Nitrogen gas and Tombstone defect

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Nitrogen gas and Tombstone defect - 11-/21-11 by Sean

Nitrogen gas and Tombstone defect - 11-/21-11 by ScottE

Nitrogen gas and Tombstone defect - 11-/21-11 by davef

Nitrogen gas and Tombstone defect - 11-/24-11 by davef

Nitrogen gas and Tombstone defect - 11-/29-11 by josh

Sean

#65499

Nitrogen gas and Tombstone defect | 21 November, 2011

All,

I try to find explanation(Article)on how Nitrogen gas can make tombstone defect even worst. However, I can't find one in the net. Anyone that has this information or article, appreciate if you can share with me...Thanks in advance.

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ScottE

#65500

Nitrogen gas and Tombstone defect | 21 November, 2011

I've never seen a good article with a definitive explanation - just speculation that the increased wetting forces due to nitrogen result in increased tombstones. My own experience is that nitrogen is a very minor contributor to tombstones and can pretty safely be ignored. Much more important are proper pad design (don't make the pads too long), print & placement accuracy (especially bad is print offset in one direction and placement in the other), and reflow profile (short profiles worse than longer ones).

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davef

#65507

Nitrogen gas and Tombstone defect | 21 November, 2011

Google: nitrogen reflow tombstone https://www.google.com/search?q=nitrogen+reflow+tombstone&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

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davef

#65521

Nitrogen gas and Tombstone defect | 24 November, 2011

Here's a paper from the SMTnet Newsletter http://www.smtnet.com/library/files/upload/dispelling_10_myths_about_nitrogen_reflow__andy_mackie.pdf

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josh

#65552

Nitrogen gas and Tombstone defect | 29 November, 2011

N2 is a reflow process widener so to speak, for leaded reflow less of a impact, for LF more impact, and if using finer LF solder pastes T4,T5 and smaller paste deposits generally, it helps widen window for flux in paste in oxide protection during soak thus improving wetting etc. Having access to it on your oven is a handy tool if available for certain assemblies.

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josh

#65553

Nitrogen gas and Tombstone defect | 29 November, 2011

Sorry on N2 and tombstone, many other aspects cause tombstones and n2 in itself does not cause tombstones. It can help make other bad variables tip over edge to cause tombstones more than with no N2. Get these right then N2 is not issue.

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