C
Clarence
- Jan 1, 1970
- 0
Larry Brasfield said:Hand soldering can be very hard on SMD ceramic capacitors.
The high temperature gradiant created by applying heat suddenly
at one end can fracture the ceramic. This can lead to excess noise
or a tendency to break down at a lower than rated voltage as
moisure gets into the crack(s). The insidious aspect of this kind
of damage is that it can show up in the field, quite some time
after the parts perform alright in initial testing.
At Siemens Ultrasound, we learned this the hard way, then had it
confirmed by at least one vendor's examination of abused parts.
--Larry Brasfield
Of course this may have actually happened, and Boy, you had some pretty lousy
assembly people. I've seen the pre-prod units used for test assembled and
soldered by hand and subjected to extensive testing. Never saw a solder
related failure of a component. We tested for very long periods on many
boards. Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.