Silicon Pr0n

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====== 2015-09-06 ======

https://twitter.com/johndmcmaster/status/640699417897517056
  * Lapping films applied more evenly using silicone rolling pin


https://twitter.com/johndmcmaster/status/640701284673155076
  * Excessive pressure caused die to dig into lapping film


====== 2015-09-13 ======

https://twitter.com/johndmcmaster/status/643284839097962496
  * Acquired 1 um and 3 um lapping films for removing upper layers quicker

https://twitter.com/johndmcmaster/status/643284509564145664
  * Tried to use 3 um film on virtex die (waxed to SBT jig) and removed center before sides
  * Every previous lapping attempt I've done removed the edges first
  * Unusually large die: possibly wax accumulated in center causing bulge


====== 2015-09-26 ======

Virtex die
  * Mostly decapped already by soaking in WFNA for a few days
  * Used piranha etch to clean up
  * Discovered remaining black epoxy/silicone doesn't quickly etch in piranha
  * Still have a pile of ones that require decap cleanup
  * Should have plenty for lapping R&D for a while
  * Decapping: https://twitter.com/johndmcmaster/status/642410779304570880
  * Bulk package removed via hotplate + pliers: https://twitter.com/johndmcmaster/status/642406536854138880
  * Original chips: https://twitter.com/johndmcmaster/status/641020243159052288
  * Sample:
    * Thickness: 0.331 mm min, possibly as high as 0.335 mm
    * WH: 19.9 x 20.4 mm
    * Cut 20.5 x 20.5?

Lapping stencil
  * Idea: try to get closer to wafer lapping by not gluing chip down
  * Requires making a stencil to hold die in place
  * Use wax to affix stencil to fixture
  * Still using lapping films.  Looking into getting condition rings + cast iron plate
  * All material: 0.01" => 0.254 mm
    * Should be < sample height but close to it
  * Kimwipe: 0.056 mm
    * Must be < stencil thickness

Lapping jig stencil holder?
  * Should the stencil itself by held by a retention ring that slides up and down?
  * For now just lightly wax it on
    * How much height will this add?
    * Propose make slightly larger than sample holder and wax along top edge

Stencil cutting holder
  * Hold stencil in place on milling machine
  * Lapping surface 2" => 50.8 mm diameter
    * 50.6 mm measured
  * Lapping jig cavity: 57.1 mm
  * Lapping stencil target diameter: 54 mm
    * Add 1.5 mm to each side w/ 1.5 mm clearance
  * Support at least entire cavity size + 1/8" endmill => 57.1 + 1/8 * 25.4 = 60.3 mm
  * Add some good clearance so I don't mill the jig: 5 mm each side => 70 mm total ID => 2.75"
  * 0.5" each side => 3.75" Al square stock
  * 1.5" from sherline t-slot to slot
    * 10-32 (0.1900") close fit => #9 drill (0.1960")