JP2019179915A - Method for manufacturing printed circuit board and printed circuit board - Google Patents

Abstract

To improve elasticity of a printed circuit board.SOLUTION: A method for manufacturing a printed circuit board includes: a first insulator film forming step of forming an insulator film on a metal mold; a conductive film forming step of forming a conductive film on the insulator film; a film to be transferred forming step of providing a film to be transferred to which a laminate of the insulator film and the conductive film is transferred, to be in contact with the conductive film; and a peeling step of peeling the metal mold from the film to be transferred and the laminate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a printed circuit board manufacturing method and a printed circuit board.

  In recent years, wearable electronic devices that can be worn on the human body and clothes, and robot arms that have joints and can perform complex operations are becoming widespread. In such wearable electronic devices and robot arms, there are cases where a flexible substrate that expands and contracts in accordance with the operation of the human body, robot arm, or the like is used.

  Conventional flexible boards use a large number of electric wires for power supply and signal transmission, but in general, electric wires have a structure in which a copper wire is the core and the outer periphery is covered with an insulator. Therefore, it is necessary to form a wiring pattern so as to correspond to the expansion and contraction of the flexible substrate. For this reason, the freedom degree of wiring is low. Moreover, in the conventional flexible substrate, if the expansion and contraction is performed in a direction other than a certain direction, the wiring may be disconnected or peeled off.

  The disclosed technology has been made in view of the above circumstances, and aims to improve the stretchability of a printed circuit board.

  The disclosed technology is a method for manufacturing a printed circuit board, wherein a first insulating film forming step of forming an insulating film on a mold, a conductive film forming step of forming a conductive film on the insulating film, and the insulating A transfer film forming step of providing a transfer film to which the laminate of the film and the conductive film is transferred so as to be in contact with the conductive film; and a peeling step of peeling the mold from the transfer film and the stack; Have

  The stretchability of the printed circuit board can be improved.

It is a figure explaining the printed circuit board of 1st embodiment. It is a figure explaining the manufacturing process of the printed circuit board of 1st embodiment. It is a figure explaining the metal mold | die used for preparation of the printed circuit board of 2nd embodiment. It is a 1st figure explaining the manufacturing process of the printed circuit board of 2nd embodiment. It is a 2nd figure explaining the manufacturing process of the printed circuit board of 2nd embodiment. It is a figure which shows the example by which the wiring pattern was laminated | stacked.

(First embodiment)
The first embodiment will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a printed circuit board according to the first embodiment.

  The printed circuit board 100 of this embodiment is a flexible printed circuit board that follows expansion, and a wiring pattern in which an insulating base material 2 is laminated on an insulating film 1 that is a base material is formed. In the printed circuit board 100 according to the present embodiment, the wiring pattern is formed in a corrugated shape, and the insulating film 1 is made elastic by using an elastic member such as rubber.

  Below, with reference to FIG. 2, the manufacturing process of the printed circuit board 100 of this embodiment is demonstrated. Drawing 2 is a figure explaining the manufacturing process of the printed circuit board of a first embodiment.

  In the present embodiment, in step 1 shown in FIG. 2, the metallic mold 11 is subjected to a mold release process, and an insulating base material is pattern printed on the mold subjected to the mold release process using an insulating ink. Insulating film) 2 is formed.

  In the mold release process of step 1 shown in FIG. 2A, the mold release process method is not particularly limited, but heat resistance is required for the mold release agent, and therefore a baking type silicon or fluorine resin is used as a base. It is preferable to use a release agent.

  Moreover, as an insulating base material which forms the insulating pattern 2, heat resistant resins, such as a polyimide and a liquid crystal polymer, are preferable from viewpoints, such as insulation and heat resistance. Firing of the heat-resistant resin used as the insulating substrate is preferably performed at a high temperature of 200 ° C. or higher, preferably 300 ° C. or higher in order to ensure sufficient strength and remove the residual solvent in the resin.

