SMT Parts Poor Reflow at Wave Solder (Cold Solder)

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I'm having a problem getting sufficient solder reflow on a S... - Aug 13, 2020 by IronSMT

Is that no solder on the left hand pins in the picture? If ... - Aug 13, 2020 by robgd3

Thanks for the feedback Rob, Yes that is a no solder. Ther... - Aug 13, 2020 by IronSMT

Are you getting the same solder issues on all of the compone... - Aug 13, 2020 by robgd3

We understand you can't change the board design, but can you... - Aug 14, 2020 by Evtimov

IronSMT

#85449

Poor Reflow with Ground Planes for Wave Solder | 13 August, 2020

I'm having a problem getting sufficient solder reflow on a SMD part. The board design (which can't be changed) is covered in ground planes that cause a lot of uneven heat distribution. I believe heat is wicking away from the culprit part, causing the solder to flow across the pad.

I've tried slowing down the rails, but the flux burns up too quickly causing shorts elsewhere. I've tried adjusting my preheat with no success there either. Any higher temps and I might de-laminate the board. Any thoughts?

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robgd3

#85450

Poor Reflow with Ground Planes for Wave Solder | 13 August, 2020

Is that no solder on the left hand pins in the picture?

If so, it could be a directional thing. Have you tried turning the board 90º or 180º from the current direction of travel?

Not a huge fan of wave solder for SMT components personally, though, I have implemented it in the right circumstances in the past. One thing I've found is that there are some components that just won't work out the way you want them to, especially at wave.

You could try thermal-profiling the board across pre-heat/wave, and see what those pads are experiencing. It doesn't look like they're tied to significant copper pours (unless there's a plane down through that via). To my eye, though, in this picture, if the pads on the right are getting soldered, and the pads on the left are not, I wouldn't expect it to be a thermal misbalance on this component.

Good luck. ..rob

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IronSMT

#85453

Poor Reflow with Ground Planes for Wave Solder | 13 August, 2020

Thanks for the feedback Rob,

Yes that is a no solder. There are 7 of these parts on each board and around 30-40% of the time the leads will have a no solder.

I have to agree with you on waving surface mount components; I try to steer clear whenever possible. Labor changes are not a very popular opinion at the moment so I'm working with what I got.

I'll have to try and rotate it, although I've been told they tried that already. Always good to see it for myself.

-Luke

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robgd3

#85454

Poor Reflow with Ground Planes for Wave Solder | 13 August, 2020

Are you getting the same solder issues on all of the components on the board?

Any consistency in the ones that come up with no-solder? Same pins, same orientation, etc? Could be a solderability issue on the component or pads.

I hate random issues more than I hate soldering SMT parts at wave :)

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Evtimov

#85460

Poor Reflow with Ground Planes for Wave Solder | 14 August, 2020

We understand you can't change the board design, but can you change the process? Why do you have to run SMT parts on the wave? The suggestion above are great, but if they don't help, I feel you should build a case and change process.

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