JP2009006512A - Method for manufacturing flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a flexible printed wiring board capable of decreasing unevenness of an insulating layer, improving flexibility and suppressing generation of warpage. <P>SOLUTION: In the method for manufacturing the flexible printed wiring board which laminates the insulating layer 5 on the surfaces of a substrate 2 and a conductive body 3 by performing a heating and pressing processing by a press-bonding member 14, and sticking an adhesive layer 6 of the insulating layer 5 composed of the adhesive layer 6 comprising a thermosetting resin as a main component and an insulating film 7 laminated on the surfaces of the adhesive layer 6 on the substrate 2 and the conductive body 3 provided on the surface of the substrate 2, the heating and pressing processing by the press-bonding member 14 is performed by placing a cushioning material 12 with a hardness of 60-90 by a Rockwell hardness (a scale R) between the press-bonding member 14 and the insulating layer 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a flexible printed wiring board that performs heat and pressure treatment via a cushion material.

  Generally, a flexible printed wiring board includes a base material, a conductor provided on the surface of the base material, and an insulating layer that covers the conductor. This insulating layer is composed of an adhesive layer and an insulating film laminated thereon, and is subjected to heat and pressure treatment from above via a cushion material by a pressure-bonding member heated to a predetermined temperature. Thus, the adhesive layer of the insulating layer is bonded to the base material and the conductor. Thus, a flexible printed wiring board is manufactured by laminating | stacking an insulating layer on the surface of a base material and a conductor (for example, refer patent document 1).

In general, a cushion material used in the above-described method for producing a flexible printed wiring board is excellent in flexibility. That is, the conductor formed on the surface of the base material has a wiring pattern formed by etching or the like, and performs heat and pressure treatment with uniform pressure on the insulating layer placed on the base material and the conductor. For example, a cushion material using an ethylene-vinyl acetate copolymer is used as the cushion material. By using such a cushioning material excellent in flexibility, air bubbles are released to the outside at the interface between the base material and the conductor and the insulating layer, and the adhesive layer is heated and melted on the conductor not provided with the insulating layer. Insulating layers can be laminated on the surface of the base material and the conductor while suppressing the flow of.
International Publication WO2005 / 002850 Pamphlet

  However, the cushioning material excellent in flexibility releases bubbles at the interface between the base material and the conductor and the insulating layer to the outside, and the heated and melted adhesive layer flows into the conductor on which the insulating layer is not provided. Although effective as a means for suppressing, there is a problem that irregularities occur in the insulating layer of the flexible printed wiring board. That is, when the adhesive layer of the insulating layer is bonded onto the substrate and the conductor with a uniform pressure in the thickness direction, the conductor constituted by the adhesive layer 106 and the insulating film 107 as shown in FIG. Since the insulating layer 105 on 103 protrudes by the thickness of the conductor 103, there is a problem that the insulating layer 105 of the flexible printed wiring board 101 is uneven. The problem that the flexibility of the flexible printed wiring board 101 is deteriorated due to the unevenness of the insulating layer 105, and a case where a plurality of conductors 103 are provided with a small interval as shown in FIG. 4B. Had the problem of warping.

  The present invention has been made in view of such circumstances, and provides a method for manufacturing a flexible printed wiring board that can reduce the unevenness of an insulating layer, improve flexibility, and suppress warpage. The purpose is to do.

  In order to achieve the above-mentioned object, in the invention according to claim 1, a heat and pressure treatment with a pressure bonding member is performed, and the adhesive layer mainly composed of a thermosetting resin and the surface of the adhesive layer are laminated. Flexible printed wiring that laminates an insulating layer on the surface of the base material and the conductor by adhering the adhesive layer of the insulating layer constituted by the insulating film to the base material and the conductor provided on the surface of the base material In the manufacturing method of a board, the heat-pressing process by a crimping | compression-bonding member is performed by interposing the cushioning material which has a Rockwell hardness of 60-90 between a crimping | compression-bonding member and an insulating layer.

