JPH07297553A - Adhesive film for manufacturing multilayer wiring board with ivh and multilayer wiring board with ivh - Google Patents

Abstract

PURPOSE:To completely prevent the squeezing out of resin from an IVH by a method wherein an adhesive film, which is composed of a substrate film and a bonding agent, is adhered to a wiring board, which becomes an IVH, and a multilayer adhesion state is obtained. CONSTITUTION:As an adhesive film 3 blocks up the through hole 2 of an IVH (interstitial via hole) 1 and an adhesive agent 9 is closely adhered to the circumference of the through hole, the resin coming from the prepreg and the adhesive film 3 passing the through hole 2 of the IVH is stopped there, the squeezing out of the resin can be prevented. Also, a substrate film 8 and the adhesive agent 9 absorb the irregularity in thickness of a substrate 5 and the inclination of pressure, the projection of inner layer circuit configuration to the surface can be eliminated, and air is not left in the through hole because the air confined in the through hole 2 is diffused to the adhesive agent 9.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A multilayer wiring board with an IVH (interstitial via hole) is a plated through hole for connecting two or more conductor layers of a multilayer printed wiring board as shown in FIG. It is a hole that does not penetrate. It is also called an interstitial beer hall or an inner via hole. The IVH-equipped multilayer wiring board shown in FIG. 1 is generally manufactured using three copper-clad laminated substrates and two sets of prepregs or adhesive films. Although there are various manufacturing methods, for example, three double-sided copper-clad laminated boards A, B, and C are drilled according to the circuit and through-hole plated to form IVH. Then, the A and C boards are left with the outermost copper foil, and the opposite surfaces of the A and C boards and the double-sided copper foil of the B board are processed by etching to form wiring. Then, the prepreg and the wirings of the A and C substrates are laminated on both sides of the B substrate so that the prepreg side is laminated and heated and pressed by a press to form a multilayer laminate.
After that, the holes are drilled, through-hole plating is performed, and the wiring of the outermost copper foil is processed. In the IVH-equipped multilayer wiring board manufactured in this manner, the resin of the prepreg used for interlayer insulation and adhesion is IVH-pressed during pressing as shown in FIG.
Even if an attempt is made to form a wiring on the outermost copper foil through the through-hole portion, the protruding resin acts as a resist during etching and cannot be etched, resulting in defective wiring formation. In order to prevent this, after making a multi-layer laminate by pressing, the outermost layer is physically sanded or buffed, and chemically or chemically combined with a chemical such as a release agent to form the outermost layer. The resin that had run off was removed.

[0003]

However, in this method, the belt sander and the buffing have a problem that the heat of polishing and mechanical stress due to the polishing are applied to the multi-layer laminated plate to cause the dimensional change and deformation of the substrate. . Further, when a chemical solution is used, there is a problem in its removal and waste solution treatment. In order to solve these problems, the outermost layer should be 3
There is a method of preventing the resin from squeezing out from the IVH by installing a layered plastic film, but this method cannot completely prevent the squeezing out.

[0004]

Therefore, as a result of intensive research for solving the above-mentioned problems, the present inventor has studied the use of an adhesive film as a first invention in order to prevent resin from squeezing out from IVH. In the above-described method for manufacturing a multilayer wiring board with IVH, an adhesive film is roll-laminated and pasted on the opposite side of the A and C boards on which wiring is formed, and the A and C boards are adhered to both sides of the B board via prepregs. The films were laminated so that the films were on the outside and heated and pressed by a press to produce a multilayer laminate. As a result, this method could completely prevent the resin from squeezing out, and could solve the initial problem. However, according to this method, when the adhesive film is removed from the multilayer laminate, the adhesive film must be peeled off with a large force, which puts a heavy burden on the operator and sometimes bends the multilayer laminate. In addition, the adhesive film was sometimes torn and it took a lot of time to peel it off. Further, as shown in FIG. 3, the pressure-sensitive adhesive layer digs into the IVH portion to form a dent, which makes it difficult to peel off the pressure-sensitive adhesive film, resulting in poor workability.
Since the H part is not completely filled with resin, the pad becomes concave when a wiring pad is formed in this part, and when solder is provided on the pad, the solder flows into the concave part and there is little solder that contributes to connection when mounting parts There was a problem that the pad and the component could not be connected, or even if they could be connected, the reliability was poor. In this case, as the second invention, the crosslinking agent is a trifunctional or higher functional isocyanate,
It is also possible to use an isocyanate whose addition amount is 2 to 5 times the equivalent amount, and use it as an acrylic acid copolymer or methacrylic acid copolymer pressure-sensitive adhesive having a functional group that reacts with this isocyanate.

