to-39 heat sink thermal resistance

[coppercone2]

my HP unit had to-39 heat sinks in it, they are kind of like a springy stamping that you put over the transistor.

I assume it has poor performance as a heat sink.

I also have some of those old style To-18 aluminum heatsinks with the diode slot on them (the one where you can fit a through hole 'compensator') that are more difficult to put on but are basically extruded aluminum and fairly solid.

Does any body know what the c/w might be for those two heat sink types?

The 'better' one looks kinda like this one
https://www.marcospecialties.com/pinball-parts/HS-TO39


the 'flimsy' one looks like this kind of
https://elektronik-lavpris.dk/p115570/62530321-28-heatsink-for-to-39-284mm/


Does anyone know if that extruded one is significantly better?

its almost not worth the bother but I thought someone might have this information in their head


and it does need something, because I can start to smell the unit when I forgot to put the heat sink back on.

[bostonman]

This may not be much help, and I'm sure you already thought of this, but seems the larger one has more surface area and would dissipate heat better.

[David Hess]

TO-39 parts are good for about 1 watt without a heat sink with a junction-to-ambient thermal resistance of 175C/W, so it does not take much of a heat sink to considerably improve the performance.  It would help to add thermal grease, especially on the extruded aluminum heat sink.

[coppercone2]

You know actually it looks like that stamped heat sink has quite a bit of surface area, I was thinking maybe it might be close to the performance of the other one.


Just the problem is that when you put that one on, its pretty tight, you want to leave it on, it does not remove easy like the stamping.. it has the potential to start tearing leads if I do experiments

maybe I should do a junk box experiment to see if I have a dummy to39 device to heat up

its actually not super obvious to me which one has higher thermal performance. I feel like it might just go either way lol



the biggest thing, I think one of em is made from... spring something, and the other is aluminum. No matter how fancy you can make a springy heat sink in terms of dissipators.. i wonder if its spring copper or magnetic. if its magnetic i am putting my money on the aluminum.

and it turns out the springy one is non magnetic.

What the hell is it made out of? its silver under neath. Spring aluminum? I thought it would be too likely to crack. what metal could that be?



I am just gonna use themral greased extruded aluminum heatsinks instead of the mystery spring sheet heat sinks unless someone offers critical information within 2 weeks when the boxes are gonna be reassembled and tested