JP4577526B2 - Method for manufacturing flexible printed circuit board - Google Patents

Description

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

  A flexible printed circuit board obtained by patterning a copper foil having a thickness of 35 μm or less laminated on one side of a polyimide base film having a thickness of 25 μm or less into a wiring circuit by a subtractive method is widely used.

  As a method for manufacturing such a flexible printed circuit board in a roll-to-roll manner, a method is proposed in which a copper-clad laminate is adhered on a carrier film with an adhesive whose adhesiveness is reduced by light irradiation. (See Patent Document 1). In this manufacturing method, a copper-clad laminate having a structure in which a copper foil is adhered to a polyimide film base is coated with a pressure-sensitive adhesive whose adhesiveness is reduced by light irradiation from the polyimide film base side surface. After forming the wiring circuit on the copper foil of the copper-clad laminate, the adhesive is cured by irradiating with ultraviolet rays from the carrier film side to reduce its adhesive strength, and the interface between the adhesive and the polyimide base film A flexible printed circuit board can be obtained by peeling and removing the carrier film. In this manufacturing method, since the copper-clad laminate is held on the carrier tape, it is possible to suppress the occurrence of folds and wrinkles during wiring circuit formation processing, and it is possible to reduce the adhesive strength of the adhesive. Further, curling and folding can be suppressed even when the carrier film is peeled off.

JP-A-7-99379

  However, with the recent increase in the density of electronic devices, the manufacturing method disclosed in Patent Document 1 using a carrier tape under the present situation that the flexible printed circuit board is thinned and densified. In this case, when the pattern pitch of the wiring circuit is 40 μm or less, there is a problem that the patterning accuracy is lowered due to the influence of the surface distortion and unevenness of the carrier tape. In addition, there has been a problem that pattern defects are easily caused by chips from the cut surfaces on both ends of the carrier tape, adhesives exposed on the cut surfaces, and the like.

  In addition, when implementing the manufacturing method disclosed in Patent Document 1, a roll unwinder and a winder are indispensable, making it difficult to reduce the size of the equipment and increasing the running cost of the incidental equipment. In addition, since the roll-to-roll process is performed, the condition setting time, the rewinding time, and the like become long, so that there is a problem that the manufacturing lead time becomes long.

  In addition, after patterning the copper foil, when punching the copper-clad laminate as necessary, the die-cutting method is applied, so that the end of the cut surface can be burred or the flexible wiring circuit There was a problem that the substrate itself was easily deformed. Moreover, an expensive metal mold must be prepared for each flexible wiring board having different wiring circuit patterns, and there has been a problem that the punching cost cannot be suppressed. For this reason, it is conceivable to apply a laser cutting method that can easily create various blank patterns by changing the program. However, the laser cutting method simultaneously cuts the carrier tape, so the flexible printed circuit board is placed on the carrier tape. In other words, the handleability is greatly reduced, and the incidence of defective products is increased.

  The present invention is intended to solve the above-described problems of the prior art, and even when the pattern pitch of the flexible printed circuit board becomes very small, the patterning accuracy does not decrease and the pattern defect is not caused. It is an object of the present invention to provide a method for manufacturing a flexible printed circuit board, which is less likely to occur, the manufacturing equipment can be reduced in size relatively easily, the lead time can be reduced relatively, and the punching can be performed by a laser cutting method. And

  The present inventor uses a transparent hard substrate such as a glass substrate or an acrylic substrate having excellent flatness in place of the carrier tape so that a flexible printed circuit board can be manufactured in a sheet-fed type instead of roll-to-roll, and its A laminated body in which a conductive layer is formed on an insulating support film with a pressure-sensitive adhesive layer capable of reducing the adhesive strength by ultraviolet irradiation or the like is attached to the transparent hard substrate from the side of the insulating support film, and patterning of the conductor layer is performed. After that, the adhesive strength of the pressure-sensitive adhesive layer is reduced and the laminate is peeled off from the transparent hard substrate, or the conductor layer is directly bonded to the transparent hard substrate with the polyimide precursor-based pressure-sensitive adhesive layer. Immediately after the patterning of the conductor layer, the polyimide precursor system pressure-sensitive adhesive layer is imidized, thereby making the insulating polyimide support film and reducing its adhesive strength, It found that the above object can be achieved by peeling the polyimide support film from the transparent hard substrate after, and completed the present invention.

