....and Salt spray...and Vibration..and Humidity test...also nonsencical.
I add to Werner's revolt.....because it's Friday...
On Monday I'm performing a Rapid Temperature Change test on boards with
greyish solder joints with a needlelike micro structure. I've told people here
that the very surface of a solder joint isn't telling what's in the
bulk. (Harmless, normal)Intermetallics can sometimes occur like needles or
dendrites in the uppermost region of a solder joint. Has to do with the solidification rate and recrystalization direction. And also with the way gold plating is dissolved and 'alloyed' into the solder joint.
So, in my opinion, greyish or creased or wrinkled solder can be quite normal
on the inside. But, as many still disbelief and demand proof tests, I'll
satisfy them by doing such, e.g. temp change. The hysteric requirement for all
shiny and voidfree solder surface is sometimes boring...
Ingemar Hernefjord
Ericsson Microwave System
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
Sent: den 21 januari 2005 00:05
To: [log in to unmask]
Subject: Re: [TN] Thermal Shock Requirements
Hi Roger,
"Thermal shock Requirements" are by their very nature nonsensical. Thermal
shock does not proof or disproof reliability, because the loading conditions TS
creates are totally different to what product sees in operation. TS can be
used as a screening procedure, but since their are better ones, TS is not
recommended for this purpose either.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
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