You could develop a profile with a 20 second excursion from 200 through 205 and back and stay above 180 for a minute. It would be a ramp up and down at about .5 degree per second. 205-180=30 30x2=60 205-200=5 and back 5x2=10 10x2=20. But, what happens to the parts on the board that are difficult to heat? That part may have to be hand soldered. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Lance Mayes > Sent: Tuesday, June 22, 2004 5:15 PM > To: [log in to unmask] > Subject: [TN] Reflow Profile(Temperature and Times) > Importance: High > > Technetters Hello again; > > We are having a problem with a Token crystal oscillator. > During the month of April there was a fallout spike of plus > 10% from testing in manufacturing. The supplier was > contacted and some defective components returned. After > their evaluation they indicated that the components were > damaged due to over-heating. They attached a copy of the > desired temperature profile we should be using. > > We ran the mole through the oven and came up with the real > profile (note, the thermocouple was attached to the body of > the resonator). They are having trouble actually > interpreting the wording of the spec, especially when > compared to the recommended profile for the solder paste. > > The component spec has a cautionary note as follows: > "Heating conditions shall be within 20 seconds at +230 deg C > min, but peak temperature shall be lower than +240 deg C. > The profile figure shows a breakout above +200 deg C and > states the maximum time above 200 should be 20 seconds. The > two statements together seem confusing and we are asking for > some clarification. > > To add confusion to the issue the solder paste spec: > Qualitek 670I No-Clean Paste (Sn63/Pb37) shows a recommended > profile for reflow of Minimum Temp 205 deg C ranging from > approx. 180 deg C with a minimum time of 60 seconds. Again > it appears using this paste we cannot meet the component > reflow profile? > > We then looked at our current profile and found the following: > > We are above 200 deg C for about 45 seconds, the peak > temperature is 218 deg C. > > Any help/comments would be appreciated. > > > > > P. Lance Mayes --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------