Tony: We have used Fiberite, without issue, on Copper and Aluminum cores up to 0.180" thick. Robert B. Denbo Engineering Manager Midwest Printed Circuit Services, Inc. http://www.midwestpcb.com mailto:[log in to unmask] 847.740.4120 847.740.4187 Fax -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of tony steinke Sent: Wednesday, April 10, 2002 4:07 PM To: [log in to unmask] Subject: [TN] core fill Hello Techies, Can anyone tell me what type of reliable core fill materials are on the market. I have been looking at the Howefilm and Fiberite, but both have some limitations. We have a .050 solid copper core to fill. And the Tg or operating temperature must be 170C or greater. Thanks in advance Tony Steinke