JPH1187920A - Adhesive film for manufacturing multilayered circuit board with ivh - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overhanging of resin of a prepareg by incorporating heating type foaming agent and thermoplastic resin, having a melting point of specific temperature at a specific weight ratio in adhesive. SOLUTION: As a foaming agent, thermally expandable particles are preferable in view of ease of handling. Thermoplastic resin to be mixed with the adhesive is polymer having a melting point 30 to 80 deg., and its adding amount is 2 to 40 wt.%, or preferably 5 to 30 wt.% to main agent. If it is less than 2%, an effect of deformation to a through-hole of the prepreg is not present, while if it is 40 wt.% or more, cohersive force of the main agent of the adhesive is lowered to cause a residual paste. An adhesive film blocks the through-hole of IVH, and the adhesive is brought into close contact with a periphery of the through-hole. Further, the thermoplastic resin in the adhesive is deformed to block the through-hole with a plug, by heating a press to stop the fluidization of the prepreg, thereby preventing its overhanging.

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 As shown in FIG. 1, a multilayer wiring board with an IVH is a plated through hole for connecting two or more conductive layers of a multilayer printed wiring board, and is a hole 1 not penetrating the printed wiring board. is there. It is also called an interstitial beer hall or inner via hole. The multilayer wiring board with IVH shown in FIG. 1 is generally manufactured using three copper-clad laminates and two sets of prepregs or adhesive films. There are various methods for manufacturing a multilayer wiring board with an IVH. For example, three double-sided copper-clad laminates A, B,
C is drilled according to the circuit and plated through-hole to form IVH. Then, wiring is formed by etching the A and C substrates on the opposite surfaces of the outermost layers of the A and C substrates and the copper foil on both surfaces of the B substrate, leaving the copper foil to be the outermost layer. Then, the prepreg and the side on which the wiring of the A and C substrates are formed are laminated on both sides of the B substrate with the prepreg side formed, and heated and pressed by a press to form a multilayer wiring board. After that, a hole is drilled and plated with through holes, and wiring processing of the outermost copper foil is performed. As shown in FIG. 2, the multilayer wiring board with the IVH manufactured as described above has a prepreg resin using interlayer insulation and adhesion, which is pressed to pass through the through-hole portion of the IVH to the surface layer, and the outermost copper foil is formed. Even if an attempt is made to form a wiring, the protruding resin also acts as a resist at the time of etching, and 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., combined with a chemical solution such as a physical release agent, etc. The resin protruding into the outermost 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, and dimensional change or deformation of the substrate occurs. In addition, when a chemical solution is used, there is a problem of its removal and waste liquid treatment. Therefore, the present inventors have previously proposed a method using an adhesive film (Japanese Patent Application No. 8-208716).

[0003]

However, in this method, the resin slightly protrudes depending on the type of resin used for the prepreg and pressing conditions, and some restrictions such as pressing conditions have been obliged. The present invention has been made in view of such circumstances, and has as its object to provide an adhesive film for manufacturing a multilayer wiring board with an IVH, which can prevent the resin of the prepreg from protruding even under mild conditions and can be easily peeled off.

[0004]

That is, the present invention relates to a pressure-sensitive adhesive film comprising a support and a pressure-sensitive adhesive, wherein the pressure-sensitive adhesive comprises a heating foaming agent and a thermoplastic resin having a melting point of 30 to 80 ° C. IV characterized by containing -40% by weight.
The present invention relates to an adhesive film for manufacturing a multilayer wiring board with H.

[0005]

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. The pressure-sensitive adhesive suitable for the present invention is mainly composed of an acrylic acid polymer or a methacrylic acid polymer, and includes an acrylic acid monomer, a methacrylic acid monomer, an alkyl acrylate monomer, an alkyl methacrylate monomer, and a functional group for crosslinking. It is a copolymer of the contained monomer and a modified product thereof. Preferably, the acrylic or methacrylic acid monomer comprises 50
% By weight or more, and the weight average molecular weight of the copolymer is 60% or more.
It is 10,000 or more, more preferably 1,000,000 or more. If it is less than 600,000, even if crosslinked, the flowability is so good that the pressure-sensitive adhesive flows into the holes of the IVH at the time of molding, and the outer layer surface of the multilayer wiring board cannot have smoothness. As a method for measuring the molecular weight, there are a high-performance liquid chromatography method, a viscosity method, an ultra-long distance method, a light scattering method, a membrane osmotic pressure method, and the like, and the high-speed chromatography method is widely used as a general method. Further, with respect to fluidity, the glass transition temperature of the copolymer is preferably from -30C to -50C. -30
If the temperature is higher than 0 ° C., the flowability of the pressure-sensitive adhesive is so poor that it is impossible to prevent the resin from protruding from the IVH. If the temperature is lower than −50 ° C., the fluidity of the pressure-sensitive adhesive is too good, so that the pressure-sensitive adhesive easily penetrates into the IVH portion, and the smoothness of the outermost layer of the multilayer wiring board deteriorates.

