# How to remove Black cooling paste on IC?

I am trying to reverse engineer a product, but I ran into a problem:

One IC had a heatspreader on top of it.

With a bit of force I could remove it, but I am unable to read what's written on the IC, because there is some kind of black cooling paste on it.

It's solid - I can only scratch it with a screwdriver. But I'm afraid that I'm destroying the text on the IC.

Do you have some idea what it could be and how to remove it?

It is probably a stepper motor driver, but I want to know which.

If it could help you, I can measure some voltages or watch it with an oscilloscope if you want. The whole circuit is working fine.

• It is a DIP-16 with the Stepper motor connected to pins: 6-3-14-11
• Pins 4-5-12-13 are connected to ground.
• Pin 8 is the only other big Trace on the IC, guess that's VCC then.

I hope you can help.

• black cooling paste ... i can only scratch it with a screwdriver .... if it was thermal compound, then it would be soft .... what you have is potting compound ... there may be a bare IC chip underneath .... there probably is no IC package with printing underneath ....... electronics.stackexchange.com/questions/9137/… – jsotola Jun 5 '18 at 18:54
• Can you share a photo? It could be thermal glue... – Jeroen3 Jun 5 '18 at 18:57
• @jsotola Well i never seen a DIP-16 as bare chip.... – Timon M Jun 5 '18 at 19:14
• @jeroen3 added it. Did try my best to get my phone to focus – Timon M Jun 5 '18 at 19:17

## 1 Answer

It seems to be some kind of thermal glue.

I removed it with (which I think was a lot) acetone and after a few attempts I saw some signs of a writing. It's an L293D.

In case someone else has this problem: It's best if you use some towel to soak in acetone (just a small piece of it) and then leave it on the IC for a few seconds. After that you can scrape it off with your fingernails (wash your hands after everything involving acetone of course).

• I use rubbing alcohol. It's more effective and it's not harmful. You should be careful with acetone. – KingDuken Jun 5 '18 at 19:58
• I just had acetone laying around, that's why i used it. Will probably also work with rubbing alcohol. – Timon M Jun 5 '18 at 20:11