- Jan 1, 1970
Eeyore said:I'd agree with your analysis. I have seen both hairline cracks such as you
mention and 'cold joints' caused by failure to use an appropriate soldering
temperature, or soldering time when soldering components with large thermal mass
such an IEC connector PCB pin ( pressure will keep it working for a while but
it'll finally go high resistance ). Even seen that on TO-220 devices.
p.s. ( The TO-220 device acting as a heatsink to the solder via its leads, hence
preventing the alloying connection needed ). I've literally seen TO-220 devices
'fall out' of a PCB after a year or two leaving 3 nice rectangular holes in what
look to be perfect solder joints.
p.p.s The hairline crack around soldered joints is especially common where the
drilled hole size is not ideal ( oversize ) for the lead diameter. I have seen
manufacturers specify hole sizes very poorly with the inevitable outcome. Hence my
PCB footprints often use my own estimation of the appropriate drill size rather than
the data book one. Plenty of other people do the same.