For Christmas my company handed me a small LED "work light" that wasn't bright enough to light up any real work, so I figured I'd tear it down see what was inside hoping the the lesson would be worth more than the light.
I expected a tiny circuit with a button and resistor. I got two of those things, but how did the resistance work in this circuit? I didn't take a before photo, but the only thing different is a mound of dried, opaque white paste where there is only a paste circle now.
I tried Googling resistive paste, and there is such a thing, but I don't think this is it. Did I chip off a tiny resistor in there that I didn't see?
Edit: After some comments pointing out that this was likely COB, I've come to the conclusion that the momentary switch couldn't, on it's own, maintain the state of the light. Therefore there would need to be some logic in an IC. The original question wasn't so much focused on what COB is (although I learned that), but instead why a COB would be utilized instead of a much simpler circuit.