The functional group-containing monomer is a monomer having a functional group which reacts with and is crosslinked with an isocyanate such as an amino group such as acrylamide, methylolacrylamide, hydroxyalkyl methacrylate and vinyl glycidyl ether, and a hydroxy group and an epoxy group. The amount of the functional group-containing monomer is 1% by weight to 50% by weight, preferably 3% by weight to 20% by weight. When the amount is less than 1% by weight, the crosslinking is not sufficiently performed, and when the amount exceeds 50% by weight, the pressure-sensitive adhesive does not have appropriate elasticity, so that the resin cannot be prevented from protruding. As a crosslinking agent for the functional group-containing monomer, an isocyanate compound is used. The isocyanate compound is a compound having a functional group represented by -N = C = O and is a tri- or more-functional 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'-
Examples thereof include triisocyanate, polyfunctional aromatic isocyanate, aromatic polyisocyanate, polyfunctional aliphatic isocyanate, block type polyisocyanate, and polyisocyanate prepolymer.

Examples of the foaming agent used in the present invention include thermally expandable particles such as Expancel (trade name of Nippon Philite Co., Ltd.) and Matsumoto Microsphere (trade name of Matsumoto Yushi Co., Ltd.), inorganic foaming agents, and nitroso. Foaming agent, azo foaming agent,
There are sulfonyl hydrazide-based foaming agents and the like, but heat-expandable particles are preferred from the viewpoint of easy handling. The expansion start temperature of the thermally expandable particles needs to be 80 ° C. or higher. The amount of the foaming agent is not particularly limited, but is 1 to 30% by weight, more preferably 2 to 15% by weight, based on the whole pressure-sensitive adhesive. If it is less than 1%, the adhesive force is too strong when the film is peeled off, making it difficult to peel off. If it exceeds 30%, the film tends to protrude. The foaming agent has an expansion start temperature of 80 ° C. or higher, an average particle size of 1 to 30 μm,
Desirably, the particles (heat-expandable particles) whose volume expands twice or more by heating.

[0008] The thermoplastic resin mixed with the pressure-sensitive adhesive is a polymer having a melting point of 30 to 80 ° C, and examples thereof include polyether polyols and side-chain crystalline polyacrylates. The addition amount is 2 to 40% by weight or less based on the main agent,
Preferably it is 5 to 30% by weight. If it is less than 2%, the effect of deformation of the prepreg into the through-hole portion does not appear, and if it is 40% by weight or more, the cohesive force of the main component of the pressure-sensitive adhesive is reduced and adhesive residue is caused.

As the support, generally used plastic films or metal foils, woven fabrics, papers and the like made of polyester, polypropylene, polyvinyl chloride, polycarbonate, polyurethane, polyimide, polyamide, fluorine compound and the like, and composites thereof Is mentioned.
Particularly, a plastic film is preferable from the viewpoint of economy and workability of applying the pressure-sensitive adhesive, and the thickness is preferably 12 to 125 μm. 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 thickness of the adhesive is suitably from 2 to 35 μm.
The method for manufacturing the multilayer wiring board with IVH is the same as in a conventional method.
A general method such as a roll laminator can be used for attaching to the IVH substrate. When using an adhesive film in which an adhesive has been applied to both sides of a base film, a substrate with an IVH can be attached to both sides of the adhesive film to produce two sets of multilayer wiring boards.

According to the present invention, the adhesive film closes the through-hole of the IVH, the adhesive adheres to the periphery of the through-hole, and the thermoplastic resin in the adhesive plugs the through-hole by heating of the press. To prevent the prepreg from flowing and prevent the prepreg from protruding. Further, the base film and the pressure-sensitive adhesive absorb variations in the thickness of the substrate and deviations in the pressure, so that the influence on the surface of the inner layer circuit shape is reduced. Furthermore, since the thermally expandable particles expand in the resin curing temperature range of the prepreg, the adhesiveness between the pressure-sensitive adhesive and the substrate is reduced, the adhesive force is reduced, and the substrate can be easily peeled without being damaged.

