Figure 3-1.
Typical circuit boards.
(3) Ceramic material.
(4) Glass.
(5) Mylar.
b. Circuit Patterns.
(1) Most circuit patterns are made by the "etched-foil" process.
Copper
foil bonded to a mounting board with epoxy resin is coated with a
light-sensitive material.
A photographic negative of the circuit
pattern is placed on top, and the assembly exposed to light.
Next,
washing in an acid bath removes all the foil except the desired circuit
pattern. The assembly is then baked to set the bond between the copper
and the mounting board.
309 L3
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