Graham, UV or light curing coatings: - Solvent free - Full cure in seconds, on-line - Single part - Non flammable - Can meet MIL I-46058C and UL - Good to excellent environmental resistance - Can be "rigid" or "flexible" (Shore D80 to Shore D40) - Can be used on flex - Can have strong fluorescence for inspection, or even be black They are not suitable for all applications - are better sprayed, not so good for dipping. If sprayed (say, using PVA or Nordson type selective spray equipment), then full cure can often be achieved just with light. Otherwise, secondary cures for shadowed areas may be achieved with heat, anaerobic, moisture or other mechanisms. To answer Mike Fenner's question, most pcb coatings are acrylic based, which is a free radical cure. Expose to the correct wavelength/intensity of light for required time and full cure is achieved. In fact, if the light is taken away, curing stops. All the coating must be exposed to the light. There are some coatings (a few) based on epoxy chemistry and a cationic cure. Some cross linking will continue after the light is removed, but only for thin sections (i.e. it doesn't propagate far), and just like the free radical cure, all the coating must be exposed to the light. So, an interesting technology which certainly has its place in the panoply of coatings available for circuit protection. Whilst not a universal panacea, they can often offer processing speed and simplicity, including perhaps some environmental and health & safety advantages. IMHO, they should not be dismissed totally out of hand by competitors to the technology in an open forum; for one thing, this might insult the many companies who are successfully using them! Regards, Peter -- ========================================================= Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the electronics manufacturing and other technology based industries, with the highest levels of technical support and customer service. -----Original Message----- From: Graham Naisbitt [mailto:[log in to unmask]] Sent: 09 December 2001 19:01 To: [log in to unmask] Subject: Re: [TN] 2 Conformal Coating ?'s Peter, I am semi-comatose now, so please, tell us what exactly are the advantages of UV curable coatings? Regards, Graham Naisbitt [log in to unmask] www.concoat.co.uk <http://www.concoat.co.uk> For instant access to Product Data Sheets register on the Tech-Shot area of http:// www.concoat.co.uk <http://www.concoat.co.uk> Concoat Limited Alasan House, Albany Park CAMBERLEY GU16 7PH UK Phone: +44 (0)1276 691100 Fax: +44 (0)1276 691227 Mobile: +44 (0)79 6858 2121 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Peter Swanson Sent: Friday, December 07, 2001 05:51 To: [log in to unmask] Subject: Re: [TN] 2 Conformal Coating ?'s Graham, You really must see someone about your delusions over UV cured coatings, which are successfully used to coat many thousands of pcb's each year. I know someone who has a nice sofa you can stretch out on whilst you tell him all about it.... <g> Suitability for UV has nothing to do with 3D v. 2D, more to do with the complexity of the assembly geometry and the application methodology. These will determine if a secondary cure mechanism is needed for the application. In many instances (and with some of our customers), full cure is achieved just with light. Regards, Peter -- -------------------------------------------------------- Peter Swanson [log in to unmask] INTERTRONICS http://www.intertronics.co.uk INTERTRONICS is dedicated to providing quality material, consumable and equipment solutions to the electronics manufacturing and other technology based industries, with the highest levels of technical support and customer service. -----Original Message----- From: Graham Naisbitt [mailto:[log in to unmask]] Sent: 06 December 2001 16:52 To: [log in to unmask] Subject: Re: [TN] 2 Conformal Coating ?'s Mike You would be better to go with a conventional coating. UV is not ideal for 3D objects - works great in 2D, cos you don't have to bend light! :-) I cannot remember what the operating environment was for your circuit - if you would care to repeat, I can recommend something - however, I am sure that a one part AR or UR coating from a reliable supplier will give you the best overall results - process and operating environment. Regards, Graham Naisbitt [log in to unmask] www.concoat.co.uk <http://www.concoat.co.uk> For instant access to Product Data Sheets register on the Tech-Shot area of http:// www.concoat.co.uk <http://www.concoat.co.uk> Concoat Limited Alasan House, Albany Park CAMBERLEY GU16 7PH UK Phone: +44 (0)1276 691100 Fax: +44 (0)1276 691227 Mobile: +44 (0)79 6858 2121 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Mike Manwell Sent: Thursday, December 06, 2001 02:41 To: [log in to unmask] Subject: [TN] 2 Conformal Coating ?'s Hello, Thanks in advance if you have taken the time to read this! #1- Im trying different materials in a spray application. Both are cured using UV. One material does a "secondary cure" w/ moisture. This is cool because after 100 hours after UV cure, all material is fully cured. The other material Im trying uses HEAT for a secondary cure, or, if shodowed during UV cure, the material wont cure and never will. Obviously I dont want the stuff dripping or running anywhere, but being new to this wonderful process, just dont feel good about leaving uncured material on a product for it's entire life. Iv been told that you can "test" the product to see if the uncured material is causing a problem but Im not sure what type of test that would consist of. Any insight? #2- Has anyone out there ever installed refelctive metal plates in their UV oven to limit shadowing? Thanks so much, Mike Manwell --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------