  According to this configuration, since the cushion material having a Rockwell hardness of 60 to 90 is interposed between the crimping member and the insulating layer, the adhesive layer is applied to the base material by heat and pressure treatment using the crimping member. Are adhered, and the adhesive layer on the conductor is adhered with a larger pressure than the adhesive layer on the substrate. Accordingly, the unevenness of the insulating layer of the flexible printed wiring board can be reduced by changing the thickness of the insulating layer provided on the surfaces of the base material and the conductor. As a result, the flexibility of the flexible printed wiring board can be improved and the warpage can be suppressed. Here, the Rockwell hardness is a value measured according to the standard of R scale of ASTM D785.

  In the invention according to claim 2, the cushion material is formed of a resin sheet, and the resin sheet is made of polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, methacrylic resin, and vinyl chloride. It is formed of at least one resin selected from the group.

  According to this configuration, the cushion material 12 can be formed of a resin that is harder than the ethylene-vinyl acetate copolymer used in the conventional cushion material and is inexpensive and versatile. As used herein, “a resin harder than an ethylene-vinyl acetate copolymer” refers to a resin having a hardness measured in accordance with the standard of R scale of ASTM D785 and higher than that of an ethylene-vinyl acetate copolymer. Say. For example, the Rockwell hardness (85-110) of a polypropylene resin measured according to the standard of ASTM D785 R scale is an ethylene-vinyl acetate copolymer (Shore D hardness measured according to the standard of ASTM D2240 is The polypropylene resin is considered to be harder than the ethylene-vinyl acetate copolymer.

  The invention according to claim 3 is characterized in that a sheet member subjected to a release treatment is provided on the surface of the resin sheet. According to this configuration, it is possible to prevent the inconvenience that the resin component constituting the resin sheet adheres to the flexible printed wiring board when the heating and pressurizing process is performed by the crimping member.

  The invention described in claim 4 is characterized in that a deformable corrugated cardboard paper is interposed between the cushion material and the pressure-bonding member, and heat-pressing treatment with the pressure-bonding member is performed. According to this configuration, even when the parallelism between the crimping member and the cushioning material is not maintained when performing the heat and pressure treatment with the crimping member, the planar direction (that is, the crimping member is in contact with the cushioning material). Load distribution in the direction of the surface to be made). Therefore, the load applied to the cushion material becomes uniform, and bubbles at the interface between the base material, the conductor and the insulating layer can be discharged to the outside.

  ADVANTAGE OF THE INVENTION According to this invention, the unevenness | corrugation of the insulating layer of a flexible printed wiring board can be made small, flexibility can be improved and generation | occurrence | production of curvature can be suppressed.

Hereinafter, a preferred embodiment of the present invention will be described.
FIG. 1 is a cross-sectional view for explaining a method for producing a flexible printed wiring board according to the present invention, and shows a state before an adhesive layer of an insulating layer is bonded to a substrate and a conductor. FIG. 2 is a cross-sectional view for explaining the method for producing a flexible printed wiring board according to the present invention, and is a view showing a state where pressure is applied through a cushion material by a pressure-bonding member. FIG. 3 is a cross-sectional view showing a flexible printed wiring board according to the present invention. In addition, the arrow W in FIG. 1 represents the thickness direction of a flexible printed wiring board, and thickness is the length in the thickness direction W.

  As a manufacturing method of the flexible printed wiring board in the present embodiment, an insulating layer laminated on the surface of the adhesive layer having the thermosetting resin as a main component and the adhesive layer by performing a heat and pressure treatment with a pressure bonding member. The insulating layer is laminated on the surface of the base material and the conductor by adhering the adhesive layer of the insulating layer composed of the film to the base material and the conductor provided on the surface of the base material. Thus, a flexible printed wiring board is manufactured by laminating | stacking an insulating layer on the surface of a base material and a conductor.

