Use of a heated package combined with sanding techniques. Heating makes the package soft. Some success with using a Dremel to rapidly remove the top layer until chip was just showing. Major issues have been scratching of the die due to particulates. It may be possible to mitigate this issue by switching to a finer grinder or by pouring a high temperature liquid (mineral oil?) for lubrication.

Procedure

1. Under development

Notes

• Tried Dremel + grinding wheel followed by dropping room temp nitric on preheated IC with decent results

Advantages

• No chemicals

Disadvantages

• Not suitable for live analysis

This technique takes advantage of the following:

• The layers above a die can be effectively removed by sanding
• The layers below a die can be effectively removed by heating the glue onto the carrier island and pulling up pins
• The remaining die with minimal epoxy can be finished off with nitric acid (best results)

Procedure

1. Heat chip
2. Using rotary tool (Dremel), sand down until bond wires are present.
   1. Should be able to be done in a few minutes
   2. Sanding down until the die is visible is possible, but if will be followed with nitric bath anyway, is not worth the risk
   3. Squirting with fluid or using magnification may help to show the bond wire
3. Pull up external leads towards the ground surface. This should deteriorate the top layer and leave the die on a small island in the middle
   1. If package cracks during this, should not be a problem
4. Combination of glue on carrier island to die being soft from heat and missing epoxy around die should allow die to separate from package with minimal epoxy attached
5. Turn off heat
6. Use nitric acid techniques to finish off the sample

Notes

• Inline

Advantages

• Low chemical use
• Quick turnaround time
• Fairly reliable

Disadvantages

• Not suitable for live analysis
• Still requires caustic chemicals
• Multiple areas for failure
• Risk of sanding down too far and damaging die
  • Mitigated by watching for bond wires
• Risk of cracking die during package breakup
  • Probably caused by applying too much pressure