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Thu, 30 Aug 2001 09:27:58 -0500 |
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-----Original Message-----
From: Howard Watson [mailto:[log in to unmask]]
Sent: Thursday, August 30, 2001 8:58 AM
To: [log in to unmask]
Subject: [TN] Any MELF experts?
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
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