization with the irradiation frequency. The control device 80 uses the bitmap data BD1 to generate an emission control signal SI1 synchronized with a predetermined frequency, and serially transfers the emission control signal SI1 to the laser device driving circuit 84.

The laser device drive circuit 84 performs serial / parallel conversion on the emission control signal SI1 from the control device 80. Further, every time the laser device driving circuit 84 receives the irradiation timing signal LT1 from the control device 80, the laser device driving circuit 84 latches the serial / parallel converted emission control signal SI1,
Each of the laser devices 70 selected by the emission control signal SI1 has a drive control signal COM1.
Supply.

The control device 80 is connected to a rubber heater drive circuit 85. The control device 80 outputs a drive control signal to the rubber heater drive circuit 85. The rubber heater drive circuit 85 drives the rubber heater H1 in response to the drive control signal from the controller 80, and controls the heating of the green sheet 4G placed on the stage 63 so as to have a predetermined temperature. In the present embodiment, the temperature of the green sheet 4G is made equal to the temperature (46 ° C.) at which the green sheet 4G is heated by the droplet discharge device 20.

Next, a method of forming the internal wiring 6 on the green sheet 4G using the droplet discharge device 20 will be described with reference to FIGS. 2 and 9 to 11.
First, the surface of the green sheet 4G is washed with pure water pressure spray and then dried to sufficiently remove dust and moisture adsorbed on the surface. Subsequently, as shown in FIG. 9A, a protective sheet S is attached to the surface of the green sheet 4G. This protective sheet S is light transmissive,
Although it has heat resistance and expansion / contraction properties and adheres closely to the surface of the green sheet 4G, when it is peeled off from the green sheet 4G, it is easily peeled off without sticking to the surface. It is composed of a polymer resin.

Next, the green sheet 4G is placed on the placement portion 64 of the via hole forming apparatus 60. And the green sheet 4 at the time of forming the pattern of the internal wiring 6 using the rubber heater H1
Heat to a temperature consistent with the G heating temperature. In this embodiment, it heats to 46 degreeC. Then, the green sheet 4G is heated using the via hole forming device 60 while the green sheet 4G is heated.
A via hole 7 is formed in the first step. More specifically, the via hole forming apparatus 60 sequentially irradiates a predetermined position on the green sheet 4G with the laser beam LZ based on the preset bitmap data BD1.

At this time, as shown in FIG. 9B, the green sheet 4G expands at a predetermined coefficient of thermal expansion when heated to 46 ° C., and its surface area is expanded. That is, the green sheet 4G has a square shape with one side having a length Ls longer than Lo. In this state, a laser beam LZ is emitted from the laser device 70 and the via hole 7 passes through the protective sheet S.
Is formed. The via hole 7 of this embodiment has a diameter of about 30 nm.

Then, it cools to normal temperature (26 degreeC). Then, as shown in FIG.9 (c), the green sheet 4G returns to the square shape where the length of one side is Lo. Thereafter, the mounting portion 6 of the laser device 70
4 remove the green sheet 4G.

Thereafter, as shown in FIG. 9D, a conductive paste (for example, silver paste) P as a wiring material is applied on the protective sheet S, and a squeegee K is used as shown in FIG. Then, the conductive paste P is leveled on the protective sheet S. Then, the conductive paste P is injected into the via hole 7 as shown in FIG. Then, the protective sheet S is green sheet 4G
(See FIG. 10C).

Next, the green sheet 4G is dried using a drying furnace (not shown). Then, the solvent component of the conductive paste P injected into the via hole 7 is removed, and the via wiring 8 is formed in the via hole 7 (second step).

Subsequently, as shown in FIG. 2, the green sheet 4G is supported and fixed to the stage 23 so that the upper surface (discharge surface 4Ga) of the green sheet 4G faces the upper side (Z arrow direction side). At this time,
The stage 23 arranges the green sheet 4G on the side opposite to the Y arrow direction from the carriage 29. FIG. 11A is a top view of the green sheet 4G at this time, that is, at normal temperature (26 ° C.). In FIG. 11A, for convenience of explanation, 3 × 3 (= 9) via holes 7 (via wirings 8) are shown. However, in actuality, the number is more than 3 × 3 (= 9). Many via holes 7 (via wirings 8) are formed.

