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SMT electronics assembly manufacturing forum.

intrusive reflow with OA paste



intrusive reflow with OA paste | 23 May, 2000

Hi all,

I'm would like to try intrusive reflow (pin in paste, paste in hole, etc.) on a connector using WS-609 solder paste (halide free, water-washable). I'm concerned about entrapped flux in the barrel of the solder joints. If there were to be entrapment, will the flux remain active? Could there be any long-term reliability issues if it were to remain active? Changing to no-clean is not an option.

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Travis Slaughter


Re: intrusive reflow with OA paste | 24 May, 2000

Its my understanding that so long as the paste is not exposed to air it is not going to be active, someone else might be more sure about this than I am. Be ready for lots of half soldered leads using this process. Its quick and easy but will not be acceptable unless you have low end build to specs, or plan to resolder the components.

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Re: intrusive reflow with OA paste | 24 May, 2000

Hello Travis I'm going to have to disagree with your evaluation of intrusive reflow. It's not just for low end and,if done correctly, you will not have lots of half soldered leads and touch up will be minimal if at all. I'm sure that others will agree that it is a viable process when used with a suitable assembly. Granted there is and "inspection factor" that can account for a fillet that is slightly smaller than your would expect in a conventional process but it is not a quality or reliability concern. I suggest that anyone considering intrusive reflow search the SMTnet archives for much information. Amp has a paper on solder volume Also search for Phil Zarrow (sorry, I mislaid the URL for this)and Bob Willis. - good luck John Thorup

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Bob Willis


Re: intrusive reflow with OA paste | 27 May, 2000

Many thanks for the name check from John Thorup PIHR can be done very simply and it can provide positive fillets on both sides of the board. I have just finished a line with SDSRS, Simultanouse Double Sided Reflow Soldering thats sodering both sides of the board and the through hole with one pass.

We had problems of bulbus joints on both sides of the board, too much solder so it can be done. In the case of OA, I dont belive the issue of flux still in the bulk of the joint will be an issue to you but I would always run a no clean process.

Best of luck with your PIHR project, its good fun.

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