On Sunday 10 May 2015 05:08:08 Erik Christiansen wrote: > On 09.05.15 23:21, Gene Heskett wrote: > > > As far as I can tell the best selective soldering machines use a > > > solder fountain. > > > > That I am not at all familiar with. > > A static solder bath may be used to solder one connector or one chip > to a board, but the production-line "solder baths" I'm familiar with > feed boards through on a conveyor, preheat with infra-red lamps, then > the board slowly traverses a centimeter above a bath of molten solder > with a board-wide rectangular tube protruding a millimeter. As the > board approaches, the solder pump starts, and a wave of solder > fountains, striking the underside of the passing board. It gives > complete through-hole solder penetration in half a second. More > importantly, I guess, the inevitable surface oxide dross is entirely > absent from the wave, having instantly slid to the surrounding lower > pool. That pretty much eliminates solder bridges, so long as the board > is fed > perpendicular to the rows of chip pins. We always laid them out one > way, to make that easy, and simplify chip insertion. (Dunno what the > rules are for SMD)
I had visions of something like that, but the board wide nozzle hadn't crossed my mind yet. Thanks Erik. > > I think that the operator skimmed the bath now and then, but on my few > escapes from the design lab to the factory, boards just went through > on their own, at a steady pace. (Up to "double-euro", which is 220 x > 160 mm, IIRC. So a modest sized bath.) I assume the tank of hot solder would only have to be a narrow one as long as it was as long as the board was wide. I throw a few bullets out of wheel weights now & then for use in my Ruger Old Army, dross control in the pot is a PITA. > Erik Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