  In addition, as a method for printing the insulating pattern 2, ink jet printing in which an insulating ink 2 is drawn by discharging insulating ink from the ink jet nozzle 50 may be used. In the case of inkjet printing, it is not necessary to prepare a plate like screen printing, and the labor for creating and storing the plate is not required. That is, in the present embodiment, an arbitrary insulating pattern 2 can be easily drawn on the mold 11.

  In ink jet printing without using a plate, the mold 11 subjected to the mold release process needs ink wettability. If the mold 11 has sufficient ink wettability, even a low-viscosity ink jet ink can produce a uniform pattern film without causing ink repellency.

  2B, a conductive ink is ejected from the inkjet nozzle 50 onto the insulating pattern 2 formed on the mold 11, and the wiring pattern (conductive film) 3 is printed. At this time, the wiring pattern 3 is formed so as not to protrude from the insulating pattern 2.

  After the step 2, the wiring pattern 3 is cured by drying and baking. The firing temperature is 200 ° C. or higher, preferably 300 ° C. or higher. This is because the electrical resistance of the metal particles of the conductive film (wiring pattern 3) is lowered when firing at a high temperature. High temperature baking is also preferable from the viewpoint of removing the dispersant and solvent residues added to the conductive ink. Adhesion with the insulating pattern 2 is also improved.

  As a printing method of the wiring pattern 3, inkjet printing is preferable. The conductive ink for inkjet used for inkjet printing is composed of a dispersion containing ultrafine metal particles having a particle diameter of 1 to 100 nm or ultrafine metal particles having a metal oxide coating layer on the surface. Specifically, for example, a silver nano ink in which silver nanoparticles are dispersed in a solvent, a copper nano ink in which copper nanoparticles are dispersed in a solvent, and the like are preferable because of low electric resistance. By setting the particle diameter of the ultrafine metal particles to 100 nm or less, it is possible to stably discharge the conductive ink from the inkjet nozzle 50.

  In step 3 shown in FIG. 2C, an insulating film 1 is formed as a member to be transferred (transfer target film) onto which the insulating pattern 2 and the wiring pattern 3 formed on the mold 11 are transferred.

In other words, in step 3, the film to be transferred is provided so that the wiring pattern 3 and the film to be transferred are in contact with each other in the laminate 7 of the insulating pattern 2 and the wiring pattern 3. In other words, in step 3, the film to be transferred is covered so as to cover the wiring pattern 3 of the laminate 7.
In this embodiment, the member to be transferred is an insulating film, but the member to be transferred is not particularly limited as long as the insulating pattern 2 and the wiring pattern 3 can be transferred. The member to be transferred is preferably formed of a liquid thermosetting elastic member or the like. Further, the member to be transferred has a lower heat resistance than the insulating base material on which the insulating pattern 2 is formed.

  2D, the insulating film 1 formed on the mold 11 is released from the mold 11 together with the insulating pattern 2 and the wiring pattern 3, and the insulating pattern 2 and the wiring pattern 3 are laminated. The object is transferred to the insulating film 1. In other words, in step 4, the mold 11 is peeled from the insulating film 1 which is a member to be transferred. When this step 4 is completed, the printed circuit board 100 is formed.

  In this embodiment, for example, the mold release process is performed using the mold 11 as the SUS304 mold. As a baking mold release agent, KS-700 (Shin-Etsu Chemical Co., Ltd.) was dissolved in a toluene solvent, diluted to a solid content of 3 wt%, and applied onto the mold 11. When applying, it is applied while drying so as to wipe the mold 11 with a coating solution soaked in the waste cloth. Thereafter, firing was performed at 300 ° C. for 1 h, and the mold release agent was sufficiently baked onto the mold 11.

  Further, polyimide varnish was used as an insulating ink when drawing the insulating pattern 2 by inkjet. Specifically, varnish A (manufactured by Ube Industries) is diluted with an NMP solvent, BYK-333 (manufactured by BYK Chemie) is added as a surfactant, and the viscosity is adjusted to 10 mPa · s and the surface tension is 30 mNm. A polyimide ink (insulating ink) for inkjet application was used.

