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Thiourea exposure in manual soldering of immersion tin PCBs

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#72170

Thiourea exposure in manual soldering of immersion tin PCBs | 1 June, 2014

Hello to everybody in this forum,

I would like to know any information that you kindly may have about the following subject:

We very often do manual soldering assembly of immersion tin finished PCBs. Since thiourea is used in the formulation of the immersion tin plating solution, I have big concerns about health safety exposure of manual soldering operators. Does thiourea reacts in any form (maybe volatiles are released) with the heat produced by the soldering iron in manual soldering?

Thank you very much for any kindly information you may provide.

Regards.

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#72171

Thiourea exposure in manual soldering of immersion tin PCBs | 1 June, 2014

Eurolanders and Asians are the primary users of immersion tin. In the US, the use of immersion tin is restricted due to the concern over the thiourea that used in tin plating process. Thiourea is a suspected carcinogen.

I’m inclined to say, “aww, assemblers don’t need to concern themselves with a board fab process material, but then again, you just never know … " Triourea MSDS: https://www.fishersci.ca/viewmsds.do?catNo=AC220050010

BR ... davef

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#72172

Thiourea exposure in manual soldering of immersion tin PCBs | 1 June, 2014

Thank you for your reply davef.

Although the US restriction, I think that there are plenty of users of immersion tin in Americas, mainly low-volume fabs that do not plan to outsource finishing, or do not plan or can not invest in a HASL.

If we restrict use of all hazard potential chemicals, we should back to cave age then (but please understand that I do not want to start a discussion battle about ROSH, WEEE, regulations, conformals, etc. and similar subject matters here).

The doubt presented here is simple and specific: do you have some information about thiourea decomposing and maybe volatiles released with heating from soldering iron in manual soldering assembly of immersion tin plated PCBs?

Thank you very much.

Regards.

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#72174

Thiourea exposure in manual soldering of immersion tin PCBs | 2 June, 2014

I've never heard of anyone affected by thiourea during assembly soldering operations. I believe the greatest concern of exposure to thiourea is during the board fabrication process.

BR ... davef

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#72176

Thiourea exposure in manual soldering of immersion tin PCBs | 2 June, 2014

Thank you so much again davef for your new reply.

This past weekend I was looking for more information regarding this subject, but, as you stated there is no information about thioruea concerns during assembly soldering operations, mainly focused into manual soldering operations.

Also, the same question arise to me in the case of OSPs. Since Benzotriazole and Benzimidazole are aromatic compounds, I wonder if the thin molecular OSP layer gets decomposed and hazard volatiles are released to human operators when manual soldering is used.

Should I open a new post thread for this question about OSPs? I do not want to disobey forum rules, or spread different themes in a single post.

Thank you very much for any information you may provide.

Regards.

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#72177

Thiourea exposure in manual soldering of immersion tin PCBs | 2 June, 2014

I believe that you get better responses when you start a new thread, but that's just an opinion, not a rule.

BR ... davef

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