That is, the first aspect of the present invention is a method for producing a flexible printed circuit board in which a wired circuit is formed on an insulating support film, and includes the following steps (a) to (d):
(A) The process of sticking the laminated body by which the conductor layer was formed on the insulation support film with the adhesive layer from the insulation support film side to a transparent hard substrate;
(B) patterning the conductor layer of the laminate to form a wiring circuit;
(C) reducing the adhesive strength of the pressure-sensitive adhesive layer; and (d) peeling the laminate on which the wiring circuit is formed from the transparent hard substrate so that the pressure-sensitive adhesive layer remains on the transparent hard substrate side. A manufacturing method is provided.

Moreover, 2nd this invention is a manufacturing method of the flexible wiring circuit board by which the wiring circuit was formed on the insulating polyimide support film, Comprising: The following processes (aa)-(dd):
(Aa) a step of laminating a conductor layer on a transparent hard substrate via a polyimide precursor adhesive layer;
(Bb) patterning the conductor layer to form a wiring circuit;
(Cc) imidating the polyimide precursor adhesive layer to form an insulating polyimide support film; and (dd) separating the polyimide support film on which the wiring circuit is formed from the transparent hard substrate. A manufacturing method is provided.

In the first aspect of the present invention, when the punching process is performed by the laser cutting method, it is further performed between the step (b) and the step (c) or between the step (c) and the step (d). Step (e)
(E) It is preferable to further include a step of performing a punching process on the laminated body on which the wiring circuit is formed by a laser cutting method. Similarly, in the second aspect of the present invention, a step (ee) is further provided between the step (bb) and the step (cc) or between the step (cc) and the step (dd).
(Ee) It is preferable to further include a step of performing a punching process on the laminated board on which the wiring circuit is formed by a laser cutting method.

  According to the method for manufacturing a flexible printed circuit board of the present invention, the process operation is performed on a transparent hard substrate having excellent flatness. There is no variation and the yield is dramatically improved. In particular, even fine patterning by subtractive method enables stable refinement and facilitates product impedance control. Moreover, since a carrier film is not used, pattern defects due to adhesion of foreign matters such as dust resulting from the use of the carrier film can be eliminated.

  Moreover, since it can manufacture by a single wafer type on a transparent hard base plate, manufacture with a very compact installation is attained. Therefore, manufacturing space and incidental equipment space can be reduced, resources such as electric power, chemicals, and water can be saved, and lead time can be shortened. Furthermore, since the punching process can be performed by the laser cutting method, various problems associated with the die cutting process can be eliminated.

  Hereinafter, an example of a method for producing a flexible printed circuit board having a wiring circuit formed on an insulating support film according to the present invention will be described in detail with reference to the drawings.

  The manufacturing method of the first aspect of the present invention will be described step by step with reference to FIG.

Step (a)
First, as shown to Fig.1 (a), the laminated body 3 in which the conductor layer 2 was formed on the insulation support film 1 is stuck on the transparent hard substrate G by the adhesive layer 4 from the insulation support film 1 side. . Specifically, a pressure-sensitive adhesive is applied onto the transparent hard substrate G by a known method, for example, spin coating, and dried to form a pressure-sensitive adhesive layer 4, and the laminate 3 is formed on the insulating support film 1. Adhere from the side using a rubber roller.

  Here, examples of the transparent hard substrate G include an acrylic substrate and a glass substrate, but it is preferable to use a glass substrate that is more excellent in flatness and heat resistance. The pressure-sensitive adhesive layer 4 may be formed on the entire surface of the transparent hard substrate G.