The adhesive film is composed of a plastic film as a support and an adhesive. As a support,
Polyester film, polypropylene film and polyethylene film are preferably used. The thickness of the polyester film and polyethylene film is 12 to 12
5 μm is preferable, and the polyethylene film is 40 to 1
25 μm is preferable. These may be subjected to sandblasting, corona treatment, coupling agent treatment, chemical treatment with an oxidizing agent, or the like in order to improve adhesion with the adhesive.

The pressure-sensitive adhesive film according to the first aspect of the invention is one in which a pressure-sensitive adhesive containing rubber or synthetic resin as a main component is applied to the surface of a support. Specifically, a tackifier, a stabilizer, a colorant, a filler and the like are added with polyisobutylene, butyl rubber, polybutene, an acrylic acid polymer, a methacrylic acid polymer as a main component. The method for producing the IVH-attached multilayer wiring board is as described above, and a general method such as a roll laminator can be used for attaching the IVH-attached board. When a pressure-sensitive adhesive film in which a pressure-sensitive adhesive is applied to both sides of a base film is used, two sets of multilayer laminates can be manufactured by sticking the IVH-attached substrate to both sides of the pressure-sensitive adhesive film. The pressure-sensitive adhesive according to the second invention comprises an acrylic acid polymer or a methacrylic acid polymer as a main component, an acrylic acid monomer, a methacrylic acid monomer, an acrylic acid alkyl ester monomer, a methacrylic acid alkyl ester monomer, and a functional machine for crosslinking. It is a copolymer of a contained monomer and its modified product. Preferably, the acrylic acid monomer or the methacrylic acid monomer is 50% by weight or more,
The weight average molecular weight of the copolymer is 600,000 or more, more preferably 1 million or more. If it is less than 600,000, the fluidity will be good even if it is crosslinked, and the adhesive will flow into the holes of the IVH during molding, and the smoothness of the outer layer surface of the multilayer laminate will not be obtained. As for the molecular weight, there are a high performance liquid chromatographic method, a viscosity method, an ultracentrifugation method, a light scattering method, a membrane permeation pressure method and the like, but the high speed chromatographic method is high speed and widely used as a general method. Regarding the fluidity, the glass transition temperature of the copolymer is -30 ° C.
The temperature is preferably -70 ° C, more preferably -40 ° C to -50 ° C. Above -30 ° C, the flowability of the adhesive is poor and IVH
It will not be possible to prevent the resin from squeezing out. Also, -7
At 0 ° C. or lower, the flowability of the pressure-sensitive adhesive is good, and the pressure-sensitive adhesive penetrates into the IVH portion, and the smoothness of the outermost layer of the multilayer laminate is deteriorated.

The functional group-containing monomer is acrylamide,
It is a monomer having a functional group capable of reacting with an isocyanate such as an amino group such as methylol acrylamide, hydroxyalkyl methacrylate, or vinyl glycidyl ether, a hydroxy group, an epoxy group, or the like and crosslinking. The amount of the functional group-containing monomer is 1% by weight or more and 50% by weight or less, preferably 3%
It is from 20% by weight to 20% by weight. Below 1% by weight,
If it is not sufficiently cross-linked and exceeds 50% by weight, the pressure-sensitive adhesive does not have appropriate elasticity and the resin cannot be prevented from squeezing out.

The isocyanate used as the crosslinking agent is-
It is a compound having a functional group represented by N = C = O 2, and is a trifunctional or higher 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'-triisocyanate, polyfunctional aromatic isocyanate, aromatic polyisocyanate, polyfunctional aliphatic isocyanate, block polyisocyanate, polyisocyanate prepolymer, etc. are exemplified. You can The addition amount is 2 to 5 times in terms of an equivalent ratio with respect to the functional group of the acrylic acid copolymer or the methacrylic acid copolymer. If it is less than 2 times, the cross-linking property will not be sufficient and the peelability will be deteriorated. If it exceeds 5 times, the fluidity of the pressure-sensitive adhesive will be too low to prevent the resin from protruding from the IVH. In the pressure-sensitive adhesive of the present invention, a compounding agent that is usually mixed with a pressure-sensitive adhesive such as an antioxidant, a rust preventive, a crosslinking accelerator, a coloring agent, and a softening agent may be added.

