JPH06240213A - Copper foil coated with adhesive and copper-clad laminate made using the same - Google Patents

Abstract

PURPOSE:To provide a copper foil coated with a tracking-resistant adhesive which is improved in water resistance unlike conventional adhesives for this use and is comparable in adhesion strength, heat resistance, and tracking resistance to the conventional adhesives; and to provide a copper-clad laminate made using the foil. CONSTITUTION:The adhesive in the copper foil, which is for use in producing a copper-clad laminate for a printed circuit board, comprises a poly(vinyl acetal) resin, epoxy resin, polyisocyanate resin, and polyester resin. The laminate has this foil on at least one side thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive-coated copper foil for copper-clad laminates used in electric and electronic equipment and a copper-clad laminate using the same, and more particularly to an adhesive having improved moisture resistance. The present invention relates to a coated copper foil and a copper clad laminate using the same.

[0002]

2. Description of the Related Art Printed wiring board paper base material copper clad laminates, which are currently used in the manufacture of general consumer electric and electronic equipment, have excellent workability and thermal characteristics. Widely used from. This paper-based copper-clad laminate is made of kraft paper or linter paper impregnated with a resin component containing phenolic resin as the main component, dried, and a specified number of prepregs, and an adhesive coated with adhesive on one side. It is manufactured by laminating a coated copper foil and heat-pressing.
Paper-based copper-clad laminates have wiring pattern formation by copper etching, insulation layer formation by solder resist ink,
It is processed into a printed wiring board through plating processing, drilling, external processing, etc. of the terminal part.

In recent years, with the miniaturization and higher functionality of electronic and electrical equipment, the density of wiring and the miniaturization of mounted parts have been increasing. With respect to component mounting, surface mounting becomes the mainstream, and component soldering technology is changing. Due to the higher density of wiring and surface mounting, higher adhesive strength of conductor circuits and improved heat resistance during soldering of components are required for paper-based copper-clad laminates. ing. Further, since the paper-based copper-clad laminate has higher tracking resistance than the glass-based copper-clad laminate, it is also used for a printed wiring board such as a TV to which a high voltage is applied. Conventionally, a wiring board that attaches importance to tracking resistance has a tracking resistance adhesive obtained by blending polyvinyl butyral with a melamine resin, an epoxy resin, a polyisocyanate resin, etc. A paper-based copper clad laminate using 3-192184 and JP-A-62-116682) is used. As described above, the tracking resistant adhesives have been improved, and the current ones sufficiently satisfy the requirements regarding the adhesive strength and the heat resistance.

However, since the conventional tracking resistant adhesive contains the melamine resin, it may cause a problem due to the low water resistance of the melamine resin. The step of processing the copper-clad laminate into a printed wiring board includes the step of immersing the laminate in water such as etching the copper foil to form a wiring pattern. At that time, if the water resistance of the adhesive layer is poor, the adhesive layer adsorbs a large amount of water. Therefore, the adhesive layer having poor water resistance tends to be insufficiently dried, and the moisture remaining in the adhesive layer causes deterioration of the performance of the wiring board. For example, if moisture is left on the adhesive layer and solder resist, which is an insulating layer, is applied on top of it, the solder resist will not adhere well when soldering components, and the solder resist will no longer function as an insulating layer. .

The object of the present invention is to improve the water resistance, which is one of the drawbacks of the tracking resistant adhesives used in conventional adhesive-coated copper foils, and to provide the same adhesive strength, heat resistance and heat resistance as the conventional ones. An object of the present invention is to provide an adhesive-coated copper foil coated with a tracking-resistant adhesive that maintains tracking resistance, and a copper-clad laminate using the adhesive-coated copper foil.

[0006]

The adhesive-coated copper foil of the present invention uses a polyvinyl acetal resin, an epoxy resin, a polyisocyanate resin, and a polyester resin as a tracking-resistant adhesive. It is characterized by being applied to. The copper-clad laminate of the present invention is characterized in that the adhesive-coated copper foil is laminated on at least one side.

[0007]

As described above, the tracking resistant adhesive used in the adhesive-coated copper foil of the present invention and the copper clad laminate laminated with the same does not contain a melamine resin having a problem in water resistance. Since it contains a polyester resin instead, the water resistance is improved, and since the hydroxyl groups in the polyester resin act as a curing agent that reacts with the epoxy resin and polyisocyanate resin, adhesion and heat resistance do not deteriorate. .

The polyvinyl acetal resin used in the present invention includes polyvinyl formal, polyvinyl acetal,
Examples include polyvinyl butyral and mixtures thereof. The average degree of polymerization and the degree of acetalization of the polyvinyl acetal resin are not particularly limited, but those having an average degree of polymerization of 1000 to 2500 and an degree of acetalization of 65% by weight or more are preferable.

