JP2010056417A - Method of forming wiring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form excellent wiring to electrically connect laminated substrates each other even when the extending direction of a step between the substrates is not perpendicular to the connecting direction of electrodes. <P>SOLUTION: A method of forming wiring is to form the wiring for connecting electrodes 112 disposed on substrates 11a-11c by making an ink drop R containing a conductive material reach the laminated substrates 11a-11c from a printing head 2. This method includes a wiring forming process to form conductive layers 12a on the top faces 113 of the substrates 11a-11c and conductive layers 12b on the sides 115 of the substrates 11a-11c, using substrates laminated so that the extending direction P of the step part D between the substrates 11a-11c and the connecting direction Q connecting the electrodes 112 to be connected each other by a straight line are mutually inclined when viewing from the top, as the substrates 11a-11c, and to form the wiring by conductive layers 12a, 12b. In the wiring forming process, the conductive layer 12 in a region close to the level difference part D between the conductive layers 12a, 12d is formed perpendicularly to the extending direction P. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wiring forming method.

  In recent years, in response to demands for miniaturization and high integration of electronic components, development of methods for three-dimensional mounting of semiconductor chips has progressed. As such a method, for example, wire bonding in which electrodes of a plurality of stacked substrates (electronic devices) are electrically connected by wires is known.

  However, when a plurality of stacked substrates are bonded, there are problems such that the thickness of the entire device is further larger than the thickness of the stacked device due to the height of bonding, and processing time is required.

  Therefore, in recent years, instead of wire bonding, a method has been proposed in which conductive ink droplets are ejected from the ink jet head onto the upper and side surfaces of each semiconductor chip to form a conductive layer between the electrodes (for example, Patent Documents). 1).

By the way, when the substrates are stacked, as shown in FIG. 18, the upper and lower substrates are displaced at the time of bonding. As a result, the tangential direction of the step portion D between the substrates (hereinafter referred to as the step extending direction P) and the connection of the electrode 112 In some cases, the direction Q (the formation direction of the conductive layer 200) is inclined, that is, not orthogonal. Here, in FIG. 18A, the upper substrate is stacked in a state of being shifted in the step extending direction P with respect to the lower substrate (hereinafter referred to as “parallel shift”), thereby extending the step. The direction P and the connection direction Q are not orthogonal to each other. Also, in FIG. 18B, the upper substrate is rotated with respect to the lower substrate in the stacking plane, and the two sides are stacked in a tilted state (hereinafter referred to as “rotational deviation”). Thus, the step extending direction P and the connection direction Q are not orthogonal to each other, and the distance between the electrodes to be connected is increased as the distance from the rotation center increases.
JP 2006-135236 A

  However, as shown in FIGS. 19A and 19B, when the electrodes 112 of the substrates stacked in a state of parallel displacement or rotational displacement are connected by a conductive layer 200 of conductive ink, the step extending direction P Since the connection direction Q is inclined with respect to the ink, the ink is pulled in the shear direction (see the shaded arrow in the figure) by the surface tension as shown in FIG. Disconnection occurs, and good wiring cannot be formed.

  An object of the present invention has been made in view of the above circumstances, and even when the step extending direction between the substrates and the connection direction of the electrodes are not orthogonal to each other, the stacked substrates are electrically connected. It is to provide a wiring forming method capable of forming a simple wiring.

In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that ink droplets of ink containing a conductive material are ejected and landed on a plurality of stacked substrates from an ink jet print head. A wiring formation method for forming a wiring for electrically connecting electrodes disposed on an upper surface or a side surface of a substrate to each other,
As the plurality of substrates,
The tangential direction of the stepped portion between these substrates and the connection direction in which the electrodes to be connected are connected with a straight line are stacked so as to be inclined with respect to each other in a top view,
A wiring forming step of forming an upper surface conductive layer on the upper surface of the substrate, a side surface conductive layer on a side surface of the substrate, and forming the wiring with the upper surface conductive layer and the side surface conductive layer;
In this wiring formation process,
Of the upper surface conductive layer and the side surface conductive layer, a conductive layer in a region close to the stepped portion is formed so as to be orthogonal to a tangential direction of the stepped portion.

The invention according to claim 2 is the wiring forming method according to claim 1,
Before the wiring formation step,
A first position acquisition step of acquiring a positional relationship between the stepped portion and each electrode;
A second position acquisition step of acquiring the position of the conductive layer to be formed on the stepped portion;
A route determination step of determining a route of the wiring based on information obtained in the first position acquisition step and the second position acquisition step.

The invention according to claim 3 is the wiring forming method according to claim 1 or 2,
The wiring is characterized in that it is bent twice in a top view to form a substantially Z-shape.

The invention according to claim 4 is the wiring forming method according to claim 1 or 2,
The wiring is characterized in that it is bent three times in a top view to form a substantially W shape or a substantially M shape.

Invention of Claim 5 is the wiring formation method as described in any one of Claims 1-4,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
By forming the plurality of wirings at a time by the print head, the plurality of wirings having the same number of bendings and the same bending angle are formed.

Invention of Claim 6 is the wiring formation method as described in any one of Claims 1-5,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated with the lower substrate rotated in the lamination plane, and the distance between the electrodes to be connected increases as the distance from the rotation center increases. Use
In the wiring formation step,
A plurality of the wirings having different lengths are formed.

The invention according to claim 7 is the wiring forming method according to any one of claims 1 to 6,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
By forming the plurality of wirings at once with the print head, the plurality of wirings are formed in parallel with each other.

Invention of Claim 8 is the wiring formation method as described in any one of Claims 1-7,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated in a state of being rotated in the lamination plane with respect to the lower substrate, and the distance between the electrodes to be connected increases as the distance from the rotation center increases 2 Using two substrates
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A stage that can rotate in a plane perpendicular to the direction of ink droplet ejection by the print head and can move in a direction along the vertical plane while the two substrates are supported facing the print head. Use
By moving the stage while ejecting ink droplets from each nozzle of the print head, a conductive layer is formed from the electrode on the upper substrate to the vicinity of the stepped portion on the upper substrate, and the upper A first drawing step of forming a conductive layer in a direction orthogonal to the stepped portion from the vicinity of the stepped portion on the substrate to the upper surface of the lower substrate across the stepped portion;
After the first drawing step, the stage is moved, and ink droplets are discharged to different timings for each nozzle of the print head, so that from the end point of each conductive layer formed in the first drawing step, A second drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected on the upper surface of the lower substrate;
After the second drawing step, the stage is rotated in a vertical plane in the discharge direction around the end point of the conductive layer drawn between the electrodes connected on the side farthest from the rotation center. A rotation step of making the arrangement direction of the plurality of electrodes on the lower substrate parallel to the arrangement direction of the plurality of nozzles;
After the rotation step, the stage is moved, and ink droplets are ejected at different timings for each nozzle of the print head, so that the lower end of each conductive layer formed in the second drawing step is And a third drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected up to the electrodes on the side substrate.

The invention according to claim 9 is the wiring forming method according to claim 8,
The conductive layer formed from the electrode on the upper substrate to the vicinity of the stepped portion on the upper substrate, and from the vicinity of the stepped portion on the upper substrate to the upper surface of the lower substrate across the stepped portion, The first drawing step is characterized in that the first drawing step is performed so that the conductive layer formed in a direction orthogonal to the stepped portion is linear when viewed from above.

Invention of Claim 10 is the wiring formation method as described in any one of Claims 1-7,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated in a state of being rotated in the lamination plane with respect to the lower substrate, and the distance between the electrodes to be connected increases as the distance from the rotation center increases 2 Using two substrates
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A stage that can rotate in a plane perpendicular to the direction of ink droplet ejection by the print head and can move in a direction along the vertical plane while the two substrates are supported facing the print head. Use
By moving the stage and ejecting ink droplets at different timings for each nozzle of the print head, the length of the electrodes according to the distance between the electrodes to be connected is reduced from the electrodes on the lower substrate. A first drawing step of forming a conductive layer;
After the first drawing step, the stage is rotated in a vertical plane in the discharge direction around the end point of the conductive layer drawn between the electrodes connected on the side farthest from the rotation center. A rotation step in which the arrangement direction of the plurality of electrodes on the upper substrate is parallel to the arrangement direction of the plurality of nozzles;
After the rotating step, the upper stage is moved from the end point of each conductive layer formed in the first drawing step by moving the stage and discharging ink droplets at different timings for each nozzle of the print head. A second drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected, on each straight line in the orthogonal direction of the stepped portion passing through the electrode of the substrate on the upper surface of the lower substrate When,
After the second drawing step, the stage is moved while discharging the ink droplets from the nozzles of the print head so as to straddle the stepped portion from the end point of each conductive layer formed in the second drawing step. The conductive layer is formed in the direction perpendicular to the stepped portion to the vicinity of the stepped portion on the upper substrate, and the conductive layer is formed from the vicinity of the stepped portion on the upper substrate to the electrode on the upper substrate. 3 drawing processes are performed.

