Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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SMT electronics assembly manufacturing forum.


lead free for multiple reflow process

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#51752

lead free for multiple reflow process | 11 September, 2007

We are testing SAC paste for thru-hole components in the 2nd reflow process. The solder joint is alright but some problem encountered in FR1 or CAM2 PCB after multiple times of reflow due to the temperature. We are very interested in Zn or Bi-based lead free for 2nd reflow purpose but not so sure about the SnZn or SnZnBi alloy performance. (Rarely heard of people use for PCBA in the industry)

We are thankful if you have any information or experience regarding the Zn or Bi-based lead free.

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#51783

lead free for multiple reflow process | 13 September, 2007

While you're waiting for others to respond, here's one take on bismuth in lead-free soldering [ http://smt.pennnet.com/Articles/Article_Display.cfm?Section=Articles&Subsection=Display&ARTICLE_ID=229915 ] by a long term friend of SMTnet. Find more by searching the web.

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#51883

lead free for multiple reflow process | 23 September, 2007

I presume you are looking at low melting point solders. Firstly, I would consider running BOTH sides with the same paste - this will cut down the opportunities for a mix up with rework or retro-fit. Secondly, check that there is a cored wire available for that particular alloy for rework or retro-fit, otherwise you will have to train your people in the old fashioned application of flux using a brush or dipping etc.

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