  More specifically, first, as shown in FIG. 1, a flexible base 2 formed of a flexible resin film on a base 8 via a cushion material 9, and a surface of the base 2 A wiring board 4 composed of the provided conductor 3 having a thickness of 8 to 36 μm is placed. Then, as shown in FIG. 1, the adhesive layer 6 having a thickness of 0.015 to 0.05 mm mainly composed of a thermosetting resin and the surface of the adhesive layer 6 are laminated on the wiring board 4. An insulating layer 5 composed of an insulating film 7 having a thickness of 0.0125 to 0.05 mm is placed. Then, in a state where the adhesive layer 6 of the insulating layer 5 is heated to a predetermined temperature, the adhesive layer 6 is temporarily bonded onto the wiring board 4 by applying pressure to the base material 2 with a predetermined pressure.

Next, as shown in FIG. 1, the crimping member 14 is installed above the wiring board 4 and the insulating layer 5, and the press cushion 10 is disposed between the crimping member 14 and the insulating layer 5. The press cushion 10 includes a deformable release film 11 made of a fluororesin and having a thickness of 0.01 to 0.04 mm, and a thickness of 0.060 to 0.200 mm laminated on the surface of the release film 11. It is comprised from the cushion material 12 and the corrugated paper 13 of thickness 0.4-1.0mm laminated | stacked on the surface of the cushion material 12. FIG. And the crimping | compression-bonding member 14 is moved to the direction of the arrow A in a figure, and it is set as the state shown in FIG. 2, and the adhesive layer 6 is 20-20 in the direction of the base material 2 through the press cushion 10 and the insulating film 7. In a state where the pressure is 30 kgf / cm ² , the adhesive layer 6 is heated and melted at a temperature of 140 to 180 degrees and heated to a curing temperature. As described above, since the adhesive layer 6 is mainly composed of a thermosetting resin, the adhesive layer 6 softens once when heated at the above-described curing temperature, but the heating is continued. Will be cured. When the preset curing time of the adhesive layer 6 elapses, the heating state by the pressure-bonding member 14 is released, the maintenance state of the curing temperature of the adhesive layer 6 is released, and cooling is started. The adhesive layer 6 of 5 is adhered to the base material 2 and the conductor 3 provided on the surface of the base material 2.

  Thus, the insulating layer 5 is laminated | stacked on the surface of the base material 2 and the conductor 3, and the flexible printed wiring board 1 as shown in FIG. 3 is manufactured. In addition, it is good also as a structure which provides the conductor 3 on the base material 2 via an adhesive bond layer (not shown).

  As the resin film and the insulating film 7 constituting the base material 2, those made of a resin material having insulating properties with excellent flexibility are used. As such a resin film, for example, any resin film that is versatile for flexible printed wiring boards, such as a polyester film, can be used. In particular, those having high heat resistance in addition to flexibility are preferable. Examples of such a resin film include polyamide resin films, polyimide, polyamideimide resin films, and polyethylene naphthalate. Are preferably used. Moreover, copper foil etc. are used suitably as metal foil which comprises the conductor 3 provided on the surface of the base material 2. FIG.

  Moreover, as a material of the adhesive layer 6 mainly composed of a thermosetting resin, for example, an adhesive mainly composed of an epoxy resin which is an insulating thermosetting resin can be used. The epoxy resin to be used is not particularly limited. For example, bisphenol A type, F type, S type, AD type, or a copolymer type epoxy resin of bisphenol A type and bisphenol F type, or naphthalene type epoxy is used. Resin, novolac type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin and the like can be used. A phenoxy resin that is a high molecular weight epoxy resin can also be used.

  Here, in the present embodiment, the cushioning member 12 having a Rockwell hardness of 60 to 90 is interposed between the crimping member 14 and the insulating layer 5, and the heat and pressure treatment by the crimping member 14 is performed. It is characterized by. With such a configuration, the adhesive layer 6 is bonded to the base material 2 by the heat and pressure treatment by the crimping member 14, and the adhesive layer 6 on the conductor 3 is bonded to the adhesive layer 6 on the base material 2. In comparison, it is possible to change the thickness of the insulating layer 5 which is bonded with a large pressure and is provided on the surfaces of the base material 2 and the conductor 3. That is, the thickness X of the insulating layer 5 on the surface of the conductor 3 can be made smaller than the thickness Y of the insulating layer 5 on the surface of the substrate 2. Here, the Rockwell hardness is a value measured according to the standard of R scale of ASTM D785.