The invention according to claim 11 is the wiring forming method according to claim 10,
A conductive layer formed in an orthogonal direction of the step portion from the end point of each conductive layer formed in the second drawing step to the vicinity of the step portion in the upper substrate across the step portion, and the upper substrate The third drawing step is performed so that the conductive layer formed from the vicinity of the step portion to the electrode on the upper substrate has a linear shape in a top view.

Invention of Claim 12 is the wiring formation method as described in any one of Claims 1-11,
In the wiring formation step,
A conductive layer is formed by landing ink droplets at equal intervals in a top view in an orthogonal direction of the stepped portion.

Invention of Claim 13 is the wiring formation method as described in any one of Claims 1-11,
In the wiring formation step,
The conductive layer is formed by landing ink droplets so as to be equidistant in the formation direction of the conductive layer in a top view.

Invention of Claim 14 is the wiring formation method as described in any one of Claims 1-13,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
One having a plurality of nozzles arranged linearly in accordance with the interval of the electrodes in the substrate is used.

Invention of Claim 15 is the wiring formation method as described in any one of Claims 1-14,
In the wiring formation step,
A voltage is applied between the plurality of substrates and the print head to charge the ink droplets, and an electrostatic attraction force is applied to the ink droplets to land the ink droplets on the plurality of substrates. And

  According to the first aspect of the present invention, the conductive layer in the region adjacent to the stepped portion is formed so as to be orthogonal to the tangential direction of the stepped portion. Even when the substrate is stacked in a state where the step extension direction and the electrode connection direction are not orthogonal, the conductive layer formation direction is orthogonal to the step extension direction in the region close to the step portion. It becomes. Therefore, since the ink is prevented from being pulled in the shearing direction (step extending direction) by the surface tension, it is possible to form a favorable wiring that electrically connects the stacked substrates.

  According to the invention described in claim 5, by forming a plurality of wirings at once with a print head, the plurality of wirings are formed with the same number of bendings and the same bending angle. Compared with the case of forming, formation of wiring can be facilitated.

  According to the seventh aspect of the present invention, since the plurality of wirings are formed in parallel with each other by forming the plurality of wirings at once with the print head, each wiring is formed separately. In comparison, the formation of the wiring can be facilitated.

  According to the fifteenth aspect of the present invention, by applying a voltage between the plurality of substrates and the print head to form an electric field, the print head is directed to the rising surface of the step between the plurality of stacked substrates. Electric field lines are formed. Then, by charging the ink droplets and applying an electrostatic attraction force, the ink droplets can fly along the lines of electric force, and the ink droplets are sufficiently applied to the rising portions between the stacked substrates. It becomes possible to adhere to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the substrate unit 10 according to the present embodiment will be described.
FIG. 1 is a perspective view showing a schematic configuration of the substrate unit 10.

  As shown in FIG. 1 (a), the substrate unit 10 is formed by laminating a plurality of rectangular substrates 11 so that the end portion forms a stepped stepped portion D. In this embodiment, the substrate unit 10 is laminated in three steps. Is. Hereinafter, for convenience of explanation, the uppermost substrate 11 is identified as the substrate 11a, the second substrate 11 is identified as the substrate 11b, and the lowermost substrate 11 is identified as the substrate 11c, and the step portion D between the substrates 11a and 11b is defined as the step portion Da. The step portion D between the substrates 11b and 11c is distinguished as a step portion Db.

Each substrate 11 is not particularly limited, but is an electronic device such as a semiconductor chip or a semiconductor wafer. On these substrates 11, a plurality of integrated circuits (for example, circuits having transistors and memories) 111 and a plurality of electrodes (for example, pads) 112 are mounted. The substrate 11 has at least one insulating film (not shown) formed thereon. This insulating film is called a passivation film, and can be formed of, for example, SiO ₂ , SiN, polyimide resin, or the like. However, the insulating film exposes at least part of the electrode 112.

  The electrodes 112 are provided on the upper surface 113 of each substrate 11 exposed at the stepped portion, and the same number is arranged along one side 114 of each substrate 11 in the present embodiment. The electrode 112 is made of an aluminum-based or copper-based metal and is not particularly limited, but its surface shape is rectangular.

  Each of the electrodes 112 described above is electrically connected to the integrated circuit 111 and is also electrically connected to other electrodes 112 corresponding to each other between the substrates 11 by the conductive layer 12. The conductive layer 12 is a wiring in the present invention, and the upper surface conductive layer 12 a formed on the upper surface 113 of the substrate 11 and the side surface conductive layer 12 b formed on the side surface 115 of the substrate 11 are connected. . The conductive layer 12 is formed by drying the ink droplets R of the conductive ink I and further sintering the metal nanoparticles contained in the ink I.

  In the present embodiment, alignment marks 116 for acquiring the orientation and position of the substrate 11 are provided at both ends of the side portion 114 where the electrodes 112 are arranged.

  More specifically, the substrate unit 10 described above includes the tangential direction (hereinafter referred to as the step extending direction) P of the stepped portion D between the substrates 11 and the electrodes to be connected, as shown in FIG. 112 and 112 are connected in a straight line so that the connection direction Q is inclined with respect to each other when viewed from above (a state in which the upper substrate 11 is shifted in the step extending direction P with respect to the lower substrate 11) 18 (a))) or a state of rotational deviation (the upper substrate 11 is rotated within the laminated surface with respect to the lower substrate 11, and the sides thereof are inclined (see FIG. 18 (b)). ). However, as long as the substrate unit 10 is laminated in a state of parallel deviation or rotational deviation as described above, the substrate unit 10 is provided with the tapered insulating member 13 at the stepped step portion as shown in FIG. Alternatively, as shown in FIG. 1C, the substrates 11 may be laminated with the outer periphery of each substrate aligned. However, in the latter case, each electrode 112 of the substrate 11 other than the uppermost stage is provided on the side surface 115 of the substrate 11. In FIG. 1, for the sake of simplification, the step extending direction P and the connection direction Q of the electrodes 112 are illustrated as being orthogonal.

Next, a conductive layer 12 forming device (hereinafter referred to as a wiring forming device) 7 in the substrate unit 10 will be described with reference to FIGS.
Here, FIG. 2 is a schematic diagram showing an overall configuration of the wiring forming apparatus 7, and FIG. 3 is a schematic diagram mainly showing a drawing unit 71 in the wiring forming apparatus 7.

As shown in FIG. 2, the wiring forming apparatus 7 includes a measuring unit 70 and a drawing unit 71.
Among these, the measurement part 70 measures the positional relationship of each board | substrate 11 in the board | substrate unit 10 before formation of the conductive layer 12, the measurement stage 701 for mounting the board | substrate unit 10, and the said measurement object A measuring camera 702 disposed opposite to the stage 701.

  The measurement stage 701 includes a measurement XY stage 701a that supports the substrate unit 10 horizontally on the upper surface and can be independently moved and controlled in two directions orthogonal to each other in the horizontal plane (X direction and Y direction in the drawing). And a measuring θ stage 701b that can be rotationally controlled in a horizontal plane while supporting the XY stage for upper surface, and the mounted substrate unit 10 is moved in an arbitrary direction in the horizontal plane by the measuring XY stage 701a. In addition, the measurement θ stage 701b can be rotated in a horizontal plane.

  The measurement camera 702 photographs the alignment mark 116 of each substrate 11 in the substrate unit 10 on the measurement stage 701.

  On the other hand, as shown in FIGS. 2 and 3, the drawing unit 71 performs wiring formation of the substrate unit 10 by drawing the conductive layer 12 with the ink droplet R of the ink I, and the substrate unit 10 is placed thereon. And a drawing camera 712 and a print head 2 disposed opposite to the drawing stage 711.

  The drawing stage 711 includes a drawing XY stage 711a that supports the substrate unit 10 horizontally on the upper surface and can be independently moved and controlled in two directions orthogonal to each other in the horizontal plane (X direction and Y direction in the drawing). A drawing θ stage 711b that supports the XY stage on the upper surface and can be controlled to rotate in a horizontal plane, and the mounted substrate unit 10 is moved in an arbitrary direction in the horizontal plane by the drawing XY stage 711a. In addition, the drawing θ stage 711b can be rotated in a horizontal plane.

  Among these, the drawing XY stage 711 a in the present embodiment is a counter electrode facing the print head 2 as shown in FIG. 3, and the drawing is performed by cooperating with an electrostatic voltage power source 51 described later. A voltage is applied between the substrate unit 10 on the XY stage 711a and the print head 2. More specifically, the drawing XY stage 711a is grounded and is always maintained at the ground potential. Therefore, as described later, when the charged ink droplet R lands on the substrate unit 10, the drawing XY stage 711a releases the charge by grounding. Further, the drawing XY stage 711a is disposed in parallel to an ink discharge surface 211c of the print head 2 to be described later and separated by a predetermined distance. The separation distance between the drawing XY stage 711a and the print head 2 is appropriately set within a range of about 0.1 to 5.0 mm. Although not shown in FIGS. 2 and 3, the above drawing XY stage 711 a is provided with positioning means and vacuum chucking means for positioning and fixing the substrate unit 10.

  The drawing camera 712 captures an image of the substrate unit 10 on the drawing stage 711.

  The print head 2 has an ink ejection surface 211 c substantially parallel to the upper surface 113 of each substrate 11 constituting the substrate unit 10. A plurality of nozzles 211 are arranged on the ink ejection surface 211c. However, details of the print head 2 will be described later.

