JP2880628B2 - Adhesive for metal-clad laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding a metal foil and a laminate when manufacturing a metal-clad laminate, which has excellent tracking resistance and long-term stability of the adhesive life (pot life). Long) metal-clad laminate adhesive.

[0002]

2. Description of the Related Art Consumer electronic devices have become smaller and more sophisticated.
Printed wiring boards used therefor tend to have high density and fine wiring. For this reason, metal-clad laminates are strongly required to have solder heat resistance, metal foil peeling strength, track-king resistance, and the like. Conventionally, the adhesive used for these metal-clad laminates is polyvinyl butyral (hereinafter referred to as PV).
B), and a resin and a phenol resin as main components, to which an epoxy resin or the like has been added to satisfy various performances as an adhesive. However, tracking resistance has been strongly demanded in the wake of TV fires, etc.
The conventional adhesive system containing PVB resin and phenol resin as main components cannot cope with tracking resistance. The reason is that the phenol nucleus of the phenol resin is carbonized to easily form a conductive path (track), thereby easily causing dielectric breakdown. For this reason, it has become clear that the conventional adhesive based on PVB resin and phenol resin cannot improve the tracking resistance.

Therefore, as an adhesive for improving the tracking resistance, a resin obtained by blending various resins having a good tracking resistance such as a melamine resin with a PVB resin has been devised and industrialized. However, many of these require various curing agents and curing accelerators such as organic acids and amines, and therefore, the life of the adhesive (pot life) is as short as several days to about two weeks, which is a disadvantage in production management. have.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a conventional PV
An adhesive for metal-clad laminates that improves the tracking resistance of adhesives containing B resin and phenolic resin as main components, and can prevent the shortening of the life of the adhesive that is common in adhesives with improved tracking resistance. The basic performance as
It is an object of the present invention to provide an adhesive for a metal-clad laminate, which does not reduce the peel strength and the solder heat resistance.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has adopted polyvinyl acetoacetal resin (hereinafter referred to as PVAA resin) instead of PVB resin. By limiting the phenolic resin used at least 30% by weight or more to a resol type phenolic resin and limiting it to 15% by weight or less,
It has also been found that the purpose can be achieved by blending an amino resin and an epoxy resin, and the present invention has been completed. That is, the present invention provides: 30 to 70% by weight of polyvinyl acetoacetal resin, B. 15% by weight or less of resole type phenol resin, C.I. Amino resin 5
50% by weight, D.I. The gist of the present invention is an adhesive for metal-clad laminates containing 5 to 40% by weight of an epoxy resin. The mixing ratio of the resin indicates a ratio to the total amount of the resin.

[0006] PVB resins conventionally used are basically resins having good tracking resistance, but are susceptible to the low tracking resistance of phenolic resins in the presence of phenolic resins. In contrast, in the present invention, PV
By selecting PVAA resin instead of B resin and adopting resol type as phenol resin, this basic combination was able to overcome the low tracking resistance caused by phenol resin. .

[0007] PVB resin is obtained by reacting polyvinyl alcohol (hereinafter referred to as PVA) with butyraldehyde and acetalizing a part or all thereof.
The resin is obtained by similarly acting acetaldehyde in place of butyraldehyde on PVA. Due to the difference in the raw aldehyde, when used as a raw resin for an adhesive for a metal-clad laminate, there is a marked difference in its properties. It is surprising. PVAA resin is obtained by acetalizing a part or all of polyvinyl alcohol with acetaldehyde, and is a kind of polyvinyl acetal resin, and usually has unreacted hydroxyl group and vinyl acetate group in addition to acetal group in a molecular chain. . Therefore, polyvinyl acetoacetal resin, polyvinyl alcohol portion,
It is composed of a polyvinyl acetate portion and an acetal (formal, acetoacetal and the like are collectively referred to as an acetal) portion. In the present invention, the ratio of the entire acetalized portion described later refers to the ratio to ++.

[0008] The PVAA resin used in the present invention preferably has a degree of polymerization of 2,000 to 3,000. 2,00
If it is less than 0, it tends to be affected by the low resistance to tracking of the phenolic resin, and if it exceeds 3,000, it is difficult to dissolve in an organic solvent, and the viscosity of the adhesive becomes high, so that there are practical disadvantages such as difficulty in application. Occurs. Further, with respect to the degree of polymerization, the ratio of PVAA contained in the range of 2,000 to 3,000 is preferably 80% by weight or more. If it is less than 80% by weight, the degree of improvement in tracking resistance is small. In order to adjust the degree of polymerization, PVAA resins having different degrees of polymerization may be mixed with each other. In the present invention, the degree of polymerization means an average degree of polymerization defined in JIS K 6728.

The PVAA resin used in the present invention is obtained by acetalizing polyvinyl alcohol with acetaldehyde as described above. However, other resins such as butyraldehyde may be used as long as the object of the present invention is not hindered from realizing the tracking resistance. It may contain a moiety acetalized by an aldehyde. The degree of acetalization of polyvinyl alcohol is preferably such that the ratio of all acetalized portions is 65 mol% or more, and the ratio of acetalized portions with acetaldehyde is 85 to 100 mol% of all acetalized portions. The ratio of all acetalized parts is 65 mol%
When the amount is less than the above, heat resistance and adhesiveness are inferior, and when the proportion of the acetalized portion by acetaldehyde is less than 85 mol of the entire acetalized portion, the degree of improvement in the tracking resistance is not preferred.

The amount of the PVAA resin in the adhesive of the present invention is preferably in the range of 30 to 70% by weight, more preferably 40 to 55% by weight. If the amount of the PVAA resin is less than 30% by weight, the peeling strength and the tracking resistance are weak and insufficient, and if it exceeds 70% by weight, it is difficult to dissolve in an organic solvent, and there are practical disadvantages such as lowering the solid content. Occurs.

