Guess this blue DIP-like part

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spiffed said:
This blue DIP16 size 4-pinned part showed up in a recent purchase. I have um, hundreds of them, and no idea what they are. Any guesses?
Click to expand...

Google thinks the 303A20 part number belongs to a Rogers or CCI 0.03uF capacitor in a package like a 20-pin DIP. I couldn't find any pictures of it, though. It looks like the part coding is <capacitor code>A<package code>: i.e. a 104 (100nF) in a DIP40-like package is a 104A40. No idea what the A stands for.

The numbers I found could just be total coincidence, though. I've never seen one in my life.


Good luck with the search!

Torben
 
It looks like a capacitor which is intended to be installed UNDER a DIL IC package.
The active connections are pins 7 and 14 (or 8 and 16), the GND and Vcc connections of the average 74 series IC.
The idea of mounting the capacitor under the IC is to minimise the lead length and improve the high frequency decoupling of the supply lines.

JimB
 
i agree with the capacitor theory, but I also hypothesize it may also be a heat sink of some sort.

what material is it made from spiffed?
 
After abusing the one on my desk, it's made of plastic, with two metal plates inside. This pretty much confirms the capacitor theory. When I find out who borrowed my RCL meter, I'll confirm that.

Thanks everyone.
 
OK, it's a capacitor. The RCL meter and **broken link removed** confirms it.

Now I just need to think of something that needs hundreds of decoupling caps.
 
spiffed said:
OK, it's a capacitor. The RCL meter and **broken link removed** confirms it.

Now I just need to think of something that needs hundreds of decoupling caps.
Click to expand...
So Nice, Spiffed-- you brought it out nicely. I do recollect it now as being used in telecom PCBs particularly in digital microwave equipments.
 
Like JimB said, it's a decoupling capacitor for a DIL logic chip - I've never actually seen one, but I have seen them listed in catalogues.
 
what is the advantage over just installing a few 0603 decoupling caps on the solder side under the IC?
 
justDIY said:
what is the advantage over just installing a few 0603 decoupling caps on the solder side under the IC?
Click to expand...

Takes up zero space on the PCB, and the capacitor is as close as possible to the the chip.

You appear to be unaware of the age of these devices? - they long predate SM components.
 
Nigel Goodwin said:
Like JimB said, it's a decoupling capacitor for a DIL logic chip - I've never actually seen one, but I have seen them listed in catalogues.
Click to expand...

Hi Nigel,

you should have had the chance to look inside an early wireless C-Net telephone made by Motorola. There were hundreds of ICs all equipped with that kind of decoupling capacitors. There is one thing interesting to know about those too: the ground terminal was arranged on the upper part for extra ground shielding of the ICs.

BTW, this device had a total weight of 15kg!

Regards

Hans
 
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