The conductivity of these things is low compared to metal but higher than air so the answer is as little as possible. Or said another way just enough to give good thermal coupling (fill in the gaps) but not so much that you increase the thermal gradient by substituting a low conductor for the metal contact. How much is just enough? as much as it takes to just become visible all round perimeter when clamped. I'm sure any standards and procedures people could write this up into an impressive looking ISO style 20 step instruction which should floor anybody and solve this for you ...... ? Alternatively there are better products these days than grease. I thought phase change stuff had wiped out greases? Mike Fenner Indium Corporation of Europe T: + 44 1908 580 400 F: + 44 1908 580 411 M: + 44 7810 526 317 W: www.indium.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Phil Nutting Sent: Tuesday, August 14, 2001 4:42 PM To: [log in to unmask] Subject: [TN] Application of Thermal Grease We use many TO-220 and TO-247 packages mounted to heatsinks. Some of these applications require the use of thermal grease. The age old question is how much grease is enough? This is a political football that is constantly tossed around. Does anyone know of a manufacturer's specification or some organization's standard that clearly defines how much thermal grease is the correct amount? Thanks, Phil Nutting Manufacturing Engineer Kaiser Systems, Inc. ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------