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I am hacking a circuit and it has this black plastic thing (see picture below) that hides part of the circuit.

enter image description here

How can I remove them to see what is inside?

What they are for? I think they are for chips that have no packaging, is this right?

What the real name of this?

Thanks for your help.

koike
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    The real name is "glob top". As for how to remove it, I suspect that nasty chemicals are involved (strong HCl, maybe?) but have never done it. – The Photon May 02 '14 at 15:58
  • Interesting blog post: http://uvicrec.blogspot.com/2013/04/heatgun-h2so4-decap.html – The Photon May 02 '14 at 16:02
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    possible duplicate of [What kind of components are black blobs on a PCB?](http://electronics.stackexchange.com/questions/9137/what-kind-of-components-are-black-blobs-on-a-pcb) – Ricardo May 02 '14 at 16:19
  • Here's [a very similar question to yours](http://electronics.stackexchange.com/questions/9137/what-kind-of-components-are-black-blobs-on-a-pcb). See [this answer in particular](http://electronics.stackexchange.com/a/16768/29792) as it mentions that one of the purposes of this blob is to protect the IC from reverse engineering. – Ricardo May 02 '14 at 16:21
  • And by your picture, it looks like you've already tried to scratch it out, haven't you? – Ricardo May 02 '14 at 16:22

2 Answers2

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This is known as Chip-On-Board (COB) technology, the black material is epoxy resin, it is the same as the black material on ICs. Note than the bonding wires encased in the resin are very thin and fragile. COB technology is sometimes used to prevent reverse engineering.

This YouTube video demonstrates a process for removing the resin packaging on ICs using a hotplate, nitric acid, acetone, and a rotary tool.

This video YouTube video demonstrates a simpler (but more destructive) method for removing the resin from a COB, using just a heat-gun and a hobby knife. This method destroys the bonding wires.

And here's a related question, with more information about COBs: What kind of components are black blobs on a PCB?

Community
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wgardiner
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Red fuming nitric acid is supposedly the stuff to use. It's very nasty.

Leon Heller
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