JPH0272700A - Composition of paste for forming insulating layer - Google Patents

Abstract

PURPOSE:To improve adhesive property and heat resistance with low permittivity property being maintained by using epoxy denatured polybutadiene, mixing epoxy resin, and adding fluororesin powder. CONSTITUTION:The main components of thermosetting resin vanish are epoxy denatured polybutadiene, epoxy resin, carboxylic acid anhydride and radical polymerization starting agent. Plasma treated fluororesin powder of 10-200 weight parts is added into the unhardened resin mixture of said thermosetting resin vanish of 100 weight parts. It is desirable that the maximum grain size of the fluororesin powder is 50mum or less. The thermosetting resin and the fluororesin are mixed the solid material. For the solid material, the adding quantity of silane coupling agent incorporating epoxy group of 20-100mol PPM is desirable. It is important that any added material is uniformly dispersed in the paste. In this constitution, permittivity is low, and adhesive property, heat resistance, moisture resistance, water resistance and the like are made excellent.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has a low dielectric constant (hereinafter abbreviated as ε) and is suitable for adhesive layers, thickness adjustment layers, overlay layers, etc. in circuit boards and multilayer circuit boards. The present invention relates to a paste composition for forming an insulating layer to be used.

[Prior art]

In recent years, in the field of electronics, plastic insulating layers have been used in combination with conductor layers for an extremely wide range of applications such as circuit boards, and the required properties have also been wide-ranging. Among these, for the purpose of increasing the signal propagation speed, it is necessary to develop an insulating layer with a low ε, and in particular, recently, ε is required to be 3 or less. Conventionally, there has been a method of forming an insulating layer from a thermosetting resin paste composition, but the ε of the insulating layer is greatly influenced by the ε of the resin itself, making it difficult to use conventional thermosetting resins. If used, ε cannot be lowered.

As a means of forming a plastic insulating layer with low ε,
Fluorine resin, polyethylene resin, polybutadiene resin,
A method of using a thermoplastic resin with a low ε such as polysulfone resin in the form of a film is being considered. However, such insulating layer multilayer moldability, dimensional change, drilling workability, heat resistance, etc. are inferior, and a highly reliable circuit board itself has not been obtained.

(Problems to be Solved by the Invention) The present invention has a low ε of 3 or less, and can form a reliable insulating layer with excellent adhesion to other layers, heat resistance, moisture resistance, water resistance, etc. It is an object of the present invention to provide a base+-m acid that can be processed into a circuit board.

[Means to solve the problem]

The present invention provides a thermosetting resin varnish containing epoxy-modified polybutadiene, an epoxy resin, a carboxylic acid, an anhydride, and a radical polymerization initiator as main components, with a maximum particle size of 50 μm or less based on 100 parts by weight of the resin component. Adding 10 to 200 parts by weight of fluororesin powder that has been subjected to plasma surface treatment, and 20 to 100 mol PPM of epoxy-based silane coupling based on the solid content of the thermosetting resin and the fluororesin. It is obtained by adding and mixing the agent. The present invention relates to a paste composition for forming an insulating layer.

The epoxy-modified polybutadiene may be polybutadiene with an epoxy group added to the main chain or end. The epoxy resin may be general-purpose epoxy resins such as bisphenol A type, alicyclic type, tetrabromobisphenol A type, or dibromobisphenol. Examples include flame-retardant epoxy resins such as A type.

Carboxylic anhydrides include chlorendic anhydride, methylbutenyltetrahydrophthalic anhydride, alkenylsuccinic anhydride, 5-(2,5-dioxotetrahydrofuryl)-
Examples of radical polymerization initiators include organic peroxides such as dixyl silver oxide, t-butyl perbenzoate, t-butyl peroxylaurate, and hentyl peroxide. can be given. To make these into varnishes, one or more organic solvents such as dimethylformamide, methyl isobutyl ketone, and methyl cellosolve are used.

Examples of the fluororesin powder used in the present invention include powders of 4-fluorinated ethylene resin, 4-fluorinated ethylene-hexafluorinated propylene copolymer resin, and 47-fluorinated ethylene/perfluoroalkyl vinyl ether copolymer resin. Use one that has been plasma treated.

Plasma processing methods include methods using external electrodes and internal electrodes depending on the positional relationship between the electrodes and the reactor, and methods for supplying power using capacitive coupling, inductive coupling, and waveguides.
The power supply frequency ranges from DC to GH2 band, and any method is possible. In order to uniformly plasma-treat the entire powder charged in the reactor, it is necessary that the powder be stirred in the reactor during treatment.

In view of the roughness of the inner wall of through-holes when a circuit board containing an insulating layer prepared using the paste of the present invention is drilled, the maximum particle size of the fluororesin powder is preferably 50 μm or less, more preferably 20 μm or less.

If the particle size of the fluororesin powder is large, the inner wall roughness of the insulating layer during through-hole formation becomes large. If the inner wall roughness of the through hole is large, it will adversely affect chemical resistance, plating resistance, and electrical properties.

The composition when adding the plasma-treated fluororesin powder to the resin varnish is 10 to 200 parts by weight of the plasma-treated fluororesin powder per 100 parts by weight of the uncured resin mixture.

If it is less than 10 parts by weight, the effect of lowering ε will be weak, and if it is more than 200 parts by weight, the function of the thermosetting resin as a binder will decrease.
Strength, appearance, etc. become poor (50 to 180 parts by weight is particularly preferred).

