So, I finally bought my LM4780 chip off of DigiKey. I mindlessly forgot that it is a non-insulated type chip, so now I'm confused about proper isolation etc.
I'm using a wood chassis with some beefy copper heatpipe computer heatsinks doing the cooling. I know since my case is wood, it won't conduct (duh), but just incase I or someone else forgets somewhere in the future not to touch the heatsinks while it's running, I'd like to isolate them.
I'm kinda dumb with this entire concept so bare with me. What would happen if I ran a wire screwed in my heatsink to the safety ground pin on my IEC jack? Would that isolate it? Or do anything?
Thanks.
I'm using a wood chassis with some beefy copper heatpipe computer heatsinks doing the cooling. I know since my case is wood, it won't conduct (duh), but just incase I or someone else forgets somewhere in the future not to touch the heatsinks while it's running, I'd like to isolate them.
I'm kinda dumb with this entire concept so bare with me. What would happen if I ran a wire screwed in my heatsink to the safety ground pin on my IEC jack? Would that isolate it? Or do anything?
Thanks.
You need a Mounting kit , it will come with a Mica or Sil pad that isolates the chip from the heatsink and a Plastic washer type thing that isolates the mounting bolt from the chip and heatsink ..... you should put some heatsink compound between the Pad, chip and heatsink .....
They are pretty cheap and you should be able find them at any electronics shop .....
Cheers
They are pretty cheap and you should be able find them at any electronics shop .....
Cheers
the heatsink metal portion on back of the part is internally electrically connected to -Vee.
1 ) use 0.002" (2 mil) kapton film or 0.003 kapton tape. it comes in 0.5 and 0.75 widths, clean the tape with solvent and apply very thin coating of thermal grease both sides. EDIT>I think polyamid is the generic term for kapton
2) use only grease and take precautions to isolate the entire heatsink. (only recommended for advanced users )
1 ) use 0.002" (2 mil) kapton film or 0.003 kapton tape. it comes in 0.5 and 0.75 widths, clean the tape with solvent and apply very thin coating of thermal grease both sides. EDIT>I think polyamid is the generic term for kapton
2) use only grease and take precautions to isolate the entire heatsink. (only recommended for advanced users )
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That ebay mica doesn't look thermal washer grade. For this duty you need very thin sheets, flat, and void-free. Mica washers for heat sinking should be glass-clear with no "bubbles" in it. Cutting that with scissors is bound to leave broken up edges, so would need to be cut a bit larger than the device/sink seating area. Heat sink washers are normally made from the highest quality mica sheet and likely punched on a very sharp die.
Even if you have to use a couple pieces made for TO3P, you'd probably be further ahead than trying to make your own from this ebay stuff.
It does look like just the material used in building a vacuum tube, not that anyone we know is going to.
Even if you have to use a couple pieces made for TO3P, you'd probably be further ahead than trying to make your own from this ebay stuff.
It does look like just the material used in building a vacuum tube, not that anyone we know is going to.
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I used this for my LM4780: THERMAL PAD SIP .006" K10 - SPK10-0.006-00-105
It's a bit too large but completely covers the back of an LM4780. You can cut it to size or just leave the extra like I did.
It's a bit too large but completely covers the back of an LM4780. You can cut it to size or just leave the extra like I did.
I think that's double thickness, where less is better given good flatness of the interface and electrical "isolation" of the kapton backing is maintained.
the measured thermal resistance is surely higher on this one.
I swear I looked on Digikey and all I saw was TO-3 packages.
And good thing I just got a package from them in the mail today with some other things...great timing! *sarcasm*Alright, Digikey only charges like $2 so ship so that looks good. Thanks! I'm thinking I might use some thermal epoxy actually, since I'm using these computer heatsinks with heatpipes that I can't exactly drill into...The ones I saw were non electrically conductive, so I could possibly just use that...provided I filled in all the nooks and crannies.
I swear I looked on Digikey and all I saw was TO-3 packages.
err.. did you skip post #8 ?
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