  The important point in this step (a) is that the transparent hard substrate G having excellent flatness is used in a single wafer type, and the insulating support film 1 and the transparent hard substrate G are good during processing such as a patterning step. It is relatively more than with respect to the transparent hard substrate G by being subjected to some processing (for example, ultraviolet irradiation processing, heat processing, cooling processing, ultrasonic irradiation processing, electron beam irradiation processing, etc.) while maintaining good adhesion. It is to use the adhesive layer 4 in which the adhesiveness with respect to the insulating support film 1 is greatly reduced.

  Even when the pattern pitch of the flexible printed circuit board becomes very small by using the transparent hard substrate G having excellent flatness in a single-wafer type, the patterning accuracy is not lowered and pattern defects are less likely to occur. The manufacturing equipment can also be reduced in size relatively easily, and the lead time can be relatively shortened. Further, by using the pressure-sensitive adhesive layer 4 whose adhesion to the insulating support film 1 is relatively lower than that to the transparent hard substrate G due to treatment such as ultraviolet irradiation treatment, the patterning of the conductor layer 2 is performed. In this case, the laminate 3 can be reliably held on the transparent hard substrate G, and the laminate 3 can be easily separated from the transparent hard substrate G after patterning.

  As the insulating support film 1, the same insulating base film as a conventional copper-clad laminate can be used, and a polyimide film is preferable. Although there is no restriction | limiting in particular also in the thickness, Usually, it is 50 micrometers or less, Preferably it is 20-25 micrometers.

  Examples of the conductor layer 2 include electrolytic copper foil, SUS304 foil, SUS430 foil, aluminum foil, beryllium foil, and phosphor bronze foil. Moreover, a copper-nickel alloy plating layer etc. can also be mentioned. Although there is no restriction | limiting in particular also in the thickness, Usually, 35 micrometers or less, Preferably it is 8-12 micrometers.

  If the thickness of the transparent hard substrate G is too thin, it is likely to be deformed or broken by external stress, and the workability at the time of manufacture is reduced. If it is too thick, the weight becomes heavy, increasing the load on the manufacturing equipment. Therefore, the thickness is preferably 1.0 mm to 5.0 mm, more preferably 1.5 to 2.5 mm.

  If the thickness unevenness of the transparent hard substrate G (flatness 1-measured by the TTV method) becomes large, when exposing a fine pattern, the focus at the time of exposure may not be achieved, and pattern defects may occur. It is desired to suppress the thickness unevenness to 0.02 mm or less.

  Further, when the warpage of the transparent hard substrate G (result of measurement by flatness 2-LTV method) becomes large, the transparent hard substrate G is removed by a vacuum chuck at the time of patterning of the conductor layer 2 in step (b) described later. Since it becomes difficult to fix and a pattern defect may occur, it is preferably suppressed to 0.1 mm or less.

  The transparent hard substrate G is an ultraviolet curable adhesive when irradiated with ultraviolet rays from the transparent hard substrate G side in order to cure the ultraviolet curable adhesive as the adhesive layer 4 in the step (c) described later. It is preferable to be UV transmissive so that can be sufficiently cured. Here, if the ultraviolet transmittance is too low, it is necessary to lengthen the irradiation time or increase the irradiation amount in order to cure the ultraviolet curable pressure-sensitive adhesive 4, and the work efficiency is significantly reduced. It is preferably at least 30% (measurement result with an ultraviolet spectrophotometer in a wavelength region of 250 to 450 nm).

  Examples of the pressure-sensitive adhesive layer 4 include an ultraviolet curable pressure-sensitive adhesive layer, a thermosetting pressure-sensitive adhesive layer, and the like, and an ultraviolet curable pressure-sensitive adhesive layer is particularly preferable in terms of realizing good thermal stability. .

  As such an ultraviolet curable pressure-sensitive adhesive layer, a layer having a certain degree of adhesive strength before irradiation with ultraviolet rays and being cured by irradiation with ultraviolet rays to reduce its adhesive strength is used. In this case, it is necessary that the adhesive force (peel strength) of the laminate 3 to the insulating support film 1 is smaller than that of the transparent hard substrate G. As such an ultraviolet curable pressure-sensitive adhesive layer, an ultraviolet curable adhesive having an initial peel strength (JIS K6854) before ultraviolet irradiation of 3 N / cm or more and a peel strength after ultraviolet irradiation of 1 N / cm or less. It is preferable to use a film formed of an agent. Specifically, a photo radical polymerization type acrylic ultraviolet curable pressure sensitive adhesive or the like can be used.