The adhesive composition of the present invention has a B.I. The component is a resol type phenol resin. The novolak type phenol resin cannot achieve the intended purpose, and the resol type phenol resin must be used in an amount of 15% by weight or less in the adhesive composition. Under these conditions, the PVA
By combining with the resin A, the peeling strength and the solder heat resistance can be maintained at preferable levels while maintaining high tracking resistance. In addition, the use of resole-type phenolic resins allows the use of additives that reduce the life of the adhesive, such as other curing agents and curing accelerators, which are conventionally used to impart desired adhesive properties. An adhesive for a metal-clad laminate having a long time and a long life of the adhesive can be obtained. The amount of the resol-type phenolic resin is set to 15% by weight or less, because if it exceeds this upper limit, the improvement of the tracking resistance becomes insufficient. A more preferred amount is 10% by weight or less. C. used in the present invention. The amino resin component is a thermosetting resin that has the role of complementing the reduced amount of the phenolic resin compared to the conventional one, and is compounded with the expectation of improved solder heat resistance and tracking resistance. . The content of the amino resin is preferably in the range of 5 to 50% by weight, more preferably 15 to 50% by weight.
The range of ５０50% by weight is good.

When the amount of the amino resin is less than 5% by weight, the tracking resistance is weak, and when it exceeds 50% by weight, the solder heat resistance is reduced. C. used in the present invention. The amino resin of the component is not particularly limited, and those widely used for adhesives can be widely used. Examples thereof include amino resins such as melamine resin, benzoguanamine resin, and urea resin. These can be used in combination. Particularly, an alkyl etherified melamine resin is preferably used.

The D.I. used in the present invention. The component epoxy resin is not particularly limited, and those widely used for adhesives can be widely used, for example, bisphenol A type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, polyfunctional epoxy resin, Epoxy resins such as orthocresol novolak type epoxy resin,
These can be used alone or in combination of two or more. Ortho-cresol novolak type epoxy resin is preferably used. The amount of the epoxy resin is preferably in the range of 5 to 40% by weight, and more preferably in the range of 5 to 30% by weight.

When the amount of the epoxy resin is less than 5% by weight, the solder heat resistance decreases, and when it exceeds 40% by weight, the tracking resistance deteriorates. The adhesive of the present invention can be obtained by adding an organic solvent to the above-mentioned compounding materials as necessary and mixing them. The organic solvent is not particularly limited as long as it dissolves the above compounding materials, but toluene,
It can be easily produced by dissolving in a mixed solvent such as acetone and methanol.

[0015] In addition, a flame retardant, a filler, a coupling agent, a curing agent which does not adversely affect the life, and a curing accelerator can be added and compounded within the limits not contrary to the object of the present invention. Then, the adhesive is applied to the metal foil and dried to produce a metal foil with an adhesive. The metal foil used here is not particularly limited,
Electrolytic copper foil, rolled copper foil, aluminum foil and the like are preferred. Also,
The metal-clad laminate can be easily manufactured by heating and pressurizing the metal foil with the adhesive in a conventional manner.

[0016]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to the examples. In the following Examples and Comparative Examples, “parts” means “parts by weight”.

Examples 1 to 3 and Comparative Examples 1 and 2 The resin compositions shown in Table 1 were dissolved in a mixed solvent of toluene, acetone and methanol to obtain an adhesive for a metal-clad laminate having a solid content of 20% by weight. The adhesive thus produced was applied to a thickness of 35 μm.
m of electrolytic copper foil was applied at 30 g / m ² and dried to produce a copper foil with an adhesive. Eight paper / phenolic resin prepregs were stacked on the adhesive side of the copper foil with the adhesive, and heated and pressed by a conventional method to produce a 1.6 mm-thick copper-clad paper / phenolic resin laminate. The copper-clad paper / phenolic resin laminate thus manufactured was tested for peel strength, solder heat resistance, tracking resistance, and adhesive life (pot life). The results are shown in Table 1. The present invention was excellent in all the characteristics, and the effect of the present invention was confirmed.

[0018]

[Table 1]

[0019]

As described above, the adhesive of the present invention has not only excellent tracking resistance, but also excellent peeling strength and solder heat resistance, and in addition to the conventional tracking resistant adhesive. It is possible to obtain a highly reliable adhesive for a metal-clad laminate without the disadvantages in production management such as shortening the life of the adhesive, which is often seen.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H05K 3/38 H05K 3/38 E (56) References JP-A-56-166061 (JP, A) JP-A-49-99637 ( JP, A) JP-A-4-39306 (JP, A) JP-A-4-225086 (JP, A) JP-A-63-301208 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) C09J 163/00-163/10 C09J 129/04 C09J 161/06-161/14 C09J 161/20-161/32 H05K 3/38 B32B 15/08

Claims (2)

(57) [Claims] 1. A. First Embodiment Polyvinyl acetoacetal resin 3
0-70% by weight, B.I. 15% by weight or less of resole type phenol resin, C.I. 5 to 50% by weight of an amino resin, An adhesive for a metal-clad laminate, comprising 5 to 40% by weight of an epoxy resin. 2. The ratio of the total acetalized portion in the polyvinyl acetoacetal resin is 65 mol% or more, the ratio of the acetoacetalized portion by acetaldehyde is 85 to 100 mol% of the total acetalized portion, and The degree of polymerization of the acetal resin is 2,000-
The adhesive for metal-clad laminates according to claim 1, wherein the ratio of 3,000 is 80% by weight or more.