JP2000144068A - Pressure sensitive adhesive film for producing multi- layer wiring board with ivh - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film excellent in a releasing property suffering from no protrusion of a resin constituting an insulating adhesive layer by forming a barrier layer such as a resin film or a metal film between a support layer made of a polyester and a pressure sensitive adhesive, thereby preventing the migration of an oligomer to the pressure sensitive adhesive layer. SOLUTION: A pressure sensitive adhesive film comprises a support having a thickness of 12-125 μm made of a polyester film such as a polyethylene terephthalate or the like, a pressure sensitive adhesive coated on one side of the film and a barrier layer formed between the support and the pressure sensitive adhesive and composed of a resin film, a metal foil or a metalized film or the like. The pressure sensitive adhesive is obtained by compounding a copolymer having a wt. average mol.wt. of at least 500,000 and a glass transition temperature of -30 to -50 deg.C and comprising at least 50 wt.% of an acrylic monomer or methacrylic acid monomer and 1-50 wt.% of a functional group- containing monomer such as hydroxyalkyl methacrylate or the like with an isocyanate crosslinking agent such as triphenylmethane triisocyanate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive film used for manufacturing a multilayer wiring board having an IVH (interstitial via hole).

[0002]

2. Description of the Related Art A multilayer wiring board with an IVH (interstitial via hole) is a plated through hole that connects two or more conductive layers of a multilayer printed wiring board as shown in FIG. Is a hole that does not penetrate. It is also called an interstitial beer hall or an inner via hole. The multilayer wiring board with IVH shown in FIG. 1 is generally manufactured using three copper-clad laminated substrates and two sets of prepregs or adhesive films. There are various manufacturing methods. For example, three double-sided copper-clad laminated substrates A, B, and C are drilled in accordance with a circuit by a drill, and plated through holes to form an IVH. And A, C
On the substrate, wiring is formed by etching and processing the copper foils on the opposite sides of the outermost layers of the A and C substrates and the B substrate by etching, while leaving the copper foil to be the outermost layer. Then, the prepregs are arranged on both sides of the B substrate, and the A and C substrates are laminated with the wiring side formed on the prepreg side, and heated and pressed by a press to form a multilayer laminate.
Thereafter, drilling is performed, through-hole plating is performed, and wiring processing of the outermost copper foil is performed.

[0003] In the multilayer wiring board with IVH manufactured in this manner, as shown in FIG. 2, the resin of the prepreg used for interlayer insulation and bonding protrudes into the surface layer through the through hole portion of the IVH at the time of pressing to form the outermost layer. Even if an attempt is made to form a wiring on a copper foil, the resin that has run out acts as a resist during etching, and the wiring cannot be etched, resulting in a wiring formation defect. To prevent this, after making a multilayer laminate by pressing, the outermost layer is subjected to a belt sander, buffing, etc., physically and in combination with a chemical solution such as a release agent, etc. The resin protruding into the outer layer was removed. However, in this method, in the belt sander or the buff polishing, there is a problem in that polishing heat or mechanical stress due to the polishing is applied to the multilayer laminate, which causes a dimensional change or deformation of the substrate. In addition, when a chemical solution is used, there is a problem of its removal and waste liquid treatment.

Accordingly, the present inventors have disclosed in Japanese Patent Application Laid-Open No. 7-2975.
No. 53 and Japanese Patent Application No. 9-139457 have proposed a method of using a pressure-sensitive adhesive film to prevent the resin from protruding. Further, the present inventors have disclosed in Japanese Patent Application No. Hei 10-1251.
In No. 34, an adhesive film for manufacturing a multilayer wiring board with an IVH using a polyester, polypropylene, polycarbonate, polyurethane, polyimide and polyamide as the material of the support was proposed, but from the viewpoint of heat resistance, smoothness of via holes and economy. Polyester films have been found to be optimal as supports.

