JPH09219569A - Flexible printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of static electricity by temporarily sticking flexible printed circuits onto a sheet with a slight adhesive whose surface specific resistance is at a specified value or under. SOLUTION: A fixed width of sheet 3 with an slight adhesive is bonded in the specified position of a flexible printed board 1, and a plurality of flexible printed circuits 2 are temporarily stuck onto the sheet 3 with a slight adhesive. For the sheet 3 with a slight adhesive, specified electrification preventive treatment is applied to it to put its surface specific resistance to 10<10> Ω or under. Hereby, the occurrence of the static electricity can be suppressed to the utmost, and the adhesion of foreign matters can be effectively prevented. By the above, the pollution of FPC product by foreign matters in the manufacture process vanishes, and the performance of the product can be improved. Moreover, the foreign matter removal work becomes needless, and the maintenance in view of environmental management can be lightened.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a surface resistivity of 1
The present invention relates to a flexible printed circuit board in which a plurality of flexible printed circuits are temporarily attached to a sheet with a slight adhesive having an antistatic function of 0 ¹⁰ Ω or less. More specifically, the present invention relates to a sheet with a slight pressure-sensitive adhesive, in which a plurality of flexible printed circuits are temporarily bonded together, in order to prevent foreign matter from adhering to the slight pressure-sensitive adhesive layer, an antistatic treatment is performed to The present invention provides a flexible printed circuit board in which a plurality of flexible printed circuits in which the occurrence of static electricity is suppressed as much as possible is temporarily attached to a sheet with a slight adhesive having a surface specific resistance of 10 ¹⁰ Ω or less.

[0002]

2. Description of the Related Art Conventionally, a flexible printed circuit board (hereinafter, abbreviated as FPC) in which a plurality of flexible printed circuits are formed on a flexible substrate at the same time is prepared, and a cover lay is performed, followed by punching or the like to produce one product. It is common to use them separately. In that case, FPC
In order to prevent wrinkles and folds and to improve the workability of transportation, various measures have been taken such as temporarily adhering a plurality of flexible printed circuits on a sheet with a slight adhesive to facilitate handling (Japanese Patent Laid-Open No. 4-264790). Publication, Japanese Patent Publication No. 5-24
676, JP-A-5-37123, JP-A-6
-160542, etc.). However, such an FPC has also become a problem in terms of product performance, especially in an FPC used for a computer, because foreign matter is attached by static electricity generated from the sheet with the slight adhesive.

[0003]

The conventional method has the above-mentioned problems, and therefore, the present invention provides a sheet with a slight pressure-sensitive adhesive in which a plurality of flexible printed circuits are temporarily attached, and the pressure-sensitive adhesive layer is used. To prevent foreign matter from sticking to
It is an object of the present invention to provide a sheet with a slight pressure-sensitive adhesive having a surface specific resistance of 10 ¹⁰ Ω or less, which is subjected to antistatic treatment to suppress the generation of static electricity, which causes it, as much as possible.

[0004]

As a result of various studies on the above problems, in a flexible printed circuit board composed of a sheet with a slight pressure-sensitive adhesive on which a plurality of flexible printed circuits are temporarily adhered, antistatic treatment is performed and By using a sheet with a slight adhesive whose surface specific resistance is 10 ¹⁰ Ω or less, which suppresses the generation of static electricity as much as possible,
The inventors have found that the adhesion of foreign matter to the pressure-sensitive adhesive sheet is effectively reduced, and have completed the present invention.

That is, the present invention provides a flexible printed circuit board in which a plurality of flexible printed circuits are temporarily attached to a sheet with a slight adhesive having a surface specific resistance of 10 ¹⁰ Ω or less. Another feature is that the sheet with the slight adhesive is treated with a liquid containing an antistatic agent. It is also characterized in that an antistatic agent is preliminarily mixed in the pressure-sensitive adhesive constituting the sheet with the slight pressure-sensitive adhesive. Another feature is that the antistatic agent is a cationic surfactant.

The present invention will be described in detail below with reference to the drawings. In FIG. 1, a sheet 3 with a slight adhesive is adhered to a predetermined position of a flexible printed substrate 1 in advance, and a plurality of flexible printed circuits 2 are provided on the sheet 3 with a slight adhesive.
Fig. 1- (a)] Fig. 1- (a)]
FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. In the present invention, the sheet 3 with a slight adhesive is subjected to a predetermined antistatic treatment and has a surface specific resistance of 10 ¹⁰ Ω or less, preferably 10 ⁸ Ω or less, more preferably 10 ⁶ to 10 ⁴
It is necessary to have Ω. As a result, the generation of static electricity can be suppressed as much as possible and the adhesion of foreign matter can be effectively reduced.