As shown in FIG. 3, an electrostatic voltage power source 51 that applies an electrostatic voltage to the print head 2 is connected to the print head 2.
The electrostatic voltage power source 51 applies an electrostatic voltage to the print head 2 to generate an electrostatic field between a later-described nozzle plate 21 in the print head 2 and a drawing XY stage 711a, and at the same time, a piezoelectric element. The ink droplets R are ejected from the nozzles 211 by controlling the deformation of the nozzles 23, respectively. The voltage applied by the electrostatic voltage power supply 51 is a direct current, but may be an alternating current. The electrostatic voltage power source 51 may be connected to the drawing XY stage 711a and apply a voltage to the drawing XY stage 711a. In this case, the print head 2 is grounded.

  As shown in FIG. 2, a substrate loader 72 that moves the substrate unit 10 on the measurement unit 70 onto the drawing unit 71 is disposed between the measurement unit 70 and the drawing unit 71. As the base material loader 72, a conventionally known device such as a suction chuck for the substrate unit 10 can be used.

  Further, as shown in FIG. 3, a control means 75 is connected to the measurement unit 70, the drawing unit 71, and the substrate loader 72 described above. In FIG. 3, the measurement unit 70 and the substrate loader 72 are not shown.

  The control means 75 is a computer composed of a CPU, ROM, RAM, and the like (not shown), and controls the measurement unit 70, the drawing unit 71, and the base material loader 72, thereby using the ink droplet R of the ink I to form the substrate unit 10. The conductive layer 12 is drawn on the surface.

Next, details of the configuration of the print head 2 will be described with reference to FIGS.
FIG. 4 is an exploded perspective view of the print head 2, and FIG. 5 is a side sectional view of the print head 2.

As shown in FIG. 4, the print head 2 includes a nozzle plate 21, a body plate 22, and a piezoelectric element 23.
The nozzle plate 21 is a silicon substrate or a silicon oxide substrate having a thickness of about 150 to 300 μm. A plurality of nozzles 211 are formed on the nozzle plate 21, and the plurality of nozzles 211 are arranged in a line. In the present embodiment, as shown in FIGS. 11 and 12 to be described later, the interval between the nozzles 211 is equal to the interval between the electrodes 112 in each substrate 11, but is formed narrower than the interval between the electrodes 112. In addition, only the nozzle 211 at a position corresponding to each electrode 112 may be used.

  The body plate 22 is a silicon substrate having a thickness of about 200 to 500 μm. In the body plate 22, an ink supply port 221, an ink storage chamber 222, a plurality of ink supply paths 223, and a plurality of pressure chambers 224 are formed. The ink supply port 221 is a circular through hole having a diameter of about 400 to 1500 μm. The ink storage chamber 222 is a groove having a width of about 400 to 1000 μm and a depth of about 50 to 200 μm. The ink supply path 223 is a groove having a width of about 50 to 150 μm and a depth of about 30 to 150 μm. The pressure chamber 224 is a groove having a width of about 150 to 350 μm and a depth of about 50 to 200 μm.

  The nozzle plate 21 and the body plate 22 are joined to each other, and in the joined state, the nozzle 211 of the nozzle plate 21 and the pressure chamber 224 of the body plate 22 are in a one-to-one correspondence. .

  When ink is supplied to the ink supply port 221 in a state where the nozzle plate 21 and the body plate 22 are joined, the ink is temporarily stored in the ink storage chamber 222, and then each ink supply from the ink storage chamber 222 is performed. The pressure chambers 224 are supplied through the passages 223.

  The piezoelectric element 23 is bonded to a position corresponding to the pressure chamber 224 of the body plate 22. The piezoelectric element 23 is an actuator made of PZT (lead zirconium titanate), and is deformed when a voltage is applied to eject ink in the pressure chamber 224 from the nozzle 211.

  Although not shown in FIG. 4, a borosilicate glass plate 24 (see FIG. 5) is interposed between the nozzle plate 21 and the body plate 22.

  As shown in FIG. 5, one nozzle 211 and one pressure chamber 224 are formed corresponding to one piezoelectric element 23.

  In the nozzle plate 21, the nozzle 211 is formed with a step, and the nozzle 211 is composed of a lower step portion 211a and an upper step portion 211b. Both the lower step portion 211a and the upper step portion 211b have a cylindrical shape, and the diameter S1 of the lower step portion 211a (the distance in the left-right direction in FIG. 5) is the diameter S2 of the upper step portion 211b (the distance in the left-right direction in FIG. 5). It is getting smaller.

  The lower part 211a of the nozzle 211 is a part that directly ejects ink circulated from the upper part 211b. The lower step portion 211a has a diameter S1 of 1 to 10 μm and a length H (a distance in the vertical direction in FIG. 4) of 1.0 to 5.0 μm. The reason why the length H of the lower step portion 211a is limited to the range of 1.0 to 5.0 μm is that the ink landing accuracy can be remarkably improved.

  On the other hand, the upper part 211b of the nozzle 211 is a part that circulates the ink circulated from the pressure chamber 224 to the lower part 211a, and has a diameter S2 of 10 to 60 μm. The lower limit of the diameter S2 of the upper step portion 211b is limited to 10 μm or more. If the lower limit is less than 10 μm, the flow passage resistance of the upper step portion 211b cannot be ignored with respect to the flow passage resistance of the entire nozzle 211 (lower step portion 211a and upper step portion 211b). This is because the ink ejection efficiency decreases.

  On the contrary, the upper limit of the diameter S2 of the upper step portion 211b is limited to 60 μm or less because the lower step portion 211a as the ink ejection site becomes thinner as the diameter S2 of the upper step portion 211b increases (the lower step portion 211a increases in area). This is because the mechanical strength is reduced), and the ink is easily deformed when ejected, and as a result, the ink landing accuracy is lowered. That is, when the upper limit of the diameter S2 of the upper step portion 211b exceeds 60 μm, the deformation of the lower step portion 211a becomes very large as the ink is discharged, and the landing accuracy is a specified value (± 0.5 ° with respect to a desired discharge direction). This is because there is a possibility that it will not be able to be suppressed within.

  A borosilicate glass plate 24 having a thickness of about several hundred μm is provided between the nozzle plate 21 and the body plate 22, and the borosilicate glass plate 24 has an opening for communicating the nozzle 211 and the pressure chamber 224. A portion 24a is formed. The opening 24 a is a through hole that communicates with the pressure chamber 224 and the upper stage portion 211 b of the nozzle 211, and is a part that functions as a flow path through which ink flows from the pressure chamber 224 toward the nozzle 211. The pressure chamber 224 is a portion that receives pressure from the piezoelectric element 23 and applies pressure to the ink inside the pressure chamber 224.

  In the print head 2 having the above configuration, when the piezoelectric element 23 is deformed, pressure is applied to the ink inside the pressure chamber 224, and the ink flows from the pressure chamber 224 through the opening 24 a of the borosilicate glass plate 24. It reaches the nozzle 211 and is finally discharged from the lower stage 211a of the nozzle 211.

Next, the ink I for forming the conductive layer 12 will be described.
Ink I is an ink having conductivity and chargeability by dispersing metal nanoparticles. Examples of the metal nanoparticles include silver, gold, copper, palladium, platinum, nickel, rhodium, tin, indium, and alloys thereof.

There are two main methods for producing such metal nanoparticles. One is the physical method and the other is the chemical method. The physical method is generally a method for producing nanoparticles by pulverizing bulk metal, and the chemical method is a method for producing nanoparticles by generating metal atoms and controlling their aggregation.
The chemical method is roughly classified into a wet method performed in a liquid and a dry method performed in air or in a reduced pressure atmosphere. The chemical reduction method, which is well known as a wet method, is a method of generating nanoparticles by reducing metal ions by adding a reducing agent to a metal ion solution or heating a metal salt solution containing a reducing agent. is there. As the ink in which such nanoparticles are dispersed, for example, the ink disclosed in Japanese Patent No. 3933138 can be used. A gas evaporation method is known as a dry method. The gas evaporation method is a method in which a metal is evaporated in an inert gas and cooled and aggregated by collision with the gas to generate nanoparticles. It is known that the dry method can make the particle size smaller than the wet method, and the dry method can also generate nanoparticles having a particle size of about several nanometers.

  The particle size of the metal nanoparticles in the ink I used in the present embodiment is 1 to 100 nm, preferably 1 to 50 nm. Although metal nanoparticles having a particle size of less than 1 nm may be used, such particles are extremely difficult to produce and are not practical. Further, when metal nanoparticles having a particle diameter exceeding 100 nm are used, the nozzle 211 may be clogged.

  The concentration of the metal nanoparticles dispersed in the ink I is high so that the resistance value of the conductive layer 12 described later formed by drying the ink I becomes a value closer to the resistance value of the electrode 112. Is preferred. Specifically, 10 wt% or more is preferable, and 20 wt% is more preferable. However, the concentration of the metal nanoparticles can be about 80 wt% at the maximum.

