Hi TechNet! Dennis - just to add to Hector's comments: if you are using the same solder alloy and only the form changes (solder paste versus solder preform) then having solder joint problems with only one of the solder "form" choices is an indication that your processing is suspect. Processing could be reflow method, handling, flux, temperatures, etc - all relating to process type variables. Take a look at those things rather than spending lots of time chasing solder alloy questions. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: General Soldering Author: [log in to unmask] at ccmgw1 Date: 5/12/97 9:43 AM Dennis, What your are getting is more voiding in the solder paste than in the solid solder. I would suggest you xray your samples, and assure you minimize the voiding. I think you may find out that the solderpaste is much more sensitive process. Hector Valladares [log in to unmask] Honeywell Space Systems 813-539-3683 Subject: GEN: Soldering Problem Author: [log in to unmask] at internet-mail Date: 5/12/97 8:49 AM I have a customer that states that they solder a silver tab to a solar cell with Sn95 5Ag and that when thermal cycling the resistance of the joint goes high. The resulting voltage drop is unacceptable. The customer states that the drop is due to a change in the resistance in the solder joint. When the tab is soldered with a preform the problem does not occur. Only when soldered with solder paste. The thermal cycle is +150 to -170 degrees C. The problem occurs when cold. Any suggestions? Thanks to all!! Denis Meloche Technical Sales Engineer Heraeus Cermalloy Division 24 Union Hill Rd West Conshohocken Pa., 19428 610-825-6050 Fax 610-825-7061 E-Mail [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] * ***************************************************************************