[0009]

In the first aspect of the invention, since the adhesive film closes the through hole of the IVH and the adhesive adheres to the periphery of the through hole, the resin from the prepreg or the adhesive film is stopped there through the through hole of the IVH. Therefore, the resin can be prevented from protruding. In addition, the base film and the adhesive absorb variations in the thickness of the substrate and the pressure, and the projection of the inner layer circuit shape on the surface is reduced.
It is considered that the air trapped in the through hole of H diffuses into the adhesive, but no air is left behind in the through hole. In the second invention, the first
In addition to the invention of (1), since the acrylic acid copolymer or methacrylic acid copolymer of the pressure sensitive adhesive is crosslinked with 2 to 5 times equivalent of trifunctional or more isocyanate, the fluidity of the pressure sensitive adhesive is suppressed,
When the multi-layer laminate is made by pressing, etc., the IVH through-holes are blocked without the adhesive entering the through-holes of the IVH. The outermost layer surface is smooth because the resin is filled without squeezing out and the resin is filled up to the outermost layer surface. Moreover, since the adhesive force is suppressed by crosslinking, the adhesive film can be easily peeled off after the multilayer laminate is prepared.

[0010]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these examples. In the following, all parts are parts by weight.

Example 1 85% butyl acrylate, ethyl acrylate and 2-hydroxyethyl acrylate were used.
Parts: 10 parts: 5 parts by weight, using hydrogen peroxide as an initiator and a nonionic surfactant as an emulsifier for 3 hours at 75 ° C., followed by emulsion polymerization, followed by washing with water and drying, and a weight average molecular weight of 800,000, glass transition. An acrylic acid copolymer having a temperature (Tg) of −47 ° C. was obtained. Then, this was dissolved in toluene so as to be 10% by weight, and 3 parts with respect to 100 parts of solid content of this solution.
As a functional isocyanate, 25 parts of Coronate L (trade name of Nippon Polyurethane Industry Co., Ltd.) was added (twice the equivalent amount) to prepare an adhesive solution. This was applied to a polypropylene film (thickness: 40 μm) that had been corona-treated on one side with a solid content of 10
It was applied so as to have a thickness of μm, and heated and dried at 100 ° C. for 5 minutes to obtain an adhesive film. Then, the glass cloth base material 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, and after plated with the through hole, a circuit is formed on one surface and the other surface (copper foil and copper foil). The obtained adhesive film was roll-laminated on the side having plated copper). Roll lamination was performed by placing a substrate on a metal plate. An IVH through hole having a diameter of 0.2 mm is plated on the both sides of the board after the through hole is plated, and a glass cloth base material epoxy resin prepreg with a thickness of 80 μm is interposed on both sides of the board. The laminated substrates were laminated so that the pressure-sensitive adhesive film was the outermost layer and heated and pressed at 170 ° C. for 2 hours to obtain a 6-layer substrate. The protrusion of the resin from the IVH of the pressure-sensitive adhesive film of the obtained 6-layer substrate was evaluated as the sealing property. In addition, the peelability when peeling the adhesive film from the 6-layer substrate was evaluated, and the results are shown in Table 1.

(Example 2) 90 parts by weight of butyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyl methacrylate were used as the acrylic acid copolymer.
Parts: 2 parts (molecular weight 1,000,000, Tg = -55 ° C.), a polyfunctional aliphatic isocyanate as an isocyanate crosslinking agent,
Sumijour N (trade name of Sumitomo Bayer Urethane Co., Ltd.)
An adhesive film was prepared in the same manner as in Example 1 except that 15 parts (3 times the equivalent amount) was used, and evaluation was performed using a 6-layer substrate. The results are shown in Table 1.

Example 3 In Example 1, the addition amount of Coronate L (trade name of Nippon Polyurethane Industry Co., Ltd.) was 3
A pressure-sensitive adhesive film was prepared in the same manner as in Example 1 except that the amount (0.25 times the equivalent weight) was used, and evaluation was performed using a 6-layer substrate. The results are shown in Table 1.

Example 4 In Example 1, the amounts of butyl acrylate, ethyl acrylate, and 2-hydroxyethyl acrylate in the acrylic acid copolymer were changed to 30:10:60.
Example 1 except for parts (molecular weight 800,000, Tg = 3 ° C.)
A pressure-sensitive adhesive film was prepared in the same manner as above, and evaluated using a 6-layer substrate. The results are shown in Table 1.