  Further, the cushion material 12 used in the present embodiment is formed of a resin sheet, which is made of polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, methacrylic resin, vinyl chloride. It is preferably formed of at least one resin selected from the group consisting of: With such a configuration, the cushion material 12 can be formed of a resin that is harder than the ethylene-vinyl acetate copolymer used in the conventional cushion material and is inexpensive and versatile. As used herein, “a resin harder than an ethylene-vinyl acetate copolymer” refers to a resin having a hardness measured in accordance with the standard of R scale of ASTM D785 and higher than that of an ethylene-vinyl acetate copolymer. Say. For example, the Rockwell hardness (85-110) of a polypropylene resin measured according to the standard of ASTM D785 R scale is an ethylene-vinyl acetate copolymer (Shore D hardness measured according to the standard of ASTM D2240 is The polypropylene resin is considered to be harder than the ethylene-vinyl acetate copolymer.

  Moreover, in this embodiment, the release film 11 as a sheet | seat member by which the release process was carried out is provided in the surface of the resin sheet which forms the cushioning material 12. FIG. With such a configuration, it is possible to prevent the inconvenience that the resin component constituting the resin sheet adheres to the flexible printed wiring board 1 when performing the heat and pressure treatment by the crimping member 14.

  In the present embodiment, a heat-pressing process using the pressure-bonding member 14 is performed with a deformable corrugated paper 13 interposed between the cushion material 12 and the pressure-bonding member 14. With such a configuration, even when the parallelism between the pressure-bonding member and the cushion material 12 is not maintained when the heat-pressure treatment is performed by the pressure-bonding member 14, the parallel direction (that is, the pressure-bonding member 14 is insulated). The load distribution in the direction of the surface in contact with the layer 5) can be made uniform.

According to the manufacturing method of the flexible printed wiring board 1 of the said embodiment, the following effects can be acquired.
(1) In the present embodiment, the pressure member 14 and the insulating layer 5 are interposed between the cushioning material 12 having a Rockwell hardness of 60 to 90, and the heat and pressure treatment by the pressure member 14 is performed. Yes. For this reason, the adhesive layer 6 is bonded to the base material 2 by the heat and pressure treatment by the crimping member 14, and the adhesive layer 6 on the conductor 3 is compared with the adhesive layer 6 on the base material 2, Bonded with great pressure. Therefore, the unevenness of the insulating layer 5 of the flexible printed wiring board 1 can be reduced by changing the thickness of the insulating layer provided on the surfaces of the base material 2 and the conductor 3. As a result, the flexibility of the flexible printed wiring board 1 can be improved and the warpage can be suppressed.

  (2) In the present embodiment, the cushion material 12 is formed of a resin sheet, and this resin sheet is made of polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, methacrylic resin, vinyl chloride. And at least one resin selected from the group consisting of: Therefore, it is possible to form the cushion material 12 made of a resin sheet with a resin that is harder than the ethylene-vinyl acetate copolymer and is inexpensive and versatile.

  (3) In the present embodiment, a release film 11 as a sheet member subjected to a release process is provided on the surface of the resin sheet forming the cushion material 12. Therefore, it is possible to prevent the inconvenience that the resin component constituting the resin sheet adheres to the flexible printed wiring board 1 when performing the heat and pressure treatment by the crimping member 14.

  (4) In the present embodiment, the deformable corrugated paper 13 is interposed between the cushion material 12 and the crimping member 14, and the heating and pressurizing process by the crimping member 14 is performed. Accordingly, the load distribution in the parallel direction (that is, the direction of the surface where the crimping member 14 contacts the insulating layer 5) can be made uniform, the load applied to the cushion material 12 becomes uniform, and the base material 2 and Bubbles at the interface between the conductor 3 and the insulating layer 5 can be discharged to the outside.

