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SnPbAg solder paste at reflow oven

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brodalvin

#45314

SnPbAg solder paste at reflow oven | 20 November, 2006

Does SnPbAg solder paste have a reliability risk if subjected 2 times in reflow oven at 230�C? I want to implement my project immediately. If samples will be subjected to our reliability it would take three months before I can implement my project. i was hoping that there is an industry standard for this topic. Thanks you in advance.

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RDR

#45316

SnPbAg solder paste at reflow oven | 21 November, 2006

nope, but why such a high reflow temp for lead paste?

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JAX

#45317

SnPbAg solder paste at reflow oven | 21 November, 2006

I assume you are talking about Sn62Pb36Ag2 solder. You should not see any added concerns when subjecting Sn62 to multiple reflow cycles as compared to Sn63.

As compared to Sn63Pb37:

Reduced leaching issues Increased Wetting due to lower surface tension Higher Yield / Ultimate strength (Ag3Sn formation) Higher creep resistance

Comparable but lower Thermal / Electrical conductivity

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CK the Flip

#45324

SnPbAg solder paste at reflow oven | 21 November, 2006

It probably depends on the Silver content. We are also using Sn62Pb36Ag2. The paste manufacturer told us that the reason for the small silver content was so that it could wet better to the lead-free component and board finishes bearing silver. 230*C is a pretty common peak temperature for these new, so-called "hybrid profiles" (those profiles designed to get hotter to ensure coaelesence of lead-free component finishes if using SnPb paste).

I'm positive that this solder paste can withstand 2 heat cycles minimum at 230*C (standard double-sided reflow) with no impact on reliability...

If it is just a paste with a small silver content like I describe above, I wouldn't subject the board to more than say....4 heat cycles. That's probably where you'd have the reliability concern, as extended heat cycles can accelerate excessive IMC formation. But...the best people to ask about this would be your paste manufacturer.

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brodalvin

#45340

SnPbAg solder paste at reflow oven | 22 November, 2006

Thanks a lot for the responses...��

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Reflow Oven