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Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
Sulaiman wrote ...
eBay is much cheaper, e.g.
You can buy a silicone sheet and cut your own, but good sheet is also expensive,
or you can use Mylar, polyamide or similar self-adhesive tape which works well and is cheaper.
Thanks Sulaiman, hadn't seen those.
By the way, does anyone know the max speed in kHz of CM300DY-24NF IGBT bricks? im working on a driver for a 3kW Transformer that requires mains @ 60kHz.
also working on a driver for 6 of them (18kW) requiring the same frequency of 60kHz.
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Be sure to check the thermal resistance/conductance of the material. Some silicone-based insulators can severely cripple thermal performance.
I found 1 mil kapton to be the best answer for my isolation needs. For a TO-247 it adds about 0.5*C/W thermal resistance. Mica is usually thicker so it adds more resistance despite having better conductance. I haven't found a silicone type pad that even comes close to the performance of the 1mil kapton. The best stuff is the fancy alumina ceramic insulators, but even those can perform poorly if they are extra thick.
The CM300DY-24NF should be fine at 60khz provided you are operating at much less than 300A. No one can tell you the max switching speed of a transistor because its a function of other things (like current and temperature). Generally, the higher the operating frequency, the lower the allowed current.
Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
Steve Ward wrote ...
Be sure to check the thermal resistance/conductance of the material. Some silicone-based insulators can severely cripple thermal performance.
I found 1 mil kapton to be the best answer for my isolation needs. For a TO-247 it adds about 0.5*C/W thermal resistance. Mica is usually thicker so it adds more resistance despite having better conductance. I haven't found a silicone type pad that even comes close to the performance of the 1mil kapton. The best stuff is the fancy alumina ceramic insulators, but even those can perform poorly if they are extra thick.
The CM300DY-24NF should be fine at 60khz provided you are operating at much less than 300A. No one can tell you the max switching speed of a transistor because its a function of other things (like current and temperature). Generally, the higher the operating frequency, the lower the allowed current.
Kapton tape brought off ebay will work then? Im using a reel of the stuff i brought of Brocotts.
Registered Member #11591
Joined: Wed Mar 20 2013, 08:20PM
Location: UK
Posts: 556
Kapton tape is a brilliant insulator however it was designed for withstanding high temperatures, not conducting heat well, so I didn't expect it to conduct heat well. I'll try it!
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Should work, but it might be a good idea to remove the adhesive to lower thermal resistance more. A bit of thermal grease can also help by displacing air at the surfaces.
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TO-247 Insulating pads
