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Lead Free Alloy

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#52360

Lead Free Alloy | 7 November, 2007

Although greatly publicized and many papers on the subject, I wish to hear experiences from the field from professionals who have migrated from SnPb wave soldering to PbFree wave soldering. I am being pushed by one of my largest clients, an international french company, to comply with European RoHS laws as soon as aprill 2008. I am a small company that can�t afford an expensive trial and error migration to lead free, looking for the correct alloy to switch to. I would appreciate input form companies that use the Sn99.3% and 0.7Cu % lead free alloy, in the long term �is it the best option? the alloy with Ag is very expensive, I�m sure it must be a better choice, but tin whiskers are my concern, besides higher temps and all, I don�t wish to have problems with my products in a few years...

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#52376

Lead Free Alloy | 7 November, 2007

I can't answer for wave, but we tried some Sn100 paste for reflow, and couldn't get it to work worth a darn. I then got some SAC305, and was relieved to see it work almost as well as SnPb at its best! Much better wetting and flowing to the various component platings and the board. I imagine a big tank of SAC305 would be really expensive, though.

Jon

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#52393

Lead Free Alloy | 8 November, 2007

SN100C is popular for wave soldering:

http://www.nihonsuperior.co.jp/english/products/leadfree/

Its good for Pb Fee solder finish for HAL on PCBs too. Wave solders better than gold finishes.

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#52406

Lead Free Alloy | 8 November, 2007

Ok, thanks for the input.

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#52426

Lead Free Alloy | 9 November, 2007

By and large, the industry has determined that SAC alloys are the "best fit" for replacement of SnPb in our industry. SAC305 seems to be the default alloy at this time. There are several other alloys out there, each with their own strengths and weaknesses. The Sn100C is a viable option, but several studies I have seen make me wary of the long term reliability concern you expressed. Alpha SACX0307 is another viable option, with a need to have a supply of "pellets" on hand to replenish the "X" component upon occasion. Sn100C has this same issue also, (replinishment of "trace" elements within the alloy), but (at least in my experience), the Alpha pellets are at least readily available. Both will have a cost of about 30% below the cost of SAC305 if you negotiate. The SnCu alloys I have worked with have experienced production issues etc...and seem to be replaced fairly quickly with one of the three I have mentioned above.

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#52435

Lead Free Alloy | 9 November, 2007

Smt paste= SAC305 Wave Solder= SN100C no real problems with either of these. good luck

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#52436

Lead Free Alloy | 9 November, 2007

Don't forget that leadfree solder can leach the iron out of old solder tanks. Make sure yours is compatable with leadfree solder. You don't want the tank disolving, unleashing a tidal wave of molten solder.

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#52443

Lead Free Alloy | 9 November, 2007

We are using SAC305 for reflow and SN100C for our selective solder.

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#52498

Lead Free Alloy | 13 November, 2007

We use SAC305 for solder paste, and we have been pretty happy with it. When we jumped in to this Pb-free business I was a little nervous due to all the horror stories you hear about the process changes. It's not that big of a deal (at SMT).

Over at the Pb-free wave my company uses Metallic Resources Cobalt 995, which is another alloy similar to SN100C. I'm not the Wave Master where I work, so I can't tell you if it's great or not. The Wave Master we had was pretty happy with it, but he up and quit. If there are any Wave Masters in south central Wisconsin, USA looking for work, send me an email.

I don't think anyone here is going to be able to tell you that if you pick a certain alloy you won't have long-term reliability issues. I don't think anyone here knows that.

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#52499

Lead Free Alloy | 13 November, 2007

Thanks to all of you for the positve input, I understand that my best option, after reviewing opinions and certain studies, that SN100C is adequate for wave and SAC305 for SMT. Thanks again.

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#52507

Lead Free Alloy | 13 November, 2007

I have been using sn100c for over a year now on our wave solder process and I am plenty satisfied so far. The secret for success with this alloy is to have your solder pot near 270 celsius and your dwell time has to be near 4 sec and your temperature on top of the pcb has to be near of 100 celsius at the wave entrance. Apply and you will get great results.

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