[0005]

However, when a polyester film is used as a support, the polyester film is processed under high-temperature and high-pressure pressing conditions, so that it passes through the pressure-sensitive adhesive coated with an oligomer which is a by-product contained in the polyester resin. To transfer the adhesive to the substrate, or to reduce the cohesive force of the adhesive, thereby causing the adhesive to migrate to the substrate, that is, to induce adhesive residue. After the press treatment, the substrate may be subjected to a blackening treatment with a chemical such as hydrochloric acid in some cases. However, when a component such as an oligomer is transferred to the substrate, the chemical is not wetted and causes a decrease in the removability. In addition, when the adhesive is transferred to the substrate, if there is adhesive residue or the like, not only does the removability of the blackening process deteriorate, but also when removing the resin exuded from the via hole by polishing, the belt or buff of the abrasive is removed. It can cause clogging, shortening its life and causing the abrasive to fail. The present invention has been made in view of such circumstances,
In the production of a multilayer wiring board with an IVH, the migration of the oligomer coming out of the support to the adhesive is prevented, and the resin as the insulating adhesive layer does not protrude from the through hole that becomes the IVH, and the multilayer wiring with the IVH is excellent in releasability. An object of the present invention is to provide an adhesive film for a board.

[0006]

That is, the present invention relates to an adhesive film in which an adhesive is applied to one side of a support made of a polyester film, wherein a barrier layer such as a resin film or a metal film is provided between the support and the adhesive. And a pressure-sensitive adhesive film for manufacturing a multilayer wiring board with an IVH.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressure-sensitive adhesive film according to the present invention is obtained by coating a surface of a support with a pressure-sensitive adhesive mainly composed of rubber or synthetic resin. For example, polyisobutylene, butyl rubber, polybutene (meth) acrylic polymer and the like can be mentioned, and a tackifier, a stabilizer, a coloring agent, a filler, a foaming agent and the like may be further added. The method for manufacturing the multilayer wiring board with an IVH is as described above, and a general method such as a roll laminator can be used for sticking to the IVH substrate.

The pressure-sensitive adhesive is mainly composed of an acrylic acid polymer or a methacrylic acid polymer, and is composed of an acrylic acid monomer, a methacrylic acid monomer, an alkyl acrylate monomer, an alkyl methacrylate monomer, and a monomer having a functional group for crosslinking. Polymers and modified products thereof. Preferably, the content of the acrylic acid monomer or the methacrylic acid monomer is 50% by weight or more, and the weight average molecular weight of the copolymer is 500,000 or more, more preferably 100,000 or more.
More than ten thousand. If the molecular weight is 500,000 or less, the fluidity is good even when cross-linked, and the pressure-sensitive adhesive flows into the holes of the IVH during molding, and the outer layer surface of the multilayer laminate cannot have smoothness. The measurement of molecular weight
There are a high-speed chromatographic method, a viscosity method, an ultra-distant method, a light scattering method, a membrane osmotic pressure method, and the like. The high-speed chromatographic method is fast and widely used as a general method. Further, regarding the fluidity, the glass transition temperature of the copolymer is −30 ° C. to −50.
C is more preferred. At -30 ° C or higher, the flowability of the adhesive is so poor that it is impossible to prevent the resin from protruding from the IVH. At -80 ° C or lower, the flowability of the pressure-sensitive adhesive is good.
The pressure-sensitive adhesive enters the VH part, and the outermost layer of the multilayer laminate has poor smoothness.

The functional group-containing monomers include acrylamide,
It is a monomer having a functional group which reacts and crosslinks with isocyanate such as amino group, hydroxy group, epoxy group and the like such as methylol acrylamide, hydroxyalkyl methacrylate and vinyl glycidyl ether. The amount of the functional group-containing monomer is from 1% by weight to 50% by weight, preferably 3% by weight.
% By weight or more and 20% by weight or less. If the amount is less than 1% by weight, crosslinking will not be sufficiently performed, and if it exceeds 50% by weight, the pressure-sensitive adhesive will not have appropriate elasticity, and it will not be possible to prevent the resin from protruding.

The isocyanate used as a crosslinking agent is
It is a compound having a functional group represented by N = C = O, and is a trifunctional or higher isocyanate. Tris (4-phenylisocyanate) thiophosphite, triphenylmethane triisocyanate, tolylene diisocyanate trimer, trimethylpropane-1-methyl 2-isocyano-4-carbamate, polymethylene polyphenyl isocyanate, diphenyl ether-2,4,4 ' -Triisocyanate, polyfunctional aromatic isocyanate, aromatic polyisocyanate, polyfunctional aliphatic isocyanate, block-type polyisocyanate, polyisocyanate prepolymer and the like.

