Hi Peter: "Shadowed areas will need to be cured by a separate mechanism, like heat, chemical activator, moisture, anaerobic, etc, depending on the adhesive type." Yes, my point exactly: ""capable of secondary cure properties to continue to polymerize"" After the cure is initiated by UV to visible areas, those areas that are shadowed cure by secondary means totally independent of the UV light. It is not a chain reaction that propagates from the visible areas to the shadow areas. Such as the reaction of the visible adhesive to UV light releasing free radicals leading to the propagation of polymerization. Sorry if I made it come across that way. Regards Mike Barmuta -----Original Message----- From: Peter Swanson [mailto:[log in to unmask]] Sent: Wednesday, June 29, 2005 7:00 AM To: TechNet E-Mail Forum Cc: Barmuta, Mike Subject: RE: [TN] Light Cure Adhesives Mike sagely points out: "There are also variations of U/V adhesive if you have shadowing i.e. a non-clear path for the light energy to reach the adhesive. In this case you want one capable of secondary cure properties to continue to polymerize after being initiated by the U/V light." But to clarify, any adhesive which is in a shadowed area will not cure by the reaction to light; the cure does not propagate from exposed areas into the shadowed ones. Curing stops when the curing light is removed (essentially). Shadowed areas will need to be cured by a separate mechanism, like heat, chemical activator, moisture, anaerobic, etc, depending on the adhesive type. I guess I picked up on the word "initiated" - the cure needs to be started and completed by exposure to the correct wavelengths and intensity of light. Picky, picky, picky.... <grin> Peter -- -------------------------------------------------------- Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk Tel: +44 1865 842842 Oxfordshire, England INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the high technology, high performance assembly industries, incorporating outstanding levels of technical support and customer service. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Barmuta, Mike Sent: 27 June 2005 22:06 To: [log in to unmask] Subject: Re: [TN] Light Cure Adhesives Phil: U/V cure adhesives work well and are quite fast to cure. One down side is they are usually higher in price than more conventional adhesives. We have used both Dymax and Henkel/Loctite. The application was for component securement prior to reflow. The products used are somewhat thixotropic to prevent flow after application but are certainly dispensable. The Dymax was their 621 and 921, the Loctite was 3526. Speed of cure is dependent on type of adhesive material, thickness of deposit, light intensity, distance from light source and shadowing. But in most cases less than a minute is normal. You can use spot or flood light to cure. There are also variations of U/V adhesive if you have shadowing i.e. a non-clear path for the light energy to reach the adhesive. In this case you want one capable of secondary cure properties to continue to polymerize after being initiated by the U/V light. Regards Michael Barmuta Staff Engineer Fluke Corp. Everett WA 425-446-6076 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Phil Nutting Sent: Monday, June 27, 2005 10:03 AM To: [log in to unmask] Subject: [TN] Light Cure Adhesives Our current adhesive of choice is RTV. Unfortunately it has a long cure time and may be banned from use in products going to the European Union in the coming years. Our application is bonding 4 capacitors together. The adhesive needs to be thick (medium to high viscosity) so it won't sag, drip or run before curing. UV cure would be best from a time standpoint. A "glob" of about 1/4" should be about right for this bonding application. The capacitors have an epoxy coating and the operating temperature is about 50° C maximum submerged in a dielectric oil. Electrical or thermal conductivity is not needed. Method of application is expected to be via small air actuated syringe or similar. Anyone want to put in their 2¢? Sales calls offline please. Phil Nutting Design for Manufacturing Engineer Kaiser Systems, Inc. 126 Sohier Road Beverly, MA 01915 voice: 978-922-9300 x1310 fax: 978-922-8374 e-mail: [log in to unmask] <mailto:[log in to unmask]> www.kaisersystems.com <http://www.kaisersystems.com/> --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- 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 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------