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Hidden Pillow Phenomenon

Views: 2783


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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#45039

Hidden Pillow Phenomenon | 14 November, 2006

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

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#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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#45219

Hidden Pillow Phenomenon | 17 November, 2006

realchunks

#45220

Hidden Pillow Phenomenon | 17 November, 2006

As close to my pillows as you can get Jim.

21028181@N00/?saved=1" target="_blank">http://www.flickr.com/photos/21028181@N00/?saved=1

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#45225

Hidden Pillow Phenomenon | 17 November, 2006

Sorry Jim, this forum likes to scrambles everything useful, except the REAL spam.

www.flickr.com/photos/21028181@N00/?saved=1

Put it together, you're a smart guy!

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Bob Ash

#45249

Hidden Pillow Phenomenon | 17 November, 2006

Dang Chunks, you puttin' on weight? JK! You can inspect my BGAs any time!

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table top X-ray inspection

Reflow Oven