Mr. Charles Windsor, I love to, but I don't think I can converse in Swedish tongue. And don't they have Swedish language police going around to check everybody speaks Swedish like in Quebec, Canada? Excuseeeee me for this nonsense. I'm getting my head put together in early monday morning... 1. Your first question: No, we have no problem at all with paste release. As per the faxed stencil aperture spec, acute angles are 60' to 65' degrees. I tried 45'degree acute angles with no paste release problem. Fillet radius for these apertures are 130um, 0.005" or 150um, 0.006". Solderpaste release problem is more of the function of stencil aperture aspect ratio, seperation speed of board and stencil, and conditon of solderpaste. I allowed a large process window to eliminate this sort of problem by using the aspect ratio of 2:1(min of 1.5:1), a very slow seperation speed, 180um (0.007") stencil for 1.27mm pitch and 130um (0.005") stencil for 0.65 and 0.5mm pitch, and electropolished aperture walls. Trapezoidal stencil apertures will further enchance paste release. 2. I presume you are still using polyurethane squeegees, sometimes called as "rubber". I dropped using rubber squeegees 4 or 5 years ago. Metal squeegees are the way to go for printing solderpaste. If you must, use a hard rubber saying a durometer of 95 or up and easy on the downward pressure of squeegee. regards Matthew Park >>> <[log in to unmask]> January 9, 1998 10:33 am >>> Mr Park, Feel free to call me Clinton please... I recieved the pages this time thank you very much! When we began trialling different aperture shapes, we actually considered trying a similar shape to the one you have sent me. We were a bit dubious about using this shape for two reasons. 1 We felt a concave angle less than 90 degrees might cause problems with paste release. Do you know what fillet radius is used on these apertures? 2 If the PCB pad is not perfectly level or should paste be trapped under the stencil, we thought it could be possible for the pointed part of the stencil to "curl" or project up above the rest of the stencil. Thus when the squeegee passes over, it could tear the stencil or bend/kink the pointy part (excuse the techno speak!). Have you had any experience with these problems or are there any guidelines to stop this from occurring? Thanks for your help so far! Clinton ############################################################## 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 ##############################################################