On Sunday 10 May 2015 22:40:58 Peter wrote: > Surface mount is predominately done in relow ovens. There are not a > lot of throgh hole components that are designed for the reflow > process. Also appling the solder pate is problematic. There are > through hole connectors that are designed for reflow ovens. The paste > stencils have larger opening for the through hole parts so that enough > paste is applied. Also the hole size for the through hole parts > becomes more critical. I have done it on one of my boards where I was > using a DIP8 through hole socket. Works OK. > > The KISS machines are designed for through hole parts only. > > I had a chance to purchase a benchtop vapour phase solding machine but > wasn't quick enough. It's a very simple process. The machines use a > liquid (expensive) that boils at 235C. The process is to heat the > liquid to the boiling temp is a container until the vapour fills the > container. There is a cooling coil at the top of the container that > condenses the vapour if it rises too high as you don't want it to > escape.
Might that be Safflower oil? It has a quite high flash point, and I have used it in a misting system while carving alu. It does extend tool life considerably by blocking the alu's acess to oxygen in the air, slowing the alox formation that eats even carbide tooling. Disadvantage of that was that I had no vapor removal system, and the 2 oz of oil used filled the building with such a fog that it took considerable cleaning to remove from my glasses. And I didn't want to think about what it might be doing to the efficiency of my lungs! Doing a board by lowering it into the hot vapor would rapidly bring the board to the vapor temp by the vapor condensing on the board, and would be pretty uniform. But I'd not hazard a guess as to the effects of the oil on the solder pastes predeposited. In blocking oxygen access as it condensed on the boards components it would enhance the activity of the rosins in the paste, potentially makeing a very good "gas tight" joint. But would the hot oil also degrade the resins in the solder paste. IDK. > The PCB is then lowered into the vapour. The PCB is then heated to the > vapour temperature. The advantage of this system is that unlike > infared reflow, larger components don't end up as a heat sink causing > uneaven temperatures across boards components. > > I know guys who have made vapour reflow maching with a 5 gallon drum, > PID heater along with a cooling coil wrapped around the top of the > drum. I've never tried it though. The amount of energy needed to achieve that vapor would indicate a need for some decent insulation around the bucket, but if the cooling coil did its job, and running water from the cold water faucet would do for that I'd think, you wouldn't need that much oil, half a cm in the bottom, so heating time to operating temps could be fairly short. Maybe a minute a board, you could have 100 boards ready to go and do them in under 2 hours one at a time. Several in a wire basket a bit smaller than the bucket would speed that up. 8 up maybe for a small board? Washing the oil back off the board would take some aromatics, alcohol for instance. That would also remove the rosins from the paste, leaving it very clean indeed. Food for an experiment? > Cheers, > Peter > Peter Homann > http://www.homanndesigns.com/store 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
