On Mar 11, 1997 Darrel Daigle wrote: Hello Technetters, I am having a slight problem with the amount of solder on fiducials. This is causing optical recognition problems during the pick and place. Any suggestions, maybe an alternative surface finish. Darrel: Many of the older binary based fiducial recognition vision systems that saw in only black or white have the same problem you describe. The solder "bump" produced by a HASL finish will reflect the light source in random directions causing the vision system to "see" it in a location other than the correct one. The newer 256 gray-scale vision systems are far less prone to this type of error, but that may not help you if you have the older stuff. Masking over the fiducial with LPI (liquid photo-imagable solder mask) has been suggested, or use most other solder masks, for that matter. That's a good option, IF you vision system can read through the mask. Many of the older binary systems can't. Another option is to specify that the fiducial marks be left as bare copper. This will produce a nice planar, unglaring surface that nearly all fiducial cameras will read nicely. This requires an extra masking step during PCB fabrication, but the cost should be minimal, if any. Hope this helps, Larry Morse Celwave RF [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] * ***************************************************************************