JPH0394494A - Laminate for flexible printed circuit board - Google Patents

Abstract

PURPOSE:To improve operability, quality and reliability of a flexible printed board(FPC) during manufacturing steps by forming it of a metal-plated flexible laminated plate and a peelable lining material layer. CONSTITUTION:A laminate for a flexible printed circuit board formed of a metal-plated flexible laminated plate and a peelable lining material layer is provided. That is, peelable adhesive is laminated on a foil, a film, a sheet or a thin plate to become a base material by coating, rolling, adhering, fusion- adhering or other method. In this case, if the adhesive is hotmelt type, it is coated while being thermally fused. When a lining material is obtained in this manner, a conventional metal-plated flexible laminated plate such as a copper- plated flexible plate is superposed, and laminated on the side of viscous, adhesive layer at a temperature and under a pressure suitable for the adhesive by using a laminator. Thus, its operability during manufacturing steps is improved, and a flexible printed circuit board having simplicity, economy and high quality can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminate used for manufacturing flexible printed wiring boards with excellent workability.

[Conventional technology]

Copper-clad laminates used for flexible printed wiring boards (hereinafter referred to as FPC) are generally made of polyester, polyimide, or other film as a base material, and copper foil is laminated on top of that using an epoxy or other adhesive. . This F
The most important characteristic of a PC is flexibility, but with recent electronic
With the miniaturization, higher performance, and lower cost of electroclarifiers,
Strict high functionality and economic efficiency are now being required for this FPC as well.

(Problem to be solved by the invention) However, among these demands, high functionality and economy are often in a contradictory relationship, and it has been difficult to achieve both simultaneously without contradiction. Moreover, the higher the functionality, the more difficult it becomes to handle during the manufacturing process, especially during the transportation process, and the more difficult it is to handle it during the manufacturing process, especially during the transportation process.
! In general, it becomes difficult to perform such tasks. On top of that,
Being flexible tends to cause curls and wrinkles, which can lead to defective products. Therefore, as a temporary measure, the FPC is attached to a rigid thick plate-like reinforcing plate.
They were temporarily fixed with tape, etc. and sent to the process. However, this method is surprisingly time-consuming and does not lend itself well to automation. Therefore, we have developed and used specially designed machines and devices, but this leads to an increase in the cost of FPC.
There was a need for a simpler and more economical method.

The present invention meets the above-mentioned desire, and by devising the structure of the laminate, the present invention improves workability during the FPC manufacturing process at once, and also improves the quality and reliability of the FPC. An object of the present invention is to provide a laminate for a printed wiring board.

(Means for Solving the Problem) As a result of research into the method for improving workability described above, the present inventors found that by releasably laminating a special backing material layer on a conventional metal-clad laminate for FPC. The inventors have discovered that the above problems can be solved and have arrived at the present invention.

That is, the present invention provides a laminate for a flexible printed wiring board comprising a metal-clad flexible laminate and a peelable backing material layer.

The present invention will be explained in detail below.

The backing material used in the present invention is made of a specific substrate and a releasable adhesive having certain requirements.

The biggest feature of this backing material is that, unlike conventional copper-clad laminates for printed wiring boards, where the substrate and adhesive remain as part of the printed wiring board product, The problem is that it peels off from the metal conductor layer and does not remain at all in the printed wiring board product.

Because of this feature, if a board material with appropriate rigidity and toughness is used, it becomes possible to reuse conventional equipment for rigid printed wiring boards, which improves workability in terms of equipment costs. From this point of view, significant rationalization has become possible.

For the present invention, which has such effects, the releasable adhesive used in the backing material plays an important role.
It must meet the following conditions.

■At least until the conductor pattern is formed, the flexible laminate with the conductor layer, such as metal foil, must have enough adhesive strength to be held on the base material layer that is the support; ■It is also necessary. At the end of the process, the entire backing material must have enough adhesive strength to be peeled off cleanly without destroying the conductor pattern that remains as a product; ■Various chemicals used to form the conductor pattern, such as resist developer and resist stripping agent. , have chemical resistance to conductor etching agents, 2) and, if necessary, when applying a coverlay, have heat resistance to withstand drying or heat-pressing after the coverlay; 2) furthermore, the cover When the overcoating method is used for overcoating, it must be resistant to the solvent of the overcoat resin solution.

Specifically, in order to satisfy the above (1) and (2), it varies depending on the surface condition of the conductor layer, etc., but in general, the 180 degree peel strength is 50g/25# to 2500g/25Mn1, preferably 200 to 1000g/25m. adhesive strength is required. Regarding (2), it must not have solvent resistance to the solvent of the overcoat resin solution.

Rough heat resistance is 80℃/45 minutes to 150℃/20
Heat resistance of about 10 minutes is required.

In pattern forming and other processes, chemical resistance is specifically determined by Na if the resist is of the alkaline development type.
It is necessary to have resistance to a developer consisting of an aqueous solution such as 2C03, and a stripping solution consisting of an aqueous solution such as NaO, KO, etc.
In the case of a solvent-developed type, it must be resistant to a developer such as t,i,i-trichloroethane and a stripping solution such as methylene chloride. Similarly, it is necessary to withstand metal etching agents such as hydrogen peroxide monosulfuric acid, persulfate, ferric chloride, and cupric chloride.

