JP2002146314A - Adhesive sheet for producing process of flexible circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive sheet used for a producing process of a flexible circuit having excellent handleability and operating efficiency. SOLUTION: This adhesive sheet for the production process of the flexible circuit is characterized in that an adhesive mass layer is composed of 100 pts.wt. of a resin prepared by copolymerizing dibutyl acrylate with 2-ethylhexyl acrylate and vinyl acetate and having 500,000-2,000,000 weight-average molecular weight and 2-15 pts.wt. of a cross-linking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure-sensitive adhesive sheet used in a flexible circuit manufacturing process.

[0002]

2. Description of the Related Art Generally, a flexible circuit which is thin and has high flexibility is manufactured as follows. That is, a plurality of flexible circuits are arranged and formed by performing exposure, pattern formation, etching, and the like on the copper foil surface of the copper-clad flexible circuit board. Next, a polyimide resin cover lay film that is perforated at a desired position and is coated on one side with an adhesive is laminated on the copper foil surface on which the flexible circuit is formed, so as to enable component mounting or wiring. . Then, after subjecting the circuit surface to a predetermined surface treatment, an adhesive sheet is further stacked in a fixed state at the four corners. Then, in this state, a punching blade is inserted along each flexible circuit and cut to punch out the flexible circuit. Each of the flexible circuits thus obtained is adhered to the punched portion of the copper-clad flexible circuit board in a punched state (the outer peripheral portion of the flexible circuit and the punched portion of the copper-clad flexible circuit board). (Adhering to the inner peripheral portion due to adhesive friction), and is supplied to the consumer after inspection as it is.

[0003]

However, when the above-mentioned state is passed through the inspection step and the transportation step, the flexible circuit falls off from the punched portion of the copper-clad flexible circuit board with a slight impact. Extremely poor handling. In addition, when using a flexible circuit,
The flexible circuit is removed from the punched part of the copper-clad flexible circuit board.However, the flexible circuit that is thin and has high flexibility reduces the possibility of defective products due to bending due to bending during handling without straining. Have. An object of the present invention is to provide a pressure-sensitive adhesive sheet used in a flexible circuit manufacturing process excellent in handleability and workability.

[0004]

According to the present invention, the adhesive layer has a weight average molecular weight of 5000 obtained by copolymerizing dibutyl acrylate, 2-ethylhexyl acrylate and vinyl acetate.
A pressure-sensitive adhesive sheet for a flexible circuit manufacturing process, comprising 100 to 100 parts by weight of a base resin of 100 to 2,000,000 and 2 to 15 parts by weight of a crosslinking agent. Preferably, the pressure-sensitive adhesive sheet is characterized in that the sheet has an adhesive strength defined by JISZ0237 of 10 gf / 25 mm to 50 gf / 25 mm with respect to the polyimide film.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Weight average molecular weight 500 obtained by copolymerizing dibutyl acrylate, 2-ethylhexyl acrylate and vinyl acetate
By using a base resin of 2,000 to 2,000,000,
The sheet can be provided with an adhesive force to prevent the flexible circuit from falling off during the process.

The mixing ratio of the crosslinking agent is 2 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the base resin. If the amount is less than 2 parts by weight, there is a problem that when the circuit is peeled off from the pressure-sensitive adhesive sheet, adhesive residue occurs on the printed surface of the flexible circuit and the flexible circuit board is curled. When used in an amount exceeding 15 parts by weight,
Insufficient adhesive strength causes the flexible circuit to fall off during the transport process.

The crosslinking agent used in the present invention includes a polyisocyanate compound of a polyvalent isocyanate, a trimer of a polyisocyanate compound, and a terminal isocyanate compound obtained by reacting the polyisocyanate compound with a polyol compound. Examples include a trimer and a blocked polyisocyanate compound in which a terminal isocyanate urethane prepolymer is blocked with a phenol, an oxime or the like.

Specific examples of polyvalent isocyanates include, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate,
4-xylene diisocyanate, diphenylmethane-4-4'-
Diisocyanate, diphenylmethane-2-4'-diisocyanate, 3-methyldiphenylmethane diisocyanate,
Hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4-4'-diisocyanate, dicyclohexylmethane-2-4'-diisocyanate, lysine isocyanate and the like.

The pressure-sensitive adhesive of the present invention contains rosin resin, terpene resin, coumarone resin, phenol resin, styrene resin, aliphatic petroleum resin, aromatic petroleum resin, and aliphatic aromatic resin in order to increase cohesion. A tackifier such as a polymerized petroleum resin may be added.

