Electronics Forum | Mon Aug 23 13:59:18 EDT 2010 | swag
Under a scope, make sure the PCB has soldermask between pads.
Electronics Forum | Thu Aug 12 20:17:12 EDT 1999 | Kelly Morris
| Hello | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | 100 durometer blade. Getting "tails" on deposi
Electronics Forum | Sun Sep 09 10:53:05 EDT 2001 | bentzen
For reflow soldering, you are correct ! The higher surface tension of the solder paste in nitrogen atmosphere can increase the number of solder bridges if the component or solder paste print is inaccurate. Another defect that might increase is tomb
Electronics Forum | Fri Aug 13 12:52:17 EDT 1999 | Steve Schrader
| Hello | | Having a problem with bridging on 20mil pitch qfp, only on the lead groups where squeegee goes over width of apertures. Using MPM sp-200 semi-auto, chem-etch stencil, 9-10mil width opening | 100 durometer blade. Getting "tails" on deposi
Electronics Forum | Mon Aug 23 03:12:57 EDT 2010 | grahamcooper22
Possible route causes of bridging on fine pitch ICs are; too much paste (stencil aperture wrong), poor print quality (paste smudges during printing), pcb pads not flat depending on the solderable coating, paste has poor cold slump properties, too muc
Electronics Forum | Mon Aug 23 14:09:56 EDT 2010 | davef
Similar to Coop's comments, above ... Bridging: * Mis-placement: misplaced components, high placement force mushrooms paste * Too much paste: HASL thickness, lead finish, poor underside support, poor underside wipe frequency, printing with too lar
Electronics Forum | Mon Aug 23 17:43:18 EDT 2010 | davef
SAG: Questions on solder mask webbing with fine pitch parts are: * What is the minimum pitch that you can use webbing between fine pitch pads? * What solder mask do you use?
Electronics Forum | Wed Sep 01 08:05:28 EDT 2010 | sachu_70
Solder mask between pads in case of fine-pitched device footprint may not be a practical solution to implement. Cheers !!!
Electronics Forum | Tue Aug 17 10:41:13 EDT 1999 | Steve A
Wayne, Sounds like a gasketing problem. When the horizontal apertures are bleeding but not the vertical apertures. Could be poor underside support, HASL miniscus issues, masking or plugging issues, but what many people do not account for is that t
Electronics Forum | Fri Sep 07 08:57:28 EDT 2001 | Hussman
Por, You talking wave solder or reflow solder? At wave, nitrogen is the way to go. Just like you stated, it does affect the surface tension. If you're reflowing, I wouldn't go nitrogen unless you have to. Improper stencil design is usually the c