Any removable adhesive used in the present invention can be used as long as it satisfies the above-mentioned requirement 1, and includes commercially available hot melt adhesives such as polyethylene, polyamide, and polyester, as well as acrylic and polyvinyl adhesives. It is also possible to select and use adhesives that meet the above requirements from among alcohol-based, silicone-based, and other adhesives.

The base material used in the present invention is necessary to have strength and rigidity as a support for the guiding layer, and sufficient bending strength, toughness, and flexibility to be able to be peeled off together with the above-mentioned release agent during the flexible printed wiring board manufacturing process. There is.

In addition, the base material must have strength and heat resistance that will not cause thermal deformation or damage during the flexible printed wiring board manufacturing process, and it must also be resistant to solvents and chemicals used during the process, similar to the peelable adhesive mentioned above. Must have.

Metals, plastics, etc. that satisfy the above requirements
Any material or structure can be used, such as paper, nonwoven fabric, ceramics, or a laminate made of an appropriate combination thereof.

Preferably, metal sheets or metal foils such as aluminum, copper, stainless steel, etc. (more preferably those whose outer surfaces are coated with plastic etc. to improve chemical resistance), polyester, polypropylene, FRP, etc.
plastic film or sheet.

The thickness is selected depending on the purpose of use, but is usually o. oi
~3m is easy to use.

When the base material has a certain strength, rigidity, and toughness, it becomes possible to use conventional rigid printed wiring board manufacturing equipment.

Traditionally, manufacturing equipment for FPCs has been expensive and unreliable, but the fact that conventional rigid PC board manufacturing equipment can be used is a great industrial advantage.

The conductor layer used in the present invention is preferably a metal foil or sheet layer that is generally used as a conductor.

Copper is the most common metal, but other metals such as gold, silver, aluminum, tin, nickel, tin-lead, and stainless steel can also be used depending on the purpose.

Although the above examples are those used for good conductor circuit boards, the present invention is also applicable to resistive circuit boards using copper-nickel, stainless steel, nickel-chromium, etc. as conductors.

The flexible printed wiring board laminate of the present invention has the above structure, and can be manufactured by the following method.

First, the above-mentioned releasable adhesive is laminated onto the above-mentioned single material foil, film, sheet, or thin plate by coating, spreading, pasting, fusing, or other methods.

At this time, if the adhesive is a hot-melt adhesive, a method is used in which the adhesive is heated and melted and coated.

Once the backing material referred to in the present invention is obtained as described above, the adhesive layer side of this backing material is stacked with a conventional metal-clad flexible laminate, such as a copper-clad flexible board, and a laminator is used to adjust the temperature to a temperature that is compatible with the adhesive. By laminating under pressure, the desired laminate for a flexible printed wiring board can be obtained.

Next, a method of using the laminate for flexible printed wiring boards of the present invention will be explained.

(2) A resist is coated on the metal layer of the package for a flexible printed wiring board of the present invention, and a DFR is laminated. (2): A photomask having a target pattern is used to expose and develop the resist.

(2): Etching the metal layer to obtain a desired conductor pattern.

■: Peel off the resist on the metal layer.

■: Overcoat by bonding to a film or printing method (applying a coverlay).

Incidentally, by using the polyimide resin developed by the present inventors, printing methods that were previously difficult to perform can be suitably performed.

■: Peel off the backing material on the laminate.

The above steps (1) to (2) can be said to be unique steps when using the laminate of the present invention. Also, the order of steps ① and ② may be reversed.

In this way, a method for manufacturing a flexible printed wiring board was realized in an extremely simple manner and in which a conventional rigid wiring board device could be used as is.

〔Example〕

EXAMPLES The present invention will be specifically explained below using Examples and Application Examples, but the present invention is not limited thereto.

Real M@1 50μ thick aluminum foil {manufactured by Sumikei Aluminum Foil■} and thickness 2
Dry-laminate a 5 μm polyester film (manufactured by Toray), then apply polyethylene adhesive (manufactured by Tokyo Cellophane Paper, product name: Linear Roden TU) to the aluminum foil side.
X-TC> is coated to a thickness of about 30 μm using a hot melt method.

Next, a steel-clad flexible laminate plate (GAF-33 manufactured by Shin-Etsu Chemical Co., Ltd.) was placed on the polyethylene adhesive layer side of the obtained laminate.
3M) using a laminator (HL-700 manufactured by Asahi Kasei Kogyo ■)
Using a laminating roll pressure of 5 K'J/ci, laminating roll temperature of 120° C., and laminating roll speed of 1.5 Trt/min. Through the above steps, the desired laminate for a flexible printed wiring board is obtained.

Example 2 An acrylic adhesive is blade coated on a 125 μm thick polyester film (Lumirror manufactured by Toray Industries Ltd.) and dried. Next, a protective IPP film is laminated to the adhesive to form a laminate. possible).

