Rob, I would be similarly confused if your vendor was actually printing solder paste onto the fiducials during assembly. Here's my view of how fiducials should be used during assembly. Fiducials are features that are etched onto the board during the same process that creates the SMT features where you are placing components. These will allow you to compensate for any individual dimensional error when printing paste or placing components by adjusting the offset from "virgin" cad data on a board by board basis. If you are using a screen printer that has a stencil alignment system, you should half etch the fiducials into the solder paste stencil, so that you can align the stencil to the board. Here's where I see a problem starting with the scenario you describe. If you print solder paste onto the global fiducials, your pick and place equipment will be aligning to the error of your solder paste printing operation, NOT to the error of your board fab process. Sorry for the long winded response, that didn't directly answer your questions, but I don't think the solder paste should be printed onto the fids in the first place! Hal Winslow Sr Mfg Engineer SCI Systems Hooksett, NH HI, WE HAVE AN ISSUE HERE THAT NEEDS SOME CLARIFICATION. WE'VE BEEN BUILDING FIDUCIALS FOR 4 YEARS NOW THAT HAVE NOT HAD SOLDER PASTE ON THEM (NO RELIEFS IN THE PASTE MASK). NOW OUR VENDORS, (YES THE SAME ONES WHO HAVE BEEN BUILDING THE BOARDS FOR 4 YEARS), ARE SAYING THAT THEY'VE ALWAYS PUT SOLDER PASTE ON THE FIDUCIALS. THE FIDUCIALS IN QUESTION ARE GLOBAL BOARD FIDUCIALS. MY QUESTIONS ARE; 1. WON'T THE SOLDER PASTE, (PRE-REFLOW), LACK CONTRAST/REFLECTIVITY? 2. WHAT PURPOSE DOES SOLDER PASTE SERVE ON THE FIDUCIAL? THANKS, ROB ROBERT BUTTERWORTH CAD DESIGN ENGINEER<-----WHAT THE HELL IS THIS? ADC BROADBAND COMMUNICATIONS 11 FAIRFIELD BLVD WALLINGFORD, CT 06492 203-630-5755 [log in to unmask] ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################