Electronics > Projects, Designs, and Technical Stuff

Are these MB510 ICs fake?

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james_s:
After the first ones I bought turned out to be fake (not even the right package, they were too narrow) I ordered a pair from another seller and these finally showed up. They're the right footprint this time at least but there are some red flags. The top had a slight texture that made me think blacktopped so I scrubbed it on a paper towel soaked in acetone and got a slight brown smudge on the towel but the numbers didn't rub off. I went ahead and installed one on the board and was disappointed to find it doesn't work, I get an approximately 4MHz square wave on pin 4 with nothing on the input, doesn't seem right but it's possible there's another fault on the prescaler board. The next red flag I noticed while photographing the ICs, they came side by side in IC tape a if they were cut from a reel but looking at the bottom they each have different stampings.

Thoughts? I just want to be 100% certain before I accuse the seller of sending me fakes and put in a claim for a refund. The lighting was different for some of the photos, they're actually the same shade however as it appears, the bottom is glossy and the tops have a bit of a texture to them.

magic:
The top does look suspicious with those diagonal stripes. Are the sides glossy too? What if you rub it more? The markings are laser-cut so they will never come off, but perhaps the surface?

I think the numbers at the bottom indicate position in a multi-package mold or something like that. I could never find any meaning in them and often noticed that they aren't identical on chips from one batch.

james_s:
I'll try rubbing it some more and see what happens. The stripes may just be from rubbing on the paper towel before, but I'm suspicious that they are sanding marks that have been blacktopped and then re-marked.

If not a prescaler, I wonder what this IC could be that is resulting in a 4MHz square wave? I suppose it's possible that the input stage is oscillating but I didn't see anything on the scope. Not that I'd expect much from a passive probe at >500MHz which is what it would be with the IC set to divide by 128.

amyk:
Fast ICs like that can definitely oscillate if given a chance to.

bin_liu:
Looking at the first picture, the traces of polishing are obvious.
This is a refurbished, or even renumbered IC.
In China, there is such an industry.
Feeling embarrassed. |O

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