JP2002018998A - Protection film and conductor foil laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective film for sticking a conductive foil, which is excellent in protecting property of a conductive foil, is free from dust and the like, hardly causes wrinkles and breaks, and has good handleability. The present invention provides a laminated conductor foil. SOLUTION: This is a conductor foil sticking protection film 10 in which an adhesive is partially formed on one surface of a support, and the adhesive layer 14 is a circuit formation scheduled area for forming a circuit on the conductor foil. 12 is formed on the periphery. It is preferable that the circuit forming region 12 is subjected to a mold release treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film for a conductor foil laminate used as a laminated wiring board widely used in electronic equipment and the like, and a conductor foil laminate using the same.

[0002]

2. Description of the Related Art Conventionally, a conductor foil used for a laminated wiring board generally has a structure of a laminated body laminated on some kind of support from the viewpoint of improving the handleability. For example, Japanese Patent Application Laid-Open No. 9-214137 describes a method for manufacturing a laminate using a conductor foil with a release film in which a conductor foil and a release film are laminated. JP-A-8-1859
Japanese Patent Application Laid-Open Publication No. H11-146,086 discloses a metal release sheet in which a metal foil is laminated on a support formed of a conductive material via an adhesive whose adhesive strength is reduced by heating.

[0003] These supports function as a protective film for the conductor foil and are releasably attached to the conductor foil. The conductive foil and the protective film are usually adhered via an adhesive layer which can be peeled off by means such as heating, and the adhesive layer is often provided on the entire surface of the support. However, in consideration of the ease of peeling and the influence of foreign matter such as fiber dust and resin pool of the prepreg on the surface of the prepreg, if the elasticity of the adhesive layer is low, such foreign matter will penetrate and cause the conductor foil to tear. In such a case, it is conceivable to provide a part thereof.
No. 9 describes that the adhesive may be provided so as to be scattered on the support, or may be provided in a band shape with a predetermined width at both ends in the longitudinal direction.

[0004] In recent years, there has been a demand for thinner conductive foils with the increase in the density of circuits to be formed. However, due to the demand for improving the handleability of such thin conductive foils, they have been required to be handled as a laminate with a support. Has become commonplace. However, since the thickness of the conductive foil is extremely thin, when the adhesive layer is partially provided or when the adhesive layer is scattered over the entire surface, the influence of the step of the adhesive layer thickness and the low elasticity of the adhesive layer There are many problems to be solved from the viewpoint of the influence of the rate, and in the case of the adhesive provided at both ends in the longitudinal direction, there are large voids in the transverse direction, so that garbage and dust such as fiber waste of the prepreg are present. Can easily enter the circuit forming portion. In addition, there is a problem that wrinkles easily occur during molding. If dust or the like is present in the circuit forming portion, it may cause circuit defects due to irregularities or cracks in the conductive foil when forming a laminated circuit described later.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a conductor foil having excellent protection properties, no dust and the like, and no wrinkles or pushes. It is an object of the present invention to provide a conductor foil sticking protection film which is hard to leave behind and has good handleability, and a conductor foil laminate using the same.

[0006]

As a result of the study, the present inventors have found that the above problem can be solved by providing an adhesive layer only in a predetermined region of a protective film serving as a support. completed. That is, the protective film of the present invention is a conductive foil sticking protective film in which an adhesive is partially formed on one surface of a support, wherein the adhesive layer forms a circuit on the conductive foil. It is characterized in that it is formed around the formation scheduled area. This adhesive layer has a void portion that can be ventilated, and is preferably formed, for example, in the form of a broken line, and has a thickness of preferably 0.1 μm or more and less than 10 μm, and 0.1 μm to 5 μm. Is more preferred. Further, it is preferable that a region where a circuit is to be formed having no adhesive layer is subjected to a mold release treatment. In a case where a synthetic resin film is used as the support of the present invention, it is a preferred embodiment that a release layer is formed on the side opposite to the side on which the adhesive layer is formed. The conductor foil laminate of the present invention according to claim 6 is characterized in that a conductor foil is attached to the adhesive layer of the protective film of the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the material used as the support substrate of the protective film is not particularly limited, and may be a metal foil such as an aluminum foil or a synthetic resin film. When a synthetic resin film is used as a support substrate for a protective film, polyethylene terephthalate (PE)
T) film, polyester resin film such as polyethylene naphthalate (PEN) film, polyphenyl sulfide (PPS) film, polyimide (P
I) film, biaxially oriented polypropylene (OPP) film, methylpentene copolymer (PTX) film,
Ethylene fluoride (1F), ethylene trifluoride (3F),
Examples thereof include a fluororesin film such as tetrafluoroethylene (4F) and a laminate film of two or more of these. Among these, a polyphenylsulfide (PPS) film having a smooth surface, excellent heat resistance, and relatively easy to obtain is preferable.