  As the solvent for dispersing the metal nanoparticles in the ink I, water or a water-soluble organic solvent is used. Such a so-called water-based ink is superior in electric conductivity as compared with an oil-based ink using a nonpolar solvent. Further, this solvent preferably has a low vapor pressure and a high boiling point so that the viscosity of the ink I does not easily rise or dry. As a boiling point of a solvent, 150 degreeC or more is preferable and 200 degreeC or more is more preferable. The water content is preferably 40 wt% or less from the viewpoint of drying properties.

The viscosity of the ink I is preferably 2 mPa · s or more and 10 mPa · s or less at the discharge temperature, more preferably 3 mPa · s or more and 6.5 mPa · s or less. About discharge temperature, 20-60 degreeC is preferable and 25-50 degreeC is more preferable. If the temperature is lower than 25 ° C., cooling may be required. If the temperature is higher than 50 ° C., the print head 2 and the flow path member of the ink I may be burdened.
The surface tension of the ink I is preferably 20 mN / m or more and 50 mN / m or less. Furthermore, from the viewpoint of ejection stability, it is more preferably 25 mN / m or more and 45 mN / m or less.
The electrical conductivity of the ink I is preferably 0.1 μS / cm or more and 2000 μS / cm or less at 25 ° C. in order to apply an electrostatic attraction force. However, from the viewpoint of high-definition drawing, 1 μS / cm or more and 1000 μS / cm More preferable is cm or less.
The relative dielectric constant of the ink I is preferably 10 or more.

Next, a wiring forming method for forming the conductive layer 12 as wiring on the substrate unit 10 will be described with reference to FIGS.
6 and 7 are flowcharts showing a schematic configuration of the wiring forming method in the present embodiment.

  First, as shown in FIG. 6, when the substrate unit 10 is placed on the measurement stage 701 of the measurement unit 70 (step T1), the control means 75 makes a predetermined point on the substrate unit 10, for example, an alignment mark on the substrate 11c. A coordinate plane having an origin at 116 or the like is set on the substrate unit 10 (on the measurement stage 701) (step T2).

  Next, the control means 75 causes the measurement camera 702 to photograph the alignment mark 116 of each substrate 11 in the substrate unit 10, and based on this photographed image, the position of the electrode 112 on each substrate 11 and the side portion 114 (stepped portion). The position and angle of D) are calculated within the coordinate plane set in step T2 (step T3) (first position acquisition step). At this time, the control means 75 calculates the position of the conductive layer 12 to be formed in the step portion D (second position acquisition step).

  Next, the control means 75 calculates the route of the wiring connecting the electrodes 112 of the substrates 11a to 11c based on the calculation result of step T3, and stores it as drawing data (step T4) (route determination step).

  Specifically, when the substrates 11 of the substrate unit 10 are stacked in a state of being shifted in parallel, the control means 75 is positioned between the electrodes 112 to be connected as shown in FIG. Each substrate 11 is bent once at the upper surface 113 and is formed of straight lines L2a to L4a between the electrodes so as to be orthogonal to the step extending direction P in a region close to the step portion D, and is bent twice in the top view. A Z-shaped path is calculated. In this case, if the straight lines L1a to L4a in the drawing are viewed from the top, the shape is M-shaped bent three times, and if the straight lines L2a to L5a in the drawing are viewed from the top, the shape is substantially W-shaped. .

  On the other hand, when the substrate units 10 are stacked in a state including rotational deviation (rotational deviation and parallel deviation state or rotational deviation state), as shown in FIG. It is formed by straight lines L1b to L3b between the electrodes so that it is bent twice at the upper surface 113 of the one substrate 11 located between the electrodes 112 and is orthogonal to the step extending direction P in the region close to the step portion D, A substantially Z-shaped path bent twice in top view is calculated.

  When the wiring path is stored, the control means 75 moves the substrate unit 10 from the measurement unit 70 to the drawing unit 71 via the base material loader 72 and places it on the drawing stage 711 (step T5), and draws XY. After positioning on the stage 711a and vacuum chucking, the drawing camera 712 images the substrate unit 10 and sets a coordinate plane similar to that in step T2 to the drawing stage 711, and then wiring is formed (step T6) ( Wiring formation process).

  Specifically, as shown in FIG. 7, first, the control means 75 includes a wiring path from the electrode 112 of the substrate 11a to the electrode 112 of the substrate 11b, from the electrode 112 of the substrate 11a to the first bending point K1. After setting the path as the drawing target path, the drawing data stored in step T4 is read for the drawing target path (step T7), and the operation pattern of the drawing stage 711 in the drawing target path is set based on the drawing data. (Step T8).

  Next, the control means 75 draws the conductive layer 12 on the drawing target path by ejecting ink droplets R from the respective nozzles 211 of the print head 2 while moving the drawing stage 711 (step T9).

  In step T9, the control means 75 controls the electrostatic voltage power supply 51 to apply an electrostatic voltage to the print head 2, thereby generating an electrostatic field between the nozzle plate 21 and the drawing XY stage 711a. . At this time, care is taken so that the potential difference generated between the print head 2 and the substrate 11 is less than the dielectric breakdown voltage of air (about 3 kV / mm). In this state, the ink droplet R is ejected from the nozzle 211 while moving the drawing stage 711. Then, an electric field line from the print head 2 to the substrate unit 10 is formed by the electrostatic field between the nozzle plate 21 and the drawing XY stage 711a, and the ink droplet R that has received the electrostatic attraction force After flying in a direction along the upper surface 113, the upper surface conductive layer 12 a and the side surface conductive layer 12 b are formed by landing on the upper surface 113 and the side surface 115 of the substrate 11. In this way, by causing the electrostatic attraction force toward the substrate 11 to act on the ink droplet R, the flying distance of the ink droplet R can be extended as compared with the conventional on-demand type ink jet head. In other words, the extension of the flight distance is an increase in the landing force, that is, the ink droplet R is landed with a stronger landing force than before due to the action of the electrostatic attraction force. For example, an ink droplet having a large volume of 2 pl or more Even when R is landed on the side surface 115 of the substrate 11, the ink droplet R can be prevented from dripping. In addition, a sufficient amount of ink droplets R that do not break during drying can be landed on the corners of the substrate 11 where the lines of electric force are concentrated. At this time, the moving speed of the drawing stage 711 and the ejection frequency of the ink droplets R are such that the first bullets land on the electrode 112 of the uppermost substrate 11 and the ink droplets R that land continuously overlap and overlap. Each is set to an appropriate constant value. However, as shown in FIG. 10A, the conductive layer 12 may be formed by landing the ink droplets R at equal intervals in the top view in the orthogonal direction of the stepped portion D, or FIG. As shown in FIG. 5, the conductive layer 12 may be formed by landing the ink droplets R so as to be equidistant in the formation direction of the conductive layer 12 when viewed from above. The ejected ink droplet R preferably has a volume of 0.001 pl to 5 pl. Thereby, the air resistance and inertia force which act on the ink droplet R can be suppressed. The diameter of the ink droplet R upon landing depends on the physical properties of the ink I and the surface energy or surface state of the landing substrate 11, but when landing on the substrate 11 that does not absorb the ink I, the flying time is as follows. The diameter is about 1.5 to 4.0 times.

Next, the control means 75 determines whether or not the conductive layer 12 has been drawn up to the bending point K (step T10).
When it is determined in step T10 that the drawing has been performed up to the bending point K (step T10; Yes), the control unit 75 determines the next bending point in the wiring path from the electrode 112 of the substrate 11a to the electrode 112 of the substrate 11b. After setting the path to K or the connection destination electrode 112 as a drawing target path, the drawing data stored in step T4 is read for the drawing target path, and the drawing stage 711 in the drawing target path is read based on the drawing data. The operation pattern is reset (step T11), and the process proceeds to step T9 described above.

  If it is determined in step T10 that drawing has not been performed up to the bending point K (step T10; No), that is, drawing has been completed only before the bending point K, or the electrode 112 of the lowermost substrate 11c. When it is determined that the drawing has been completed, the control means 75 determines whether or not the entire wiring has been formed, that is, whether or not the drawing has been completed up to the electrode 112 of the lowermost substrate 11c (step T12). If it is determined that the entire wiring is not formed (step T12; No), the process proceeds to step T9 described above. If it is determined that the wiring is formed (step T12; Yes), the wiring forming process is terminated.

