Dear
TechNetters,
I have a situation
involving a surface mount MELF Resistor, 270 ohm, 3W. During
environmental testing, one solder joint separated at the pad causing
intermittent failure. Unfortunately, the technician repaired the solder
joint so I have nothing to evaluate. Based on information given to me, I
suspect it was a mismatch of CTE between the MELF and the PCB (FR4,.062).
Does anyone have any
experience, pad design or CTE data, with large, cylindrical MELF's?
This part is .5" x .156" dia. and is custom manufactured by RCD.
We are stuck with this part in surface mount, as someone got a great
"deal" on 100,000 or so parts, so it critical that I prove reliability (or
lack of) with the solder joints. In advance, I appreciate any
information that can point me in the right direction.
Howard Watson
Manufacturing
Engineer
AMETEK/Dixson