[0008] When a synthetic resin film is used as the support substrate, the thickness is 12 to 10 from the viewpoint of handleability.
The thickness is preferably about 50 μm, and when a metal foil such as an aluminum foil is used, it is preferably about 12 to 100 μm. If the film is too thick, when prepregs are laminated during the production of wiring boards, the conductor foil will be pushed into the adhesive layer by the unevenness of the reinforcing glass fiber, causing damage to the adhesive layer, and furthermore, disadvantageous in terms of cost Become. Also,
If the thickness is too small, the workability and the protection are reduced, and neither is preferred.

In the case where a film made of a synthetic resin is used as the support, a conductive foil is provided to facilitate removal of the jig after pressurizing and heating in a method of manufacturing a laminate described later. It is preferable that the surface on the side opposite to the side to be subjected to the mold release treatment. The release treatment is a process of providing a thin release layer made of a material having heat resistance, hardness and release properties so that the resin does not weld to the jig even when heated. As a material for forming this layer, Specific examples thereof include thermosetting resins such as epoxy resins and cyanate resins, and silicon-based compounds and glass-based inorganic compounds containing silicon, aluminum, and the like. Hydroxyl-containing silicon-based compounds (siloxane-based compounds) which are also excellent in hardness and hardness are preferred. The siloxane compound is a chain or network compound having a siloxane (Si-O-Si) chain, and is also available as a commercial product such as an antistatic paint "Colcoat" (trade name: manufactured by Colcoat). .

In the protective film of the present invention, an adhesive layer is formed on one side of the support at a peripheral portion of a region where a circuit is to be formed for forming a circuit on the conductive foil. A conductor foil is laminated and adhered through the adhesive layer of the support to form a conductor foil laminate.

FIG. 1 is a plan view showing one embodiment of the adhesive forming surface of the protective film of the present invention. On one surface of the protective film 10 (hereinafter, referred to as an adhesive layer forming surface), an adhesive layer 14 is formed around the circuit forming area 12. The area where the circuit is to be formed is usually determined at the time of designing the wiring board. The adhesive layer may be formed over the entire peripheral portion as shown in FIG. 1, and as shown in the plan views of FIGS. 2 (B), and may be formed discontinuously, such as a dotted form as shown in FIG. 2 (D), and a dotted form as shown in FIG. 2 (B). . Providing the adhesive layer with air-permeable voids is preferable from the viewpoint of preventing cracks on the conductor foil surface. The size of the air-permeable space is not particularly limited, but is preferably as narrow as possible from the viewpoint of effectively preventing dust and dirt from entering the circuit formation region.

The base polymer used for the adhesive layer is preferably a polymer having an adhesive property capable of being peeled off by heating, and a physical property is preferably a material having heat resistance and made of a highly elastic polymer. A foaming agent or a thermosetting resin may be blended in the base polymer of the adhesive layer serving as a base material in order to give the adhesive layer heat release properties, that is, a property that its adhesive strength is reduced by heating. .
The highly elastic polymer for an adhesive which can be used in the present invention preferably has a small dynamic elastic modulus change rate from normal temperature to 150 ° C. The degree of the change is preferably within 5 times, more preferably within 3 times. There is no particular limitation on the monomer components forming the base polymer. Any of the monomer components used in the preparation of known pressure-sensitive adhesives such as an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a styrene / conjugated diene block copolymer-based pressure-sensitive adhesive can be used.

