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surface mount connector, disturbed solder

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#54439

surface mount connector, disturbed solder | 18 April, 2008

I have a small board with some chips and 2 connectors (1 large and 1 small) with gull wing leads. The large connector has some "disturbed" solder joints per my QA people. These joints are toward the ends of the connector, not toward the middle. The small connector doesn't show any problems. This is a tim-lead solder application. Any ideas how to correct?

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#54444

surface mount connector, disturbed solder | 18 April, 2008

Do you have a picture? SMTNet HAS the technology now to post pictures.

"Disturbed" to the typical Q.E. usually means grainy or dull, or a wrinkly solder appearance. All of this has to do with the "grain structure" of the solder joint. Here's a pretty interesting white paper on the topic: http://circuitsassembly.com/cms/content/view/4083/95/

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#54450

surface mount connector, disturbed solder | 21 April, 2008

That you have 'grainy' solder only at the ends of the connector and not at all solder connections indicates that your quality types are on track and are pointing you in a direction worthy of investigation and developing a better understanding of the situation.

It's possible that the longer connector has a greater amount of warping during the thermal cycle of soldering. This warping could be where the ends of the connector curl up from the board and then curl back to the board at the end of the heat cycle. This movement of the leads at the ends of the connector through the molten solder would create a grainy appearance in the solder.

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#54451

surface mount connector, disturbed solder | 21 April, 2008

"Disturbed" usually means some form of movement. I would think your leads are moving due to warp as the board exits the reflow zone. Not knowing your profile, I would suggest checking your profile. Make sure you have adequate "above liquidous" and or check your first cooling zone (if you have one) to make sure you are not ramping down to fast. Profiling is you best method to do this - but if you want a quick and dirty way to do this, try turning off your first cooling zone. See if it makes a difference.

Also, on a side note: Doe this product go over wave? If so it may be your wave solder causing the "disturbed" looking joint. You can easily tell if it�s wave by looking before and after wave.

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#54452

surface mount connector, disturbed solder | 21 April, 2008

Profiling can't happen outside of North Avenue.

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