Step (b)
Next, the wiring layer 2a is formed by patterning the conductor layer 2 of the multilayer body 3 using, for example, a normal photolithography technique (FIG. 1B). Specifically, a photosensitive resist film was stuck on the conductor layer 2 using its adhesive force, exposed through a patterning mask, and developed to form an etching resist pattern for the conductor layer 2. Thereafter, the conductor layer 2 is etched and patterned, and then the photosensitive resist pattern is removed to form the wiring circuit 2a.

  Although only one wiring circuit 2a may be formed on the insulating support film 1 of the laminate 3, a plurality of wiring circuits 2a are usually formed. When a plurality of wiring circuits 2a are formed, as will be described later, the wiring circuits 2a are divided into individual flexible wiring circuit boards by punching.

Step (c)
Next, the adhesive strength of the adhesive layer 4 is reduced (FIG. 1C). For example, when an ultraviolet curable pressure-sensitive adhesive layer is used as the pressure-sensitive adhesive layer 4, the ultraviolet light UV is irradiated from the transparent hard substrate G side, the ultraviolet curable pressure-sensitive adhesive layer is cured, and is insulated more than the transparent hard substrate G. The adhesive strength is lowered so that the adhesion strength to the support film 1 is lowered (FIG. 1 (c)).

  In addition, as another means for reducing the adhesive strength of the pressure-sensitive adhesive layer 4, it is possible to set the atmosphere temperature of the pressure-sensitive adhesive layer 4 to be lower than the temperature at which the pressure-sensitive adhesive layer 4 is attached. Thereby, the adhesive layer 4 becomes hard and adhesive force can be reduced.

Step (d)
Next, the laminate 3 on which the wiring circuit 2a is formed is peeled from the transparent hard substrate G so that the adhesive layer 4 whose adhesive strength is reduced by curing remains on the transparent hard substrate G side. Thereby, the flexible printed circuit board 10 is obtained.

  In the embodiment of FIG. 1, the transparent hard substrate G and the laminate 3 are laminated with a single adhesive layer 4. However, as shown in FIG. 2, the adhesive layer 4 and the adhesive layer 4 described above are formed on both surfaces of the plastic film 5 a. The transparent hard substrate G and the laminate 3 may be laminated with a double-sided adhesive film 5 on which an adhesive layer 5b (for example, an ultraviolet curable adhesive layer) having the same characteristics is formed. Even in this case, the insulating support film 1 of the laminate 3 and the pressure-sensitive adhesive layer 5b of the double-sided pressure-sensitive adhesive film 5 are finally peeled off.

  A preferable example of the plastic film 5a is a polyester film having a thickness of 50 to 125 μm. Moreover, as an adhesive layer 5b, what shows the same characteristic as the above-mentioned adhesive layer 4 can be mentioned preferably, The thickness becomes like this. Preferably it is 10-30 micrometers.

  By the way, when a plurality of wiring circuits 2a are formed on one laminated body 3, it is necessary to punch them into individual flexible wiring circuit boards. The laminated body 3 on which the wiring circuit 2a is formed may be separated into individual flexible wiring circuit boards by a die-cutting method. However, it is difficult to generate burrs and deformation, and a laser that can easily create various punching patterns. It is preferable to apply a cutting method.

  Specifically, it is preferable to provide the following step (e) between step (b) and step (c) or between step (c) and step (d).

Step (e)
As shown in FIG. 1E, the laminate 3 on which the wiring circuit 2a is formed is punched by irradiating a known high-power laser beam L for cutting in accordance with the punching pattern. The laser device to be used and the laser irradiation conditions can be appropriately determined from known ones according to the material to be cut.

  In addition, it is more preferable that the step (e) is provided between the step (c) and the step (d) from the viewpoint of preventing contamination with the uncured adhesive.

