JP2002292802A - Release film and method for manufacturing printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film used at the time of molding processing of a printed board, especially excellent in releasability and reducing the staining of the molded printed board, and the printed board using the release film. SOLUTION: The release film used for molding processing of the printed board is constituted by providing a transfer layer comprising a resin transferable to the printed board on at least the single surface of a film based on a syndiotactic polystyrenic resin. The method for manufacturing the printed board using the release film is also disclosed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film used for forming a printed circuit board, and more particularly to a release film having excellent releasability and less contamination of a manufactured printed circuit board. The present invention relates to a method for manufacturing a printed circuit board using a release film.

[0002]

[Unknown technology] Films using syndiotactic polystyrene resin have excellent properties such as low wettability, heat resistance, electrical properties, dimensional stability and chemical resistance. Examples of use as have been proposed recently. Utilizing this property, application as a release film used in forming a printed circuit board in which a multilayer prepreg and a copper foil or the like are integrated has been studied.

[0003]

Normally, a film using a syndiotactic polystyrene resin has a drawback that it has low mechanical strength due to low toughness due to the three-dimensional structure of the resin itself, and the film is easily cracked or broken. are doing. As a technique for remedying this drawback, a film made of a composition obtained by adding another thermoplastic resin such as styrene-butadiene rubber to a syndiotactic polystyrene resin has been studied. In such a film, the mechanical strength is certainly improved by the addition of the thermoplastic resin finger, but the properties possessed by the syndiotactic polystyrene itself cannot be sufficiently exhibited, and the following problems may occur during use. found.

That is, when the amount of the thermoplastic resin is increased to improve the low toughness, the mechanical properties are certainly improved, but the excellent releasability inherent in the syndiotactic polystyrene itself is lowered. In addition, the added thermoplastic resin is thermally decomposed during the molding of the printed circuit board, and a part of it is exposed on the film surface and contaminates the printed circuit board. Often causes. Further, if the amount of the thermoplastic resin is reduced to suppress the generation of contaminants bleeding on the film surface, the required mechanical strength cannot be obtained, and even if the film thickness is increased in order to increase the mechanical strength. Even if increased, the bending strength of the syndiotactic polystyrene itself does not improve much. In order to use this film without any problems, the film thickness must be considerably thick and the bending strength must be improved. There was a problem that a problem occurred.

Therefore, in order to solve the above problem, a laminated film in which the amount of the thermoplastic resin added to the syndiotactic polystyrene resin for the intermediate layer is increased and the outer layer is composed of a single resin layer of the syndiotactic polystyrene resin has been studied. I have. The problem of mechanical strength and contamination can be almost completely eliminated by such a laminated film, but the problem that the releasability is not sufficient depending on the printed circuit board has arisen. In order to strengthen the adhesion between copper foil and prepreg, IVH
(Inter via hole) In the substrate, the etching effect of the copper foil is devised to enhance the anchor effect. Even if the above-mentioned laminated film is used as the release film used in processing such a printed circuit board, a fine There is a problem that the resin enters into the etched surface, the mold releasability cannot be adequately coped with, and the film is broken when peeled off.

[0006]

In order to solve the above-mentioned problems, the present invention provides a transfer layer on at least one side of a film surface of a syndiotactic polystyrene resin, and easily transfers the transfer layer between the syndiotactic polystyrene film and the transfer layer. It is intended to provide a syndiotactic polystyrene-based film with a transfer layer that can be removed and the transfer layer transferred to the printed circuit board in post-processing is removed.
(1) In a release film used at the time of forming a printed board, the release film is a transfer layer made of a resin which can be transferred to a printed board on at least one surface of a film mainly composed of a syndiotactic polystyrene resin. Is provided on the mold release film. (2) The release film according to the above (1), wherein the main component of the transfer layer is a water-soluble resin. (3) A method of manufacturing a printed circuit board, which comprises peeling between a film and a transfer layer when the printed circuit board is formed using the release film of (1) or (2).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The syndiotactic polystyrene resin, which is a main component of the film material in the present invention, has a stereoregularity of syndiotactic structure, that is, a phenyl group or a substituted phenyl group which is a side chain with respect to a main chain formed of carbon-carbon bonds. It has a steric structure in which phenyl groups are alternately located in opposite directions. In order to improve the mechanical strength, the above-mentioned syndiotactic polystyrene resin as the main component is added to SBS (styrene-styrene).
Butadiene-styrene copolymer), SEBS (hydrogenated styrene-butadiene-styrene copolymer), SEPS (hydrogenated styrene-isoprene-isoprene-styrene block copolymer), and PE (polyethylene) as necessary. Or may be laminated.

