Jim, In addition to some of the other responses, I agree with those who say use elongated stencil apertures over the solder mask, this has worked very well for me in the past, and most of the newer pastes I've tried this with have fairly descent "wick-back" properties. After doing the calculations per Phil's directions, I would suggest using a test pattern and trying apertures larger then the calculated, to optimize paste volume and to learn where the max size is, since there is a fine line that will start to produce solder balls with too much paste. I would also suggest slowing down the print speed and increasing pressure slightly to help fill the holes (assuming metal blades, rubber blades you will be defeating the purpose (scoop-out)). Having the blades at an angle <45 degrees has also shown improvement, but you may not need to go to this extreme. You have the right ingredients with minimized lead protrusion. If the board is .062" thick, you should be able to achieve good results. Of course, the thicker the board, the more paste volume needed and the tougher to get 100% fillets. Good Luck Jeff Hempton United Technologies Electronic Controls ______________________________ Forward Header __________________________________ Subject: [TN] Pin-in-paste for 50 mil part Author: Jim Gryga <[log in to unmask]> at Internet Date: 12/15/98 2:03 PM Hey Techhies, Is there any body out there using pin-in-paste (intrusive reflow, whatever you want to call it) on parts with a lead pitch of 50 mils? I have a 38 pin and 30 pin 50 mil pitch through hole right angle header I need to solder on a double reflow board. I can't slelective wave solder because they sit on right angles to one another (I'm sure one would have solder bridges), I don't want to hand solder because of the added cost, and I prefer not to use a fountain solder (we've had bridging and insufficient hole fill fountain soldering other 50 mil connectors). The pth diameter is about 0.022". The leads are 0.015" square. There is minimal lead protrusion through the board, about 0.025". We've done some experimental p-i-p boards with a 6 mil stencil but only acheive acceptable (75%) hole fill on about 50% of the connections. We also tried 0.025" holes with worse results. I have 20 mil QFP's on the same side as the connectors so I'm hesitant to go with a thicker stencil. Next step will be to try a step down stencil. If you have any experience or recommendations on stencil aperture configurations, stencil technology, paste types, etc., etc, I'm all ears. Jim Gryga ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################