  In applying the ink, a pattern was drawn using a GEN4 head (manufactured by Ricoh). In drawing the insulating pattern 2, the stage on which the mold 11 was placed was heated to 80 ° C. and repeatedly applied while drying the coating solution on the stage to form an insulating film. The thickness of the insulating film created at this time was 10 μm. Thereafter, baking was performed at 300 ° C. for 1 h to sufficiently cure the insulating film (insulating pattern).

  Moreover, silver nano ink for inkjet and NPS-J (made by Harima Chemicals) were used for the conductive ink at the time of drawing the wiring pattern 3 with an inkjet. Similarly to the insulating pattern 2, the wiring pattern 3 was drawn using GEN4 (manufactured by Ricoh). In drawing the wiring pattern 3, the stage on which the mold 11 was placed was heated to 80 ° C. and repeatedly applied while drying the coating solution on the stage to obtain a conductive film. The film thickness of the conductive film created at this time was 5 μm. Then, it baked at 300 degreeC for 1 h, and fully hardened the electrically conductive film.

  In the mold 11, a release agent for an elastic member is applied to a region where the insulating pattern 2 is not drawn. In the release agent application region, it is necessary to draw a release pattern in accordance with the insulating pattern 2. Therefore, a release pattern was drawn using the release agent as an inkjet ink. The ink for inkjet was made into an ink by diluting x-24-9264 (manufactured by Shin-Etsu Silicone) as a release agent with a PGMEA solvent. At this time, the ink viscosity was 10 mPa · s, and the surface tension was 32 mNm. After the release agent was applied, it was baked at 150 ° C. for 1 hour to sufficiently react the release agent. In ink-jet application, a release pattern was drawn using a GNE4 head (manufactured by Ricoh). In drawing the mold release pattern, the stage on which the substrate was placed was heated to 80 ° C. and repeatedly applied while drying the coating solution on the stage, and the release agent was baked onto the substrate.

  Moreover, in this embodiment, the elastic member used as the insulating film 1 (transferred member) used KER-6020-F (made by Shin-Etsu Silicone) as silicon rubber. In this embodiment, the elastic member is baked at 150 ° C. for 1 h after being applied using a bar coater. The film thickness of the silicon rubber layer formed at this time was 200 μm.

  Thereafter, the formed silicon rubber is released from the mold. Since the insulating pattern 2 and the wiring pattern 3 are in close contact with the silicon rubber, the insulating pattern 2 and the wiring pattern 3 are transferred to the silicon rubber as they are. As a result, a polyimide film (insulating pattern 2) and a silver wiring pattern film (wiring pattern 3) fired at a high temperature are formed on a silicon rubber base material having low heat resistance.

  In the present embodiment, the printed circuit board 100 is thus formed so that the wiring pattern 3 on the insulating film 1 is covered with the insulating pattern 2. In other words, the printed circuit board 100 is formed such that the wiring pattern 3 is sandwiched between the insulating film 1 and the insulating pattern. Furthermore, in other words, the printed circuit board 100 of the present embodiment is formed by transferring the laminate 7 of the insulating pattern 2 and the wiring pattern 3 generated by high-temperature baking to an elastic member (resin).

  In this embodiment, by covering the wiring pattern 3 with the insulating pattern 2, the insulating pattern 2 holds the wiring pattern 3 when the insulating film 1 expands and contracts, and the wiring pattern 3 can be prevented from cracking. That is, in this embodiment, since the insulating pattern 2 holds the wiring pattern 3, it is possible to prevent the wiring pattern 3 from being peeled off or disconnected even when the insulating film 1 expands and contracts.

  Moreover, in this embodiment, since the insulating pattern 2 is formed in step 1 and the wiring pattern 3 is formed on the insulating pattern 2 and then transferred to the insulating film 1, the wiring pattern 3 comes into contact with the mold 11. Therefore, it is possible to prevent adhesion of foreign matters to the wiring pattern 3.

