We did the board in two reflow cycles. Print, place, dispense, place reflow. Dispense, place, dispense place reflow. A three high stack is more common, one reflow. Just make sure the convection fans are on low, and the parts are very solderable to start. A tombstone or drawbridge ruins your whole day. Though the speed is a few Ghz the devise on the opposite side of the board is digital. Remember when we used to think a 10Mhz clock was really fast? I had a DELL 286 with 8 to 12.5 Mhz clock that, according to PC Mag, was fast enough to burn sand off the desert floor. Guy -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez Sent: Wednesday, March 03, 2010 6:09 AM To: [log in to unmask] Subject: Re: [TN] Unusual Assembly Requirement... What was the total number of reflows? Vic, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Tuesday, March 02, 2010 2:39 PM To: [log in to unmask] Subject: Re: [TN] Unusual Assembly Requirement... Hi Jon, Yes these are individual caps, each layer is a different value. The board was screen printed and the bottom layer was machine placed. The next layer was done by hand dispensing solder paste on each cap termination, and then hand placing the second layer caps. The board was then reflowed. After reflow, paste was again hand dispensed on the second layer caps terminations, the third layer caps were hand placed, and then solder paste was hand dispensed on the third layer caps termination. Finally the fourth layer caps were hand placed, and the board sent back through reflow the second time. We needed to do it in two reflow steps otherwise the stacks would have toppled over into each other... Steve -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon (SA-1) Sent: Tuesday, March 02, 2010 3:04 PM To: [log in to unmask] Subject: Re: [TN] Unusual Assembly Requirement... Steve, these were all individual caps? We have used double stack caps that were manufactured that way. It just looks fragile. Jon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Tuesday, March 02, 2010 1:52 PM To: [log in to unmask] Subject: [TN] Unusual Assembly Requirement... Hi All, I came into work today and saw something that I've not seen before. Keep in mind that the area shown is about ½" square, and that these are 0402's... http://stevezeva.homestead.com/files/Quad_Stack.JPG This was done using two reflows, and the caps were not touched by a soldering iron. You may ask why. It's because it's what we were asked to do by our customer. We have a very talented lady working on the production floor who accomplished this. Steve ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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