Specific examples thereof include methyl, ethyl, propyl, butyl, 2-ethylhexyl, isooctyl, isononyl, isodecyl, dodecyl, lauryl, tridecyl, pentadecyl, hexadecyl, Acrylic acid-based alkyl esters such as acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms, such as heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group, acrylic acid, methacrylic acid, itaconic acid, hydroxy acrylate Ethyl, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-methylolacrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, vinyl acetate Ren, isoprene, butadiene,
Polymers or copolymers such as isobutylene and vinyl ether are exemplified. In addition, natural rubber, recycled rubber, or the like that satisfies the above-described requirements for the high elasticity polymer can also be used. The thickness of the adhesive layer is preferably in the range of 0.1 μm or more and less than 10 μm, and more preferably 0.1 μm to 5 μm. When the thickness is less than 0.1 μm, the adhesiveness is insufficient, and when the thickness is 10 μm or more, dust tends to be mixed in. When prepregs are laminated, the prepreg pressed due to the flexibility of the adhesive layer. Originated powders and other foreign substances may sink into the adhesive layer together with the conductor foil, and this may cause the conductor foil to tear, which is not preferable.

Although the adhesive layer is not formed in the area of the support on which the adhesive layer is to be formed on the area where the circuit is to be formed, it is preferable from the viewpoint of workability that this area is subjected to mold release treatment. . The release treatment can be performed by the same means as the release treatment performed on the surface of the support opposite to the surface on which the adhesive layer is formed.

Since the conductor foil of the present invention is used for manufacturing a wiring board, a foil having excellent conductivity made of copper or a copper alloy may be selected. The thickness of the conductor foil may be as large as several tens of μm to several μm, depending on the requirements of the wiring board to be produced.
It can be appropriately selected up to an extremely thin foil. Further, the conductor foil may be subjected to various surface treatments in order to impart chemical resistance, oxidation resistance and the like as long as the conductivity is not impaired. In the present invention, the thickness of a metal foil such as a copper foil is 18 μm or less,
Particularly, the thickness is preferably about 12 μm, and from the viewpoint of workability, the lower limit of the thickness is usually about 5 μm. The conductor foil laminate of the present invention is obtained by forming an adhesive layer at a predetermined position on the protective film of the present invention by coating or the like, laminating a conductor foil thereon, and pressing the laminate.

When a multilayer wiring board is formed using the conductor foil laminate of the present invention, the synthetic resin film as a protective film is peeled off in the step of forming a circuit on the board on which the wiring is formed. It is preferable that the adhesive layer according to (1) has a property that can be easily peeled off according to conditions. For example,
An adhesive which can be peeled off by heating is disclosed in
Preferable examples include a heat-peelable pressure-sensitive adhesive described in JP-A-1859, and a known method such as lamination using a low-pressure-sensitive adhesive is also applicable.

According to the configuration of the present invention, it is possible to effectively prevent the prepreg fiber from entering into the portion where a circuit is to be formed at the time of press setting, and to form an adhesive layer on the portion where the circuit is to be formed. Therefore, when prepregs are laminated, even if foreign substances such as glass fiber dust and resin pools are present on the prepreg surface, these foreign substances do not enter the adhesive layer, and the Since there is no intrusion of dust or dust such as glass fiber waste from the surrounding portion, it is possible to prevent the conductor foil from being wrinkled or torn.

[0018]

Example 1 An acrylic adhesive (2-ethylhexyl acrylate / butyl acrylate copolymer) was applied to the surface of a 38 μm thick PPS film so as to have a thickness of 1 μm after forming an adhesive layer. According to the adhesive layer pattern described in (A), an adhesive layer is formed around the area where a circuit is to be formed, and a conductive foil having a thickness of 12
A copper foil of μm was laminated to obtain a conductor foil laminate. The width of the adhesive pattern was 10 mm.