Comparative Example A 6-layer substrate was prepared and evaluated in the same manner as in Example 1 except that a polypropylene film having a thickness of 100 μm was used instead of the adhesive film in Example 1. The results are shown in Table 1.

[0016]

[Table 1]

Compared with the comparative example, in the manufacturing method using the pressure-sensitive adhesive film of the first invention, the sealing property is good and the resin does not overflow. Moreover, the adhesive film which concerns on 2nd invention WHEREIN: As shown in Table 1, when trifunctional isocyanate is added in 2-5 times the equivalent range, the peelability of an adhesive film will be
It will be good. As shown in Example 3, if it is less than twice, the adhesive force will be too high. When the amount of the functional group monomer that reacts with the isocyanate of the acrylic acid copolymer is 50% by weight or more, the releasability of the resin is good, even if the trifunctional isocyanate is in the range of 2 to 5 times the equivalent weight. However, the pressure-sensitive adhesive film becomes too hard to prevent the protrusion from becoming insufficient. On the other hand, in Example 1, the emulsion polymerization time was shortened to synthesize an acrylic acid copolymer having a weight average molecular weight of 500,000, and otherwise an adhesive film was prepared in the same manner as in Example 1, and evaluated using a 6-layer substrate. Result, IVH
It was difficult to obtain a smooth IVH-equipped multilayer laminate, because the adhesive was likely to enter the holes and the IVH holes were insufficiently filled with resin.

[0018]

INDUSTRIAL APPLICABILITY When the pressure-sensitive adhesive film of the present invention is used during the production of a multilayer board with IVH, the IVH is completely filled with resin,
It is possible to prevent the adhesive from entering the VH and filling the IVH with the resin. As a result, it is possible to solve the connectivity between the wiring pads in the IVH section and the components, which was a problem when mounting on the surface of a multilayer substrate. Further, the peelability of the pressure-sensitive adhesive film also becomes good. In addition, the adhesive film acts as a cushioning agent during multi-layer pressing, prevents damage to the copper foil due to dust, foreign substances, etc., and acts as a protective film for trimming, punching, drilling, etc. It also has the effect of preventing damage to the substrate. In addition, since the adhesive film can be used as an etching resist by etching while the adhesive film is attached to the substrate, the process can be shortened and the cost can be reduced.

[0019]

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a main part of an IVH-attached multilayer board showing a resin protruding from an IVH part.

FIG. 3 is a cross-sectional view of relevant parts showing a state in which an adhesive has penetrated into an IVH part during production of a IVH-attached multilayer board when an adhesive film is used.

FIG. 4 is a cross-sectional view of a main part showing a dent in the IVH part when the adhesive film is removed when an adhesive enters the IVH part during the production of a multilayer board with IVH.

[Explanation of symbols]

1 IVH part 2 Through-hole plating 3 Adhesive resin (prepreg, adhesive film) 4 Circuit-processed copper foil surface 4'Copper foil surface without circuit processing 5 Substrate 6 Resin protruding part 7 Adhesive film 8 Plastic film support 9 Adhesive Agent A Double-sided copper-clad substrate processed substrate (first and second layers) B Double-sided copper-clad substrate processed substrate (third and fourth layers) C Double-sided copper-clad substrate processed substrate (5, 6) It becomes the layer)

Claims (3)

[Claims] 1. A method for producing a multilayer wiring board with IVH, comprising: sticking a pressure-sensitive adhesive film composed of a base film and a pressure-sensitive adhesive to a wiring board to be an IVH (interstitial via hole) and performing multilayer bonding. . 2. An acrylic acid copolymer resin or methacrylic acid containing an isocyanate in which the crosslinking agent of the pressure-sensitive adhesive is trifunctional or more and the addition amount is 2 to 5 times the equivalent amount, and a functional group which reacts with this isocyanate. A pressure-sensitive adhesive film for producing a multilayer wiring board with IVH, which is made of a copolymer resin. 3. A weight average molecular weight of an acrylic acid copolymer resin or a methacrylic acid copolymer resin, which is the main component of the pressure-sensitive adhesive, is 600,000 or more, and a glass transition temperature is -30 ° C. to -70.
The IV according to claim 2, wherein the amount of the functional group-containing monomer that reacts with isocyanate at 1 ° C is 1% by weight or more and 50% by weight or less.
Adhesive film for manufacturing multi-layer wiring board with H.