Joe Phil Zarro [[log in to unmask]] and Bob Willis [www.bobwillis.co.uk] are two of the people that has have written articles on the topic. Check their sites. Dave Fish ----- Original Message ----- From: "Macko, Joe @ IEC" <[log in to unmask]> To: "'TechNet E-Mail Forum.'" <[log in to unmask]>; "'David Fish'" <[log in to unmask]> Sent: Monday, June 30, 2003 5:57 PM Subject: RE: [TN] Double-sided reflow with Altera RQFP... > Dave, > > Interesting calculation. I have never seen the numbers worked out. Is this > calculation and your ratio documented in a reference book or something? > Does the formula also apply to BGAs? > > Some of our new designs have BGAs on both sides which I am evaluating. > > Look forward to your reply. thanks > > joe > > -----Original Message----- > From: David Fish [mailto:[log in to unmask]] > Sent: Monday, June 30, 2003 1:38 PM > To: [log in to unmask] > Subject: Re: [TN] Double-sided reflow with Altera RQFP... > > > > Hi Steve > > > We don't double reflow this part. We wouldn't consider it without a fixture > or some other support. > > > You know that sound, the almost involuntary sound that patrons in a > restaurant make when a waiter drops a glass or a tray? It's kind of an > "oooooo" sound. Well if you run these parts, the sound that the troops at > your plant will make will be so loud as those pups start Peter Panning to > the floor that the people in the front will stop playing games on the > computer and walk out back to find-out what's going on. > > > Do the numbers: > * Part weight: 15.1 gm > * Lead toe to heel: 0.46/0.66 mm > * Lead width: 0.17/0.27 mm > > > Lead wetting area = 240* [0.46*0.17] mm^2 = 18.7 mm^2 [0.03inch^2] > Weight of component to total pad mating area ratio: 15.1 gm / 18.7 mm^2 = > 804.6 mgm per mm^2 [519.1 gm per inch^2] > > > A commonly acceptable ratio is: 50 mgm per mm^2 [30 gm per inch^2] > Pushing the boundary ratio is: 44 gm per inch^2 > > Dave Fish > > ----- Original Message ----- > From: Steve Gregory <mailto:[log in to unmask]> > To: [log in to unmask] <mailto:[log in to unmask]> > Sent: Monday, June 30, 2003 8:42 AM > Subject: [TN] Double-sided reflow with Altera RQFP... > > Mornin' All! > > Just a quick question, has anybody ever done a double-sided reflow with a > 240-pin Altera RQFP on the bottom that has a metal heatsink in the top? > > Thanks! > > -Steve Gregory- --------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8e > 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/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > ----------------------------------------------------- > > > --------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8e > 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/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > ----------------------------------------------------- > > > --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------