Next, the bitmap data BD is input from the input / output device 51 to the control device 50. The control device 50 stores the bitmap data BD from the input / output device 51.
Thereafter, a drive control signal is output from the control device 50 to the rubber heater drive circuit 55, and the green sheet 4G placed on the stage 23 in response to the drive control signal has a predetermined temperature (in this embodiment, 46 ° C.). ) Is controlled by heating. As a result, the green sheet 4G is 46
When heated to 0 ° C., it again expands. FIG. 11B is a top view of the green sheet 4G at this time, that is, at the heating temperature (46 ° C.). Accordingly, since the green sheet 4G has the same temperature as that when the via hole 7 is formed, the green sheet 4G expands by the same amount as that when the via hole 7 is formed and has the same surface area. That is, the green sheet 4G has a square shape with a side length Ls.

Subsequently, the control device 50 drives the Y-axis motor MY via the Y-axis motor drive circuit 53 and conveys the stage 23 so as to pass a predetermined position immediately above the green sheet 4G in the X arrow direction. Then, the control device 50 drives the X-axis motor MX via the X-axis motor drive circuit 52 to start scanning (forward movement) of the ejection head 30.

When the control device 50 starts scanning (forward movement) of the ejection head 30, the control device 50 generates the ejection control signal SI based on the bitmap data BD, and outputs the ejection control signal SI and the drive signal COM to the head drive circuit 54. To do. That is, the control device 50 drives and controls each piezoelectric element PZ via the head drive circuit 54, and each time the ejection head 30 is positioned at the landing position for forming the internal wiring 6, the selected nozzle N The droplets Fb are discharged sequentially. At this time, FIG.
), Since the green sheet 4G expands as much as when the via hole 7 is formed, the landing position of the droplet Fb is a desired position, that is, the circuit elements 5 are electrically connected to each other. As described above, the via holes 7 (via wirings 8) formed previously are arranged so as to be connected to each other (third step).

Then, it cools to normal temperature (26 degreeC), and removes the green sheet 4G from the droplet discharge apparatus 20. FIG. Therefore, as shown in FIG. 11 (d), the green sheet 4G returns to a square shape with a side length of Lo. Then, the green sheet 4G is dried using a drying furnace (not shown). Then, the solvent component of the droplet Fb landed on the surface of the green sheet 4G is removed. In this way, the internal wiring 6 is formed.

As described above, according to the present embodiment, the following effects are obtained.
(1) According to this embodiment, since the droplet Fb is discharged while heating the green sheet 4G to 46 ° C., the droplet Fb landed on the green sheet 4G is immediately heated to remove the solvent component. Is done. Therefore, the internal wiring 6 can be formed in a short time.

(2) According to the present embodiment, when the via hole 7 is formed in the green sheet 4G by the laser device 70, the droplet discharge device 20 is used, that is, the pattern of the internal wiring 6 is discharged by discharging the droplet Fb. During the formation, the green sheet 4G was heated to a temperature equal to the heating temperature (46 ° C.). That is, when forming the via hole 7 and the pattern of the internal wiring 6, the green sheet 4G was formed under the same temperature condition.

Therefore, the bitmap data BD1 used when forming the via hole 7 and the bitmap data BD used when forming the pattern of the internal wiring 6 are resistant to variations in the size of the green sheet 4G due to thermal expansion or the like. They can be unified without the need for correction separately.

As a result, the internal wiring 6 that is electrically connected without deviation from the via hole 7 (via wiring 8) can be obtained only by making the temperature of the green sheet 4G when forming the via hole and the pattern of the internal wiring 6 the same. The pattern can be formed.

(3) According to the present embodiment, since the pattern of the internal wiring 6 is formed at the same temperature as that for forming the via hole 7 (via wiring 8), the green sheet 4G with higher productivity is provided. Can do.

