A few years back (Long, long ago.....) No, just kidding! I've built initial prototypes out of DFSM as high as .004" thick (DryFilm that is). The goal was to have solder paste thickness' to yield a higher volume of reflowed solder. Two problems came up. 1: DFSM is not gaining a lot of popularity lately. Due to many issues. The majority of the parts I see are moving towards LPI. DFSM conforms with the shape of the outerlayer circuitry. This can greatly contribute to gasketing issues during solder paste application. LPI provides higher productivity therefore it is more economical. Some (past) DryFilms are no longer available. 2: LPI provides better image resolution. Finer features are capable. This is associated with the thickness. Most assemblers are controlling that solder paste thickness by stencil thickness. LPI provides a more planar surface for paste application. (Its' applied fully wet as opposed to a (dry) film.) My thoughts anyways...... I'm sure others will join in to. Groovy ______________________________ Reply Separator _________________________________ Subject: ASSY: Solder Paste Volume Author: [log in to unmask] at SMTPLINK-HADCO Date: 10/30/96 10:31 AM Address, Is anyone applying solderpaste to PCBAs with an aperture to stencil ratio of 1.33? I have some .012 pitch QFPs with random opens. The problem is either related to the device handling (bent leads that are not visual or automatically inspected prior to assy) in the wafer prior to pick and place or the soldepaste volume on the land. Past rules have been to have a ratio of 1.6 or greater, does this still apply? Has anyone used Dryfilm S/M versus LPI to increase solderpaste volume on the lands? Please advise. *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************