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Michael Nguyen

#13637

Wavesolder solder balls | 30 October, 1998

I finally got my problem figured out on the bridging, the only thing I'm finding is that I notice some litlte solder balls on the bottom of the board. Is that normal? Is that why I'm getting bridges? Has anyone came across this problem and pass the info down. I would greatly appreciate anyy help.....=)

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Dave F

#13638

Re: Wavesolder solder balls | 30 October, 1998

| I finally got my problem figured out on the bridging, the | only thing I'm finding is that I notice some litlte solder balls on the bottom of the board. Is that normal? Is that why I'm getting bridges? Has anyone came across this problem and pass the info down. I would greatly appreciate | anyy help.....=) | Mike: Nice that you cleaned-up one mess, but too bad that created another one. Not that we haven't all done that before.

It's strange to have solder balls on the bottom side after wave soldering. Solder balls usually are formed by excess flux, water from the flux, or water entrapped in the board boiling up through the holes to the top side and blasting little bits of solder sky-ward. The little bits coalesce and drop on to the board surface.

Please talk more about your current process. Are the balls loose or are they imbedded in the mask?

Dave F

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Dennis Barry

#13639

Re: Wavesolder solder balls | 31 October, 1998

| I finally got my problem figured out on the bridging, the | only thing I'm finding is that I notice some litlte solder balls on the bottom of the board. Is that normal? Is that why I'm getting bridges? Has anyone came across this problem and pass the info down. I would greatly appreciate | anyy help.....=)

Mike, I agree with Dave. It is very strange to see solder balls on the bottom of the board after wave solder. We've all fought with topside solder balls, but the only time I've ever seen bottomside solder balls is when I was working with a Hollis wave solder machine using their hot-air knife. Is this the case with you? Please give some more details on your process. DB

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ChrisK

#13640

Re: Wavesolder solder balls | 2 November, 1998

In my experience, solder balls are normally caused by only a few things. In order of likelyhood:

1) Water based fluxes (VOC-Free)not having the water carrier completely dried from the board before going into the solder. I.E, too fast conveyor speed relative to the amount of heat being applied. Solution: More heat or slower conveyor speed.

2) Too much flux; either alcohol OR water based. This is sort of related to #1. Solution: Put as little flux on the board as possible while still achieving acceptible soldering performance.

3) A combination of flux propensity to generate solder balls AND the board mask type which also has a certain propensity to cause solder balls to adhere to it. Certain fluxex JUST GENERATE more solder balls. You may have even seen certain flux vendors advertising a flux as being a low solder ball producing flux. This gets into flux chemistry which isn't my expertise so I'll leave it at that. The other, Mask type, plays a pretty significant role in the appearances of solder balls. Just to be clear though, a board masking will NOT generate solderballs per se, but rather will cause solder balls that ARE being generated by another source to adhere to the mask and not fall away. Normally, the fix for this is to get a mask type that has a rough texture instead of the flat, shiny types of mask. If you want to know more about this, your board vendor 'Should' be up-to-speed on the issue. Solution: Change fluxes (yeah right! I hear laughter from some of you, I know. ;)) and change the mask type to a more appropriate type to cut down on solder ball adhesion (STOP laughing people!! This is only a suggestion for those who have the luxary to actually do so)

There are a couple more things that can cause solder balls but their likelyhood of being the culprit is small. I'd check these first items before going any farther.

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