  Further, in this embodiment, the insulating pattern 2 and the wiring pattern 3 are corrugated, and an elastic member such as rubber is used for the insulating film 1. Therefore, it is possible to provide a printed circuit board 100 that is less likely to be loaded and is less likely to be disconnected or cracked.

  Note that, after the insulating pattern 2 and the wiring pattern 3 of the present embodiment are stacked, the insulating pattern may be formed again on the wiring pattern 3, and the wiring pattern 3 may be sandwiched between two layers of insulating patterns. Since the wiring pattern is reinforced by the upper and lower insulating patterns, disconnection and cracks are less likely to occur.

  Moreover, the laminated body 7 of the insulating pattern 2 and the wiring pattern 3 of the present embodiment can be repeatedly stacked to be multilayered. It is preferable to increase the wiring density by increasing the number of layers because the printed circuit board 100 can be further downsized. In that case, pattern printing of insulating ink and conductive ink and drying / firing may be repeated alternately. However, if you want to energize the conductive ink wiring pattern in the upper and lower layers, pattern printing holes for wiring connect with insulating ink. Then, by filling the hole with conductive ink, conduction between the upper and lower wirings can be secured. In addition, since the film thickness is increased due to the multilayering, cracks and disconnection are less likely to occur.

  When the member to be transferred cannot be released from the mold, a release agent for the member to be transferred may be applied to the mold. In that case, it is desirable to apply a release agent for the member to be transferred only to the member to be transferred (insulating film 1) and the grounding surface of the mold 11. Since the release agent needs to be pattern-printed, it may be applied by inkjet printing in the same manner as the insulating pattern 2 and the wiring pattern 3.

  In this embodiment, by applying a release agent for the transfer member only to the transfer member and the grounding surface of the mold 11, the insulating pattern 2 and the wiring pattern 3 do not come into close contact with the transfer member and the separation failure occurs. Can be suppressed.

(Second embodiment)
The second embodiment will be described below with reference to the drawings. In the second embodiment, a cavity is formed inside the printed circuit board. In the following description, only the differences from the first embodiment will be described, and the same reference numerals as those used in the description of the first embodiment will be used for those having the same configuration as the first embodiment. The description is omitted.

  FIG. 3 is a diagram for explaining a mold used for creating a printed circuit board according to the second embodiment. FIG. 3 shows a front view, a top view, and a side view of a mold 11A used for creating the printed circuit board of the present embodiment.

  As can be seen from the front view and the side view, the mold 11A of the present embodiment has a plurality of concave portions 11b formed in each of the vertical direction and the horizontal direction. Accordingly, the concave portion 11b and the flat portion 11c are formed on the surface of the mold 11A. In other words, the mold 11A has recesses formed in a lattice shape. In other words, the concave portion is a curved portion.

  In the present embodiment, a plurality of cavities (spaces) are formed in a lattice pattern in the printed circuit board by creating a printed circuit board using such a mold 11A.

  Below, the manufacturing process of the printed circuit board of this embodiment is demonstrated with reference to FIG.4 and FIG.5. FIG. 4 is a first diagram illustrating a manufacturing process of a printed circuit board according to the second embodiment, and FIG. 5 is a second diagram illustrating a manufacturing process of the printed circuit board according to the second embodiment.

  In step 1 shown in FIG. 4A, insulating ink is ejected from the inkjet nozzle 50 to draw the insulating pattern 2A on the mold 11A. Then, conductive ink is discharged from the inkjet nozzle 50 to form an arbitrary wiring pattern 3A on the insulating pattern 2A.

  At this time, the insulating pattern 2A is formed on all the concave portions 11b and the flat portion 11c formed on the surface of the mold 11A. The wiring pattern 3A is an arbitrary pattern according to the use of the printed board. The wiring pattern 3A is formed so as not to protrude from the insulating pattern 2A.

  When step 1 is completed, wiring pattern 3A is cured by drying and baking. The firing temperature is 200 ° C. or higher, preferably 300 ° C. or higher.

  The insulating pattern 2A and the wiring pattern 3A formed in step 1 are each formed in a shape that matches the concave portion 11b and the flat portion 11c of the mold 11A. That is, the insulating pattern 2A and the wiring pattern 3A have a shape having a concave portion and a flat portion.