  Moreover, although the aspect of FIG. 1 is an example which patterned the conductor layer 2 by the subtractive method, you may pattern by the built-up method. Also in this case, a flexible printed circuit board can be obtained through steps (a ′) to (d ′) shown below as in FIG. If necessary, a blanking process can also be performed by applying a laser cutting method as the step (e ′).

Step (a ′)
Similar to the step (a) described with reference to FIG. 1, the laminate 3 having the thin conductor layer 2 formed on the insulating support film 1 is formed on the transparent hard substrate G from the insulating support film side 1 by a known method. The adhesive layer 4 is adhered (FIG. 3A). Alternatively, after the insulating support film 1 is adhered to the transparent hard substrate G with the adhesive layer 4, a metal thin film may be formed on the surface of the insulating support film 1 as a thin conductor layer 2 by electroless plating (see FIG. 3 (a)).

  Here, the pressure-sensitive adhesive layer 4 is preferably formed on the entire surface of the transparent hard substrate G. Thereby, the adhesiveness with respect to the transparent hard board | substrate G of the plating resist pattern mentioned later can be improved.

Step (b ′)
Similar to the step (b) described in FIG. 1, a plating resist pattern 6 is formed on the thin conductor layer 2 of the multilayer body 3 (FIG. 3 (b1)), and a plating metal 2 ′ is deposited (FIG. 3 (b2)). The plating resist pattern 6 is removed (FIG. 3 (b3)), and the wiring circuit pattern 2a is formed by soft etching (FIG. 3 (b4)).

Step (c ′)
Similar to the step (c) described in FIG. 1, the adhesive strength of the pressure-sensitive adhesive layer 4 is reduced (FIG. 3 (c)).

Step (d ′)
Similar to the step (d) described in FIG. 1, the laminate 3 on which the wiring circuit 2 a is formed is peeled from the transparent hard substrate G so that the adhesive layer 4 remains on the transparent hard substrate G side. Thereby, the flexible printed circuit board 10 is obtained.

  As necessary, between the steps (b ′) and (c ′) or between the steps (c ′) and (d ′), as in the step (e) described in FIG. 1, the step (e It is also possible to perform punching by applying the laser cutting method as').

  Next, the manufacturing method of the second aspect of the present invention will be described step by step with reference to FIG.

Step (aa)
First, the conductor layer 42 is laminated on the transparent hard substrate G via the polyimide precursor system pressure-sensitive adhesive layer 41 (FIG. 4A). Specifically, a polyimide precursor adhesive is applied to the transparent hard substrate G and dried to form a polyimide precursor adhesive layer 41, and a conductor layer 42 such as a copper foil is pasted thereon with a pressure roll. Just wear it.

  Here, the polyimide precursor system pressure-sensitive adhesive layer 41 becomes an insulating polyimide support film by being subjected to an imidization treatment of heating to 250 ° C. to 350 ° C., for example. This polyimide support film functions as a support for the conductor layer 42 and has a lower adhesive force to the transparent hard substrate G than to the conductor layer 42. This makes it easy to peel off at the interface between the transparent hard substrate G and the polyimide support film.

  The polyimide precursor adhesive layer 41 is formed by forming a polyimide precursor adhesive as described above. Examples of such polyimide precursor adhesives include polyamic acids obtained from acid dianhydrides and diamines (Japanese Patent Laid-Open Nos. 60-157286, 60-243120, 63-239998). JP-A-1-245586, JP-A-3-123903, and JP-A-5-139027), a polyamic acid prepolymer synthesized from an excess of acid dianhydride and diamine and having a terminal acid dianhydride. Partially imidized polyamic acids obtained from polymers and diisocyanate compounds (polyamide resin handbook, published by Nikkan Kogyo Shimbun (page 536, 1988); polymer discussion, 47 (6), 1990) are used. be able to. Among these, polyamic acids obtained from acid dianhydride and diamine can be preferably used.

  Here, examples of the acid dianhydride include pyromellitic dianhydride (PMDA), 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA), 3,4,3 ′, Preferable examples include 4′-benzophenone tetracarboxylic dianhydride (BTDA) and 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA). Examples of diamines include 4,4′-diaminodiphenyl ether (DPE), paraphenylenediamine (PDA), 4,4′-diaminobenzanilide (DABA), and 4,4′-bis (p-aminophenoxy). Preferred is diphenyl sulfone (BAPS).

