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Recent content by Chauvet

  1. Chauvet

    Calculating PSI from Axial Force

    Good Morning, back from a few days of details and cedar fever.....central Texas allergies are the worst. SREID: The phase change materials are superior for gap filling, they do not have as good a TC, however due to the very thin (.003)and gap filling abilities they have outstanding LOW thermal...
  2. Chauvet

    Calculating PSI from Axial Force

    SReid, Yes the TC805 is both electircally and thermally conductive. AL to AL is a poor thermal transfer depending on the surface finish, RMS.Air "voids" between the two surfaces are the insulators. The TC805, or grease, fill in those void. Grease is excellent, however it has a dry out factor...
  3. Chauvet

    Calculating PSI from Axial Force

    Very familiar with the TO packages and a world of ceramic and plastics both with no prestress and those with prestressed bottoms, some not intentionally. We have a TO-272 Freescale 30W part soldered to the top of this heatsink. Solder has a 48-50w/mK TC. Then we bolt the HS down to an Al...
  4. Chauvet

    Calculating PSI from Axial Force

    Thanks Cory, I will get a copy. Regards CP
  5. Chauvet

    Calculating PSI from Axial Force

    Mike H, I cannot disagree, this was the previous specified dimension, will probably go to .250 and at least 2x area, this will complicate the contact pressure further. This heat sink is then bolted to a larger BASE Station HEAT SINK. That is what the two screws were for, however we will have to...
  6. Chauvet

    Calculating PSI from Axial Force

    Gents Sincerely appreicate the responses. Bare with me as I respond to each. TheTick, yes it would if I had a uniform pressure over the entire surface, I need 100 psi, I have 1.6 sq in therefore I would need 160 lbs of force, however I have only the two screws to apply force. CoryPad, thank...
  7. Chauvet

    Calculating PSI from Axial Force

    Addtional Data, I contrived a method to 'visually' show the contact pressure (impression) or lack thereof. I had a 250M surface finish put on the HS, as I increase the torque on the screw, you can see the inprint of the finish on the T805, this works well. I have tested to 2x recommended torques...
  8. Chauvet

    Calculating PSI from Axial Force

    Greg (automotive) for whom and where? I am ex-Delco, Kokomo, advanced product development. Regards
  9. Chauvet

    Calculating PSI from Axial Force

    Greg, Thanks for the response, first the the historicals, UT, Molecular Biology and Genetics, Yea , I know, what the heck am I doing here. Materials and chemistry are an easy extension, I have been in Semiconductor Packaging and doing very well for 20+ yrs. We are a start up and I like others...
  10. Chauvet

    Calculating PSI from Axial Force

    We have a heatsink .86 x 1.86 x .125, Al 6061, We are using 440 cap head screws to attach. The screws are .200 from each end, only two. The thermal conductive material is T805 and requires 100 PSI to achieve its thermal conductivity value. Thatcalculates to 160 lbs of force over the 1.6 sq in...
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