Hidden Pillow Phenomenon

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OK, I've heard of smuggling cushions, but not this: ... - Nov 14, 2006 by Rob

I've heard of bitting pillows AND heard of this phenomenon. ... - Nov 14, 2006 by Real Chunks

"Hidden pillow" seems to be a a variant of "pillow effect" o... - Nov 14, 2006 by davef

I know Indium was big into the "ambient-to-peak" parameter, ... - Nov 16, 2006 by

Real C, U got a pic.? ... - Nov 16, 2006 by

... - Nov 17, 2006 by Real Chunks

As close to my pillows as you can get Jim. ... - Nov 17, 2006 by

Sorry Jim, this forum likes to scrambles everything useful, ... - Nov 17, 2006 by Real Chunks

Dang Chunks, you puttin' on weight? JK! You can inspect my... - Nov 17, 2006 by

Rob

#45038

Hidden Pillow Phenomenon | 14 November, 2006

OK, I've heard of smuggling cushions, but not this:

http://www.ko-ki.co.jp/technical/06.html

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Real Chunks

#45039

Hidden Pillow Phenomenon | 14 November, 2006

I've heard of bitting pillows AND heard of this phenomenon.

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davef

#45047

Hidden Pillow Phenomenon | 14 November, 2006

"Hidden pillow" seems to be a a variant of "pillow effect" or "head in pillow". Pillow effect is an open, with non-wetting between the lead and the solder on the pad. Here the lead sags into the solder without any bonding or wetting.

Poor wetting can be resulted from excessive oxidation at temperature prior to the solder coalescence. Similar to the solder balling discussed above, the heat energy input prior to solder melting should be minimized in order to minimize this oxidation. The profile desired is a heating time as short as possible. If the heating time can not be shortened due to other considerations, then a linear ramp-up profile from ambient temperature to solder melting temperature is crucial for minimizing the oxidation. [Optimizing Reflow Profile Via Defect Mechanisms Analysis; Dr. Ning-Cheng Lee, 1998 Surface Mount International]

Dr. Lee briefly discusses "pillowing" opens in "Reflow Soldering Processes and Troubleshooting: SMT, BGA, CSP and Flip Chip Technologies" [Ning-Cheng Lee; Newnes 1e 2001 0750672188] p.130, where again he directs the reader to resolving nonwetting issues.

We have no relationship, nor receive benefit from the company referenced above.

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CK the Flip

#45105

Hidden Pillow Phenomenon | 16 November, 2006

I know Indium was big into the "ambient-to-peak" parameter, so now I know why. For their Sn/Pb paste, they recommended an EXACT number - I believe it was 4.5 minutes.

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Jim

#45106

Hidden Pillow Phenomenon | 16 November, 2006

Real C,

U got a pic.?

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Real Chunks

#45219

Hidden Pillow Phenomenon | 17 November, 2006

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realchunks