Ed, UL approvals of materials is different than UL approval given to fabricators. The materials usually undergo seperate material testing. The fabricators qualification is after processing of several materials together. An example would be a particular soldermask on a laminate material. The type soldermask, it's thickness, the type laminate material and it's thickness will have an affect on the final flamability rating given to a fabricator. It is not unusual for a different flame rating to be given for the combination than that given to the individual material. A case in point would be the use of polyimide laminate and soldermask. Many thin polyimide materials do not carry a 94-V0 rating. Especially once a soldermask is applied to it. But given the correct combination of soldermask and polyimide thickness, it is possible to receive a 94-V0 rating. I don't believe that the fabricator actually "fails" to receive a rating, but would receive a lower rating than he was seeking to achieve. Most fabricators will submit maerial combinations so as to receive several ratings for a given set of tests. As another example. They may submit samples of different laminate thicknesses with a specific soldermask apllied to it. The result would be a 94-HB on the thinner materials and a 94-V0 on the thicker materials. Regards, Gary Ferrari Executive Director IPC Designers Council ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################