The epoxy resin is bisphenol A.
Type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, glycidyl amine epoxy resin, heterocyclic epoxy resin, halogenated epoxy resin and the like, but not particularly limited. These resins can be used alone or in combination of two or more.

As the polyisocyanate resin, TDI
Alternatively, the isocyanate group of the isocyanate oligomer obtained by the reaction of MDI and polyol is blocked with a compound having active hydrogen such as phenols, oximes, alcohols, and caprolactam.

The polyester resin is a dicarboxylic acid or acid anhydride selected from phthalic anhydride, isophthalic acid, terephthalic acid, maleic anhydride, fumaric acid, 3,6-endomethylenetetrahydrophthalic anhydride, tetrahydrophthalic anhydride and the like. A compound obtained by reacting a glycol selected from propylene glycol, ethylene glycol, diethylene glycol, etc. and a triol selected from trimethyl roll propane, etc. is used and is not particularly limited. The acid value of the polyester resin is not particularly limited, but those having a acid value of 20 or less are preferably used.

The mixing ratio of each resin in the adhesive of the present invention is not particularly limited, but preferably 10 to 60 parts by weight of polyvinyl acetal resin, 5 to 45 parts by weight of epoxy resin, and 5 to 45 parts by weight of polyisocyanate resin. Parts and polyester resin 5 to 55 parts by weight, more preferably polyvinyl acetal resin 20 to 50 parts by weight, epoxy resin 10 to 40 parts by weight, polyisocyanate resin 10 to 35.
The amount may be 10 parts by weight and 10 to 45 parts by weight of the polyester resin. If the amount of the polyvinyl acetal resin is less than 10 parts by weight, the peeling strength is remarkably reduced, and if it exceeds 60 parts by weight, it becomes difficult to dissolve it in the adhesive varnish. If the amount of the epoxy resin is less than 5 parts by weight, the heat resistance and electrical properties of the copper clad laminate will be deteriorated, and if it exceeds 45 parts by weight, the cured product will be hard and the mechanical properties will be deteriorated. If the amount of the polyisocyanate resin is less than 5 parts by weight, the heat resistance of the copper clad laminate will be deteriorated, and if it exceeds 45 parts by weight, the storability of the adhesive varnish becomes a problem. If the amount of the polyester resin is less than 5 parts by weight, the adhesion and heat resistance of the copper-clad laminate will be deteriorated, and if it exceeds 45 parts by weight, the solubility in the adhesive varnish becomes a problem.

In the present invention, a known curing catalyst and curing accelerator are added to the tracking resistant adhesive within the range not impairing the gist of the present invention to reduce the adhesive curing temperature and the curing time. You can Further, a polysiloxane-based leveling agent may be added to enhance the smoothness of the adhesive layer surface. Furthermore, if necessary, an inorganic filler such as magnesium hydroxide, calcium carbonate, silica, alumina, or titanium oxide may be added and blended to improve the thixotropy of the adhesive.

Each resin is dissolved in an organic solvent according to the above-mentioned resin composition to prepare an adhesive varnish. The organic solvent is not particularly limited, but ketone solvents such as methyl ethyl ketone, alcohols such as methanol, aromatic hydrocarbons such as xylene and toluene, and mixtures thereof can be preferably used.

The copper foil used in the present invention includes an electrolytic copper foil and a rolled copper foil, and those having at least one surface subjected to surface roughening treatment and rustproofing treatment for improving adhesiveness can be preferably used. The thickness of the copper foil is not particularly limited,
Those having a thickness of 0.009 mm to 0.1 mm are used, and more generally, those having a thickness of 0.018 to 0.035 mm are preferably used.

The adhesive-coated copper foil used in the present invention is produced by applying the adhesive varnish on the roughened surface of the copper foil and then heating and drying. The thickness of the adhesive layer is not particularly limited, but the dry thickness is preferably 0.01 to 0.1 mm. Hot air drying and far infrared ray drying are used as the heating and drying method, and are not particularly limited. The drying temperature and time are also not particularly limited, but a drying time of 30 seconds to 10 minutes at a temperature in the range of 110 ° C to 250 ° C is preferable. The volatile content of the adhesive layer is not particularly limited, but is preferably 0.2% to 9%.

The copper-clad laminate of the present invention is formed by laminating an adhesive-coated copper foil coated with an adhesive composed of polyvinyl acetal resin, epoxy resin, polyisocyanate resin and polyester resin on at least one side of a substrate. That is, the resin to be mixed with the adhesive of the adhesive-coated copper foil used for this copper-clad laminate, the amount thereof, the copper foil, and the manufacturing method are as described above. Then, this copper-clad laminate is produced by laminating the adhesive-coated copper foil and a prepreg, which is a semi-cured state of the base material, on the adhesive side and heat-pressing.

