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{1316}
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ref: -0 tags: polyimide adhesion chromium copper tie layer upilex date: 06-24-2015 23:14 gmt revision:3 [2] [1] [0] [head]

Adhesion Evaluation of Adhesiveless Metal/Polyimide Substrate for MCM and high density packaging

  • Adhesion degradation after thermal and humidity stresses can occur for a number of reasons.
    • Copper diffusion can promote adhesion loss at elevated temperatures and can be inhibited by coating a barrier layer of metal – tie layer2.
    • Oxygen diffusion through polyimide film to the metal/polyimide interface plays a critical role in promoting degradation too3. Adhesion of Cr/polyimide interface is degraded significantly upon exposure to high temperature and humidity environment due to the hydrolysis of polyimide4,5 .
    • Catastrophic adhesion loss has been linked to moisture induced oxidation of chromium interfaces based on studies using radioactively tagged water4, 5.
  • That said, most of these vendors use Cr (20nm) as and adhesion layer, and Cu (200nm) as the conductor.
  • Upilex A faired very well after the pressure cooker test -- > 60% retention after 192 hours.
  • Seemingly Ta and Cr both adhere similarly to PI -- {1317}
    • Though Ta is much more ductile, and forms a stronger carbide, Cr is preferred... cheaper?

{223}
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ref: physics notes-0 tags: plasma physics electromagnet tesla coil copper capillary tubing calculations date: 02-23-2007 16:01 gmt revision:0 [head]

calculations for a strong DC loop magnet using 1/8" copper capillary tubing:

  1. OD .125" = 3.1.7mm^2; ID 0.065 -> copper area = 23.2mm^2 ~= AWG 4
  2. AWG 4 = 0.8 ohms/km
  3. length of tubing: 30' ~= 40 turns @ 9" each (windings packed into a torus of major radius 1.5"; minor radius 0.5")
  4. water flow rate through copper capillary tubing: 1 liter/min; assuming we can heat it up from 30C -> 100C, this is 70KCal = 292 KJ/min = 4881 W total. (better pipe it into our hot water heater!)
  5. 4.8kw / 9m of tubing = 540 W/m
  6. 540W/m / 8e-4 = 821 A ; V = 821 * 9 * 8e-4 = 5.9V (!!! where the hall am i going to get that kind of power?)
  7. 821A * 40 turns = 32.8KA in a loop major radius 1.5" = 3.8cm
  8. magnetic field of a current loop -> B = 0.54T
  9. lamour radius: 5eV electrons @B = 0.54T : 15um; proton: 2.7cm; electrons @1KeV ~= 2.66e8 (this is close to the speed of light?) r = 3mm.