  Here, when each board | substrate 11 of the board | substrate unit 10 is laminated | stacked in the state of parallel shift, said wiring formation process is performed as follows. First, as shown in the “i” portion of FIG. 8B, the first bending point K1 (the upper surface 113 of the substrate 11a) from the electrode 112 of the substrate 11a in the drawing data for the wiring path stored in step T4. ), The ink droplet R is ejected from each nozzle 211 of the print head 2 while moving the drawing stage 711 so as to bring the electrode 112 of the substrate 11b close to the print head 2, and the substrate 11a. An upper surface conductive layer 12a is drawn on the upper surface 113 of the substrate. As a result, a wiring (conductive layer 12) from the electrode 112 of the substrate 11a to the first bending point K1 is formed. Next, as shown in the “ii” portion of FIG. 8B, the second bending point K2 from the bending point K1 of the upper surface 113 of the substrate 11a in the drawing data for the wiring path stored in step T4. Based on the drawing data up to (position on the upper surface 113 of the substrate 11b), the ink droplets R are ejected from the nozzles 211 of the print head 2 while moving the drawing stage 711 in the direction perpendicular to the stepped portion Da. The upper surface conductive layer 12a is drawn on the upper surface 113 of the substrate 11a, the side conductive layer 12b is formed on the side surface 115 of the substrate 11a, and the upper surface conductive layer is drawn on the upper surface 113 of the substrate 11b so as to be orthogonal to the step extending direction P of the step portion Da. . As a result, the wiring from the first bending point K1 to the second bending point K2, that is, the wiring (conductive layer 12) in the region close to the stepped portion Da is formed orthogonal to the stepped portion Da. Next, as shown in “iii” portion of FIG. 8B, from the bending point K2 of the upper surface 113 of the substrate 11b to the electrode 112 of the substrate 11b in the drawing data for the wiring path stored in step T4. Based on the drawing data, ink drawing R is ejected from each nozzle 211 of the print head 2 while moving the drawing stage 711 so as to bring the electrode 112 of the substrate 11b close to the print head 2, and the upper surface 113 of the substrate 11b. An upper surface conductive layer 12a is drawn on the substrate. As a result, a wiring (conductive layer 12) from the second bending point K2 to the electrode 112 of the substrate 11b is formed. As a result, a wiring (conductive layer) is formed between the electrodes 112 of the substrates 11a and 11b as shown in FIG. 12) is formed. Similarly, the upper surface conductive layer 12a and the side surface conductive layer 12b are formed between the electrodes 112 of the substrates 11b and 11c, whereby wiring (conductive layer 12) is formed between the electrodes 112 of the substrates 11a to 11c. .

  On the other hand, when the respective substrates 11 of the substrate unit 10 are stacked in a state including rotational deviation as shown in FIG. 9 described above, the above-described wiring forming step is performed as follows. In FIG. 9, for simplification, the number of the electrodes 112 on each substrate 11 is four, and the electrodes 112 are distinguished as the electrodes 112a to 112d in the order in which the connection destination / connection source interval is narrow. First, as shown in the “I” part of FIG. 9, the first bending point K1 from the electrode 112 of the substrate 11a (positioned on the upper surface 113 of the substrate 11b) in the drawing data for the wiring path stored in step T4. The ink droplet R is ejected from each nozzle 211 of the print head 2 while moving the drawing stage 711 in the direction perpendicular to the stepped portion Da based on the drawing data up to the upper surface conductive layer 12a on the upper surface 113 of the substrate 11a. Are drawn on the side surface 115 of the substrate 11a and the upper surface conductive layer 12a on the upper surface 113 of the substrate 11b so as to be orthogonal to the step extending direction P of the step portion Da (first drawing step). Thus, the wiring from the electrode 112 of the substrate 11a to the vicinity of the stepped portion Da on the substrate 11a and the vicinity of the stepped portion Da to the first bending point K1 on the upper surface 113 of the substrate 11b across the stepped portion Da. A wiring, that is, a wiring (conductive layer 12) in a region close to the stepped portion Da is formed in a straight line perpendicular to the stepped portion Da. Next, as shown in the “II” portion of FIG. 9, the second bending point K2 (from the bending point K1 of the upper surface 113 of the substrate 11b to the second bending point K2 (of the substrate 11b) of the drawing data for the wiring path stored in step T4. The drawing stage 711 is moved in the direction in which the side 114 of the substrates 11a and 11b is widened (lower right direction in the figure) based on the drawing data up to the upper surface 113). The ink droplet R is discharged for each nozzle 211 at different timings, more specifically, until each bending point K2 between the electrodes 112a to 112d reaches the ink landing position of the print head 2, and the electrode 112a to be connected. The upper surface conductive layer 12a having a length corresponding to the interval of ~ 112d is drawn on the upper surface 113 of the substrate 11b (second drawing step). Thereby, the wiring (conductive layer 12) from the bending point K1 to the bending point K2 is formed. Next, based on the drawing data from the bending point K2 of the upper surface 113 of the substrate 11b to the electrode 112 of the substrate 11b among the drawing data for the wiring path stored in step T4, 2 between the electrodes 112d and 112d. The drawing θ stage 711b is rotated with the second bending point K2 as the rotation center, thereby making the arrangement direction of the electrodes 112a to 112d on the substrate 11b parallel to the arrangement direction of the nozzles 211 on the print head 2 (rotation process) 9) As shown in the “III” portion of FIG. 9, the ink droplet R is separately applied to each nozzle 211 of the print head 2 while moving the drawing stage 711 so that the electrode 112 of the substrate 11b is brought close to the print head 2. More specifically, from the timing, each bending point K2 between the electrodes 112a to 112d is Ejected from reaching the tank landing position, the upper surface conductive layer 12a having a length corresponding to distance to be connected electrode 112a~112d drawn on the upper surface 113 of the substrate 11b (third drawing step). As a result, a wiring (conductive layer 12) from the bending point K2 to the electrode 112 of the substrate 11b is formed. As a result, the wiring (conductive layer 12) is formed between the electrodes 112 of the substrates 11a and 11b as shown in FIG. It is formed. Similarly, the upper surface conductive layer 12a and the side surface conductive layer 12b are formed between the electrodes 112 of the substrates 11b and 11c, whereby wiring (conductive layer 12) is formed between the electrodes 112 of the substrates 11a to 11c. . In FIG. 9 described above, the nozzle row in the print head 2 is indicated by a one-dot chain line, the landing position of the ink droplet R and the formation direction of the conductive layer 12 are indicated by black or shaded arrows, and the ink droplet R is not landed. The regions that pass directly under the nozzle 211 are indicated by broken lines.

When the wiring formation step is completed, the conductive layer 12 is baked and the solvent of the ink droplets R is evaporated to fix the conductive layer 12 to the substrate unit 10.
Here, examples of the firing method include sintering in a dryer or a hot plate. In the present embodiment, in order to control the wettability of the ink I and improve the adhesion elasticity, the substrate 11 is coated with a subbing agent (a silane coupling agent or a titanium coupling agent). Therefore, sintering under conditions that can ensure the heat resistance of various coupling agents is preferable. In this sintering, it is preferable to perform main sintering at 150 to 200 ° C. for 60 to 180 minutes after preliminary drying at 100 to 150 ° C. for 10 to 30 minutes. If the preliminary drying is not performed, the solvent remains in the fused metal, and the resistance value may increase. When the temperature of the preliminary drying is 100 ° C. or lower, the solvent hardly evaporates and there is a possibility that the effect does not occur. When the temperature is 150 ° C. or higher, the fusion of the metal nanoparticles may start. When the sintering temperature is 150 ° C. or lower, the metal nanoparticles are not fused, and the resistance value may be increased. When the sintering temperature is 200 ° C. or higher, the subbing agent is deteriorated and mixed with the fusion metal, resulting in a resistance value of There is a risk of becoming higher. A hot plate is preferably used for the main sintering. This is because when the hot plate is used, heat is directly transmitted to the ink I, and the fusion of the metal nanoparticles is facilitated.

  As described above, according to the wiring forming method of the present embodiment, the conductive layer 12 in the region adjacent to the stepped portion D is formed so as to be orthogonal to the tangential direction of the stepped portion D, that is, the step extending direction P. Therefore, even when the substrate 11 is laminated in a state where the step extending direction P between the substrates 11 and the connection direction Q of the electrodes 112 are not orthogonal, such as a parallel displacement state or a rotation displacement state, FIG. As shown in (c), the formation direction of the conductive layer 12 is orthogonal to the step extending direction P in the region close to the step portion D. Therefore, the ink that has landed on the substrate 11 is prevented from being pulled in the shearing direction (step extending direction P) by the surface tension, so that a good wiring that electrically connects the stacked substrates 11 is formed. Can do.

  Further, by forming a plurality of wirings (conductive layer 12) at once with the print head 2, these wirings are formed in parallel with each other and having the same number of bendings and the same bending angle. Compared with the case of forming the wiring, the formation of the wiring can be facilitated.

  Further, when the substrates 11 are stacked in a state of being displaced in parallel, the wiring is formed in a substantially Z shape so as to be bent once at the upper surface 113 of each substrate 11. This is a case where the exposed layer is small and the conductive layer 12 having a sufficient length (the amount of displacement between the electrodes in the step extending direction P) in the upper surface 113 so as to be inclined to the step portion D cannot be drawn with one straight line. However, since the conductive layer 12 inclined to the step portion D can be drawn for each of the substrates 11 and drawn with two straight lines, the electrodes 112 can be reliably connected to each other.

  Further, by applying a voltage between the plurality of substrates 11a to 11c and the print head 2 to form an electric field, an electric force directed from the print head 2 to the rising surfaces of the step portions Da and Db between the substrates 11a to 11c. A line is formed. Then, by charging the ink droplets R and applying an electrostatic attraction force, the ink droplets can fly along the lines of electric force, so that the ink also rises between the stacked substrates 11a to 11c. The droplet R can be sufficiently adhered.