Further, an antistatic agent can be added to the above-mentioned pressure-sensitive adhesive layer. By adding an antistatic agent, static electricity generated when the flexible circuit is peeled off from the pressure-sensitive adhesive sheet can be suppressed, so that reliability is improved.
As the antistatic agent, specifically, anionic, cationic, nonionic, or zwitterionic generally known activator, carbon black, silver, nickel, antimony-doped tin oxide, tin-doped indium oxide, etc. Powder is used. The antistatic agent is preferably used in the adhesive layer in an amount of 0 to 30 parts by weight, particularly preferably 0 to 20 parts by weight.

In the present invention, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 5 to 35 μm. In the present invention, to form the pressure-sensitive adhesive layer on the substrate, to produce a carrier sheet for a circuit,
The components constituting the pressure-sensitive adhesive layer are used directly or in the form of a solution with an appropriate organic solvent, and are applied on a substrate by coating or spraying to an appropriate thickness according to a generally known method such as a comma coater, a gravure coater, a die coater, and a reverse coater. For example, it can be obtained by drying by heat treatment at 80 to 100 ° C. for about 30 seconds to 10 minutes.

As the substrate used in the present invention, a sheet needs to be stiffened in order to have a blade in the cutting step, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, and polycarbonate.

[0013]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Example 1 20 parts by weight of dibutyl acrylate, 70 parts by weight of 2-ethylhexyl acrylate, and 10 parts by weight of vinyl acetate were copolymerized with 100 parts by weight of a base resin (A) having a weight average molecular weight of 150000000 and 2,4-triene. A resin solution for forming a pressure-sensitive adhesive layer containing 5 parts by weight of a range isocyanate (B) is applied to a release-treated polyester film having a thickness of 38 μm so that the thickness after drying becomes 15 μm.
Dry for 5 minutes. Thereafter, a polyethylene terephthalate sheet having a thickness of 100 μm was laminated as a base material to produce an adhesive sheet for semiconductor processing.

Example 2 A sample was prepared and evaluated in the same manner as in Example 1 except that B was changed to 3 parts by weight. Example 3 A sample was prepared and evaluated in the same manner as in Example 1 except that B was changed to 8 parts by weight. << Comparative Example 1 >> A sample was prepared and evaluated in the same manner as in Example 1 except that B was changed to 1 part by weight. << Comparative Example 2 >> A sample was prepared and evaluated in the same manner as in Example 1 except that B was changed to 20 parts by weight.

[0015]

[Table 1]

The following evaluation methods were used to evaluate the examples and comparative examples. (1) Adhesive force The adhesive film obtained in the example or the comparative example was adhered to a polyimide film by reciprocating a 2 kg rubber roller under an atmosphere of 23 ° C. and 65% RH,
After standing for 20 minutes, 180 ° peel adhesion was measured at a peel strength of 300 mm / min using a universal tensile tester (TENSILON).
Based on JISZ 0237. (2) Particle Measurement The polyimide film was held and fixed on a 10 cm × 10 cm pressure-sensitive adhesive sheet, and the particles were peeled off from the pressure-sensitive adhesive sheet and evaluated by observing particles adhered to the back surface with a stereoscopic microscope. Evaluation criteria ○: 3 or less △: 3 to 10 ×: 10 or more (3) Curl measurement The amount of curl when a 1.5 cm × 5 cm flexible circuit is attached to a 100 cm × 100 cm adhesive sheet and peeled from the adhesive sheet. Was measured and evaluated. Evaluation criteria ：: Curls of 1 mm or less ×: Curls of 1 mm or more (4) Workability When 100 pieces of a 1.5 cm × 5 cm flexible circuit are adhered to a 100 cm × 100 cm adhesive sheet and a punching process is performed. The number of flexible circuits dropped from the adhesive sheet was measured and evaluated. Evaluation criteria ○: 3 or less dropped circuits ×: 4 or more dropped circuits

[0017]

According to the present invention, it is possible to obtain a pressure-sensitive adhesive sheet which is excellent in handleability and workability and is used in a flexible circuit manufacturing process.

Claims (2)

[Claims] 1. An adhesive layer comprising 100 parts by weight of a resin having a weight average molecular weight of 5,000,000 to 2,000,000 obtained by copolymerizing dibutyl acrylate, 2-ethylhexyl acrylate and vinyl acetate, and 2 to 15 parts by weight of a crosslinking agent. A pressure-sensitive adhesive sheet for a flexible circuit manufacturing process. 2. The adhesive strength of the sheet defined by JISZ0237 is 10 gf / 25 mm to 50 g with respect to the polyimide film.
The pressure-sensitive adhesive sheet according to claim 1, wherein f / 25 mm.