Hello Gary,
In this relationship 1 K/W equals 1 C/W. As one example, see http://www.diffen.com/difference/Celsius_vs_Kelvin Br. Helge Knudsen Denmark From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of McInturff, Gary Sent: 9. oktober 2012 22:29 To: 'EMC-PSTC@LISTSERV.IEEE.ORG' Subject: thermal resistance - K versus C Thought I knew what I was doing, obviously I don't I have a device with a thermal resistance ThetaJA (J-P in this documentation). It's for SMT CHIP LED the specified value is 400C/W. for a plastic package that seems about right. I am looking at another LED but it lists ThetaJA as 400K/W. (Kelvin/Watt) Seems pretty good as it would convert to 126C/W - the lower the better. But then I converted the ThetaJS (I think its junction - solder point), and that value was 180K/W. When converted its -93C. Does the change in sign just indicate the direction heat is flowing? ThetaJA is positive since the heat is leaving the die through the package, and the ThetaJS is negative because it is heating entering the die through the solder process? Gary McInturff Reliability/Compliance Engineer Esterline Interface Technologies Featuring ADVANCED INPUT, MEMTRON, and LRE MEDICAL products 600 W. Wilbur Avenue Coeur d'Alene, ID 83815-9496 Office:208-635-8306 Cell: 509 868 2279 Toll Free: 800-444-5923 X 1238 <mailto:brian.s...@esterline.com> gary.mcintu...@esterline.com <http://www.esterline.com/advancedinput> www.esterline.com/interfacetechnologies Technology, Innovation, Performance... - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to < <mailto:emc-p...@ieee.org> emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: <http://www.ieee-pses.org/emc-pstc.html> http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at <http://product-compliance.oc.ieee.org/> http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: <http://www.ieee-pses.org/> http://www.ieee-pses.org/ Instructions: <http://listserv.ieee.org/request/user-guide.html> http://listserv.ieee.org/request/user-guide.html List rules: <http://www.ieee-pses.org/listrules.html> http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas < <mailto:emcp...@radiusnorth.net> emcp...@radiusnorth.net> Mike Cantwell < <mailto:mcantw...@ieee.org> mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher < <mailto:j.bac...@ieee.org> j.bac...@ieee.org> David Heald < <mailto:dhe...@gmail.com> dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