The support may be a polyester film such as polyethylene terephthalate polybutylene naphthalate or polyethylene naphthalate which is generally used for the adhesive film. ~ 125 µm is preferred. Further, these may be subjected to sandblasting, corona treatment, treatment with a coupling agent, chemical treatment with an oxidizing agent, or the like in order to improve the adhesion with the adhesive. The barrier layer between the support and the pressure-sensitive adhesive is composed of a resin film, a metal foil, a metal deposition, or the like. Here, examples of the resin film include polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol, but polyvinyl alcohol is preferable from the viewpoint of gas barrier properties, incineration treatment, and the like.

Further, examples of the metal foil to be laminated include aluminum, stainless steel, and copper, but are not limited thereto. Here, the thickness of the metal foil is 5 to 35 μm
If it is 5 μm or less, wrinkles are likely to be formed during lamination with a polyester film, and if it is 35 μm or more, the cushioning property of the polyester film as a support is lost, and the function of preventing resin leakage is reduced. further,
Examples of the metal to be deposited include aluminum, aluminum oxide, nickel, and gold. Aluminum is preferable from the viewpoint of economy and the like. The thickness of the vapor deposition is preferably from 50 to 1000 °.
If it is more than 00 °, there is a disadvantage that the deposited metal is easily peeled off.

According to the present invention, the adhesive film closes the through-hole portion of the IVH, and the adhesive adheres to the periphery of the through-hole, deforms so as to plug the through-hole portion by heating, and stops the flow of the prepreg. Can be prevented. In addition, the support film and the pressure-sensitive adhesive absorb variations in the thickness of the substrate and bias in the pressure, and the influence of the inner layer circuit shape on the surface is reduced. In addition, it blocks oligomers migrating from the polyester film of the support and prevents migration to the substrate after pressing.

[0014]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to only these examples. In the following, all parts are parts by weight. Example 1 butyl acrylate, ethyl acrylate and acrylic acid-
Emulsion polymerization of 2-hydroxyethyl in a ratio of 85 parts: 10 parts: 5 parts using hydrogen peroxide as an initiator and a nonionic surfactant as an emulsifier at 75 ° C. for 3 hours, followed by washing with water, drying and weight average. Molecular weight 800,000, glass transition temperature (T
g) An acrylic acid copolymer at -47 ° C was obtained. Next, this was dissolved in toluene so as to be 10% by weight, and 10 parts of Coronate L (trade name of Nippon Polyurethane Industry Co., Ltd.) was added as a trifunctional isocyanate to 100 parts of the solid content of the solution, and the adhesive solution was added. Was adjusted. This was sandblasted to a non-processed surface of a 25 μm PET film (manufactured by Teijin Limited), and polyvinyl alcohol was coated to a thickness of 10 μm.
15μ in solid content on the surface obtained by coating with thickness
m and dried by heating at 100 ° C. for 5 minutes to obtain an adhesive film. Next, a glass cloth base epoxy resin double-sided copper-clad laminated board is drilled with a drill having a diameter of 0.2 mm to form a through hole for IVH, plated with a through hole, formed a circuit on one side, and formed the other side (copper foil). Then, the obtained adhesive film was roll-laminated on the side with the plated copper). Roll lamination was performed by placing a substrate on a metal plate. After plating through holes with IVH through holes with a diameter of 0.2 mm, an adhesive film is further placed on both sides of the circuit board on both sides of which via an 80 μm thick glass cloth base epoxy resin prepreg, Were laminated so that the adhesive film was the outermost layer, and heated and pressed at 190 ° C. for 2 hours to obtain a six-layer substrate. The protrusion of the resin from the via holes of the obtained six-layer board was evaluated for sealing properties and transferability to the board, and the results are shown in Table 1.

Example 2 In Example 1, PET was obtained by laminating an 8 μm aluminum foil on the surface of the support that had not been sandblasted.
A pressure-sensitive adhesive film was prepared in the same manner as in Example 1 except for using, and evaluation was performed using a six-layer substrate. Table 1 shows the results.

Example 3 In Example 1, PET was formed by vapor-depositing 600 ° of aluminum on the non-sandblasted surface of the support.
A pressure-sensitive adhesive film was prepared in the same manner as in Example 1 except for using, and evaluation was performed using a six-layer substrate. Table 1 shows the results.

