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Problems to use lead free paste in PCB with Pb

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#57918

Problems to use lead free paste in PCB with Pb | 30 January, 2009

Dear Sir. Recently we had a problem in our production. We had pcbs with no RoHs (with solder Pb in pads) but we used paste Lead Free. I want to know if we will have problems in this solders in the future, because (perhaps)the solder will be broken, or problems like this. If someone knows a study or links with information about this, please send me. It's very urgent. Thanks in advance. Jos� Luis. Spain.

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GSx

#57920

Problems to use lead free paste in PCB with Pb | 30 January, 2009

Buenas dias Jos�,

It shoul not be a problem. We had situation like that when in the early 2006 the Lead Free fase in Pb fase out, no pbm on solder joints. Today, after about 3 years, those cards are stil working in the field without any defect.

Regards

GSx

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#57922

Problems to use lead free paste in PCB with Pb | 1 February, 2009

The concern about lead contamination of lead-free solder has to with zone refining. For more, look here: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=30315

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#57951

Problems to use lead free paste in PCB with Pb | 3 February, 2009

Hi Jose, such a process is possible, but you need to confirm that the PCB material has high Tg. In additon, you need to re-look solder paste printing parameters and make required changes in stencil apperture design for optimum solder volume. Just a curiosity, is there any special reason for you to consider an expensive consumable like Pb-free paste in your process, where your final assembly is NOT going to be RoHS compliant due to non-RoHS PCB? Do let me know if you need further assistance to evaluate your process.

Cheers ! - Sachin (India)

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#57958

Problems to use lead free paste in PCB with Pb | 3 February, 2009

Hi What is the surface finish you have? Following are true if you have HASL-LeadFree surface. I have had the same problem 3years ago and we did some micro-sectioning for further analysis, still the boards are functioning properly. But you have to take note about thermal profiling and use RSS profile with dual time 10-20Sec(8Zone) at peak. Fine pitch SMDs has to be specially checked for proper wettability.By the way your product shall not be Lead-Free compliant.

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