Claims
- 1. A drop coating compound having a low coefficient of expansion for unhoused electrical and electronic components, comprising:
- a cationically curable epoxy resin mixture, curable by ultraviolet light, having, when cured, a glass temperature above 140.degree. C., and having a coefficient of thermal expansion of at most 25 ppm K.sup.-1 in the range from 25 through 75.degree. C.;
- a fine particle filler compatible with a cationic curing process and transparent to ultraviolet light having a maximum grain size of 150.mu.m and a grain size distribution allowing an optimally tight spatial packing, the filler being vitreous fused silica and comprising approximately 30 to about 80% by volume of the compound; and
- a photo-initiator for a cationic curing process.
- 2. The drop coating compound of claim 1 wherein the filler has the following grain size distribution:
- approximately 55 to about 95 weight percent of the filler particles having a diameter between approximately 1 to about 25 .mu.m; and
- approximately 0.5 to about 20 weight percent of the filler particles having a diameter below approximately 5 .mu.m.
- 3. The drop coating compound of claim 1 wherein the surface of the filler particles is chemically pre-treated with an agent so as to have organic residues with reactive groups that are suitable for reaction with the epoxy resin.
- 4. The drop coating compound of claim 1 wherein the epoxy resin mixture additionally contains a flexibilizing constituent that is adapted to provide desired properties.
- 5. The drop coating compounds of claim 1 including additional additives.
- 6. The drop coating compound of claim 1 wherein multiple alcohols capable of reacting with the epoxy resin are contained therein.
- 7. The drop coating compounds of claim 1 wherein epoxy soy bean soil is contained therein.
- 8. The drop coating compounds of claim 1 wherein a further constituent is contained therein that absorbs light of the wavelength range that covers the emission used for the laser balancing of resistors.
- 9. The drop coating of claim 1 used to coat an unhoused IC, hybrid circuit, memory component and discrete component.
- 10. A drip covering a part of a surface of an electronic component composed of a drop cover compound comprising:
- a cationically curable epoxy resin mixture;
- a photoinitiator for a cationic curing process;
- approximately 45 to about 80 volume percent of a fine-particle filler being vitreous fused silica having a maximum grain size of 150 .mu.m and having a grain size distribution so that a suitable spatially tight packing is achieved; and
- the drip cover compound being curable through initiation with ultraviolet light without additional temperature elevation, having a glass temperature of more than 140.degree. C., and having a coefficient of thermal expansion of at most 25 ppm K.sup.-1 in the range from 25 through 75.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3907535 |
Mar 1989 |
DEX |
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Parent Case Info
This is a continuation of application Ser. No. 476,713, filed Feb. 8, 1990, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0114258 |
Nov 1983 |
EPX |
0182744 |
Nov 1985 |
EPX |
Non-Patent Literature Citations (1)
Entry |
Goosey, Plastics for Electronics, Elsevier Applied Science Publishers, Ltd. 1985, pp. 43 and 99-120. |
Continuations (1)
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Number |
Date |
Country |
Parent |
476713 |
Feb 1990 |
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