The & z( [% z; Y& R4 ?: @; A: Nleads of components are connected to ground / H$ ^" z8 z# k) N' i
or power by soldering them into plated through 8 y: A2 W( q( m
holes. Since copper conducts heat well, solder-+ a% M+ X7 d3 n7 Z& Y; Q& J9 U" x
ing to a plane layer could require an excessive $ @3 _, c0 @# o& y& g! k# s
amount of heat, which could damage the com- / S' k2 ]$ v+ g. A# Wponents or the plating in the hole (called the barrel). Thermal reliefs are used to reduce the path for heat conduction but maintain 0 R8 o+ h; s# H6 p! v0 R- q9 V' }electrical continuity with the plane.