yeah I am thinking adhesive copper tape on the device, followed by aluminium tape (duct tape) on top of it with some artistically crafted "fins" 
the Cu should help absorb heat quickly and the Al should help disperse it in the air quickly.
as for the shape, here are the devices I am trying to cool -
Sigmatel STAC9460S - Codec (smd)
ST LD33 - 3.3v regulator (smd)
ST LD18 - 1.8v regulator (smd)
And a ~10mm diameter SMD inductor in the DC input section.
These are in a Audigy 2 NX usb soundcard.
the Cu should help absorb heat quickly and the Al should help disperse it in the air quickly.
as for the shape, here are the devices I am trying to cool -
Sigmatel STAC9460S - Codec (smd)
ST LD33 - 3.3v regulator (smd)
ST LD18 - 1.8v regulator (smd)
And a ~10mm diameter SMD inductor in the DC input section.
These are in a Audigy 2 NX usb soundcard.
after you figure the amount of heat necessary to dissipate you can determine the square area of copper on the board -- you might not need a heat sink -- I used board area to cool the surface mount pass transistors in my SMT super-regulator and it really works -- i have also done this with surface mount LM317 in the D-PAK.
Nat Semi has a application note on this somewhere on their website.
Nat Semi has a application note on this somewhere on their website.
I got the impression these were on a commercial sound card and he just wanted to add some extra heatsinking, but for SMT copper on the board would be the way to go for a new design.
I think with the size and type of chips involved, you'd be better off keeping it simple... trying to mix copper and aluminum is going to be past the point of diminishing returns, next you'll be looking for a MEMS fan
I think with the size and type of chips involved, you'd be better off keeping it simple... trying to mix copper and aluminum is going to be past the point of diminishing returns, next you'll be looking for a MEMS fan
Whatever you do remember to take into account the thermal conductivity of the adhesive, if the adhesive is a thermal insulator you've just taken a big leap backwards.
I have used a very tiny amount of heat transfer paste in the past, enough so it doesnt quite squeeze out the edges. Make the heatsink slightly narrower than the device and use a dab of epoxy at each edge to fix it. The surface tension of the heat transfer paste is doing most of the work.
I have used a very tiny amount of heat transfer paste in the past, enough so it doesnt quite squeeze out the edges. Make the heatsink slightly narrower than the device and use a dab of epoxy at each edge to fix it. The surface tension of the heat transfer paste is doing most of the work.
actually both the regulators are with the "on board" copper heat sink but with one of them (cant remember which one right now)
still runs quite hot!
coins or pins wont work - very little clearance.
OzMike, your point about the adhesive is good, I was a little worried about that too but the way things are going, I think its conductive - not sure how much though. Should work until I get a good thermal/heatsink paste and some copper
still runs quite hot!
coins or pins wont work - very little clearance.
OzMike, your point about the adhesive is good, I was a little worried about that too but the way things are going, I think its conductive - not sure how much though. Should work until I get a good thermal/heatsink paste and some copper
if you could find an old tv or computer monitor that used those silly "winged" vertical output chips (LM1370? comes to mind.... been a while, don't remember exact number) you could use the heat sink from that vertical chip, or cut it in half and make 2 smaller ones..... use heat conductive epoxy to glue your heatsink to the chip.......
DigitalJunkie said:I've used coins,and a dab of JB-weld before on some small bridge rectifiers.
Yeah! get those pre 1965 silver coins for your heatsink ;-)
seriously, I've used pennies glued to TO-92 devices. Pennies are not solid copper anymore, they are copper clad zinc, I forgot what year they made the change.
If you just want to buy something that you could cut and then glue on, DIP IC heat sinks might work.
Mouser.com part # 532-5012-00B00 is about 6.5mm W x 18mm L and 5mm H, with seven vertical fins that are 6.5mm wide and rise 4mm above the 1mm-thick base. It is rated at 68 deg C per Watt. If you cut off a piece with just two of the fins, it would be 4mm long, 6.5mm wide, and 5mm tall.
They also carry one that's the same overall size, but has three long fins instead of seven short ones. Part # is 532-5011-00B00. 67 deg C per Watt.
If you need better cooling than a small piece of one of those would provide, then, if you don't have much room, horizontally, but have about 3/4 inch vertically, you could use a one-fin-and-base piece of the first one, which would have a 3mm x 6.5mm footprint, and glue the second type (or part of one) to its fin, oriented vertically.
Both are black anodized aluminum.
Where space is very limited, and only a small heatsink is required, I have used these with success, for various types of devices. Two of them can be glued to the back and/or front of a TO-220 device, for example. And one can be cut shorter, if necessary, for a DIP8 package.
Good luck.
- Tom Gootee
http://www.fullnet.com/~tomg/index.html
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Mouser.com part # 532-5012-00B00 is about 6.5mm W x 18mm L and 5mm H, with seven vertical fins that are 6.5mm wide and rise 4mm above the 1mm-thick base. It is rated at 68 deg C per Watt. If you cut off a piece with just two of the fins, it would be 4mm long, 6.5mm wide, and 5mm tall.
They also carry one that's the same overall size, but has three long fins instead of seven short ones. Part # is 532-5011-00B00. 67 deg C per Watt.
If you need better cooling than a small piece of one of those would provide, then, if you don't have much room, horizontally, but have about 3/4 inch vertically, you could use a one-fin-and-base piece of the first one, which would have a 3mm x 6.5mm footprint, and glue the second type (or part of one) to its fin, oriented vertically.
Both are black anodized aluminum.
Where space is very limited, and only a small heatsink is required, I have used these with success, for various types of devices. Two of them can be glued to the back and/or front of a TO-220 device, for example. And one can be cut shorter, if necessary, for a DIP8 package.
Good luck.
- Tom Gootee
http://www.fullnet.com/~tomg/index.html
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