In addition, this invention can also be changed and embodied as follows.
In the above embodiment, the green sheet 4G is heated to 46 ° C. However, the heating temperature is not limited to this, and may be another temperature. In short, the green sheet 4G is heated at the time of discharging the droplet Fb, but the via hole 7 may be formed at the same temperature as the heating temperature.
In the above embodiment, the via wiring 8 is formed by filling the via hole 7 formed with the conductive paste P using the squeegee K after forming the via hole 7, but the present invention is limited to this. It is not a thing. For example, the via wiring 8 may be formed by depositing a conductive material such as silver (Ag) after the via hole 7 is formed and filling the via hole 7 with the conductive material.
In the above embodiment, the via hole 7 is formed by laser processing, but the present invention is not limited to this. For example, the via hole 7 may be formed by punching. Further, the via hole 7 may be formed by plasma processing or shot blast processing.
In the above embodiment, the via hole 7 is embodied as the structure, but the present invention is not limited to this and may be other. In short, any material can be used as long as it is formed on the green sheet 4G. By doing so, the same effect as described above can be obtained.
In the above embodiment, the conductive material (silver (Ag)) is embodied as the functional material for forming the internal wiring 6, but the present invention is not limited to this. For example, gold (Au), platinum (Pt), copper (
Cu), palladium (Pd), rhodium (Rh), osmium (Os), ruthenium (R)
u), iridium (Ir), iron (Fe), tin (Sn), zinc (Zn), cobalt (Co
), Nickel (Ni), chromium (Cr), titanium (Ti), tantalum (Ta), tungsten (W), indium (In), or any two or more thereof An alloy in which is combined may be used. However, since silver is reduced at a relatively low temperature, it is easy to handle. In this regard, when using a droplet discharge device,
It is preferable to use a functional liquid containing silver (Ag).

Moreover, it may replace with a metal and may contain the organic compound. An organic compound here is a compound from which a metal precipitates by decomposition | disassembly by heating. Examples of such organic compounds include chlorotriethylphosphine gold, chlorotrimethylphosphine gold, chlorotriphenylphosphine gold, silver 2,4-pentanedionan complex, copper hexafluoropentanedionacyclooctadiene complex, and the like.

Furthermore, the form of the metal contained in the functional liquid may be a form of particles represented by nanoparticles or a form of a compound such as an organic compound.
Furthermore, functional fluid. Instead of metal, a conductive polymer soluble material such as polyaniline, polythiophene, polyphenylene vinylene, poly (3,4 ethylenedioxytoophene) (PEDOT) may be included.
In the above embodiment, the green sheet 4G is used as the substrate. However, the present invention is not limited to this, and may be applied to another substrate instead of the green sheet 4G. For example,
The present invention can also be applied to an epoxy substrate, a glass epoxy substrate, a ceramic substrate, a silicon substrate, or the like.

The side sectional view of a circuit module. The whole perspective view of a droplet discharge device. The bottom view of a droplet discharge head. The principal part sectional side view of a droplet discharge head. The block diagram for demonstrating the electrical structure of a droplet discharge apparatus. The whole perspective view of a laser apparatus. Schematic of a laser device. The block diagram for demonstrating the electric constitution of a laser apparatus. (A)-(d) is a figure for demonstrating the formation method of a via hole and a via wiring, respectively. Similarly, (a)-(c) is a figure for demonstrating the formation method of a via hole and a via wiring, respectively. (A)-(d) is a figure for demonstrating the method of forming the pattern of an internal wiring, respectively.

Explanation of symbols

BD: Bitmap data, F: Functional ink and metal ink as liquid, Fb: Droplet,
H: Rubber heater, 4G: Porous substrate, low-temperature firing sheet, green sheet as substrate and circuit board, 5: circuit element, 7: via hole, 8 ... via wiring.

Claims (4)

A first step of forming a via hole in the substrate;
A second step of injecting a wiring material into the via hole;
In a circuit board forming method comprising a third step of sequentially discharging functional liquid droplets containing a functional material to a heated substrate based on bitmap data using a droplet discharge head,
A circuit board forming method, wherein a substrate temperature at the time of forming the via hole and a substrate temperature at the time of discharging the droplet are made equal. The circuit board forming method according to claim 1,
In the first step, the via hole is formed on the substrate by laser processing or punching. In the circuit board formation method according to claim 1 or 2,
The substrate is a low-temperature firing sheet composed of a porous substrate and ceramic particles and a resin,
The circuit board forming method, wherein the functional liquid is a liquid in which a metal material is dispersed as the functional material. It formed with the circuit board formation method as described in any one of Claims 1-3, The circuit board characterized by the above-mentioned.

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