| 摘要 |
1428179 Semi-conductor devices WESTING- HOUSE ELECTRIC CORP 9 April 1973 [19 April 1972] 16826/73 Heading H1K [Also in Divisions C6-C7] The leads 41 of a solid-state device are electrolytically coated by making them anodic in a solution or colloidal suspension of an amine or imidazole salt of a polyamic acid (polyamide acid) and the material thus electrodeposited is heat cured to a polyimide film which forms flexible void-free interfaces with the leads and with a subsequently applied encapsulant which covers both the device and leads. The relative quantities of amine, polyamic acid, and solvents are critical, for both solution and colloidal suspension. In each case, more than one non- aqueous organic liquid is present in the composition. One or more of these act as a solvent for the polyamic acid and one or more act as non-solvent for the amine or imidazole salt of the acid. A variety of amines and imidazoles are listed. Solvents for the acid are N : N- dialkyl carboxylamides, dimethyl-sulphoxide, and pyridine. The non-solvents listed for the salt are all ketones. As shown a P+N silicon diode 40 has its body and electrodes protected with a silicon grease coating 45 while the leads are coated with polyamic acid and the device heat treated to form the polyimide. The diode is then vacuum baked, encapsulated with a mineral filled epoxy resin, and further baked to cross-link the resin. In general, encapsulants may be epoxy, silicone, polyester, phenolic, or diallylphthalate resins and may be filled with silica, benyl, or talc. Transistors, gate-controlled switches, and integrated circuits may be similarly treated. |
