Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Patent
1973-01-02
1976-04-27
Clay, Darrell L.
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
317101B, 29625, H05K 102, H05K 322
Patent
active
039536637
ABSTRACT:
Relates to printed circuit boards which are devoid of electrical discontinuities likely to arise in the production of two-sided circuit boards having plated-through-holes and solder fillets therein for improving the electrical interconnections. Research disclosed that the cause of these discontinuities lay in the material of the boards surrounding the holes which either included entrapped gas or matter vaporizable under the high temperatures of the liquid solder applied to fill the holes and which impaired the attainment of reliable plated-through-hole connections. A vacuum evaporation operation is incorporated in the fabrication of printed circuit boards and the like and found highly useful and efficient in the production of reliable hole connections in the boards substantially reducing if not completely eliminating any need to apply solder touch-ups to the boards thereafter. Specifically, the boards are treated prior to the soldering of the plated-through-holes to a temperature of approximately 250.degree. F while concurrently being exposed to a vacuum of approximately 10.sup..sup.-2 mm Hg for a sufficient time to drive out of the boards all matter vaporizable under such conditions. Inert gas may be used in the treatment chamber to hasten the heating or the cooling of the boards. The degassed circuit boards may be placed in sealed containers or bags to prevent contact with the atmosphere and the absorption of moisture and deleterious gases therefrom.
REFERENCES:
patent: 3661675 (1977-05-01), Frankowski
patent: 3708876 (1973-01-01), Klehms, Jr.
Burroughs Corporation
Clay Darrell L.
Parker Ralzemond B.
Uren Edwin W.
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