  In step 2 shown in FIG. 4B, an insulating layer 1A is formed as a member to be transferred onto which the laminated body 7A in which the insulating pattern 2A and the wiring pattern 3A are stacked is transferred. The insulating layer 1A is formed by discharging a liquid thermosetting elastic member onto the laminated body 7A of the insulating pattern 2A or the wiring pattern 3A by the inkjet nozzle 50. Specifically, as shown in FIG. 4B, the insulating layer 1A is formed to have a concave portion (curved portion) 41 and a flat portion 42 that match the shapes of the insulating pattern 2A and the wiring pattern 3A. .

  In step 3 shown in FIG. 4C, the insulating film 4 for closing the recess 41 and forming the cavity 43 is formed on the insulating layer 1A. In the present embodiment, the insulating film 4 may be formed so as to be stuck on the flat portion 42 of the insulating layer 1A.

  In the following description, the insulating film 4 is the first insulating film, and one of the surfaces of the insulating film 4 on the insulating layer 1A (first insulating layer) side is the other surface of the insulating film 4. This surface is one surface of a printed circuit board 100A described later.

  In step 4 shown in FIG. 4D, the insulating pattern 2A, the wiring pattern 3A, the insulating layer 1A, and the insulating film 4 formed on the mold 11A are released from the mold 11A, and the insulating pattern 2A and the wiring are formed. The laminate of the pattern 3A is transferred to the insulating layer 1A.

  Next, in step 5 shown in FIG. 5A, the insulating layer 5 is formed by discharging insulating ink from the inkjet nozzle 50 onto the insulating pattern 2A released from the mold 11A. That is, in step 5, the insulating layer 5 is formed on the surface opposite to the surface on which the wiring pattern 3A is formed in the insulating pattern 2A. Therefore, the insulating layer 5 is formed in a shape having a concave portion 44 and a flat portion 45 that match the concave portion and the flat portion of the insulating pattern 2A.

  In step 6 shown in FIG. 5B, the insulating film 6 is formed under the insulating layer 5. The insulating film 6 is formed so as to circumscribe the concave portion 44 of the insulating layer 5. Therefore, as shown in FIG. 5B, a cavity 46 is formed between the flat portion 45 of the insulating layer 5 and the insulating film 6. The insulating film 6 may be formed so as to be attached to the recess 44 of the insulating layer 5. When the insulating film 6 is formed, the printed circuit board 100A is completed.

  In the following description, the insulating film 6 is a second insulating film, and one of the surfaces of the insulating film 6 on the insulating layer 5 (second insulating layer) side is the other surface of the insulating film 6. Is the other surface of the printed circuit board 100A.

  In addition, it is preferable to form the insulating layers 1A and 5 and the insulating films 4 and 6 of this embodiment with a liquid thermosetting elastic member or the like. The insulating layers 1A and 5 and the insulating films 4 and 6 are lower in heat resistance than the insulating base material forming the insulating pattern 2A.

  In the present embodiment, by forming the printed circuit board 100A as described above, the printed circuit board 100A has a plurality of grids formed by a first insulating film that forms one surface and a first insulating layer. The cavities 43 and the plurality of cavities 46 formed in a lattice pattern by the second insulating film and the second insulating layer forming the other surface of the printed board 100A are alternately arranged.

  Therefore, according to the present embodiment, the printed circuit board 100A can follow the expansion in the biaxial direction.

  In the present embodiment, the insulating pattern 2A and the wiring pattern 3A can be alternately formed in a plurality of layers on the mold 11A.

  FIG. 6 is a diagram illustrating an example in which wiring patterns are stacked. FIG. 6A is a diagram illustrating an insulating pattern 2A-1 in the printed circuit board 100A.

  The insulating pattern 2A-1 of this embodiment includes an insulating pattern 2A-11 formed on the flat surface of the mold 11A and an insulating pattern 2A-21 formed on the concave portion of the mold 11A and curved. It can also be seen that in the printed circuit board 100A, the cavities 43 are formed in a lattice pattern.

