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Solderability Issues

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#62284

Solderability Issues | 20 July, 2010

Recently we have expereinced solder issues with our reflow process. The issue is random and doesn't effect every assembly.

I'm seeing extreme solder wicking, no solder flow onto the pads, only onto the leads of the components.

I have tried to hand solder and am unable to hand solder. The same solder wick issue occurs. Due to this fact, I'm leaning away from process. I have not checked a board that has not gone through reflow soldering.

Any ideas are greatly appreciated.

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#62298

Solderability Issues | 22 July, 2010

It is likely that the pads that will not solder have been contaminated. There is something on the surface that is preventing the solder from flowing.

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#62299

Solderability Issues | 23 July, 2010

by viewing your posting i came to know this is solder ability issue which is because of marginable solder ability of PCB / components,

just ensure that issue due to PCB or component . check the msl of of substrate / component. verify the baking requirement . with regards joseph

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#62333

Solderability Issues | 28 July, 2010

> by viewing your posting i came to know this is > solder ability issue which is because of > marginable solder ability of PCB / > components, > > just ensure that issue due to > PCB or component . check the msl of of substrate > / component. verify the baking requirement . > with regards joseph

I have another thread going about warp issues from our supplier. It is possible they have tried to correct the issue by baking and have caused these effects we are seeing.

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#62334

Solderability Issues | 28 July, 2010

I took a pad that did not have any solder flow (wetting issue with pad) and not reworkable with soldering iron, and scraped with an exacto knife. After scraping the pad soldered fine.

Any suggestions?

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#62335

Solderability Issues | 28 July, 2010

What surface finish are you using?

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#62352

Solderability Issues | 2 August, 2010

I believe it is LF HASL. I will need to double check.

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#62375

Solderability Issues | 3 August, 2010

Craig,

If it is LF Hasl it sounds like it applied too thin exposing the intermetallic layer wich is not solderable. We call out a minimum thickness of 80 microinches and have good results. We have had shops in the past that did not control the Hasl thickness and had the problems you are describing.

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#62402

Solderability Issues | 9 August, 2010

#62403

Solderability Issues | 9 August, 2010

#62405

Solderability Issues | 9 August, 2010

Try tinning pads with a high pH water soluble flux like Kester 2331-ZX or Alpha Metals 3355-HB is what we use. It will remove the contamination quick;y without having to scrape with a blade. If you have a large number of bare boards you can run them through a wave solder machine with said flux and tin pads in high volume. I send them out to get Air Solder Leveled and specify the flux I want used.

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#62436

Solderability Issues | 13 August, 2010

Boards with the LF hasl finish applied too thin will genrally pass the IPC test. That is some pretty agressive flux they call out. The boards usually wave solder just fine as well. Reflow is where the you see the problem.

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