HI, YOU HAVE NOT STATED WETHER THIS IS A SMT OR THROUGH HOLE COMPONENT, PRIMARY OR SECONDARY SIDE OR THE SOLDERMASK THICKNESS. THAT HAVING BEEN SAID A GOOD RULE OF THUMB WE'VE BEEN USING FOR YEARS IS NO LESS THAN .025'. THIS ALLOWS FOR A .005" ANNULAR SOLDER MASK CLEARANCE AROUND THE PAD LEAVING .015" SOLDER MASK DAM BETWEEN PADS. DEPENDING ON THE TYPE AND THICKNESS OF YOUR SOLDER MASK YOU CAN GO SMALLER. SOME TIMES GOING SMALLER CAUSES THE SOLDER MASK TO DRAW AWAY FROM ITS SELF, LEAVING A DASHED PATTERN OF SOLDER MASK BETWEEN THE PADS. THERE IS AN IPC SPEC ON SOLDER MASKS OUT THERE, BUT I DON'T HAVE IT READY TO HAND. GARY, CAN YOU HELP OUT HERE? REGARDS, ROB BUTTERWORTH SR PWB DESIGNER ADC VIDEO SYSTEMS 999 RESEARCH PARKWAY MERIDEN, CT. 06455 [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: FAB:ASSY:pad spacing Author: [log in to unmask] at internet-mail Date: 4/18/96 10:26 PM Typically, what is the minimum spacing between printed circuit solder pads that would allow for enough LPI soldermask to prevent bridging for a wave soldering process ? Is there a design guideline that specifically addresses this ? If so, can you point me in the right direction. Any assistance would be greatly appreciated. Thanks