IF you are using vacuum to reduce voids, you might be better off pulling it on the adhesive before use, you will need to decant or dispense it into a container with at least 3x the volume of adhesive being degassed. A cartridge like those used for paste is ideal and you can get a little gizmo from the cartridge supplier to back fill regular syringes. This will get gross air out. The rheology maybe affected by doing this so you may need to adjust application parameters. You can see from this procedure why pulling a vacuum on assembly may not be such a good idea. A better alternative would be to specify de-aired material to your supplier. It might be better to adjust your application procedures, deposit shape, ramp rate, pressure etc. For example if your bond area is square then an x shaped adhesive dot is preferred. On warming the adhesive viscosity will fall before it rises with cure (assuming you can get ramp rate suitably adjusted) and with a little pressure the adhesive will wet out to fill the square. After this "degassing "stage ramp quickly to peak cure temp to get good cross linking. During this time you might want to pull a small vacuum. The x allows evolution of any volatiles and as the adhesive flows to fill square it will sweep any trapped air in front of it. Hopefully you can intuit bead shapes for different geographies from the above. Hope this helps. Regards Mike Fenner Indium Corporation T: + 44 1908 580 400 M: + 44 7810 526 317 F: + 44 1908 580 411 E: [log in to unmask] W: www.indium.com Pb-free: www.Pb-Free.com --------------------- Indium Corporation Incorporated in New York, USA Registered office: (Not for correspondence) 77-97 Harpur Street, Bedford , UK Registered number: fc16473 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Chandler Sent: Wednesday, April 02, 2008 3:01 PM To: [log in to unmask] Subject: [TN] Vacuum Assembly Anyone have experience with using vacuum assembly to attach a flex circuit to a concave surface using adhesive without voids? Any insight into this process would be appreciated. --------------------------------------------------- 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 email, its content, and any files transmitted with it, are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient, please contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. Messages sent via this medium may be subjected to delays, non-delivery, and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. Indium Corporation does not accept responsibility for changes made to this email after is was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***" --------------------------------------------------- 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 -----------------------------------------------------