A multilayer wiring board was prepared using this conductor foil laminate, and its smoothness and handleability were evaluated according to the following criteria. The results are shown in Table 1 below. [Workability] Hot press (180 ° C, 30 kg / cm ² , 9
After 0 min), the adhesive strength at the time of peeling from the mirror surface plate (sus) was measured by a peeling tester using a peeling tester at a peeling angle of 180 ° and a peeling speed of 300 mm / min for a sample having a width of 2.54 cm (1 inch). . The smaller the adhesive strength, the better the workability. In addition, as for the releasability, the adhesive force is 1 in
In a sample of ch (2.54 cm) width, 50 g or less was evaluated as a good level. [Smoothness] The above hot press (180 ° C, 30 kg / c
(m ² , 90 minutes) After visually observing the state of the surface of the upper conductive foil in the portion where the circuit is to be formed, the wrinkle, tearing, and the occurrence of unevenness due to the intrusion of dust, which was not generated after being pushed, were regarded as good. evaluated. The results are shown in Table 1 below.

Example 2 FIG. 2 shows the pattern of the adhesive layer.
A conductor foil laminate was obtained in the same manner as in Example except that an adhesive layer was provided instead of (D). This was evaluated in the same manner as in the examples. Table 1 shows the results.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the pattern of the adhesive layer was changed as shown in FIG. A conductor foil laminate was obtained. This was evaluated in the same manner as in the examples. Table 1 shows the results.

(Comparative Example 2) The pattern of the adhesive layer was changed as shown in FIG.
A conductive foil laminate was obtained in the same manner as in Example 1, except that an m-th adhesive layer was provided. This was evaluated in the same manner as in the examples.
Table 1 shows the results.

[0023]

[Table 1]

As is evident from Table 1, the conductor foil laminate of the present invention was excellent in smoothness and handleability, and neither pushing nor wrinkling due to invasion of dust was observed. On the other hand, in Comparative Example 1, a strong push due to intrusion of dust is seen, and in Comparative Example 2, in which an adhesive layer is provided on the entire surface including a portion where a circuit is to be formed, wrinkles are observed in addition to the push. Was also insufficient in smoothness. Further, Comparative Example 2 was found to have a problem in handleability because it has a strong resistance to peeling and is difficult to remove.

According to the present invention, the conductor foil has excellent protection properties, is free from dust and the like, and is resistant to wrinkles and breaks.
In addition, it is possible to obtain a conductor foil sticking protection film having good handleability, and a conductor foil laminate using the same,
There is no defect due to adhesion of dust, and even when a thin conductive foil is used, the handleability is good.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a protective film of the present invention.

FIGS. 2A, 2B, 2C, and 2D are plan views showing embodiments of the protective film of the present invention in which an adhesive layer is discontinuously formed in a region where a circuit is to be formed.

FIG. 3 is a plan view showing an embodiment of a protective film of Comparative Example 1 in which an adhesive layer is formed on both side edges of a region where a circuit is to be formed.

FIG. 4 is a plan view showing an embodiment of a protective film of Comparative Example 2 in which an adhesive layer is formed by being scattered over the entire surface including a region where a circuit is to be formed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Protective film 12 Circuit formation planned area 14 Adhesive layer

Continued on front page F-term (reference) 4F100 AB17 AK01A AK25G AT00A BA02 BA03 BA04 BA07 BA10B BA10C BA10D CB00B DC21B EH46 EH462 GB43 JD02B JG01D JL04 JL05 JL14C 4J004 AA05 AA06 AA10 CA03 CA04 FA04

Claims (6)

[Claims] 1. A conductive film sticking protective film in which an adhesive is partially formed on one surface of a support, wherein the adhesive layer is provided in a region where a circuit is to be formed for forming a circuit on the conductive foil. A protective film formed on a peripheral portion. 2. The protective film according to claim 1, wherein the adhesive layer is formed to have air-permeable voids. 3. The protective film according to claim 1, wherein a region where a circuit is to be formed on the protective film is subjected to a release treatment. 4. The support is a synthetic resin film,
The protective film according to any one of claims 1 to 3, wherein a release layer is formed on a side opposite to a side on which the adhesive layer is formed. 5. The thickness of the adhesive layer is 0.1 μm or more and 1
The protective film according to claim 1, wherein the thickness is less than 0 μm. 6. A conductor foil laminate comprising the protective film according to claim 1 and a conductor foil adhered to the adhesive layer of the protective film.