Electronics > Beginners
Teardown of a simple LED toy
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echo34:
I'm trying to understand the electronics inside this LED toy (please see attached photos of the device in operation, as well as torn down). The operation is very simple. A push button switches between 7 different modes of operation of an RGB LED, including solid white, flashing red, flashing blue, flashing green, flashing R-G-B in sequence, gradual rainbow color change, and off. It operates on 3 - 1.5V cell batteries in series (1 AG13 + 2 AG10's for a total of 4.5V). The only components on the PCB are a bare IC die, an RGB LED, and a pushbutton switch. There are no discrete resistors or caps.

I'm trying to figure out what chip and manufacturing process was used, and how I might be able to do a similar project. It looks like the 1mm by 1mm bare die was directly attached to the PCB. I assume there were tiny bond wires connecting the pads on the die to traces on the single-layer PCB board that lead to the other components (RGB LED, battery terminals, and pushbutton switch), however I wasn't able to locate the tiny wires after I broke down the product. And then it looks the IC die and bond wires were altogether encapsulated in a blob of white resin/epoxy.

Has anyone seen this type of manufacturing before? Do you think the bare die is a microcontroller or custom ASIC? I'm hoping it's an OTP microcontroller that can be pre-programmed with my own design at the time of procurement. Do you know a specific manufacturer who can make this? Fwiw, the toy indicates that it's made in China.

Btw, first time poster here. I'd appreciate any advice. Thanks!
tooki:
That's chip-on-board, which is commonly used in very low-cost electronics, like toys and calculators.

Take a look at https://learn.sparkfun.com/tutorials/how-chip-on-boards-are-made/all



As for those specific chips, who knows. It's probably a custom chip (they make LEDs with a similar driver built right in!), but it could be a microcontroller.
mayor:
Dunno anything about manufacturing processes for custom COBs, but check out this thread :
https://www.eevblog.com/forum/microcontrollers/3-cent-mcu/

Dave did a video of it. Seems this could be a good alternative driving an RGB LED through PWM or APA102C or whatever...
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