Speaking dice, you are two top experts on the stage, I take the opportunity to ask you about this one: do you practice the analysis way by backetching the chips and study them from 'underside'? What acidous process is best for GaAs resp. Si? Ingemar Hernefjord -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Creswick, Steven Sent: den 19 augusti 2004 18:19 To: [log in to unmask] Subject: Re: [TN] Picking Die Joyce, My suggestion for use of hotplate to determine presence/or not, of adhesive was considered to be a destructive test. In no way would I do this as a 100% 'fix' Any die tested in this manner would be considered as scrap Steve -----Original Message----- From: Joyce Koo [mailto:[log in to unmask]] Sent: Thursday, August 19, 2004 9:20 AM To: TechNet E-Mail Forum; Creswick, Steven Subject: RE: [TN] Picking Die depend on type of chip... adhesive residue may cause high electrical resistance if the back is used as ground. cook on the heat plate must be a short time... otherwise, you may cause some degradation of wirebondability (depend upon how clean is your hot plate... you can varify cleanliness of your chip surface before and after hot plate using DI contact angle measurement, you will see the difference)...If I were you, I'll check all the vacuum pick, process parameter, etc. If everything is OK as per qualification, you still got stuck die, I'll reject the lot for sure...(not that make me popular...) -my cold 1.52 cents.. jk -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Creswick, Steven Sent: Thursday, August 19, 2004 6:35 AM To: [log in to unmask] Subject: Re: [TN] Picking Die Karen, Bruce is correct in that the tape mastic should not be on the backside of the device IF properly ejected, however, sometimes that is a big "if". Many individuals feel that you have to poke THROUGH the tape in order to eject the device. I find that tends to transfer a small amount of adhesive, so I elect NOT to poke through the tape. It is all a game of tip diameter, needle travel, time, etc. I have had similar experiences, but never to the magnitude that caused undo grief. On occassion, I have washed waffle packs out with clean IPA and this has helped. For those [empty] waffle packs that seem prone to die sticking [naturally, assuming the cavity size is large enough, etc], I just trash them. I have a few devices which are essentially optically clear. If there is any mastic transfer during the die ejection process, it shows up as a small amber/brown dot after the die attach adhesive has been cured [can see it from the top]. I guess from a silver lining stand-point this allows me to verify just exactly where the ejection needle is contacting the device - but that is something I can generally do without :-) I wonder .... if your device is large enough ... could you carefully remove it from the waffle pack with tweezers, flip it upside down on a 200-250°C heat stage for 10-15 minutes, char the mastic a bit [if it is there], then pull it off and look at it under the microscope. I am guessing that if mastic were there, it might show up if the lighting were just right. I have had situations where the mastic is along the very edges of the device. Believe this was due to cutting too far into the nitto tape during dicing. Like Bruce said, this has been fixed with a better vacuum. Just goes to show that even the little things are not so trivial. Have a good day! Steve Creswick - Gentex Corp -----Original Message----- From: Karen Walters [mailto:[log in to unmask]] Sent: Wednesday, August 18, 2004 2:14 PM To: [log in to unmask] Subject: [TN] Picking Die Has anyone ever experience die sticking to the waffle paks during die attach. Please let me know what your solution was to this problem. We believe it is Nitto tape residue that sticks to the back of the die when the die are picked from the wafer ring to the waffle pak Please let me know your experience with this. (Embedded image moved to file: pic26500.pcx) --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------