Comparative Example 1 As Example 1, an adhesive film was prepared in the same manner as in Example 1 except that PET, which was not subjected to any treatment, was used on the surface of the support that had not been subjected to sandblasting. A layer substrate was prepared and evaluated. Table 1 shows the results.

Comparative Example 2 In Example 2, the aluminum foil to be laminated was 50 μm
Other than that, an adhesive film was prepared in the same manner as in Example 2 and evaluated using a six-layer substrate. Table 1 shows the results.

Comparative Example 3 An adhesive film was prepared in the same manner as in Example 3 except that the deposited aluminum was 20 °.
Evaluation was performed using a six-layer substrate. Table 1 shows the results.

[0020]

[Table 1] (Note 1) After molding a 6-layered wiring board with IVH of φ0.2mm, whether or not the resin protrudes from the via hole. ○: Resin protrusion less than 100 μm ×: Resin protrusion 100 μm or more (Note 2) Transfer to 6-layer wiring board surface ○: No transfer to substrate ×: Transfer to substrate

In all of Examples 1 to 3, the sealing property and the migration property were satisfied. However, Comparative Example 1 did not have a barrier layer. Therefore, the barrier effect was low and transfer to the substrate could not be prevented.
Furthermore, in Comparative Example 2, since the thickness of the laminated metal foil was too large, the cushion effect was low and the effect of preventing resin leakage was impaired.

[0022]

According to the present invention, the use of the pressure-sensitive adhesive film of the present invention can prevent the transfer of the transferred matter from the polyester film to the substrate during the production of the multilayer board with IVH, and can prevent the prepreg from protruding under various conditions. This makes it possible to manufacture a multi-layer board with an IVH having excellent properties.

[Brief description of the drawings]

FIG. 1 is a perspective sectional view of a multilayer wiring board with an IVH (interstitial via hole).

FIG. 2 is a cross-sectional view of a main part of the multi-layer board with IVH, showing the resin protruding from the IVH section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 IVH part 2 Through-hole plating 3 Adhesive resin (prepreg, adhesive film) 4 Copper foil surface with circuit processing 4 'Copper foil surface without circuit processing 5 Substrate 6 Resin protrusion 7 Adhesive film 8 Plastic film support 9 Adhesive Agent A Substrate processed double-sided copper-clad substrate (first and second layers) B Substrate processed double-sided copper-clad substrate (third and fourth layers) C Substrate processed double-sided copper-clad substrate (5, 6) Layer)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Inoue 1150 Goshomiya, Odate, Shimodate-shi, Ibaraki F-term in Goshonomiya Plant of Hitachi Chemical Co., Ltd. 4J004 AA05 AA07 AA10 AA14 AB01 CA03 CA05 CA06 CA08 CC03 CC04 CD01 CD05 FA05 4J040 DA131 DA141 DF011 EF181 GA05 GA07 GA11 GA22 JA09 JB09 LA01 LA02 NA20 PA15 5E346 CC41 DD02 EE02 EE06 EE09 EE12 GG02 GG28 HH21

Claims (6)

[Claims] 1. An adhesive film for producing a multilayer wiring board with IVH, wherein the adhesive film is obtained by applying an adhesive to one side of a support made of a polyester film, wherein a barrier layer is provided between the support and the adhesive. the film. 2. The method according to claim 1, wherein the barrier layer is a resin film.
Adhesive film for manufacturing multilayer wiring boards with VH. 3. The method according to claim 1, wherein the barrier layer is a metal film.
Adhesive film for manufacturing multilayer wiring boards with VH. 4. The pressure-sensitive adhesive film according to claim 3, wherein the metal film is a metal deposited film having a thickness of 50 to 1000 °. 5. The adhesive film according to claim 3, wherein the metal film is a metal foil having a thickness of 5 to 35 μm. 6. An adhesive which is an acrylic acid copolymer resin or a methacrylic acid copolymer resin, has a weight average molecular weight of 500,000 or more, a glass transition temperature of -30.degree. C. to -80.degree. The pressure-sensitive adhesive film for producing a multilayer wiring board with an IVH according to any one of claims 1 to 5, wherein the content of the monomer is 1% by weight or more and 50% by weight or less.