[Modification]
Subsequently, a wiring forming apparatus 7A as a modification of the wiring forming apparatus 7 according to the above embodiment will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the component similar to the said embodiment, and the description is abbreviate | omitted.
FIG. 13 is a schematic diagram schematically showing mainly the drawing unit 71A in the wiring forming apparatus 7A, and FIG. 14 is a perspective view of a substrate unit 10A described later.

  As shown in FIG. 13A, in addition to the configuration of the drawing unit 71 in the above embodiment, the drawing unit 71A of the wiring forming apparatus 7A has an electrostatic voltage applied to the print head 2A for forming the insulating layer and the print head 2A. In place of the substrate unit 10 in the above-described embodiment, and includes a drying device 61 for drying an insulating layer 14 to be described later, and a drying device 62 for drying the conductive layer 12. Wiring is formed on the substrate unit 10A.

The print head 2A is configured similarly to the print head 2 in the above embodiment. However, the print head 2A, instead of the ink I containing a conductive material, the ink I _n containing an insulating material, so as to discharge from the nozzles 211 as ink droplets R _n. In the print head 2A, an insulating layer 14 for insulating the substrate 11 and the conductive layer 12 is formed on the upper surface 113 and the side surface 115 of each substrate 11 of the substrate unit 10A (see FIG. 14).

The ink I _n is dissolved a single resin composition as an insulating material. As such a resin composition, any material containing electrical insulating material may be used. For example, epoxy resin, phenol resin, polyimide resin, polyamide resin, polyamideimide resin, silicone-modified polyamideimide resin, polyester resin , Cyanate ester resins, BT resins, acrylic resins, methacrylic resins, melamine resins, urethane resins, alkyd resins and the like, and compositions containing monomers, oligomers and polymers. These can be used alone or in combination of two or more. Moreover, it is preferable that the said resin composition contains a thermosetting resin. Insulating layer 14 comprising a cured product of the ink I _n which contains a thermosetting resin, heat resistance and insulation reliability is excellent in connection reliability.

In the modification of the present embodiment, it is particularly preferable that the resin composition contains an epoxy resin among the above-described resins. By using an epoxy resin, the adhesiveness to the conductive layer 12 can be improved.
Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenol type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, phenol Examples thereof include glycidyl ether compounds obtained by subjecting a compound and an aldehyde compound to a condensation reaction. These may be contained in combination of two or more. Furthermore, in the modification of this Embodiment, it is preferable that the said resin composition contains the hardening | curing agent which hardens the said epoxy resin and an epoxy resin.
Examples of the curing agent include amines such as diethylenetriamine, triethylenetetramine, metaxylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, m-phenylenediamine, and dicyandiamide; phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl Acid anhydrides such as tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, pyromellitic anhydride, trimetic anhydride; imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- Phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-methylimidazoline, 2-phenyl Louis imidazoline, 2-undecyl imidazoline, 2-heptadecyl imidazoline, 2-isopropyl imidazole, 2,4-dimethyl imidazole, 2-phenyl-4-methyl imidazole, 2-ethyl imidazoline, 2-isopropyl imidazoline, 2,4- Imidazoles such as dimethylimidazoline and 2-phenyl-4-methylimidazoline; imidazoles whose imino group is masked with acrylonitrile, phenylene diisocyanate, toluidine isocyanate, naphthalene diisocyanate, methylene bisphenyl isocyanate, melamine acrylate, etc .; bisphenol F, bisphenol A And phenol compounds such as bisphenol S; condensates of phenol compounds and aldehyde compounds. In addition, you may contain these hardening | curing agents individually by 1 type or in combination of 2 or more types. In addition to the components described above, the resin composition may contain a curing accelerator, a coupling agent, an antioxidant, a filler, and the like in accordance with desired properties.

The solvent of the ink I _n, as long as dispersing or dissolving the components of the resin composition, for example, .gamma.-butyrolactone, and cyclohexanone.

The viscosity of the ink I _n is preferably at most 20 mPa · s at the ejection temperature, 2 to 8 MPa · s is more preferable. The concentration of the ink I _n If it is low viscosity than 2 mPa · s in some cases thinning becomes time consuming to cure. Further, when the pressure is 8 mPa · s or more, ejection failure may occur. About discharge temperature, 20-60 degreeC is preferable like the ink I, and 25-50 degreeC is more preferable.
The surface tension of the ink I _n is preferably at least 20mN / m, 25~45mN / m is more preferable. Is less than 25 mN / m, may be difficult discharged wet and spread when ejected, the ink I _n exceeds 45 mN / m is to become difficult to fill.
Electrical conductivity of the ink I _n, in order to act electrostatic attraction is preferable than 0.1 .mu.S / cm is at 25 ° C., from the viewpoint of high definition drawing, more preferably at least 1 [mu] S / cm.
The dielectric constant of the ink I _n is preferably 10 or more.

  The electrostatic voltage power supply 51A is configured in the same manner as the electrostatic voltage power supply 51 in the above embodiment. However, instead of the print head 2, an electrostatic voltage is applied to the print head 2A.

  The drying device 61 and the drying device 62 are both provided above the drawing XY stage 711 a and connected to the control means 75. The drying device 61 and the drying device 62 can discharge hot air downward under the control of the control means 75, and the insulating layer 14 and the conductive layer 12 are dried by the hot air, respectively.

  As shown in FIG. 14, in the substrate unit 10A, in addition to the configuration of the substrate unit 10 in the above embodiment, an insulating layer 14 for insulating the substrate 11 and the conductive layer 12 is formed by a method described later. . The insulating layer 14 is formed by connecting an upper surface insulating layer 14 a formed on the upper surface 113 of the substrate 11 and a side surface insulating layer 14 b formed on the side surface 115 of the substrate 11. Although illustration is omitted, an insulating film is not formed at least on the side surface of each substrate 11 in the stepped portion. Further, like FIG. 1 described above, the illustration in FIG. 14 is simplified, but also in the substrate unit 10A, the step extending direction P and the connection direction Q of the electrodes 112 are not orthogonal to each other. It has become.

  Next, a wiring forming method for forming the conductive layer 12 and the insulating layer 14 as wiring on the substrate unit 10A will be described.

First, the control unit 75, as in step T1~T12 in the above embodiment, the insulating layer forming step from the print head 2A by landing ink droplets R _n to the upper surface 113 of the substrate 11 to form an insulating layer 14 I do. Specifically, the ink droplets R from the print head 2A are scanned in parallel with the upper surface 113 of the substrate 11 while an electrostatic field is generated between the nozzle plate 21 of the print head 2A and the drawing XY stage 711a. _n is discharged.

Thus, similarly to the wiring formation process, it is causing an electrostatic field between the print head 2A and drawing XY stage 711a, exerting an electrostatic attraction force toward the substrate 11 to the ink droplets R _n Accordingly, it is possible to extend the flying distance of the ink droplets R _n compared with the conventional on-demand type ink jet head. In other words, the extension of the flight distance is an increase in the landing force. In other words, the ink droplet R _n is landed with a stronger landing force than before due to the action of the electrostatic attraction force. For example, the ink having a large volume of 2 pl or more Even when the droplet R _n is landed on the side surface 115 of the substrate 11, the ink droplet R _n can be prevented from dripping. Further, with respect to corner lines of electric force are concentrated, the ink droplets R _n without sufficient amount of the cracking during drying can be landed.

In this insulating layer forming step, the volume of the ejected ink droplet R _n is preferably 0.001 pl to 5 pl. Thus, it is possible to suppress the air resistance and the inertia force acting on the ink droplets R _n. Furthermore, it is preferable that the upper surface insulating layer 14a is formed only on the portion where the upper surface conductive layer 12a is formed, and the side surface insulating layer 14b is formed only on the portion where the side surface conductive layer 12b is formed. By doing so, the upper surface insulating layer 14a and the side surface insulating layer 14b are formed only in the portions that need to be insulated, so that the upper surface insulating layer 14a and the side surface insulating layer 14b can be efficiently formed.

Next, the insulating layer 14 is baked.
In this step, first, the substrate unit 10A is positioned below the drying device 61 by moving the drawing XY stage 711a. Then, the drying device 61 is controlled by the control means 75 to discharge hot air downward, thereby drying and baking the insulating layer 14 of the substrate unit 10A.

Next, surface treatment is performed.
Here, a surface treatment for improving the adhesion of the ink droplets R is performed on the surface of the insulating layer 14.
As a surface treatment method, for example, a chemical method as described in Section 2 Section 2 and Section 3 of “Surface Treatment Technology Handbook” (issued by NTS Corporation, 200.1.7) And physical methods. It is also possible to process both in combination. In the modification of the present embodiment, a chemical method is used.
Among chemical methods, it is preferable to treat with a coupling agent because there is a problem of contact at the time of producing a substrate and a thin film thickness is preferable. Examples of the coupling agent include silane, titanate, aluminum, or zircoaluminum coupling agents. The concentration of the coupling agent solution is preferably 0.005 to 30 wt%, and more preferably 0.01 to 5 wt%, whereby a uniform film with good wettability can be formed. As the coating method, an existing method such as inkjet, dip, spray coating, spin coating, or the like can be used. As the physical method, plasma treatment, corona treatment, UV treatment, and the like can be given. These methods can be applied as long as the insulating film on the substrate 11 is not destroyed.