  In addition, this invention is not limited to the said embodiment, A various design change is possible based on the meaning of this invention, and they are not excluded from the scope of the present invention. The above embodiment may be modified as follows, for example.

  In the above embodiment, the flexible printed wiring board 1 is a so-called single-sided board, but may be a double-sided board. That is, it is composed of an adhesive layer mainly composed of a thermosetting resin and an insulating film laminated on the surface of the adhesive layer by performing heat and pressure treatment with the first and second pressure bonding members. Each of the adhesive layers of the first and second insulating layers is adhered to a conductor provided on the surface of both the base material and the base material. By such a method, the first and second insulating layers may be laminated on the surface of the substrate and the first and second conductors, respectively. In this case, as in the case of the above-described embodiment, a press including the cushion material 12 described above between the first pressure-bonding member and the first insulating layer and between the second pressure-bonding member and the second insulating layer. Heat and pressure treatment is performed by each of the first and second pressure-bonding members with the cushion material of the cushion 10 interposed.

The press cushion 10 may not include the corrugated cardboard 13. Even in this case, the effects (1), (2), and (3) described above can be obtained.
The press cushion 10 may not include the release film 11. Even in this case, the effects (1), (2), and (4) described above can be obtained.

  As an application example of the present invention, a method for producing a flexible printed wiring board that performs a heating and pressurizing process through a cushioning material can be mentioned.

It is sectional drawing for demonstrating the manufacturing method of the flexible printed wiring board of this invention, and is a figure which shows the state before adhere | attaching the adhesive bond layer of an insulating layer on a base material and a conductor. It is sectional drawing for demonstrating the manufacturing method of the flexible printed wiring board of this invention, and is a figure which shows the state which is performing the heat pressurization process through a cushion material with a crimping member. Sectional drawing which shows the flexible printed wiring board manufactured by the manufacturing method of the flexible printed wiring board of this invention. (A) (b) Sectional drawing which shows the flexible printed wiring board manufactured by the manufacturing method of the conventional flexible printed wiring board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Flexible printed wiring board, 2 ... Base material, 3 ... Conductor, 5 ... Insulating layer, 6 ... Adhesive layer, 7 ... Insulating film, 8 ... Base, 9 ... Cushion material, 10 ... Press cushion, 11 ... Separation Mold film (sheet member subjected to mold release treatment), 12 ... cushion material, 13 ... corrugated paper, 14 ... pressure bonding member.

Claims (4)

The adhesive layer of the insulating layer composed of an adhesive layer mainly composed of a thermosetting resin and an insulating film laminated on the surface of the adhesive layer is subjected to heat and pressure treatment with a pressure bonding member. In the method of manufacturing a flexible printed wiring board in which the insulating layer is laminated on the surface of the base material and the conductor by adhering to the material and the conductor provided on the surface of the base material,
Manufacturing of a flexible printed wiring board characterized in that a heat and pressure treatment with the pressure-bonding member is performed by interposing a cushion material having a Rockwell hardness of 60 to 90 between the pressure-bonding member and the insulating layer. Method.   The cushion material is formed of a resin sheet, and the resin sheet is at least one selected from the group consisting of polyethylene resin, polypropylene resin, polystyrene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, methacrylic resin, and vinyl chloride. It is formed with the above resin, The manufacturing method of the flexible printed wiring board of Claim 1 characterized by the above-mentioned.   The method for producing a flexible printed wiring board according to claim 2, wherein a sheet member subjected to a release treatment is provided on a surface of the resin sheet.   The flexible pressurization according to any one of claims 1 to 3, wherein a deformable corrugated cardboard paper is interposed between the cushion material and the crimping member, and a heat and pressure treatment by the crimping member is performed. Manufacturing method of printed wiring board.

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