At 08:42 AM 3/3/2010, Guy Ramsey wrote: >We did the board in two reflow cycles. >Print, place, dispense, place reflow. >Dispense, place, dispense place reflow. On PURPOSE? >:-} R&D Circuits, Crack dealers to the Semi-conductor ATE designer. >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. >For more information please contact helpdesk at x2960 or [log in to unmask] >______________________________________________________________________ > >--------------------------------------------------- >Technet Mail List provided as a service by IPC using LISTSERV 15.0 >To unsubscribe, send a message to [log in to unmask] with following text in >the BODY (NOT the subject field): SIGNOFF Technet >To temporarily halt or (re-start) delivery of Technet send e-mail to >[log in to unmask]: SET Technet NOMAIL or (MAIL) >To receive ONE mailing per day of all the posts: send e-mail to >[log in to unmask]: SET Technet Digest >Search the archives of previous posts at: http://listserv.ipc.org/archives >Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 >for additional information, or contact Keach Sasamori at [log in to unmask] or >847-615-7100 ext.2815 >----------------------------------------------------- > >This communication is intended only for use by the addressee(s) named herein >and may contain business confidential and/or legally privileged information. >If you are not the intended recipient of this e-mail, you are hereby >notified that any dissemination, distribution, disclosure or copying of this >e-mail and its contents is strictly prohibited. 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