Next, in order to laminate a flexible laminate covered with copper foil, the protective film was peeled off from the laminate, and a steel clad laminate (made by Nikkan Kogyo Co., Ltd., F33) was applied to the peeled surface.
T25C I) with a laminator (manufactured by Asahi Kakogyo ■1-
iL-700), laminating roll pressure 5Kg
/r:at, laminating roll temperature 21° C. (room temperature), laminating roll speed 1.5 TrLl.

Through the above steps, the desired laminate for a flexible printed wiring board is obtained.

Application Example 1 (1) A resist pattern is formed on the copper foil surface of the flexible printed wiring board laminate obtained in Example 1 using a commercially available dry film resist.

(2) Etch out the exposed copper of the resist pattern obtained in (2) using a commercially available copper etchant, and then remove the resist with a stripping agent to obtain a copper foil circuit pattern.

(2) Overcoat the copper pre-circuit pattern with a solvent-soluble polyamideimide resin in the desired shape by screen printing, and dry at 130°C for 20 minutes.

(2) Next, the backing material of the flexible printed wiring board laminate made of aluminum foil, polyester film, and polyethylene adhesive is peeled off from the flexible printed wiring board having the copper foil pattern.

(2) By drying the copper foil pattern roughly coated with the polyamide-imide resin at 200°C for 5 minutes and then at 300°C for 10 minutes, a flexible printed wiring board covered with the polyamide-imide resin is obtained.

Note that the above steps were performed using a rigid printed wiring board device.

Application Example 2 (2) A resist pattern was formed on the copper foil surface of the printed wiring board laminate obtained in Example 2 using a commercially available dry film resist.

(2) Using the resist pattern obtained in (2), the exposed copper is etched out using a commercially available copper etching agent, and then the resist is removed using a stripping agent to obtain a copper foil circuit pattern.

(2) A polyimide barley film (Sony Flex) manufactured by Sony Chemical Co., Ltd. was laminated onto this copper foil circuit pattern by a conventional method and preheated at 80° C. for 30 minutes to temporarily bond it.

■After that, the backing material consisting of polyester film and acrylic adhesive of the first laminate for flexible printed wiring board is peeled off and heat-pressed at 150°C for 30 minutes to obtain a flexible copper foil printed board with coverlay. .

Example 3 ■ 5μ thick nichrome foil (product sold by Takeuchi Metal Foil Industry)
and polyester film (East Rail Mirror 125μTr
L) are pasted together using 20 μm of silicone adhesive.

Heat-laminate a dry film resist (1 non-photo AQ-3040 manufactured by Asahi Kasei Corporation) on the nichrome foil of the laminate in ■■, then expose it to 50 counts using a Topro MP-600 through a photomask. After this, the resist is developed with a 1% aqueous sodium carbonate solution using Topro MD-600.

■ The part of the nichrome foil that is not covered with
Etch out using.

■ 3% resist on the nichrome foil pattern left in ■
Remove with caustic soda aqueous solution.

■ On the nichrome foil pattern obtained in ■, overcoat a solution of solvent-soluble polyimide resin (SOXR manufactured by Nippon Kokoshi Kogyo (No. 11) by screen printing method.
Dry at 120°C for 20 minutes.

■Next, peel off the previous polyester film along with the adhesive layer from the nichrome foil pattern.

■This product was heated at 200℃ for 5 minutes, then at 300℃ for 10 minutes.
Drying is performed for a minute to obtain a nichrome foil resistance wiring board in which a nichrome foil pattern is directly formed on the polyamide-imide resin.

〔Effect of the invention〕

The laminate for flexible printed wiring boards of the present invention greatly improves workability during the manufacturing process of flexible printed wiring boards, and makes it possible to easily and economically manufacture high-quality flexible printed wiring boards. Moreover, it can be said that the industrial effect of making it possible to reuse conventional manufacturing equipment for rigid printed wiring boards is extremely large.

Claims (5)

[Claims] 1. A laminate for a flexible printed wiring board comprising a metal-clad flexible laminate and a peelable backing material layer. 2. The laminate for a flexible printed wiring board according to claim 1, wherein the releasable backing layer comprises a base layer and a releasable adhesive layer. 3. The removable adhesive is sufficient to hold the metal-clad flexible laminate during the process, has enough adhesion to allow the entire backing material to be peeled off without damaging the metal pattern on the printed wiring board, and is resistant to the drying process. 3. The laminate for a flexible printed wiring board according to claim 2, wherein the adhesive is heat resistant and resistant to chemicals used in each process. 4. Peelable adhesive has a 180 degree peel strength of 50 to 20
It has an adhesive strength of 00g/25mm and has a drying time of 8
4. The flexible adhesive according to claim 3, wherein the adhesive has heat resistance of 0 to 130° C. and chemical resistance to chemicals used in each step of pattern formation, etching, and resist removal. Laminate for printed wiring boards. 5. Metal foil or metal whose base material has heat resistance, chemical resistance, and solvent resistance during the manufacturing process, and has sufficient strength to peel off from the metal layer during the manufacturing process and rigidity to support the metal layer. The laminate for a flexible printed wiring board according to claim 1, wherein the laminate is a sheet or a plastic film or sheet.