All, Beware plugging vias that have solder inside them. No matter how good the plugging and overlying soldermask job, during reflow the underlying solder will expand as it heats. When the solder hits liquidous, the pressurized fluid can force a jet of molten solder through any point of thin coverage due to misregistration or pinholes, leaving either solder balls or solder strings . I have seen microscopic "wires" of solder that have been extruded through pinholes as the pressure of the molten solder forces it out. These strings can be longer than 0.100" and are virtually invisible to the naked eye. If you must plug vias, do it in direct contact with the base metal. ---------- From: [log in to unmask] To: [log in to unmask] Subject: via plugging Date: Wednesday, June 11, 1997 7:46AM I'd recommend you fill them with solder if you can. Coating can be used, but its best if you do this AFTER a protective coating is applied to the board like Hot Air Solder Level (hasl) or on a patern plated board (SnPb plated) from which you DO NOT strip the Sn Pb . See my other append about solutions getting trapped in the vias. If at all Possible DO NOT Plug/Tent/Fill vias with anything other than a solder like material that fills them 100% of their depth. hope that helps Jim Herard IBM Microelectronics Quality Engineering [log in to unmask] ---------------------- Forwarded by Jim Herard/Endicott/IBM on 06-11-97 08:39 AM --------------------------- suixin @ elis.rug.ac.be 06-10-97 03:59 PM Please respond to [log in to unmask] @ internet To: TechNet @ ipc.org @ internet cc: Subject: via plugging Hello, everybody I want to get some information on via plugging technology. In my work, the plated through vias are 1.6mm deep and 300 micron in diameter. I have to plug them before further processing. Any input will be greatly appreciated. Thanks in advance. suixin zhang ELIS-TFCG/IMEC, University of Ghent Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium tel: 0032-9-2643371 fax: 0032-9-2643594 Email: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************