Cleaning Your Wafers

[Vlasta]

Hi - I get a lot of wafers through my hands and some are dirty through age or handling and some are marked with the red or black dots of death - i.e. the dies are marked as defective in the fab.

So - dirty discs:-

1. Warm soapy water - beware - these suckers are slippery when wet
2. Clean gently
3. Rinse carefully
4. Buff with a soft lint free cloth

Dots of death

After trying acetone, xylene, perc, bleach, meths, white spirit, turps..... I finally came across something that works - "Polystrippa" - a dichlormethane based gel paint stripper.

1. Put some "polystrippa" on a cotton bud
2. Rub off the dots of death
3. Rinse in warm soapy water
4. Buff with a soft lint free cloth

Voila - clean discs.

[aberco]

Cool tip, I have been lucky to remove the dot on most dies with acetone, but I have some that just won't go away.

Will try that tip and look for that product!

[Vlasta]

Here it is!

[Vlasta]

Before and After

[aberco]

So far acetone has worked on most dies I had, I went go shopping for paint remover that look like polystrippa.
I got something that's a transparent gel, but no brand would write the detailed chemical composition (so I don't know if they are dichloromethane based).

I was out of luck to remove the dot on my TI MicroSPARC dies, it look very waxy.