[0008] At least one surface of the film must be provided with a transfer layer made of a resin that can be transferred to a printed circuit board. As a material for the transfer layer, various resins having the above characteristics can be used. The main component is preferably. Examples of the water-soluble resin include gelatin and alginate as a natural system, water-soluble cellulosic methylcellulose and hydroxyethyl cellulose as a semi-synthetic system, and PVA (polyvinyl alcohol), PEO (polyethylene oxide), and polyacryl as a synthetic system. Acids and the like can be mentioned, but PVA, PEO, or a blend thereof is preferred from the viewpoint of the stability and quality of the raw material.

However, when only a water-soluble resin is applied to a transfer layer on a syndiotactic polystyrene film, the syndiotactic polystyrene resin is a material having low wettability. Difficult to apply. In this case, it is preferable to add a small amount of a surfactant to the aqueous solution of the water-soluble resin as the transfer layer in advance, if necessary. Surfactants that can be used for this include fatty acid polyhydric alcohol esters, non-ionic polyoxyethylenes, sulfonic acids, anionic phosphate salts, and cationic quaternary ammonium salts.
Both amphoteric betaine and alanine salts can be used, but nonionic surfactants are preferred. 0.1 ~
About 2% is preferable.

The method for forming the film of the present invention is not particularly limited. For example, when the film is produced by an extrusion casting method, the extruder cylinder temperature of the syndiotactic polystyrene layer is set at 270 to 350 ° C., and the intermediate layer is formed. Multilayering may be performed using a coextrusion lamination method, a feed block, or a multi-manifold die. In order to obtain heat resistance and the like, it is necessary to sufficiently crystallize the syndiotactic polystyrene layer, and it is necessary to perform crystallization treatment using a known heat treatment device. For example, a method of thermally fixing the film in a dryer using a tenter device, or a heat treatment using a heat treatment roll at around 150 to 220 ° C. may be performed.

Next, there is no particular limitation on the application of the transfer layer, but there are methods such as spray coating and solution coating with a gravure roll at the time of film formation, and in-line and out-line can be performed without interruption. . Further, it is also possible to carry out the coating film drying simultaneously with the crystallization treatment of the film. The coating thickness is practically preferably less than 10 μm, more preferably 5 μm or less. When the coating thickness is 10 μm or more, it is likely to be difficult to remove in a later step. For example, problems such as the time required for the removal operation and the generation of resin residue on the printed circuit board occur,
This causes a decrease in productivity and a problem when forming a circuit pattern on a printed circuit board.

When a water-soluble resin is used for the transfer layer, it is extremely easy to remove the transfer layer on the substrate in a printed circuit board washing step in a later step. The transfer layer transferred to the printed board can be easily removed by a printed board washing step (water washing, soft etching), and can be sufficiently removed by a general printed board washing step after hot press molding. As a general method of the cleaning process, after pressing, the substrate is easily cleaned with water, and then the copper surface is reduced and buried with a soft etching solution (a mixed solution of sulfuric acid and hydrogen peroxide).

[0013]

EXAMPLES Examples and comparative examples for one application of the present invention will be described below, but the present invention is not limited to these examples. Regarding the evaluation method, based on the characteristics of the release film used at the time of molding the printed circuit board, 1) coating property of the transfer layer, 2) release property of the printed board, and 3) removability of the transfer layer are practically used. The evaluation was performed in four stages.

[Printed circuit board molding method] Cushion material /
SUS decorative board / laminated film of the present invention / laminated molding material for printed circuit board formation (non-halo embedded IVH outer layer copper-clad laminate, non-halo embedded IVH inner layer copper-clad laminate, prepreg containing epoxy resin impregnated glass cloth ) / Insert the release film of the present invention / SUS decorative board / cushion material into the center of the press, and press pressure: 1, 96 × 10 ⁶ P
a, Heating temperature: 190 ° C., Heating time: Heating and pressure pressing were performed under the conditions of 2 hours.

[Method of Cleaning Substrate (Washing, Soft Etching)] H ₂ SO ₄ concentration: 100 g / l, H ₂ SO ₄ concentration: 20 g
Using a sulfuric acid-hydrogen peroxide aqueous solution at a temperature of 30 ° C. and a spray pressure of 7.85 × 10 ⁴ Pa, washing was performed for 30 seconds.

[Evaluation Method] (1) Coatability of Transfer Layer A coating solution having an aqueous solution concentration of 1% by mass was prepared, and the coating film after drying (90 ° C. × 5 minutes) when coated with a bar coater was uniform. The sex was evaluated with aim. ◎ indicates no coating unevenness. ○ shows almost no coating unevenness. △: coating unevenness is confirmed, but there is no problem in use. × indicates coating unevenness, causing repelling on the coated surface and causing a problem in use.