  FIG. 6B is a diagram illustrating a first wiring layer of the printed circuit board 100A. In FIG. 6B, a wiring pattern 3A-1 is arbitrarily formed on the insulating pattern 2A-1.

  FIG. 6C is a diagram showing a second wiring layer of the printed circuit board 100A. A wiring pattern 3A-2 shown in FIG. 6C is formed on the insulating pattern 2A-2 stacked on the wiring pattern 3A-1.

  Thus, in this embodiment, by laminating the insulating pattern 2A and the wiring pattern 3A, the wiring density is increased, and even if the member to be transferred is stretched, it is difficult to apply a load to the wiring, and disconnection and cracks are not generated. It is possible to provide a printed circuit board that is difficult to get up.

  In the present embodiment, the insulating layer 1A, the insulating pattern 2A, the wiring pattern 3A, and the insulating layer 5 having the recesses are formed by an inkjet method. Therefore, in this embodiment, the adhesion amount of the liquid can be arbitrarily adjusted. For example, a liquid with a certain amount can be adhered to a portion where the liquid is difficult to adhere, such as an inclination of a concave portion, and a pattern film having a uniform thickness can be created by ejecting the liquid multiple times.

  As mentioned above, although this invention has been demonstrated based on each embodiment, this invention is not limited to the requirements shown in the said embodiment. With respect to these points, the gist of the present invention can be changed without departing from the scope of the present invention, and can be appropriately determined according to the application form.

1, 4, 6 Insulating film 1A, 5 Insulating layer 2, 2A Insulating pattern 3, 3A Wiring pattern 43, 46 Cavity 100, 100A Printed circuit board

Japanese Patent No. 5600030

Claims (7)

A printed circuit board manufacturing method comprising:
A first insulating film forming step of forming an insulating film on the mold;
A conductive film forming step of forming a conductive film on the insulating film;
A transferred film forming step of providing a transferred film to which the laminate of the insulating film and the conductive film is transferred so as to be in contact with the conductive film;
A peeling step of peeling the mold from the film to be transferred and the laminate. In the first insulating film forming step, insulating ink is ejected from an inkjet nozzle to form the insulating film,
The method for manufacturing a printed circuit board according to claim 1, wherein, in the conductive film forming step, the conductive film is formed by discharging conductive ink from the inkjet nozzle.   The printed circuit board manufacturing method according to claim 1, wherein the insulating film is made of a thermosetting resin and is cured by baking at 200 ° C. or higher.   The printed circuit board manufacturing method according to claim 1, wherein the transfer target film is an elastic member. The mold has a plurality of recesses formed in a lattice shape,
A first film forming step of forming a first insulating film on the transferred film between the transferred film forming step and the peeling step;
A second insulating film forming step of forming another insulating film on the surface opposite to the surface on which the conductive film is formed in the insulating film after the peeling step;
5. The second film forming step of forming a second insulating film on a surface opposite to the surface on the insulating film side in the other insulating film, according to claim 1. A method for manufacturing a printed circuit board. A conductive film;
A laminate in which an insulating film formed on one surface side of the conductive film is laminated;
A film to which the laminate is transferred, and a film to be transferred having low heat resistance compared to the insulating film,
The printed circuit board, wherein the laminate is transferred to the film to be transferred so that the conductive film is disposed between the insulating film and the film to be transferred. The laminate has a plurality of recesses formed in a lattice shape,
In the insulating film, another insulating film formed on the surface opposite to the surface on which the conductive film is formed;
A first insulating film in which one surface is one surface of the printed circuit board and the other surface is a surface on the conductive film side of the transfer film;
A second insulating film in which one surface is the other surface of the printed circuit board and the other surface is a surface on the other insulating film side;
The first lattice-shaped cavities formed by the transfer film and the first insulating film, and the other insulating films and the second insulating film alternate with the first lattice-shaped cavities. The printed circuit board according to claim 6, further comprising: a second lattice-shaped cavity formed to be.

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