JPS61283671A - Electrical insulating paint - Google Patents

Abstract

PURPOSE:To provide the title paint which has excellent coating efficiency, hardness and buffer effect for retaining reliability, by blending a thermosetting resin, additives and a solvent with a high proportion of an inorg. filler so as to give a coating film whose coefficient of thermal expansion is below a specified value. CONSTITUTION:A thermosetting resin such as a resol type phenolic resin or bisphenol A type epoxy resin, 80-85wt% (based on the quantity of paint solid) inorg. filler having a low coefficient of thermal expansion such as fused silica, 0.1-1.0wt% silane coupling agent and additives such as fine silica powder, etc. are blended together. The blend is diluted with a solvent to obtain the title paint which gives a coating film having a coefficient of thermal expansion of 1X10<-5>/ deg.C or below.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to hybrid ICs, etc.
; It is related to.

[Prior art]

To connect the bare chip IC to the board circuit (-), use the U
Alternatively, either the wire bonding method using a thin wire or the flip chip method using solder bonding is used, but in order to prevent adhesive peeling due to curing stress of the resin to be packaged (= buffer coat material), As protective paint is required.

Conventionally, silicone resins, which have a very soft and flexible coating film, have been mainly used as resins for such protective coatings. Although they are suitable for buffer coating,
On the other hand, because the coating film on the other side is flexible (:, high-purity), there is a drawback that the connection part is likely to break if two parts come into contact (= coating film) during assembly work to IC.

On the other hand, if the paint has sufficient surface hardness that the connection part will not break even if it comes into contact with the assembly process (secondary contact), the repeated stress of expansion and contraction of the board, wire connection metal, and paint under severe thermal shock test conditions ( There are two problems with reliability, such as troubles such as rupture of the connection part.

[Purpose of the invention]

With conventional protective paints, it has been difficult to achieve both a buffer effect to maintain reliability and paint hardness to facilitate assembly work, but as a result of research into various paint compositions, the present inventors found that inorganic fillers By increasing the compounding ratio of the agent and reducing the coefficient of thermal expansion of the coating film to 1 x 10"
Based on this, various studies were conducted and the present invention was completed.

[Structure of the invention]

The present invention relates to an electrical insulating coating (coating material) consisting of a thermosetting resin, a filler, an additive, and a solvent, which is characterized in that the coefficient of thermal expansion of the coating film is extremely small, less than I x 10''A. It is related to insulation coating paint!

The filler used in the present invention is preferably an inorganic filler that maintains high coating hardness and has a low coefficient of thermal expansion. Examples of such fillers include calcium carbonate, crystalline silica,
, molten phosphoric acid, alumina, talc, aluminum hydroxide, etc., and these can be used alone or in combination.

Conventionally, the blending ratio of such fillers has often been kept low because it has been believed that they play an auxiliary role in the paint composition. The inventors have found that the resin is excellent. In the present invention, in order to make the coefficient of thermal expansion of the coating film 1x10/'C or less (=, the blending ratio of the filler is usually as high as 80 to 85% or more based on the weight ratio of the solid content of the paint.

Fillers have different thermal expansion coefficients depending on their type C=
The blending ratio of the filler in the paint should be adjusted according to the type of filler and the required coefficient of thermal expansion of the coating film.The filler's particle size, shape, particle size distribution, purity, etc. In the field of application where paint is used, painting workability and electrical properties have a double influence, but the purpose and effect of the present invention of lowering the coefficient of thermal expansion (2nd feature C) is not related. , these characteristics C: are not limited.

Next (: Thermosetting resin (; refers to phenolic resin, Evokin resin, silicone resin, melamine resin, polyimide resin, etc.). These resins can be used alone or in combination, but they are not suitable for workability, electrical properties, and heat resistance. Phenol resins and Evoquin resins are preferred from the viewpoints of performance, price, purity, etc., and these resins are used alone or in combination of two or more.

In addition, additives (i) are added to improve the adhesion between the substrate and the paint (2) in the paint composition (a dinolan coupling agent, preferably an Epokin νlan or a titanium coupling agent) based on the total composition. It can be contained in an amount of 1-t.ott%.As other additives, an anti-sagging agent such as finely powdered non-driving agent, an antifoaming agent, a pigment, etc. can also be appropriately blended.

〔Effect of the invention〕

The structure of the present invention is that the coating film has a coefficient of thermal expansion of 1xiO/'C or less, which is as low as that of ceramic substrates and metals (:, even when exposed to severe high temperatures or under thermal shock test conditions, the connection parts ( : It has high reliability as a paint without causing breakage. Also, the hardness of the coating film is sufficient ( : Because it is high, Hybrid I, which is a drawback of conventional flexible paints)
In the post-assembly process C2, the trouble of breakage of the connection part when it comes into contact with the paint film is also eliminated, making the handling of the first assembly process easier (==), thereby increasing the yield and speed.

〔Example〕

Hereinafter, the present invention will be explained from Example (2). However, the present invention is not limited by Example (2). Also, all "parts" described here indicate "7". .

The coating compositions used in the Examples and Comparative Examples are listed in Table 1 C-2.

Coating composition 1 shown in Table 1 C: Add an appropriate amount of MEK (special grade reagent) and mix in a mixer for 2 hours to adjust the viscosity of the paste.

Each paste was injected using die pliers (= injected onto an MO8 type IC chip that was bonded with a 30 μ thick gold wire wire).
= Completely bond the gold wire (cover two, 0.5
After drop-coating each ml, it was baked at 180°C for 2 hours to harden it.

The sample obtained by C2 was subjected to a thermal shock test by repeating 100 cycles of cooling and heating at -40°C and 150°C to investigate the failure rate of ICs due to breakage of gold wire bonding (2).

The results are shown in Table 2 along with the coefficient of thermal expansion of the coating film.

As is clear from the above table (2), since the coating film according to the present invention has a coefficient of thermal expansion of I x 10''/°C or less, there is no bonding breakage, indicating that it is highly reliable.

Table 2 Patent applicant Sumitomo Bakelite Co., Ltd. Sumitomo Durez Co., Ltd.

Claims (1)

[Claims] In electrical insulation coating paints consisting of thermosetting resin, inorganic fillers, additives and solvents, the coefficient of thermal expansion of the coating film is 1×
An electrically insulating coating paint characterized by a temperature of 10^-^5/°C or less.