Electronics Forum | Mon Mar 27 20:52:22 EST 2000 | Dave F
Marc: In printed circuit board fabrication, fabricators place sheets of prepreg between each pair of glass cores. They stack these layers into books. As they heat and press the books, the sheet melts into an epoxy glue. The thickness of the prepr
Electronics Forum | Mon Mar 27 21:25:01 EST 2000 | Dave F
Pete: Two angles on your question: 1 Yes, the layout of your board can affect the level of bridging you see. 2 That aside, the set-up of your machine also can affect the level of bridging on your board. Shaw, I could set-up your machine to bridge i
Electronics Forum | Tue Mar 21 20:36:11 EST 2000 | Dave F
Armin: Boca makes some good points about release. So, let me spin this up from a different angle ... SM-782 suggests "full radius corners" as an alternative to the more familiar square corner pads on PLCC, TSOP and QFP. We see both also. We thin
Electronics Forum | Thu Mar 23 20:31:45 EST 2000 | davef
Hey Cartman: Recently, I was over at a plant that does ICT on RMA fluxed boards and asked them about flux residue on test probes. The test machine operators: * Think flux residues are a pain in the gluteus maximus. * Change probes (from a collectio
Electronics Forum | Wed Mar 15 20:28:17 EST 2000 | Dave F
Armin: Locating vias within the courtyard of components is bad practice. Concerns are: * Poor solder paste print quality, caused by the via preventing good stencil gasketing. * Poor component reflow, caused by the via holding the component out o
Electronics Forum | Thu Mar 09 20:48:30 EST 2000 | Dave F
Van Hoang: Welcome to SMTnet!!!! Regarding your problems: 1. Cleaning glue: Check the SMTnet archives. For instance, a recent thread was: cleaning glue off of stencils - pr 13:41:43 03/03/2000 2. Bridging on the wave: Bridging on the wave h
Electronics Forum | Wed Mar 01 17:13:15 EST 2000 | Dave F
Sorin: Formulas for calculating heat dissipation of traces don�t seem to provide practical results. But there are some wonderful tables and graphs that will meet you needs. You may need to do some finagling when calculating vias and through holes,
Electronics Forum | Wed Mar 01 17:03:56 EST 2000 | Dave F
Steve: Someone is trying to trick you. He/she is trying to be very smart, but he/she didn�t anticipate this "dark haze" coating problem. I suspect that this person is someone you speak with every day in your plant. They may be the one that came-u
Electronics Forum | Thu Mar 02 21:24:27 EST 2000 | Dave F
Glen: As I mention in an earlier response in this thread, I think someone at Steve's plant (or may be in his packaging spec for the fabs) is doing something to leave a residue, but I'm also thinking solder mask ... ENIG can be applied before or aft
Electronics Forum | Fri Feb 25 16:06:51 EST 2000 | Dave F
Istv�n: Given a choice, I�d run second side PLCC44s at 90� to the wave. As far as thieves are concerned, I�d have two, mirror images of each other. Unlike most, these thieves are not connected to pads. They are out-side of the last pad on the sid
