Electronics Forum: can not solder to pad (Page 1 of 12)

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Wed Apr 28 06:26:15 EDT 2021 | jeremy_leaf

@Evtimov I can't use flux as the components being soldered can't cope with any contamination whatsoever. Even an ultra low solids no-clean flux will be too much. I also can't clean the boards after soldering due to any residual contamination from the

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Tue Apr 27 19:08:04 EDT 2021 | emeto

Jerry, just out of curiosity, why can't you use flux? Flux is essential part of soldering and it is there for multiple reasons. Flux we can also clean afterwords - even No Clean.

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Wed Apr 14 19:47:13 EDT 2021 | solderingpro

Sounds like you may have already found the issue: inconsistency from your supplier. Seeing as Gold really doesnt oxidize and you're using an inert environment (N2 I suspect), I would turn my attention to the supplier. You said yourself, the "Shine

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Mon May 17 13:21:45 EDT 2021 | SMTA-64387881

PWB Bake out or other elevated temperture processes can cause issues with oxidation of that Nickel layer. The gold porosity can vary from batch to batch, but also process changes can contribute. Are you baking the boards or have previous reflow pro

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Tue Apr 27 21:24:14 EDT 2021 | kwalker

No, you're correct. Nickel oxidation can be difficult to remove

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Tue Apr 13 11:41:18 EDT 2021 | jeremy_leaf

I have a SAC305 preform with which I am attempting to bond a gold coated component to an ENIG coated PCB pad. I've specified 2 microinches of gold for the ENIG. It worked previously but now with a new batch of boards, I am having an issue where the p

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Tue Apr 27 07:50:09 EDT 2021 | jeremy_leaf

@KWalker I think that could be the case. Though I read somewhere a while back that nickel oxidation can be quite tough to remove, even with flux. Am I wrong about that?

SAC305 preforms not wetting to ENIG pad in fluxless process

Electronics Forum | Mon Apr 26 17:09:05 EDT 2021 | kwalker

Sounds like you are getting oxidation of the nickel under the gold layer. If the gold is porous it will allow the nickel underneath to oxidize, which is the dark dull layer you are seeing, and why when you apply flux it solders just fine - the flux i

PLCC LEADS not solder in SAC305 paste

Electronics Forum | Wed Jun 27 21:53:54 EDT 2012 | davef

Questions are: * When you rework these pads, can you get solder to flow on the pads with a soldering iron? * When you profile the board during reflow, what is the temperature on these pads as compared with other similar pads in the vicinity?

Possible to temporarily store mounted but not soldered PCB's?

Electronics Forum | Wed Sep 05 08:50:04 EDT 2001 | davef

No arument with others comments about moisture, but taking a different tact, consider that the volitle elements of the solder paste disppear as a function of the amount of time the paste is out of the container. [Maybe as a function of solder paste

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