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Old 14th October 2001, 11:12 PM   #11
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The kapton isolating pads I have found say that they are 0.07K/W from Fischer. they also donīt need silicon grease. If this is wrong I donīt know. They cost in Germany 0.5 Euro.
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Old 14th October 2001, 11:13 PM   #12
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One place you can check this is in http://www.schuro.de and http://www.thel.de.
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Old 15th October 2001, 12:28 AM   #13
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Catalogs frequently present incomplete or wrong data.The people doing the layout usually know nothing about the items they are cataloging.That is why I gave a direct link to the data sheet for the part in question.In the data sheet there are charts showing *C/W at different case areas and mounting pressures.After you examine this data you will realize that the 0.07*C/W number you quoted is simply not possible for any transistor case syle used for audio.
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Old 15th October 2001, 06:36 AM   #14
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Silicon rubber wafer has at best 0,34K/W,
High performance kapton has 0,07K/W,
aluminum oxide has 0,3K/W,
mica wafers have 0,4K/W these are true figures from Fischer heatsinks.

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Old 15th October 2001, 08:29 AM   #15
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I don't find any such data at Fischer.Maybe you could link to it.Here is their heatsink catalog: http://www.fischerelektronik.de/fischer/geskat_e.htm

[Edited by djk on 10-15-2001 at 03:31 AM]
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Old 15th October 2001, 09:36 AM   #16
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Don't know about Kapton, except as oven bags and the substrate in some silipads, but its hard to beat the "High Performance Phase Change Thermal Compounds" with a low thermal impedance of 0.008 °C-inē/W like <a href="http://www.powerdevices.com/powerfilm.htm">POWERFILM
</a>.

I can't seem to find if they are insulators or not?

regards
James
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Old 15th October 2001, 06:56 PM   #17
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So since the Aleph 5 draws 150 watts per channel I would need at least 3 of theese. I figured that I needed to mount the transistors together in the groups of 3 that are indicated on the schematic. Since there are 4 sets I figured I needed an even number of sinks. So I need 4 sinks one for each group. Is that correct? I know that may be overdoing it a bit, but I think it's still cheaper than buying new isn't it? If I did get 4 what chance would there be that it wouldn't be enough? Thanks for all of the imput. I'm looking at the esp page right now.

Rob
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Old 16th October 2001, 08:57 AM   #18
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("High Performance Phase Change Thermal Compounds" with a low thermal impedance of 0.008 °C-inē/W like POWERFILM
I can't seem to find if they are insulators or not?) First off it's non-insulating.Second is that it's for hockey-puck and energy management packages at very high clamping pressure on a sink that is polished to 64 ĩ inches.At typical thicknesses and pressures used for audio semiconductors it is comparable to regular ZnO2 heatsink compound.The heatsink must also be pre-heated to apply this stuff(it is a little like the Avid Kon-Ducs that must be vulcanized to the sink).Lots of neat stuff out there.I listed my preferences earlier.
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Old 16th October 2001, 01:49 PM   #19
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AOS Thermal Compounds has these, they appear more suitable.
<i><a href="http://www.aosco.com/microfaze.shtml">AOS MICRO-FAZEŪ K</a> Dry Film Interface Material
It was developed by AOS to offer the lowest thermal resistance in a thermal interface without the mess of grease.

MICRO-FAZE K is a die-cut polymide insulating substrate coated on both sides with specially formulated thermal grease (non-silicone, non-wax-based) that is naturally tacky but dry to the touch. It offers unique heat transfer and high insulating capabilities, and has a high cut-through resistance.

<li>Unlike phase change materials, MICRO-FAZE K requires minimum force to achieve total interface contact and heat transfer starts at any temperature.

<li>A positive coefficient of thermal expansion increases the wetting action for total interface contact.

<li>MICRO-FAZE K microscopically changes to fill all microscopic voids on part surfaces.

<li>Thermal Resistance: 0.03°C in<sup>2</sup>/W</i>

Regards
James
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Old 17th October 2001, 09:14 AM   #20
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And we're back to Kapton with a coating again.I wonder what they are calling a low clamping pressure? And I wonder how much this stuff costs? The better Berquist products cost more than the 250V 250W 25A outputs I am using.Actually I am using forced convection with electrically 'hot' heatsinks isolated from the chassis.No insulators.
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