> > All, > > Does anyone have any data on the relationship between solder balls (no > > clean flux w/ N2) and various solder masks? > > Some of our lines run OK and some do not for the same mask. The hard > > part to understand is that a mask will run poorly on one line and OK on > > another. My feeling is that the mask is statistically significant, but > > not necessarily the major contributor. All DOE have shown no sweet spot, > > but of course going to aqueous or eliminating N2 have shown positive > > results. > > The other variable that has completely eliminated solder balls is to > > shorten leads to ~.080". This went over poorly with the connector > > people. > > Any help would be appreciated. > > Steve Joy > > [log in to unmask] > > > > Steve, We use no clean technology and had problems early on with solder balls adhering to the solder mask. The company that supplied our soldering equipment did do a lot of work evaluating different fluxes and solder mask finishes. They are Blundell Production Equipment Ltd at Coventry in England; Paul Blundell is the MD and their telephone number is UK 1203 473003. The solder mask surface is important and a smooth high gloss finish will enable solder balls to attach more readily than a micro matt surface. Unfortunately most solder masks today are applied by curtain coat and have a very smooth surface. The solder ball is stuck to the surface of the mask by a small residue of flux. The main emphasis is therefore in finding a flux which will give the least solder balling. The soldering parameters such as pre-heat temperature, solder temperature, and speed through the wave are also important. We use Apple House NC213 no clean flux on a Coates Imagecure XV501TSM solder mask applied by curtain coat and have no problems. Hope this assists you, Paul Gould Teknacron Circuits Ltd --------------------------------------------------------------------------- | EMail [log in to unmask] ---------------------------------------------------------------------------