Circuit board with two-layer track - has thin upper surface protective portions and has anti-solder lacquer film on conductive tracks

摘要

The circuit board is pref. of the type with conductive tracks on both sides. It has a corrosion protection and/or etching resistance cover in the form of a top layer film. Parts of both surfaces are coated with a solder-resistant lacquer. The top layer portions are much thinner than the conventionally galvanically applied layers. The circuit board parts with such surface arrangement are coated with the solder-resistant lacquer (5). Pref. the thin top layer portions are of material which becomes liquid at a temperature lower than tin on the underlayer. This top layer portion material may tend less to edge breakage at the etching edges than tin. It may be typically a lead-tin alloy. The profile of the top layer portions may surround the underlayer on three sides.