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I have run into this before, and I just have to laugh when the capacitor manufacturer tells me his parts are meant to be hand soldered.
Hand-soldering with a solder iron and no pre-heat subjects the capacitors to at least 10x the thermal shock that wave soldering does.
Ask him where on the part drawing it specifies the total thermal excursion limits, and ask him to define WHERE that is measured (internally or at the surface, or on the terminals, WHERE?)
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bogert, Gerald L
Sent: Friday, February 11, 2011 10:49 AM
To: [log in to unmask]
Subject: [TN] Metallized Plastic Capacitors, DSCC Drawing 09006; to hand solder or not to hand solder
February 11, 2011
We have an OEM who wave solders the subject capacitors on circuit card
assemblies. The OEM experienced failures during CCA bench testing. A
sample of parts was sent back to the capacitor manufacturer who
attributed the failure (capacitance value was less than the minimum
value required) to excess temperature during the wave soldering process.
He stated that his parts should be hand soldered not wave soldered. The
soldering profile used by the OEM is set so the top side CCA temperature
is < 125C.
Since the DSCC drawing rates the parts for 125C maximum, and since the
spec also requires 260C dip test for qualification, and since neither
the DSCC drawing nor the capacitor manufacture data sheets indicate his
parts must be hand soldered, I would have expected that the parts could
be wave soldered with no problem.
Does anybody have info on what the worst case capacitor body
temperature might be for the above situation in wave soldering versus
hand soldering? Since these parts are small having two leads on the
bottom surface, during wave soldering, the leads would be exposed to
approximately 260C solder pot temp, but I have no information on what
the worst case cap body temp could be during the normal wave soldering
exposure time. I know that this could be determined by adding TC on the
cap body but I am just looking for some advice on this issue at this
time.
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