SU943255A1 - Composition for sealing radioelectronic equipment - Google Patents

Description

The invention relates to the preparation of a composition for sealing radio-electronic equipment from environmental exposure under conditions of use and storage. There are a number of potting stations for sealing electronic equipment, such as compound D-U, including epoxy resin, a plasticizer based on castor oil and diethylene glycol, a hardener - maleic anhydride and a filler - dust 1 quartz. The disadvantages of this composition are low viability (the maximum lifetime for compounds of this type does not exceed ZOOmin and greater toxicity. The closest to the proposed is a composition for sealing electronic equipment, including epoxy resin, amine hardener, plasticizer based on castor oil in combination with diethylene glycol or butyl methacrylate and the filler is powdered quartz f2. The disadvantages of this composition are low viability (if-100 minutes at 20 ° C) and you It doesn’t allow to automate the process of sealing radio equipment on the production line.In addition, powdered quartz partially precipitates during casting, impairs uniformity, and gives the composition a rather high shrinkage. The goal is achieved by the fact that the composition for sealing electronic equipment, including epoxy resin Dianova, plasticizer - a mixture of castor oil and dietary Langlikol, hardener

and a filler, as a hardener, contains)) it ethyl silicate and a 50% alcohol solution of novolac phenol-formaldehyde resin mixed with hexamine, in the following ratio of components, weight, in hours:

Epoxy Diane resin100

Castor oil 10-1 Diethylene glycol 10-14 alcohol solution of novolac phenol-formaldehyde resin mixed with

7.5% hexamine 20-30 ethyl silicate Z-

Filler 150-160

As a filler, the composition contains fused silica or pyrophyllite, pretreated with ethyl acetate and diethyl glycol.

Pyrophyllite is a natural substance that gives the chemical formula A.0.4Si02-2H2.0.

Fused quartz is an artificial material obtained by melting natural quartz at a temperature of more and subsequent crushing and grinding.

An example. Fused quartz or pyrophyllite is crushed in a vibrating mill with kerosene, as a result of which filler grains with a size of less than kQ μm are obtained.

The resulting filler is treated with ethyl silicate and diethylene glycol and, before mixing with the other components, is heated to BO-CI C.

The epoxy resin, castor oil and the filler heated to 80-1OO C are mixed in a container until a homogeneous mixture is obtained, after which

with continuous stirring, a 50% solution in ethyl alcohol of novolac phenol-formaldehyde resin mixed with hexamine (pulver-bakelite) is heated to 70-80 ° C. The finished composition is evacuated at a residual pressure of 0.05 atm per 1–3 min for 3-5 minutes and used for casting at a temperature of at least 60 C.

The composition obtained on the basis of the raw filler tends to exfoliate the samples is not uniform).

Composition proposed and known

compositions are given in table. one.

The prototypes made under the production conditions of the compositions have the physico-technical properties presented in table 2.

Deviation from the specified quantitative limits is impractical for the following reasons: a decrease in the amount of filler leads to an increase in shrinkage, with an increase in the amount of filler, shrinkage decreases, but the viscosity sharply increases.

By reducing the amount of hardener, the samples are not fully cured, increasing the amount of hardener has little effect on the degree of cure.

For the rest of the performance indicators, the resulting composition is on par with the known.

The operational parameters of the known and proposed compositions are given in table, 3.

Thus, the use of this curing system in combination. The cured filler produces a low toxicity composition with a high viability, giving homogeneous, low shrinkage samples during curing.

Table 1

ED-20 epoxy resin

100

Hekeamethyliadiamine

100

100 15

Content of ingredients, parts by weight

Components

Castor oil

 butyl

methacrylic

acids

Quartz pulverized Diethylene glycol Pulver-bakelite Ethyl alcohol Ethyl silicate

Fused quartz fraction is smaller than tO µm ,, Viability, Composition h 125.0 230.0 3 20.0 Known 1.6 Composition 3, prepared on the basis of properties, Indicators

The tangent of dielectric loss angle at a frequency of 10 Hz

with PRI in the compositions

Einzv

2 12

k

} C

12

12

15

15

12

one

3

160

60 Known

0,018

0.020 0.0t2 0, Table 2 Water absorption in Shrinkage,% cold water,% «о, 0.280.18 0.290.18 0.300.20 0.280.60 e of pyrophyllite has similar tablitsa. ... with .. Composition: a I Offered

after exposure to relative humidity 95-98% and for 5b days

Dielectric constant at 10 ° Hz

at

at 100 s

after exposure to relative humidity. 95-98% and for 5b days

Electric strength, MW / m

Claims (2)

in Claim 1, a composition for sealing radioelectronic apparatus, comprising an epoxy resin, a plasticizer — a mixture of castor oil and diethylene glycol, a hardener and a filler, in order to increase the viability of the composition and reduce its toxicity, hardener, it contains ethyl silicate and a 50% alcoholic solution of novolac phenol-formaldehyde resin mixed with 7.51 hexamine, with the following ratio of components, weight, hours: Epoxy resin 100–14 wt. Lo 10-14 Diethylene glycol 50% alcohol solution of novolac phenol formal8 N tol bl 0.035 0.032 4.0 4.0 6.6 6.2 ,9 , 7 28 25 dehydrous resin mixed with 7.5 urotropine 2-4 Ethyl silicate 150-160 Filler 2. The composition according to Claim 1, which means that, in order to improve the homogeneity of the composition and reduce shrinkage, it contains as filler fused silica or pyrophyllite, pretreated with ethyl silicate and diethylene glycol. Sources of information taken into account in the examination 1. Handbook of plastics. T. 2, M., Himi, 19b9, s, 96-97. 2. Chern to K.I., Epoxy compounds and their use. L., Shipbuilding, 1967, p., 52-535 54-55 (prototype),