It is important to uniformly disperse the fluororesin powder in the varnish made of the resin mixture.

Examples of silane coupling agents for the epoxy base include T-glycidoxypropyltrimethoxysilane, T-glycidoxypropylmethyldimethoxysilane, etc., based on the combined solid content of the thermosetting resin and the fluororesin. 20~
A desirable addition amount is 100 mol PPM.

If the amount is less than 20 mol PPM, the adhesive effect will be weak, and if it is more than 100 mol PPM, the electrical performance will deteriorate. It is also important to uniformly disperse the silane coupling agent in the paste. The addition order may be either added into the varnish when preparing the thermosetting resin varnish or added at the same time as the fluororesin powder is added.

The method for applying the obtained paste is a roll coater.
- There are methods such as bar coater screen printing, and then the resin is cured by heating alone or by heating and pressurizing at atmospheric pressure or vacuum to form an insulating layer.

[Effect]

Although polybutadiene has a low ε, it has poor colorability and heat resistance. By using this epoxy-modified polybutadiene with epoxy groups added to its main chain and terminals, and by mixing an epoxy resin, adhesiveness and heat resistance can be improved while maintaining low ε properties. The epoxy resin can be made flame retardant using a bromide, and by adding fluororesin powder, the reduction in ε is further promoted, and e can be made 3 or less.

Since fluororesin is non-polar, adding it reduces the adhesiveness of the paste. In order to suppress this degradation, the fluororesin powder is treated with plasma to activate its surface (.

The epoxy group-containing silane coupling agent can improve the adhesiveness between paste and copper foil and between fluororesin and thermosetting resin.

〔Example〕

Example 1 Epoxy-modified polybutadiene with 90% 1.2 bonds and epoxy equivalent weight 550, brominated bisphenol A type epoxy resin, 5-(2,5-dioxotetrafuryl)-3-methyl 3-cyclohexene-1,2 - A varnish having a resin content of 58.3% by weight was prepared by mixing and dissolving dicarboxylic acid anhydride and dicumyl peroxide in the composition shown in Table 1 in methyl isobutyl ketone and dimethyl formamide.

Table 1 58.3 parts by weight of plasma-treated tetrafluoroethylene resin powder with a maximum particle size of 20μ and 21 parts by weight of methyl cellosolve were added to the varnish, and 1 part by weight of T-glycidoxyprobyltrimethoxysilane (30 parts by weight) was added to the varnish. mol PPM),
The mixture was mixed using a commercially available homogenizer at 10,000 rpm for 5 minutes to obtain a paste composition.

Plasma treatment of tetrafluoroethylene resin powder is 13.5
A 6 MHz power source was used, an external electrode method was used, Ar was used as a gas, a vacuum degree of 0.01 Torr, and a power of 100 W was used for 60 minutes. The inside of the plasma treatment reactor was stirred using a stirring device.

This composition was screen printed on a 35 μm thick copper foil, and
After drying for 0°CIO, combine two sheets of copper foil/coating layer with the coating layer on the inside at a temperature of 170°C and a pressure of 30kg.
/mn (, pressed in 2 hours 30 minutes, total thickness 130 μm
A double-sided copper clad plate was obtained.

The dielectric constant, dielectric loss tangent, and beer strength of the copper clad plate were determined by JIS-C.
-6486.

Example 2 The same procedure as in Example 1 was carried out except that 2 parts by weight (60 mol PPM) of γ-glycidoxypropyltrimethoxysilane was added.

Comparative Example I Same as Example 1 except that γ-glycidoxypropyltrimethoxysilane was not added.

Comparative Example 2 Same as Example 1 except that T-glycidoxypropyltrimethoxysilane was 3 parts by weight (120 mol PPM).

Table 2 shows the evaluation results of Examples and Comparative Examples.

Table 2 [Effects of the Invention] The insulating layer obtained from the paste composition for forming an insulating layer of the present invention has a lower ε than an insulating layer made of a conventional paste composition, and in addition, it has a lower ε. By changing the amount and type, ε can be adjusted arbitrarily.

Furthermore, the paste composition for forming an insulating layer of the present invention has extremely excellent adhesive properties and water resistance.

A circuit board containing an insulating layer made of the paste-like composition for forming an insulating layer of the present invention can be subjected to drilling, metal etching, soldering, etc. in the same manner as a board made of an ordinary laminate.

Furthermore, if a brominated epoxy resin is used, flame retardancy can be imparted to the insulating layer formed from the paste composition.

Therefore, the paste-like composition for forming an insulating layer of the present invention is coated and dried on the surface of an inner layer containing a signal circuit, for example, to form an insulating layer as a semi-cured material, and then a plurality of insulating layers or other outer layers are formed. It is ideal for applications where the insulating layer becomes a thickness adjustment layer when a multilayer circuit board is obtained by combining and laminating layers and applying heat and pressure.

Patent applicant: Sumitomo Bakelite Co., Ltd. Procedural amendment (voluntary) IO, 26th year of 1988

Claims (1)

[Claims] (1) A thermosetting resin varnish containing epoxy-modified polybutadiene, an epoxy resin, a carboxylic acid anhydride, and a radical polymerization initiator as main components has a maximum particle size of 50 μm or less based on 100 parts by weight of the resin component, 10 to 200 parts by weight of fluororesin powder subjected to plasma surface treatment is added, and 20 to 100 mol PPM of an epoxy group-containing silane coupling agent is added to the solid content of the thermosetting resin and the fluororesin. and a paste composition for forming an insulating layer.