🚀 go-pugleaf

In <kennehra.724560313@craft.camp.clarkson.edu> kennehra@craft.camp.clarkson.edu (Rich"TheMan"Kennehan) writes:

>Hi.  I opened up one of my atari 2600 games, and instead of a regular
>chip inside, there was this small plastic glob where the ROM chip    
>should be!!!!   what is this?  It was black and looked like a big
>bump of solder.  How is this possible for a black glob of plastic
>with no pins to be able to store information?  The black glob was like
>melted into the center of the PC board...and the game worked perfectly
>when I put it back together again.  Any help figuring out this mystery
>would be greatly appreciated!! 

If it's a small glob .25 - .5 inches around, it's a drop of epoxy-like
potting compound to protect an integrated circuit "die" which is mounted
directly to the circuit board. The chip is mounted that way (instead of
in the traditional DIP package) because it saves space, and may be less
expensive for mass production. Many small calculators - and I would guess
all digital watches - are made this way.

The black blob protects the IC and its lead wires, which are otherwise 
very fragile. Try and pry off the potting compond, and you'll ruin the 
chip.

If it's a large glob - large enough to hold a DIP packaged chip within it -
then it's probably there to keep you from messing with the ROM.
-- 

Rick McTeague
Electrical Engineering Department, Speed Scientific School
University of Louisville, Louisville, KY 40292
(502) 588-7020

Internet: sysrick@starbase.spd.louisville.edu

Disclaimer: I'm a stand-up comedian; if anyone takes me seriously, I'm
            doing something wrong!