[morzh]

Mike


Back in the USSR phenolics with one-sided copper were used in 80s. When I repaired TVs, especially the early color ones, made in end of 70-s, the circuits were exactly that - 1-sided phenolics with miniature tube sockets soldered in.
The sockets obviously heated up, which resulted in two sorts of problems:

1. The one I described earlies, where the solder pad (which was not reinforced with a through flared type via) would separate and tear off, and
2. Solder around the socket's pin would become darlk grey powder (beta-tin?) that would create intermittent, and then the absence of, contact of the trace to the pin. Worse yet, whatever that was that the solder would become, would not be melted by the iron, and was hard to clean off. It had to be removed fully, then the pad scraped to the bare copper which then would needed to be tinned and re-soldered to the freshely cleaned and scraped socket's pin. Simple rubbing with iron tip, flux and solder would not work.