  As described above, by performing the surface treatment on the surface of the insulating layer 14, that is, the upper surface insulating layer 14a and the side surface insulating layer 14b, the adhesion of the ink droplet R is improved and the wet state of the ink droplet R is made uniform. Can do.

Next, in the same manner as in steps T1 to T12 in the above embodiment, after the wiring is formed on the substrate unit 10, the conductive layer 12 is baked.
In this step, first, the substrate unit 10A is positioned below the drying device 62 by moving the XY stage for drawing 711a. Then, the drying device 62 is controlled by the control means 75 to discharge hot air downward, thereby drying and firing the conductive layer 12 of the substrate unit 10A. The temperature conditions during firing are the same as in the above embodiment.
In the firing process of the conductive layer 12, a force acts to deform the conductive layer 12 at the corners of the substrate 11 due to the difference in thermal expansion coefficient between the substrate 11 and the conductive layer 12. However, this corner, the insulating layer 14 made of the ink droplets R _n a sufficient amount is formed between the substrate 11 and the conductive layer 12, relieving the force by the elasticity of the insulating layer 14 Can be made.

  Note that the wiring forming device 7A may be configured not to include the drying device 61, as shown in FIG. In this case, firing of the insulating layer 14 is omitted.

As described above, according to the wiring forming method in the modification of the present embodiment, the same effect as in the above embodiment can be obtained, and the corner portions where the lines of electric force are concentrated are dried. A sufficient amount of ink droplets R _n that do not sometimes break can be landed, and the insulating layer 14 composed of this sufficient amount of ink droplets R _{n is applied} to the corner conductive layer 12 in the firing process of the conductive layer 12. Since the acting force can be relaxed by its elasticity, the substrate 11 and the conductive layer 12 are surely insulated from each of the stacked substrates 11, and stress generated in the conductive layer 12 in a later process is relieved. A good insulating layer 14 can be formed.

The ink I _n an electric conductivity of 0.1 .mu.S / cm or more and a relative dielectric constant is not less than 10, the ink droplets R _n ejected, since the volume is less than 5pl least 0.001, the while suppressing the air resistance and the inertia force acting on the ink droplets R _n, a sufficient electrostatic attraction to landing on the substrate 11 can be made to act on the ink droplets R _n along the electric force lines. Therefore, it is possible to reliably form a good insulating layer 14 that insulates the substrate 11 and the conductive layer 12 from each stacked substrate 11.

  Further, since the upper surface insulating layer 14a and the side surface insulating layer 14b are formed only in the portions that need insulation, the upper surface insulating layer 14a and the side surface insulating layer 14b can be efficiently formed.

  Moreover, since the upper surface insulating layer 14a and the side surface insulating layer 14b are formed of a single resin composition, that is, an insulating material, the upper surface conductive layer 12a and the side surface conductive layer 12b are formed on the upper surface insulating layer 14a and the side surface insulating layer 14b. The surface energy of the base of the ink droplet R to be formed becomes uniform. Therefore, it is possible to stably form high-definition wiring that electrically connects the stacked substrates 11.

  Further, since the surface treatment for improving the adhesion of the ink droplet R is performed on the surface of the insulating layer 14, the adhesion of the ink droplet R is improved and the wet state of the ink droplet R becomes uniform. Therefore, it is possible to stably form good wirings that electrically connect the stacked substrates 11.

  In the above-described embodiment and its modification, it has been described that the conductive layer 12 is formed by moving the substrate units 10 and 10A relative to the print heads 2 and 2A. The conductive layer 12 may be formed by moving relative to the units 10 and 10A.

  Further, although the substrate unit 10 has been described as being configured by the three substrates 11, as illustrated in FIG. 15, for example, it may be configured by another number of substrates 11 such as six. Also in this case, according to the above-described wiring formation method, the formation direction of the conductive layer 12 is orthogonal to the step extending direction P in the region close to the step portion D as shown in FIG. Therefore, it is possible to form a favorable wiring that electrically connects the substrates 11.

  Further, the conductive layer 12 is described as being formed from the uppermost substrate 11a toward the lowermost substrate 11c. However, the conductive layer 12 may be formed from the substrate 11c toward the substrate 11a, or from the substrate 11b to the substrates 11a and 11c. You may form toward. Here, when the conductive layers 12 are formed from the substrate 11 c toward the substrate 11 a when the substrates 11 a to 11 c are stacked in a state including rotational deviation, for example, on the upper surface 113 of the lower substrate 11. Bending twice and determining a substantially Z-shaped wiring path in top view between the electrodes so as to be orthogonal to the step extending direction P in an area close to the step portion D, and then forming the wiring as follows. be able to. That is, first, among the drawing data for the wiring path stored in step T4, the drawing data from the electrode 112 of the substrate 11c to the first bending point (position on the upper surface 113 of the substrate 11c) on the electrode 112 side. Based on this, while moving the drawing stage 711 in the direction in which the side portions 114 of the substrates 11c and 11b are widened, the ink droplets R are individually delivered to the nozzles 211 of the print head 2 at different timings, more specifically. The upper surface conductive layer 12a having a length corresponding to the distance between the electrodes 112a to 112d to be connected is discharged by discharging until each bending point K1 between the electrodes 112a to 112d reaches the ink landing position of the print head 2. Drawing on the upper surface 113 (first drawing step). Thereby, the wiring (conductive layer 12) from the electrode 112 of the board | substrate 11c to the bending point K1 is formed. Next, of the drawing data for the wiring path stored in step T4, the drawing data from the bending point K1 on the upper surface 113 of the substrate 11c to the second bending point K2 (positioned on the upper surface 113 of the substrate 11c) is used. Thus, by rotating the drawing θ stage 711b about the bending point K1 between the electrodes 112d and 112d, the arrangement direction of the electrodes 112a to 112d on the substrate 11b and the arrangement direction of the nozzles 211 on the print head 2 Are made parallel (rotation process), and the drawing stage 711 is moved so that the electrode 112 of the substrate 11b is brought close to the print head 2, and the ink droplets R are separated from the nozzles 211 of the print head 2 at different timings. Specifically, each bending point K1 between the electrodes 112a to 112d is an indent of the print head 2. Ejected from reaching the landing position, the upper surface conductive layer 12a having a length corresponding to distance to be connected electrode 112a~112d drawn on the upper surface 113 of the substrate 11c (second drawing step). Thereby, the wiring (conductive layer 12) from the bending point K1 to the bending point K2 is formed. Here, the second bending point K2 is located on a straight line passing through the electrode 112 of the substrate 11b and perpendicular to the step extending direction P. Next, the drawing stage 711 is moved in the direction orthogonal to the step portion Db based on the drawing data from the bending point K2 to the electrode 112 of the substrate 11b among the drawing data for the wiring path stored in step T4. Meanwhile, the ink droplet R is ejected from each nozzle 211 of the print head 2, and the upper conductive layer 12a is formed on the upper surface 113 of the substrate 11c, the side conductive layer 12b is formed on the side surface 115 of the substrate 11b, and the upper conductive layer is formed on the upper surface 113 of the substrate 11b. The layers 12a are drawn so as to be orthogonal to the step extending direction P of the step portion Db (third drawing step). As a result, the wiring from the bending point K2 across the step portion Db to the vicinity of the step portion Db in the substrate 11b, and the wiring from the vicinity of the step portion Db to the electrode 112 of the substrate 11b, that is, close to the step portion Db. As a result of forming the wiring (conductive layer 12) in the region orthogonal to the step portion Db, the wiring (conductive layer 12) is formed between the electrodes 112 of the substrates 11c and 11b. Similarly, by forming the upper surface conductive layer 12a and the side surface conductive layer 12b between the electrodes 112 of the substrates 11b and 11a, wiring (conductive layer 12) is formed between the electrodes 112 of the substrates 11a to 11c. .

  Further, in the case where the substrate 11 is laminated in a state including rotational deviation, it has been described that a wiring that bends twice on the upper or lower substrate 11 is formed. However, as shown in FIG. As long as the conductive layer 12 is orthogonal to the step extending direction P in a region close to the step portion D, a wiring that bends on each of the upper and lower substrates 11 may be formed. Here, in this drawing, as the wiring between the respective electrodes 112, the wiring composed of straight lines L1c to L5c and bent twice in the upper and lower substrates 11 in a top view is illustrated.

  Further, in the case where the substrates 11 are laminated in a state of being displaced in parallel, it has been described that a substantially Z-shaped wiring that is bent at two points is formed. As long as the layer 12 is formed perpendicular to the step portion D, a wiring bent at one point may be formed between the electrodes 112 as shown in FIG.

  Further, the wiring is formed by connecting the linear conductive layers 12. However, as long as the conductive layer 12 is orthogonal to the stepped portion D in the region close to the stepped portion D, the stepped portion D is separated from the electrode 112. The conductive layer 12 up to the adjacent region may be curved.

  In addition, although it has been described that the alignment mark 116 is provided on each substrate 11, it may not be provided. In this case, based on the captured image of the entire substrate 11, the position of the electrode 112 on each substrate 11, the position and angle of the side portion 114 (stepped portion D), and the conductive layer 12 to be formed on the stepped portion D. The position and the like are calculated.

