| I am looking for some guidelines on evaluating solder paste. I am specifically interested in No-Clean Pastes, as they are a completely new ball game when it comes to slump, tack time, stencil life, tack time, etc. | Thanks for any and all help given Yo Phil, Zarrow's really good. His article gets into it pretty well. One thing you do have to consider though is what type of surface finish you have and whether or not you want to run in an inert atmosphere. Also, are you looking for good testability or testability at all. If you are working with surface finishes other than HASL, you need to focus on your activity. The flux needs to break down the OSP, Gold, Silver, whatever. Look at wetting for this test. When you address testability, you need to think about your probes. Some residues are plastic and some are hard. Your nails need to be able to penetrate this coating and make good contact. If this parameter is overlooked, you could see a lot of false failures. The problem with the low residue pastes is they need an inert reflow atmosphere to work properly. Bang, more cash down the drain for nitrogen and good luck if you're not already plumbed for it. food for thought. Regards, justin medernach
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