(2) Release Property After the above-mentioned printed circuit board is heat-pressed and cooled to room temperature,
The strength of the film when the release film was released from the surface of the printed circuit board was evaluated in three stages. ◎: Very light peeling. ○ indicates heavy peeling but no breakage or tearing. The symbol “Δ” slightly breaks or tears when peeled, but does not cause a problem in use. × indicates unusable due to breakage, tearing, or cracking when releasing.

(3) Removability of transfer layer ◎ completely disappears within 10 seconds. ○ completely disappears within 20 seconds. △: Completely disappeared within 30 seconds, no problem during use. X: The residue remained after washing for 30 seconds.

[Example 1] Syndiotactic polystyrene resin (“Zarek 30A” manufactured by Idemitsu Petrochemical Co., Ltd.) 90
The mass part is SBS ("ToughTech 105
2 ") was added by 10 parts by mass to prepare a master pellet,
Extrusion casting method (cylinder temperature 270-300
C.) to form a crystallized film by heat setting the film in a dryer (internal temperature: 180 ° C.) using a tenter device. Next, for the application of the transfer layer, a mixed solution was prepared using a gravure roll at a concentration of 5% of PVA (“Gohsenol GH20” manufactured by Nippon Synthetic Chemical Co., Ltd.) and a nonionic surfactant at a concentration of 0.2%, followed by solution coating Was applied to one side of the crystallized film so that the film thickness after drying was 0.5 μm, and the above-mentioned evaluation was performed on the releasability and the removability of the transfer layer.

Examples 2 to 4 The thickness of the transfer layer was 1 μm
(Example 2) A film was prepared in the same manner as in Example 1 except that the thickness was changed to 3 μm (Example 3) and 5 μm (Example 4), and the above evaluation was performed.

Example 5 A film was prepared in the same manner as in Example 1 except that the surfactant of the transfer layer component was not blended, and the above evaluation was carried out.

Example 6 A film was prepared in the same manner as in Example 1 except that the PVA solution concentration was changed to 1%, and the above evaluation was carried out.

[Example 7] The transfer layer component PVA was replaced with PEO
A film was prepared and evaluated in the same manner as in Example 1 except that the product was changed to "PAOGEN PP-15" manufactured by Daiichi Kogyo Seiyaku.

Comparative Example 1 The above evaluation was carried out in the same manner as in Example 1 except that the transfer layer was not applied (syndiotactic polystyrene resin film alone).

Example 8 A film was produced in the same manner as in Example 1 except that the thickness of the transfer layer was changed to 15 μm, and the above evaluation was carried out.

Comparative Example 9 A film was prepared in the same manner as in Example 6 except that the surfactant of the transfer layer component was not blended, and the above evaluation was carried out.

Comparative Example 2 A film was prepared in the same manner as in Example 1 except that the syndiotactic polystyrene resin film as the base film was changed to PET (polyethylene terephthalate), and the above evaluation was performed.
Table 1 shows the results of the above examples and comparative examples.

[0028]

[Table 1]

[0029]

The release film of the present invention utilizes the heat resistance and release properties of the syndiotactic polystyrene resin film, and further comprises a transfer layer on the surface thereof.
A sufficient peelability can be ensured even for an IVH substrate or the like having a high anchoring effect, and no trouble occurs during use, so that a film that can be suitably used in this application is obtained.

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[Procedure amendment]

[Submission date] June 4, 2001 (2001.6.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[Evaluation Method] (1) Coatability of Transfer Layer A coating solution having an aqueous solution concentration of 1% by mass was prepared, and the coating film after drying (90 ° C. × 5 minutes) when coated with a bar coater was uniform. gender was evaluated eye view. ◎ indicates no coating unevenness. ○ shows almost no coating unevenness. △: coating unevenness is confirmed, but there is no problem in use. ×: coating unevenness, repelled coating surface, causing problems in use.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction contents]

[0026] Example 9 except that no blended surfactant of the transfer layer components to form a film in the same manner as in Example 6, evaluation was carried out as described above.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F006 AA15 AB20 BA11 CA08 4F100 AK01B AK01C AK12A AK21 BA02 BA03 BA06 BA10B BA10C EH462 GB43 HB00B HB00C JA11A JB09B JB09C JK06 JL14

Claims (3)

[Claims] 1. A release film used in forming a printed circuit board, wherein the release film is made of a resin which can be transferred to a printed circuit board on at least one surface of a film mainly composed of a syndiotactic polystyrene resin. A release film provided with a transfer layer. 2. The release film according to claim 1, wherein a main component of the transfer layer is a water-soluble resin. 3. A method for manufacturing a printed circuit board, comprising forming a printed circuit board using the release film according to claim 1 and separating the film from a transfer layer.