| Adam M. |
How does everyone attach a non-isolated chip to a heatsink to achieve isolation? I have some mica insulating plates to keep the chip off the heatsink, but I do not have a nylon washer that will fit inside the hole in the chip as well as have a lip to prevent the flat portion of the screw contact the chip?
I have a metal lathe and about 10 feet of nylon rod, but I'd really rather not have to make screws. Does anyone know a source for an appropriate washer/screw?
Thanks,
Adam |
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| HDTVman |
| Let's see, Radio Shack, Newark, Digi Key, Mouser for starters. It is part of the insolator kit. |
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| jaudio |
| Jameco have mounting kits. Each kit(TO-3) has 20 washer,20 screws,20 nuts and 10 mica insulators. |
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| leadbelly |
| If you have a junked PC power supply around you can steal the screws/washers from that. Another option is to just buy a nylon screw at the hardware store. I just use a nylon 6-32 x 1/2" to attach my LM3875T and oxide insulator to my heatsink. |
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| jackinnj |
| quote: | Originally posted by Adam M.
How does everyone attach a non-isolated chip to a heatsink to achieve isolation? I have some mica insulating plates to keep the chip off the heatsink, but I do not have a nylon washer that will fit inside the hole in the chip as well as have a lip to prevent the flat portion of the screw contact the chip?
I have a metal lathe and about 10 feet of nylon rod, but I'd really rather not have to make screws. Does anyone know a source for an appropriate washer/screw?
Thanks,
Adam |
Home Depot has nylon screws -- the other companies cited above have the "hip washers" in fiber or plastic which will work. |
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| moreismore |
Try this link smallparts.com
these guys have most things needed for chassis building. |
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| TwoSpoons |
| Don't use the mounting hole in the chip's leadframe. Use a bar across the body of the chip, with a bolt at each end. A thin piece of rubber sheet under the bar helps with pressure distribution. Using the bar will give much better pressure distribution across the copper heatsink tab of the chip, meaning it sits flatter to the heatsink giving better thermal performance. There's also less risk of distorting the leadframe of the chip by accidental over-torqueing of the mounting screws. |
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| zagisrule! |
A bit of tape should hold it...
;)
-Matt |
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