PB-Free HASL and Leaded Solder

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Want to update this question a little, I know it appears few... - May 13, 2021 by Andrey_F  

With Pb-Free HASL you can't use Pb process for sure as the m... - May 13, 2021 by Evtimov  

Yes, we can't use pure Pb PROCESS. And as I say we will not ... - May 13, 2021 by Andrey_F  

Not following the lead paste process window has a whole set ... - May 14, 2021 by Evtimov  

SAC305 Will be the best choice with minimum TAL, Maximum Soa... - May 20, 2021 by jinesh  

Andrey_F

#86629

PB-Free HASL and Leaded Solder | 13 May, 2021

Want to update this question a little, I know it appears few years ago, but I hope there is some updates...

We have to assembly few samples of motherboards with this kind of finish (customer mistake during pcb order). Normally we can use leaded solder paste and alloys for this kind of jobs, but normally we have ENIG, OSP or ImSn finish on boards like this.

Based on your expirience what kind of solder paste better to use with this finish? Leaded or Lead-Free? If Lead-Free - SAC type or SN 100C?

What kind of problems shoud we expect using SnPb solder paste, especially for reliability? If leaded solder paste will be used - anyway we will have peak temperatures for lead-free alloys, couse we have BGA and LGA sockets with SAC ball leads, but what we will have with IMC and solder joint structure - will finish alloy be normally dossolve in it?

Thanks for any comments!!!

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Evtimov

#86633

PB-Free HASL and Leaded Solder | 13 May, 2021

With Pb-Free HASL you can't use Pb process for sure as the melting point of tin is so much higher than the lead paste process. SAC305 is the most popular compound, unless your assembly requires something else for a specific reason.

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Andrey_F

#86638

PB-Free HASL and Leaded Solder | 13 May, 2021

Yes, we can't use pure Pb PROCESS. And as I say we will not use it anyway, as we have lead-free BGA's, LGAs, component with Solder Charged Terminations... It's became almost normal practice to solder it with leaded solder pastes. In this case peak reflow parameters will be like for lead-free process. Yes, HASL have higher melting point then SAC305 for example, but anyway temperature on board surface will be about 240 deg. and higher in peak, so the HASL finish will melt.

Actually the request to use SnPb paste is coming from customer, and I'm looking for additional argues to convince them to use lead free solder paste.

That's why I wondering does anyone have an expirience with combination of Lead-Free HASL and leaded alloy? What was the result?

As my colleague said - these process guys are allways looking for how to clean what is no-clean, how to solder with lead what is lead-free...)))

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Evtimov

#86646

PB-Free HASL and Leaded Solder | 14 May, 2021

Not following the lead paste process window has a whole set of risks for joints quality and reliability.

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jinesh

#86672

PB-Free HASL and Leaded Solder | 20 May, 2021

SAC305 Will be the best choice with minimum TAL, Maximum Soak Solder Profile. Surely your solder Joint strength also will be more reliable & This can pass any kind of reliable Tests.

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