  The transparent hard substrate G and the conductor layer 42 are as described in the step (a) with respect to FIG.

Step (bb)
Next, the conductor layer 42 is patterned in the same manner as in the step (b) described with reference to FIG. 1 to form a wiring circuit 42a (FIG. 4B).

Process (cc)
The polyimide precursor system pressure-sensitive adhesive layer 41 is imidized to form an insulating polyimide support film 43 (FIG. 4C). As imidation conditions, it can set suitably according to the kind of polyimide precursor system adhesive to be used.

  In addition, although this process (cc) may be implemented between a process (bb) and a process (dd), you may implement between a process (aa) and a process (bb).

Step (dd)
Next, the polyimide support film 43 on which the wiring circuit 42a is formed is peeled from the transparent hard substrate (FIG. 4D). Thereby, the flexible printed circuit board 40 is obtained.

  If necessary, the obtained flexible printed circuit board 40 may be subjected to die cutting, but it is preferable to carry out the punching by a laser cutting method as in the step (e) described in FIG. .

  Specifically, the following step (ee) is preferably performed between the step (bb) and the step (cc) or between the step (cc) and the step (dd).

Step (ee)
As in the step (e) described in FIG. 1, the polyimide support film 43 on which the wiring circuit 42a is formed is irradiated with a known high-power laser beam L for cutting according to the extraction pattern. Preferably it is done.

  The step (ee) is more preferably provided between the step (cc) and the step (dd) from the viewpoint of preventing contamination due to the scattering of the adhesive.

  Hereinafter, the present invention will be specifically described based on examples.

Example 1
An ultraviolet curable acrylic pressure-sensitive adhesive (solid content: 20%) was applied to one side of a 1 mm-thick glass substrate having an ultraviolet transmittance of 98% so that the dry thickness was 20 to 30 μm, and 60 ° C. and 100 An ultraviolet curable pressure-sensitive adhesive layer was provided by drying in two stages at C.

  Next, a copper-clad laminate (copper foil 12 μm thickness / polyimide 25 μm thickness) was adhered to the UV curable adhesive layer on the glass substrate from the polyimide surface using a rubber roller, and the copper-clad laminate The copper foil was soft etched with a mixture of hydrogen peroxide and sulfuric acid to clean the copper foil surface.

  Next, a liquid resist (PMER-P, Tokyo Ohka Kogyo Co., Ltd.) is applied to the copper foil surface by a spin coat method, and dried to form an etching resist layer having a thickness of 7 μm. A pattern is formed on the etching resist layer. It is exposed through a mask, developed with a dedicated developer for the liquid resist used (Tokyo Ohka Kogyo Co., Ltd.), and then etched into a wiring circuit by etching the copper foil with a ferric chloride aqueous solution. Etching After removing the resist layer, a solder resist layer was provided, and the pattern terminal portion was subjected to solder plating.

  Next, the ultraviolet curable pressure-sensitive adhesive layer was cured by irradiating the ultraviolet curable pressure-sensitive adhesive layer with an energy amount of 400 mJ from the glass substrate side.

  Finally, it peeled between the hardened ultraviolet curable adhesive layer on a glass substrate, and the polyimide surface of a copper clad laminated board, and obtained the flexible printed circuit board. The peeling force at this time was 0.2 N / cm, the product was not curled, the adhesive was not transferred to the polyimide surface, and could be easily peeled from the glass substrate.

Example 2
A double-sided pressure-sensitive adhesive film having a 15 μm-thick UV-curable acrylic pressure-sensitive adhesive layer (D-203DF, Lintec Co., Ltd.) on each side of a 50 μm-thick polyethylene terephthalate film was prepared, and its UV transmittance was 95%. Was attached to one side of a 2 mm thick glass substrate at 80 ° C. using a rubber roller.

