Thermal Epoxy
in [Design]
|
Prev: 1905 San Francisco
Next: ECL open input default state
From: Michael A. Terrell on 20 Mar 2010 22:00 John Larkin wrote: > > On Sat, 20 Mar 2010 12:14:56 -0700, Archimedes' Lever > <OneBigLever(a)InfiniteSeries.Org> wrote: > > >On Sat, 20 Mar 2010 11:10:18 -0700, John Larkin > ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > > > >>I had a guy, used to work for me, who used the word "characteristic" > >>about twice a sentence, to make it sound like he knew things. He > >>didn't. I had to let him go. Was that you? > >> > >> > > If I had ever worked for a dumbfuck like you, you would no longer be > >with us, as I like ridding the world of vermin. > > Pretty brave words for a guy who is too chicken to even use his real > name. What else do you expect from NoNads? -- Lead free solder is Belgium's version of 'Hold my beer and watch this!'
From: Michael A. Terrell on 20 Mar 2010 22:02 BobW wrote: > > "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message > news:1dl8q516k88j8ld0e4fm7re36rjodjc1d7(a)4ax.com... > > On Fri, 19 Mar 2010 21:37:14 -0700, Archimedes' Lever > > <OneBigLever(a)InfiniteSeries.Org> wrote: > >>>Epoxy can fail in situations like this. > >> > >> That depends entirely on the properties of the particular epoxy being > >>used. Duh. > > > > > > Thank you for another brilliant insight. > > > > John > > > > Not fair, John, With that idiot, it's like shooting fish in a barrel. His daddy's sperm had more brains, than NoNads does. -- Lead free solder is Belgium's version of 'Hold my beer and watch this!'
From: David Lesher on 20 Mar 2010 22:36 John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >Even the metal-filled stuff is mediocre thermally. Diamond-filled >epoxy is mediocre! The epoxy between the grains dominates theta. >Getting the interface very flat and very thin is the best way to >reduce theta. If the fill grain size is such as to increase the gap, >the filler usually makes things worse. I learned that when bonding some LM-35's to various pipes. I used a epoxy from Tri-con, ISTM. But even the best stuph was still FAR worse than direct contact. -- A host is a host from coast to coast.................wb8foz(a)nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
From: Archimedes' Lever on 20 Mar 2010 22:58 On Sat, 20 Mar 2010 18:16:42 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sat, 20 Mar 2010 12:16:15 -0700, Archimedes' Lever ><OneBigLever(a)InfiniteSeries.Org> wrote: > >>On Sat, 20 Mar 2010 11:33:11 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sat, 20 Mar 2010 11:10:18 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>> >>>> >>>>We just stuck an Osram surface-mount IR LED to a plastic case silicon >>>>photodiode, using optical-grade epoxy, and got 22% CTR. Not many >>>>photons escaped our clutches. I'll post a link to the product when >>>>it's done. >>> >>>Hmmm, if we wrapped all that with shiny aluminum foil tape even fewer >>>photons would escape our evil clutches. >>> >>>John >>> >> >> More retarded even than the first reference was/is. > >If you knew what CTR meant, you'd be impressed! > >John > I helped to engineer opto-isolated HV SSRs about eight years ago. I think there were two patents. It was for 6kV, and was for a high speed color laser printer/copier. The supply was as big as a full sized motherboard, and had six discreet HV supplies on it with about 3 different voltages for the corona wire, and the drum. It had encapsulated little HV daughterboards all over it and HV coupling links using 30kV HV SPC wire, and was computer controlled (microcontroller). That was an interesting supply to "come up with" The printer was a monster I guess,like the ones I now see at workplaces. Really fast tabloid sized high speed high res full color laser printer/fax(not color)/copier, etc. For the 6kV we tried 15kV wire, but the Teflon allowed the corona to worm its ways to the surface, boring a hole along the way. That is why we had to use the 30kV stuff even though we were only pushing 6kV. Capacitive loads are fun to have to design a supply to feed into.
From: John Larkin on 20 Mar 2010 23:29
On Sun, 21 Mar 2010 02:36:25 +0000 (UTC), David Lesher <wb8foz(a)panix.com> wrote: >John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: > > >>Even the metal-filled stuff is mediocre thermally. Diamond-filled >>epoxy is mediocre! The epoxy between the grains dominates theta. >>Getting the interface very flat and very thin is the best way to >>reduce theta. If the fill grain size is such as to increase the gap, >>the filler usually makes things worse. > >I learned that when bonding some LM-35's to various pipes. I >used a epoxy from Tri-con, ISTM. But even the best stuph was >still FAR worse than direct contact. I know that the Dow white thermal silicone grease squeezes down below 100 micro-inches, my resolution limit. So the fill particles must be pretty small. If the surfaces are really flat, an unfilled grease, something that truly flows out of the gap when compressed, is probably best. You can buy an LM35 in a TO-220 package, handy for bolting to things. John |