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Nonwetting Components - why won't components wet to solder?

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wagoner

#46990

Nonwetting Components - why won't components wet to solder? | 25 January, 2007

There are several smd components in our factory that don't reliably wet to solder during reflow. Paste and placement are good, but the component won't wet reliably. All of the other components on the boards solder fine, but one of these components will not wet about 10% to 50% of the time. What causes this? Component lead material? Oxidized leads from sitting on the shelf for too long?

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#46995

Nonwetting Components - why won't components wet to solder? | 25 January, 2007

Are you running a lead free process? If not, have you identified these as lead free components? If so, have you increased the temps in your profile to accomodate that?

After that, I'd look for a AgPd (silver/palladium) or some other such PITA plating.

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wagoner

#47003

Nonwetting Components - why won't components wet to solder? | 25 January, 2007

We are using tin-lead solder. The components could be lead free components, they probably are.

I will check the plating on the components and investigate changing it.

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#47004

Nonwetting Components - why won't components wet to solder? | 25 January, 2007

Good luck with that. ;)

More likely you'll have to adjust your profiles. In our case with the palladium terminations we had to touch them up. There were other parts on the board that couldn't take more than 5 seconds at ~235 C� (don't remember for sure) and that didn't reflow them well enough.

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#47012

Nonwetting Components - why won't components wet to solder? | 25 January, 2007

Wagoner,

Try switching to a transitional paste designed for no lead parts on a leaded board. Running your current paste at higher temps will dry out your flux too soon, which may be your problem.

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#47018

Nonwetting Components - why won't components wet to solder? | 26 January, 2007

You should have no problem using lead-free components with tin-lead solder.

Is your reflow oven IR or hot air? If you are using an IR oven and the components are white or light colored, they may not be heating up enough for the solder to flow on their leads.

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wagoner

#47079

Nonwetting Components - why won't components wet to solder? | 29 January, 2007

We reflow with hot air. Our peak reflow temp is 220 to 225 degrees C. Thanks for all of the ideas.

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Phil J

#47088

Nonwetting Components - why won't components wet to solder? | 30 January, 2007

Print your paste onto a ceramic tile, place the offending component onto it and send through the reflow oven; then observe the results. You will soon see if the component is solderable!

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blnorman

#47133

Nonwetting Components - why won't components wet to solder? | 31 January, 2007

We've had multiple issues with non-wetting components. You say only one part is not wetting? Profile won't be the culprit, if so you would have more part issues. We've used SnPb with lead-free parts for some time now, no issues.

The issues we had with non-wetting was contamination on the leads. We've had excessive oxidation as well as silicone contamination. Not saying this is your issue, but another area to investigate.

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