> THen there were those that that mounted vacum
tubes on PCB's and the
> circuit heat of the tubes lifted traces over time. Not to mention carbon
> trails and arcing around load resistors mounted too close and cooked the
> boards. PSB's were not reliable untill the advent of transistors !
There was a lot of resistance to using PCBs, even in the transistor age.
IIRC, the cheap Japanese transistor radios were all PCB, but you could
still buy a good US-made Automatic Radio model that featured a steel
chassis with transistors in sockets, carefully handwired together. For
years, printed (or rather, etched circuit) boards were a sign of inferior
quality. Things generally got better when the military stared used them,
because there was a demand for reliability.
The change in soldering techniques has made a big difference. I've got old
equipment from the early 60's that has every trace completely covered in
gobs of solder with oceans of old flux between the traces. They work, but
you wonder why.
I think the big problem was a shift in thought. Anyone who learned to
solder back in the handwired days remembers being told over and over again
that "Solder does not make a mechanical connection". Or in other words,
good wiring practice demanded that a wire be mechanically attached to its
terminal before solder was applied. Along come PCBs and what's holding
everything together? Solder. In fact, solder makes a great mechanical
connection--just ask any trumpet player why his instrument doesn't fall to
pieces when he picks it up--and it's the selfsame 70/30 alloy that
electronics assembly uses.