  A laminated body in which a 25 μm-thick polyimide film is provided with a 0.25 μm-thick seed layer (nickel-copper alloy layer) on a double-sided pressure-sensitive adhesive film attached to a glass substrate with a rubber roller from the polyimide film side. Laminated.

  Next, the ultraviolet curable acrylic pressure-sensitive adhesive layer was cured by irradiating the double-sided pressure-sensitive adhesive film with ultraviolet rays at an energy amount of 400 mJ from the glass substrate side.

  Next, a liquid resist (PMER-P, Tokyo Ohka Kogyo Co., Ltd.) is applied to the surface of the seed layer of the laminate by a spin coat method, and dried to form a plating resist layer having a thickness of 8 μm. , Exposed through a pattern mask, developed with a dedicated liquid resist developer (Tokyo Ohka Kogyo Co., Ltd.) to form a plating resist pattern, and then subjected to electrolytic copper plating to form 7 μm thick copper on the sheet layer. Deposited.

  Next, after removing the plating resist pattern, the exposed seed layer was removed by soft etching with a mixed solution of hydrogen peroxide and sulfuric acid. Then, a solder resist layer was provided, and the pattern terminal portion was subjected to solder plating.

  Finally, it peeled between the double-sided adhesive film on a glass substrate, and the polyimide film of a laminated body, and the flexible wiring circuit board was obtained. The peeling force at this time was 0.4 N / cm, the product was not curled, and the adhesive was not transferred to the polyimide surface.

  In the method for manufacturing a flexible printed circuit board according to the present invention, process operations are performed on a transparent hard substrate having excellent flatness, so that flatness is maintained throughout the entire process, and even if the printed circuit is refined, there is a variation in quality. In addition, the yield is dramatically improved. In particular, even fine patterning by subtractive method enables stable refinement and facilitates product impedance control. Moreover, since no carrier film is used, pattern defects due to adhesion of foreign matters such as dust resulting from the use of the carrier film can be eliminated, which is useful.

  Moreover, since it can manufacture by a single wafer type on a transparent hard base plate, manufacture with a very compact installation is attained. Therefore, manufacturing space and incidental equipment space can be reduced, resources such as electric power, chemicals, and water can be saved, and lead time can be shortened. Furthermore, since the punching process can be performed by a laser cutting method, various problems associated with the die cutting process can be eliminated, which is useful.

It is a manufacturing-process figure of one embodiment of the manufacturing method of this invention. It is an additional process drawing of the manufacturing method of the present invention. It is a manufacturing-process figure of another embodiment of the manufacturing method of this invention. It is a manufacturing-process figure of another embodiment of the manufacturing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation support film 2, 42 Conductor layer 2a, 42a Wiring circuit 3 Laminate 4 Adhesive layer 5 Double-sided adhesive film 5a Plastic film 5b Adhesive layer 6 Plating resist pattern 10, 40 Flexible wiring circuit board 41 Polyimide precursor system adhesive layer 43 Polyimide support film G Transparent hard substrate UV UV L Laser light

Claims (1)

A method for manufacturing a flexible printed circuit board in which a wiring circuit is formed on an insulating polyimide support film, the following steps (aa) to ( ee ):
( Aa ) A transparent hard substrate having a thickness of 1.0 mm to 5.0 mm, a thickness unevenness by the TTV method of 0.02 mm or less, and a warp by the LTV method of 0.1 mm or less is fixed with a vacuum chuck. A step of laminating a conductor layer on the transparent hard substrate fixed by a vacuum chuck with a polyimide precursor adhesive layer;
(Bb) Following the step (aa), a step of patterning the conductor layer to form a wiring circuit;
(Cc) Subsequent to step (bb), the polyimide precursor system pressure-sensitive adhesive layer is imidized to form an insulating polyimide support film , whereby the adhesive strength of the polyimide support film to the transparent hard substrate is determined from the adhesive strength to the wiring circuit. Also reducing the process;
(Ee) Subsequent to the step (cc), a step of punching the polyimide support film on which the wiring circuit is formed by a laser cutting method ; and (dd) a polyimide on which the wiring circuit is formed following the step (ee). Concrete methods made that have a step of peeling off the support film from the transparent hard substrate.

Images