  In addition to the points described above, the present invention is not limited to the above-described embodiments and modifications, and can be changed as appropriate.

It is a perspective view of a substrate unit. It is a schematic diagram which shows the whole structure of a wiring formation apparatus. It is a schematic diagram which shows schematic structure of a drawing part. FIG. 2 is an exploded perspective view of a print head. 2 is a side sectional view of the print head. It is a flowchart which shows schematic structure of the wiring formation method in embodiment. It is a flowchart which shows schematic structure of the wiring formation method in embodiment. (A), (b) is a schematic diagram for demonstrating a wiring formation process, (c) is a figure which shows the state of the wiring formed by the wiring formation method concerning this invention. It is a schematic diagram for demonstrating a wiring formation process. It is a schematic diagram for demonstrating a wiring formation process. It is a figure which shows the wiring formed in the case of parallel shift | offset | difference. It is a figure which shows the wiring formed in the case of a rotation gap. It is a schematic diagram which shows schematic structure of the drawing part in a modification. It is a perspective view of the board | substrate unit in a modification. It is a figure which shows the modification of a board | substrate unit. It is a figure which shows the wiring formed in the case of a parallel shift and a rotation shift. It is a figure which shows the wiring formed in the case of parallel shift | offset | difference. It is a figure which shows the state of a parallel shift and a rotation shift. It is a figure which shows the state of the wiring formed by the conventional wiring formation method, (a), (b) is a top view, (c) is a side view.

Explanation of symbols

2,2A Print head 10, 10A Substrate unit 11 (11a to 11c) Substrate 12 Conductive layer (wiring)
12a Top conductive layer 12b Side conductive layer 112 Electrode 211 Nozzle I Ink (conductive ink)
R Ink droplet (ink droplet of conductive ink)
D (Da, Db) Stepped portion P Step extending direction (tangential direction of stepped portion)
Q electrode connection direction

Claims (15)

Ink droplets of ink containing a conductive material are ejected from an inkjet print head onto a plurality of stacked substrates and landed, and the electrodes disposed on the top or side surfaces of these substrates are electrically connected to each other. A wiring forming method for forming a wiring to be performed,
As the plurality of substrates,
The tangential direction of the stepped portion between these substrates and the connection direction in which the electrodes to be connected are connected with a straight line are stacked so as to be inclined with respect to each other in a top view,
A wiring forming step of forming an upper surface conductive layer on the upper surface of the substrate, a side surface conductive layer on a side surface of the substrate, and forming the wiring with the upper surface conductive layer and the side surface conductive layer;
In this wiring formation process,
A method of forming a wiring, comprising: forming a conductive layer in a region adjacent to the stepped portion of the upper surface conductive layer and the side surface conductive layer so as to be orthogonal to a tangential direction of the stepped portion. In the wiring formation method of Claim 1,
Before the wiring formation step,
A first position acquisition step of acquiring a positional relationship between the stepped portion and each electrode;
A second position acquisition step of acquiring the position of the conductive layer to be formed on the stepped portion;
And a route determination step of determining a route of the wiring based on information obtained in the first position acquisition step and the second position acquisition step. In the wiring formation method according to claim 1 or 2,
A wiring forming method, wherein the wiring is formed by bending twice in a top view to form a substantially Z-shape. In the wiring formation method according to claim 1 or 2,
A wiring forming method, characterized in that the wiring is formed by bending three times in a top view to form a substantially W shape or a substantially M shape. In the wiring formation method as described in any one of Claims 1-4,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A wiring forming method, wherein a plurality of wirings are formed at a time by the print head, thereby forming the plurality of wirings having the same number of bendings and the same bending angle. In the wiring formation method as described in any one of Claims 1-5,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated with the lower substrate rotated in the lamination plane, and the distance between the electrodes to be connected increases as the distance from the rotation center increases. Use
In the wiring formation step,
A wiring forming method, wherein a plurality of the wirings having different lengths are formed. In the wiring formation method as described in any one of Claims 1-6,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A wiring forming method, wherein a plurality of the wirings are formed at a time by the print head, thereby forming a plurality of wirings parallel to each other. In the wiring formation method as described in any one of Claims 1-7,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated in a state of being rotated in the lamination plane with respect to the lower substrate, and the distance between the electrodes to be connected increases as the distance from the rotation center increases 2 Using two substrates
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A stage that can rotate in a plane perpendicular to the direction of ink droplet ejection by the print head and can move in a direction along the vertical plane while the two substrates are supported facing the print head. Use
By moving the stage while ejecting ink droplets from each nozzle of the print head, a conductive layer is formed from the electrode on the upper substrate to the vicinity of the stepped portion on the upper substrate, and the upper A first drawing step of forming a conductive layer in a direction orthogonal to the stepped portion from the vicinity of the stepped portion on the substrate to the upper surface of the lower substrate across the stepped portion;
After the first drawing step, the stage is moved, and ink droplets are discharged to different timings for each nozzle of the print head, so that from the end point of each conductive layer formed in the first drawing step, A second drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected on the upper surface of the lower substrate;
After the second drawing step, the stage is rotated in a vertical plane in the discharge direction around the end point of the conductive layer drawn between the electrodes connected on the side farthest from the rotation center. A rotation step of making the arrangement direction of the plurality of electrodes on the lower substrate parallel to the arrangement direction of the plurality of nozzles;
After the rotation step, the stage is moved, and ink droplets are ejected at different timings for each nozzle of the print head, so that the lower end of each conductive layer formed in the second drawing step is And a third drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected up to the electrodes on the side substrate. In the wiring formation method according to claim 8,
The conductive layer formed from the electrode on the upper substrate to the vicinity of the stepped portion on the upper substrate, and from the vicinity of the stepped portion on the upper substrate to the upper surface of the lower substrate across the stepped portion, A wiring forming method, wherein the first drawing step is performed so that a conductive layer formed in a direction perpendicular to the stepped portion is linear when viewed from above. In the wiring formation method as described in any one of Claims 1-7,
As the plurality of substrates,
A plurality of the electrodes are arranged respectively, and the upper substrate is laminated in a state of being rotated in the lamination plane with respect to the lower substrate, and the distance between the electrodes to be connected increases as the distance from the rotation center increases 2 Using two substrates
As the print head,
Using one having a plurality of nozzles arranged in a straight line,
In the wiring formation step,
A stage that can rotate in a plane perpendicular to the direction of ink droplet ejection by the print head and can move in a direction along the vertical plane while the two substrates are supported facing the print head. Use
By moving the stage and ejecting ink droplets at different timings for each nozzle of the print head, the length of the electrodes according to the distance between the electrodes to be connected is reduced from the electrodes on the lower substrate. A first drawing step of forming a conductive layer;
After the first drawing step, the stage is rotated in a vertical plane in the discharge direction around the end point of the conductive layer drawn between the electrodes connected on the side farthest from the rotation center. A rotation step in which the arrangement direction of the plurality of electrodes on the upper substrate is parallel to the arrangement direction of the plurality of nozzles;
After the rotating step, the upper stage is moved from the end point of each conductive layer formed in the first drawing step by moving the stage and discharging ink droplets at different timings for each nozzle of the print head. A second drawing step of forming a conductive layer having a length corresponding to the distance between the electrodes to be connected, on each straight line in the orthogonal direction of the stepped portion passing through the electrode of the substrate on the upper surface of the lower substrate When,
After the second drawing step, the stage is moved while discharging the ink droplets from the nozzles of the print head so as to straddle the stepped portion from the end point of each conductive layer formed in the second drawing step. The conductive layer is formed in the direction perpendicular to the stepped portion to the vicinity of the stepped portion on the upper substrate, and the conductive layer is formed from the vicinity of the stepped portion on the upper substrate to the electrode on the upper substrate. 3. A wiring forming method comprising performing three drawing steps. In the wiring formation method of Claim 10,
A conductive layer formed in an orthogonal direction of the step portion from the end point of each conductive layer formed in the second drawing step to the vicinity of the step portion in the upper substrate across the step portion, and the upper substrate The wiring forming method, wherein the third drawing step is performed so that a conductive layer formed from the vicinity of the step portion to the electrode on the upper substrate has a linear shape when viewed from above. In the wiring formation method as described in any one of Claims 1-11,
In the wiring formation step,
A wiring forming method, wherein a conductive layer is formed by landing ink droplets at equal intervals in a top view in an orthogonal direction of the stepped portion. In the wiring formation method as described in any one of Claims 1-11,
In the wiring formation step,
A wiring forming method, wherein a conductive layer is formed by landing ink droplets at equal intervals in a top view in the formation direction of the conductive layer. In the wiring formation method as described in any one of Claims 1-13,
As the plurality of substrates,
Using a plurality of electrodes arranged respectively,
As the print head,
A wiring forming method comprising using a plurality of nozzles arranged in a straight line in accordance with the interval of the electrodes in the substrate. In the wiring formation method as described in any one of Claims 1-14,
In the wiring formation step,
A voltage is applied between the plurality of substrates and the print head to charge the ink droplets, and an electrostatic attraction force is applied to the ink droplets to land the ink droplets on the plurality of substrates. Wiring formation method.

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