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Another Wave Solder Question....


Another Wave Solder Question.... | 24 January, 2002

I have recently been asked to look into some problems that we are having at wave. It is common for us to have unsoldered joints for boards that have SMT parts epoxied to the bottom side. Recently we have had a problem with a gold plated board. The wave operator stated that she always has a problem soldering to gold. When I looked at the board, there was no solder evident on the pads that were unsoldered at all. It seemed to me that the problem was not the gold as any contact with the solder would leave some residue of solder. Am I wromng in that assumption? Any input would be greatly appreciated.

Some process info

Wave solder: Dover Soltec SN63/37 Pot Temp 500 degrees F Speed= 120 cm/min

Also, we have had similar problems soldering resisrtor nets with castellated leads. Would this component be more difficult to process due to the lead configuration, or is this possible related to the aforementioned problem?

Any help would be greeatly appriciated.

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Another Wave Solder Question.... | 24 January, 2002

I�d go with the operator. But you make a good point. => If solder touches gold, you should see solder, rather than gold. Since you see gold, something is wrong. * Is the solder touching the gold? If not, why not? * If the solder is touching the gold, but the gold is not soldering, there is a problem with the gold. [Or maybe the flux, but since we�re talking only gold the flux is probably OK.] * If there�s a problem with the gold the first thing to understand is the plating [ie, thickness of gold, thickness of nickel, etc.]

Certainly, we should consider �shadowing� and orientation of parts towards the wave, but this seems to be a broader problem that a few parts here and there not getting solder caused by shadowing and orientation.

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Matt N-Stott


Another Wave Solder Question.... | 25 January, 2002

First thing to try is to rotate the board 90 deg if possible, this will let you know if shadowing is the cause.



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Another Wave Solder Question.... | 28 January, 2002

Is it just certain locations on the board, or is it random, does it occur on every board, does this happen on any other products you have been running? If this occurs only on the 1 board and in random locations I wouldn�t say its your wave setup. I would perform a sodlerability test on a bare brd and see what it yields. Are the boards OSP coated? If so are the boards handled a lot prior to build or are they being washed prior to wave? If so, Be sure the operators handle the brds by the edges and do not touch the solderable surfaces.

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