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Dewetting on Second side reflow?????

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#44790

Dewetting on Second side reflow????? | 31 October, 2006

I'm just looking for some fire-power here. We have a board that when it goes through reflow the first time, everything is fine and has good wetting. When we do the secondary side, one specific part is then Dewetting according to our production operators. I am not sure on how this could take place if it is taking place. We are getting ready to run this board again so I can take a closer look at it.

Just wanted to know everyone's thoughts.

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#44793

Dewetting on Second side reflow????? | 31 October, 2006

Are you using Houdini brand paste?

It really depends on the part and pad size, but I kinda doubt that you�re paste is disappearing during the 2nd reflow. Do a side by side comparison of first pass versus second pass reflow and show your operator.

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#44796

Dewetting on Second side reflow????? | 31 October, 2006

yeah, that's what I've explained to them is that it is not going to disappear. Currently they are in the process of running this PCB again and I'm going to do the side by side comparison.

Thanks for the input.

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#44815

Dewetting on Second side reflow????? | 31 October, 2006

So at incoming inspection, what are the results for your "dip & look" solderability testing [IPC/JEDEC J-STD-002A] of the specific problem component?

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RDR

#44822

Dewetting on Second side reflow????? | 1 November, 2006

See if the solder is leaving the pad(s) and is wicking up the component.

This is long shot but I have seen something similar to this possibly in a wave process. We had a very thin board and a very large QFP on top. During wave operation the solder would reflow on the QFP and wick up the leads and leave pad pretty much bare except for minmal attachment at end of pad. We theorized that the QFP was staying at reflow temp much longer than the board was due the difference in thermal mass and what not. We corrected this problem by shielding this QFP with pallet.

Russ

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Pete B

#44846

Dewetting on Second side reflow????? | 2 November, 2006

What surface finish is your PCB?

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