|Ask the Experts|
October 2, 2018
Use of Nitrogen for Hand Soldering
Is there any reasonable way to hand solder without flux to totally eliminate cleaning? Is there such a thing as using nitrogen in a local area while hand soldering?
|Expert Panel Responses|
I am not aware of "fluxless" soldering using metallic solder (not conductive adhesives).
One should consider the other residues potentially on an assembly besides flux residues.
In addition to the elimination of post-reflow residue related product failures, the cleaning of electronic assemblies, while intended for the removal of flux residues, actually provides for the removal of other contamination species. While the emphasis of a cleaning program is flux removal it is important to consider the many other sources of potential contamination.
The purpose of a flux is to reduce oxide and fluxless soldering could involve (a) ultrasonic soldering to scrub the oxide away; (b) forming gas / formic acid to reduce oxide. Ultrasonic hand soldering may be possible without a flux, but will need new equipment and training To a use a flux and eliminate cleaning for hand-soldering:
Technical Manager - Europe
I do not know of such a thing and there are a number of potential problems the main ones are how to prevent the Nitrogen form leaking out an depleting the oxygen and causing asfixiation of the operators. Second is how do you ensure that you have oxide free, contaminant free surfaces going into the soldering process.
Senior Applications Chemist
Ultrasonic soldering has been used without flux for many years, this certainly works with Die attach how ever not sure how useful it would be on standard PCB design (localised damage to other components). You can get Nitrogen re-work pens these should work on PWBs where solder still remains on pads and if there is a good finish on the components. How ever as there would be substantially less solder than would be normal and as the intermetalic would not be guaranteed then it would be difficult to confirm a good joint. To have any form of reliability it would be better to use a flux in conjunction with the solder.
Global Product Champion
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