[0010]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to 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 was performed at 75 ° C. for 3 hours using hydrogen peroxide as an initiator in a ratio of 85 parts: 10 parts: 5 parts and a nonionic surfactant as an emulsifier.
After washing with water and drying, an acrylic acid copolymer having a weight average molecular weight of 800,000 and a glass transition temperature (Tg) of -47 ° C was obtained. Next, this was dissolved in toluene so as to be 10% by weight,
10 parts of Coronate L (trade name of Nippon Polyurethane Industry Co., Ltd.) as a trifunctional isocyanate and Expancel 551DU as a foaming agent are used for 100 parts of the solid content of this solution.
10 parts of (Nippon Filite Co., Ltd.) and 10 parts of Paogen EP-15 (trade name of melting point of 57 ° C., Daiichi Kogyo Seiyaku Co., Ltd.) as a thermoplastic resin were added to prepare an adhesive solution. This was applied to Aflex 25 MW (trade name of Asahi Glass Co., Ltd.) so as to have a solid content of 15 μm in thickness.
It was dried by heating at 0 ° C. for 5 minutes to obtain an adhesive film. Then
Glass cloth base epoxy resin double-sided copper-clad laminate with a diameter of 0.
After drilling with a 2mm drill, forming through holes for IVH, plating through holes, forming a circuit on one side, and applying the resulting adhesive film to the other side (the side with copper foil and plated copper). Roll lamination was performed. Roll lamination was performed by placing a substrate on a metal plate. And a diameter of 0.2
80mm thick on both sides of a substrate which has a through-hole for IVH of 1 mm
m through a glass cloth-based epoxy resin prepreg, and further, a substrate on which an adhesive film is laminated is further laminated thereon such that the adhesive film is the outermost layer, and 190 ° C.
For 2 hours to obtain a six-layer substrate. The protrusion of the resin from the IVH of the resulting adhesive film of the six-layer substrate was evaluated as the sealing property. In addition, the peelability when peeling the adhesive film from the six-layer substrate was evaluated, and the results are shown in Table 1.

Example 2 A homopolymer of stearyl acrylate: cetyl acrylate: ethyl acrylate: hydroxyethyl acrylate = 60: 20: 20: 2 (melting point: 35) synthesized by a conventional method as a thermoplastic resin to be added in Example 1
° C), except that a pressure-sensitive adhesive film was prepared in the same manner as in Example 1 and evaluated using a six-layer substrate. Table 1 shows the results.
Shown in

Example 3 An adhesive film was prepared in the same manner as in Example 1 except that a 25 μm-thick polyethylene terephthalate film was used for the support in Example 1, and evaluation was performed using a six-layer substrate. Table 1 shows the results.

Comparative Example 1 An adhesive film was prepared in the same manner as in Example 1 except that PAOGEN EP-15 was omitted, and a six-layer substrate was prepared and evaluated. Table 1 shows the results.

Comparative Example 2 An adhesive film was prepared in the same manner as in Example 1 except that Paogen EP-15 and Expancel 551DU were omitted, and evaluation was performed using a six-layer substrate. Table 1 shows the results.

[0016]

[Table 1] (Note 1) After molding a 6-layer wiring board with IVH of φ0.2mm, whether or not the resin in the IVH portion protrudes. ○: No resin protrusion ×: Resin protrusion (Note 2) Adhesive strength of the adhesive film after forming a 6-layer wiring board. Peeling angle 90 °, Peeling speed 200 mm / min ○: Adhesive force is less than 350 gf / 25 mm ×: Adhesive force is 350 gf / 25 mm or more

Comparative Example 1 is an example in which an adhesive film coated with an adhesive containing thermally expandable particles is used. However, since the thermally expandable particles are used, the peelability is excellent, but the resin overflows. The result was. Further, in Comparative Example 2 from which the heat-expandable particles were removed, the adhesive force increased due to the temperature and pressure of the press, and peeling was difficult. On the other hand, in Examples 1 to 3 in which both the heat-expandable particles and the thermoplastic resin were added, it was possible to achieve both the sealing property and the peeling property.

[0018]

When the adhesive film of the present invention is used in the production of an IVH multilayer board, the resin of the prepreg can be completely prevented from protruding under various conditions, and the substrate can be peeled off after the production of the IVH multilayer board without being damaged. As a result, the step of removing the protruding resin can be omitted, and the dimensional change of the substrate, waste liquid treatment, and the like can be solved.

[Brief description of the drawings]

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

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]

Reference Signs List 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)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09J 175/04 C09J 175/04 (72) Inventor Junichi Imaizumi 1150 Goshomiya, Oji, Shimodate-shi, Ibaraki Prefecture Goshomiya, Hitachi Chemical Co., Ltd. in the factory

Claims (3)

[Claims] 1. A pressure-sensitive adhesive film comprising a support and a pressure-sensitive adhesive, wherein the pressure-sensitive adhesive has a heating foaming agent and a melting point of 30 to 8
An adhesive film for producing a multilayer wiring board with an IVH, comprising 2 to 40% by weight of a thermoplastic resin at 0 ° C. 2. The pressure-sensitive adhesive film according to claim 1, wherein the foaming agent has an average particle diameter of 1 to 30 μm, and is a particle (heat-expandable particle) whose volume expands to twice or more by heating. . 3. A pressure-sensitive adhesive whose main component is an acrylic acid copolymer resin or a methacrylic acid copolymer resin containing a functional group reactive with isocyanate, and having a weight average molecular weight of 6
The pressure-sensitive adhesive film for producing a multilayer wiring board with an IVH according to claim 1, wherein the pressure-sensitive adhesive film has a glass transition temperature of -30 ° C to -50 ° C.