Sn100C Plating, Mixed Alloy Scenario

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Here's the scenario: PCB Plating: Lead free HASL, Sn100C... - Dec 13, 2011 by Dirk Nuendyke

Contaminating lead-free solder connections with lead is gene... - Dec 13, 2011 by davef

DaveF, That's correct. This assembly is plain old tin-le... - Dec 13, 2011 by Dirk Nuendyke

There should not be a problem we have done this. If you are ... - Dec 13, 2011 by KaHrpr

Dirk Nuendyke

#65635

Sn100C Plating, Mixed Alloy Scenario | 13 December, 2011

Here's the scenario:

PCB Plating: Lead free HASL, Sn100C

Solder Paste used: Sn62 (regular tin/lead solder with 2% silver).

Anyone see any issues with this?

What are the process considerations?

Anyone???

PS-9 times out of 10, I don't get answers on this forum. Any seasoned, knowledgable industry veterans, please come forward. :-)

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davef

#65637

Sn100C Plating, Mixed Alloy Scenario | 13 December, 2011

Contaminating lead-free solder connections with lead is generally a bad idea, but that's not what you plan. You plan to add tin to your tin-lead solder connection. We don't think there is a significant problem for most applications.

Adding tin will increase the melting point of the solder connection. The amount of this increase will depend on the alloy created by the solder and the solderabilty protection on the board and the component.

It's too bad that you're dissatisfied with our responses to your questions. Keep trying and hopefully your questions will match-up better with our knowledge in the future.

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Dirk Nuendyke

#65638

Sn100C Plating, Mixed Alloy Scenario | 13 December, 2011

DaveF,

That's correct. This assembly is plain old tin-lead, but our buyer purchases the bare PCB with lead-free HASL plating.

My main concern was the regular tin-lead not coalescing with the PCB plating and having a weak intermetallic.

I'm not frustrated with the responses, but rather the lack of responses. Since most of this industry is now outsourced, most of the veterans have moved on to bigger and better things, and now the forum is riddled with rookies who are still learning Profiling 101. Sorry to be blunt, but I'm just stating a fact.

For example, *this* question. You were one that I expected would answer, but so far, 200+ views and just one response?!

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KaHrpr

#65640

Sn100C Plating, Mixed Alloy Scenario | 13 December, 2011

There should not be a problem we have done this. If you are concerned send out a test board to be analysed. we do this about twice a year mostly lead free just to make sure our process is good. the test results are also handy when customers question or think there is a solder problem.

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