Derek, having previously worked for a filter manufacturer, I was involved with a feedthrough filter design for working up to 150C. A few comments based on the discussion so far:
Working Voltage: this has not been mentioned, but considerable de-rating over room temperature ratings will probably be required. Low working voltages, a few Vdc, shouldn't be a problem. Inductor Core Materials: a glance at the Fair-Rite catalogue shows several materials with negligible change in room temp permeability up to 300C: e.g. materials 61, 65,67 68 Solders: somebody mentioned the need to weld, or silver solder. This shouldn't be necessary - 96S solder for example has a melting point of about 221C (96% tin, 4% silver), and is quite usable. Epoxy Seals: feedthroughs are commonly sealed with expoy encapsulants, and these are available with wide operating temperature ranges. BUT, temperature cycling has considerable effect, and can easily cause cracks in the sealant. So, it may be equally important to consider a) what is the minimum operating temperature, and b) how many times will the filter have to go from minimum temperature to 180C and back. The same consideration applies to an encapsulated inductor. Repeated temp cycling can be a real killer! Regards, Jeff Chambers ------------------------------------------------------------- Dr Jeff Chambers Westbay Technology Ltd Suppliers of EMC Design Software Tel: +44 1229 869 108 Fax: +44 1229 869 108 http://www.westbay.ndirect.co.uk/westbay1.htm j.chamb...@ndirect.co.uk Main St Baycliff Ulverston Cumbria LA12 9RN England ------------------------------------------------------------- ----- Original Message ----- From: lfresea...@aol.com To: emc-p...@majordomo.ieee.org Sent: 19 April 2002 21:19 Subject: High Temp Caps and Inductors Hi all, I'm designing a filter that has to live and work with an Ambient temp of 180 C. Does anyone have suggestions as to component vendors that I could contact for parts? Thanks, Derek Walton. L F Research ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