The base material used in the present invention is a paper base material obtained by impregnating a sheet-shaped paper with a resin varnish containing a phenol resin or the like as a main component, or a glass cloth with a resin varnish containing an epoxy resin or the like as a main component. There is an impregnated glass substrate.

The present invention will be described below with reference to examples. "Parts" in the examples represent parts by weight.

[Example 1] 40 parts of polyvinyl butyral resin "Denka butyral # 5000" (manufactured by Denki Kagaku Kogyo), epoxy resin "Epototo YDCN701" (manufactured by Toto Kasei Kogyo)
30 parts, polyisocyanate resin "Millionate MS-
50 "(manufactured by Nippon Polyurethane Industry) 20 parts, polyester resin" Desmofen 651 "(manufactured by Bayer Urethane)
An adhesive varnish was prepared by uniformly dissolving 30 parts in methyl ethyl ketone. This adhesive varnish was applied to the roughened surface of an electrolytic copper foil (thickness 0.035 mm, manufactured by Mitsui Mining & Smelting Co., Ltd.) so that the dry thickness would be 0.03 to 0.04 mm, and after air-drying, it was heated at 130 ° C. for 10 minutes. After drying for a minute, an adhesive-coated copper foil was obtained.

Then, eight prepregs prepared by impregnating a paper base material with a varnish in which a phenol resin and additives are dissolved and drying are laminated on the prepreg with the adhesive-coated copper foil on the adhesive side, and hot-pressed. 150 ℃, 110kgf
/ Cm ² , heated and pressed for 1 hour to produce a copper clad laminate.

[0021]

Example 2 A polyester resin was used as "Desmophen 80".
An adhesive-coated copper foil and a copper-clad laminate were produced in the same manner as in Example 1 except that 0 "(made by Bayer Urethane) was used.

[0022]

[Embodiment 3] An epoxy resin is used as "Epicoat 1001".
An adhesive-coated copper foil and a copper-clad laminate were produced in the same manner as in Example 1 except that 20 parts of "desmophen 651" was used for the (oiled shell epoxy) instead of the polyester resin.

[0023]

[Comparative example] Polyvinyl butyral resin "Denka Butyral # 5000" 45 parts, epoxy resin "Epototo YD"
CN701 ", polycyanate resin" Millionate MS
-50 "8 parts, melamine resin" Uban 22R "(manufactured by Mitsui Toatsu Kagaku) 35 parts, and 0.1 part of benzoic acid were dissolved in methyl ethyl ketone to prepare an adhesive varnish. An adhesive coated copper foil and a copper clad laminate were prepared.

The peeling strength and solder heat resistance of the copper foil of the copper clad laminate thus obtained are determined according to JIS-C-6481.
It was measured according to. The tracking resistance of the etched surface of the copper foil was tested according to IEC Publication 112. Further, a resin film having a thickness of about 0.5 mm was produced by heating and pressing from the adhesive varnishes prepared in Examples and Comparative Examples, and the water absorption rate after 24 hours was measured according to JIS-K-72.
It measured based on 09. Furthermore, the solder resist adhesion test was investigated by etching a copper clad laminate and performing a tape peel test on a printed wiring board prepared by applying a solder resist. The results are shown in Table 1.

[0025]

[Table 1]

As is clear from the above table, the adhesive for adhesive-coated copper foil of the present invention has improved water absorption and improved moisture resistance as compared with the conventional tracking resistant adhesive. Along with that, the solder resist adhesion is also improved. On the other hand, the peel strength, solder heat resistance, and tracking resistance of the copper-clad laminate produced using the adhesive-coated copper foil of the present invention are the same as those of the copper-clad laminate produced using the conventional tracking-resistant adhesive. It was equivalent.

[0027]

According to the present invention as described above, since a polyester resin is used as a tracking resistant adhesive component instead of a conventional melamine resin, moisture resistance is improved and adhesiveness and heat resistance are lowered. An adhesive-coated copper foil and a copper-clad laminate that do not occur can be obtained.

Claims (2)

[Claims] 1. An adhesive-coated copper foil used for producing a copper-clad laminate for a printed wiring board, wherein the adhesive is made of polyvinyl acetal resin, epoxy resin, polyisocyanate resin and polyester resin. Adhesive coated copper foil. 2. A copper-clad laminate obtained by laminating the adhesive-coated copper foil according to claim 1 on at least one side.