In the present invention, the term "predetermined antistatic treatment" means that a sheet with a slight adhesive is prepared in advance in an aqueous or organic solvent solution containing an antistatic agent of a certain concentration so that the surface resistivity becomes 10 ¹⁰ Ω or less. It means to be treated or to add a certain amount of antistatic agent to the adhesive. The antistatic agent is not particularly limited, but any of anionic, cationic and nonionic surfactants can be used. It is particularly preferable to use a cationic surfactant such as a quaternary ammonium salt, a higher amine halogenate or an alkylpyridinium halide.

In the present invention, the sheet with a slight adhesive is made of a material such as polybutene or polybutadiene, and even if all are made of an adhesive, the entire surface of a base film made of polyester such as a single-sided adhesive tape. It may be applied to the. In short, the flexible printed circuit 2 is fixed to the flexible printed substrate 1, but it has a relatively weak adhesiveness so that it can be easily peeled off by hand later. The sheet with the slight adhesive is joined and integrated on the flexible print substrate 1 via an adhesive, and the flexible printed circuit 2 constitutes an FPC formed by temporarily adhering to the flexible print substrate 1. .

The width of the slightly adhesive layer provided on the flexible printed substrate 1 is not particularly limited as long as the flexible printed circuit 2 temporarily attached thereto can be fixed to the necessary minimum, but in general, the flexible printed circuit 2 is not limited. It suffices that the terminal portion and / or the circuit portion forming the above is fixed. As a matter of course, the basic structure of the FPC of the present invention is a conventionally known structure, for example, a cover lay is provided to protect the flexible printed circuit, a release sheet is provided on the back surface, or cuts are provided on the whole to facilitate separation. It includes structural innovations such as doing.

[0010]

The present invention will be illustrated by the following examples, but the scope of the present invention is not limited thereto. First, an adhesive is applied onto a flexible substrate made of a 125 μm polyester film and dried to prepare a flexible substrate sheet having a sheet with a slight adhesive. An antistatic ability is imparted to the sheet with the slight adhesive by applying and drying an aqueous liquid containing a quaternary ammonium salt having a constant concentration. Separately, a flexible substrate sheet having a sheet with a slight adhesive which is not subjected to antistatic treatment is prepared. Next, a 25 μm-thick polyimide film and a 18 μm-thick copper foil are laminated and processed to form a plurality of flexible printed circuits having predetermined circuit portions, terminal portions, and the like. This is temporarily laminated as shown in FIG. 1 to manufacture FPC products (example products and comparative products) in which a plurality of flexible printed circuits are temporarily attached, and the surface specific resistance value and charge halved of these two types of products are manufactured. The period was measured and the product was also subjected to a dust adhesion test, and the results are summarized in Table 1 below.

[0011]

[Table 1] According to Table 1, it was found that the product of the example has about 1/3 the dust adhesion due to static electricity as compared with the product of the comparative example.

[0012]

According to the present invention, it is possible to improve the performance of an FPC product made of a sheet with a slight pressure-sensitive adhesive to which a plurality of flexible printed circuits are temporarily adhered and contamination of foreign substances is eliminated in the manufacturing process thereof. Further, there is a merit in the process that the foreign substance removing work is eliminated in the manufacturing process of the FPC product. Further, there is an effect that maintenance on the environmental management side is reduced.

[Brief description of drawings]

FIG. 1 shows an outline of an FPC to which a flexible printed circuit of the present invention is temporarily attached, FIG. 1- (A) is a plan view thereof, and FIG. 1- (B) is a sectional view thereof.

[Explanation of symbols]

 1 Flexible substrate 2 Flexible printed circuit 3 Slight adhesive sheet

Claims (4)

[Claims] 1. A flexible printed circuit board, wherein a plurality of flexible printed circuits are tentatively bonded onto a sheet with a slight adhesive having a surface specific resistance of 10 ¹⁰ Ω or less. 2. The flexible printed circuit board according to claim 1, wherein the sheet with the slight adhesive is treated with a liquid containing an antistatic agent. 3. The flexible printed circuit board according to claim 1, wherein an antistatic agent is preliminarily mixed in the pressure-sensitive adhesive forming the sheet with the slight pressure-sensitive adhesive. 4. The flexible printed circuit board according to claim 2, wherein the antistatic agent is a cationic surfactant.