Kapton Alternative Polyimide Tape 1 Mil - Wholesale
This Kapton tape has 1.6mil of adhesive. I have no idea what the thermal resistance of their glue is. I have no idea how easy it will be to apply without getting any air trapped in the adhesive.
This Kapton tape has 1.6mil of adhesive. I have no idea what the thermal resistance of their glue is. I have no idea how easy it will be to apply without getting any air trapped in the adhesive.
Kapton insulators for TO 247 devices (IRFP 240/9240)
Why not using professional, pre cutted Kapton discs for TO247 with thermal grease layers on both sides. They are available at DigiKey or Mouser to relatively low cost.
Technical data:
Base Material: Kapton
Dimension: 24 x 21 mm with mounting hole for TO247
Base material thickness: 50 micron (2 mil)
Thermal grease thickness: 2 x 13.5 um = 27um (~1 mil)
Total thickness: 77um (~3mil)
Thermal resistance: 0.01K/W
They are very solid and hardly to damage during mishandling, hence ideally for DIY use.
I don't know why DIY people try to invent the wheel again.
I use these parts successfully since long time at all my Pass Class A amp projects.
Gerd
Why not using professional, pre cutted Kapton discs for TO247 with thermal grease layers on both sides. They are available at DigiKey or Mouser to relatively low cost.
Technical data:
Base Material: Kapton
Dimension: 24 x 21 mm with mounting hole for TO247
Base material thickness: 50 micron (2 mil)
Thermal grease thickness: 2 x 13.5 um = 27um (~1 mil)
Total thickness: 77um (~3mil)
Thermal resistance: 0.01K/W
They are very solid and hardly to damage during mishandling, hence ideally for DIY use.
I don't know why DIY people try to invent the wheel again.
I use these parts successfully since long time at all my Pass Class A amp projects.
Gerd
BA3 front end adjustment.
Sorry Bob, but I have problems to follow and to understand all corrections made to successfully run your BA3 amp.
I don't know if you have primarely adjusted the front end before connecting the bias- and power output stages.
As long as the front end isn't adjusted for symmetrical bias and DC-offset minimum, the whole system will not work correctly.
Question:
Did you carefully read and understand the recommendations made by Nelson for firering up the amp step by step?
First, the frontend must run independently from the bias- and power boards.
If not yet done, please adjust the frontend accordingly to Nelsons instruction.
I have build all burning amp designs as BA1 / 2 and 3 with PP- as well as with
the SE- power output stages without any problem, but I have strictly followed Nelsons instruction.
Gerd
Sorry Bob, but I have problems to follow and to understand all corrections made to successfully run your BA3 amp.
I don't know if you have primarely adjusted the front end before connecting the bias- and power output stages.
As long as the front end isn't adjusted for symmetrical bias and DC-offset minimum, the whole system will not work correctly.
Question:
Did you carefully read and understand the recommendations made by Nelson for firering up the amp step by step?
First, the frontend must run independently from the bias- and power boards.
If not yet done, please adjust the frontend accordingly to Nelsons instruction.
I have build all burning amp designs as BA1 / 2 and 3 with PP- as well as with
the SE- power output stages without any problem, but I have strictly followed Nelsons instruction.
Gerd
hi bcmbob,
I got my kapton tape today and the company also answered the email I set them,I got the 30mm wide and it's 100 feet but AndrewT said should use 1mil thick and the one I got is 6mils ,what did you order and from where ?
Is it 1mil? aha I found those nice links you used,lol.sorry should have looked!
Thanks,
NS
Well that's a new way for me to think about configurations. So you are saying the output of an F5 would be considered 1 deep - and each additional 4 devices creates another depth -correct?
I was reading articles on the PassDiy site yesterday, but the Pass Labs has a better presentation. Some of the DIY site articles have sections/paragraphs out of sequence.
I left R219 open as it was described as optional. My entry into the BA universe was initially as a heat management project, but I like the sound enough to cycle back and try to optimize the output of the amp. I ordered some of these to try in C3 on the front end. Buzz gave me some suggestions on other caps and resistors choices I'll investigate later. Have a roll of 5/8" Kapton on the way. Even with shipping it is less expensive that the Mouser item mentioned earlier. Minimum order was 38 yards, so if anyone wants to try some, PM me for a free chunk of the remaining 430 inches.
I got my kapton tape today and the company also answered the email I set them,I got the 30mm wide and it's 100 feet but AndrewT said should use 1mil thick and the one I got is 6mils ,what did you order and from where ?
Is it 1mil? aha I found those nice links you used,lol.sorry should have looked!Thanks,
NS
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Thanks for that site AndrewT,
They have all the tape you need,I got my kapton today and it's 6 mils,it will work for transformer winding insulation,they gave the figure of 536 degree ,lol don't think I'll test that out,
Thanks for the info,
NS
They have all the tape you need,I got my kapton today and it's 6 mils,it will work for transformer winding insulation,they gave the figure of 536 degree ,lol don't think I'll test that out,
Thanks for the info,
NS
Actually, I'm hoping to be able to remove the adhesive with a solvent that won't touch the film itself. There are large sheets of bare film but I have not found a retailer yet - sold in large wholesale/OEM quantities so far. I did order the 1 mil Kapton product and confirmed it with an email this morning.
GKU - The amp has been singing wonderfully for two days. I'm working on a interface to allow scope type information for deeper diagnosis.
GKU - The amp has been singing wonderfully for two days. I'm working on a interface to allow scope type information for deeper diagnosis.
Great for your amp!I tried vinegar,acetone,and finally lacquer thinner did remove the adhesive,the view through the tape changes color when the adhesive comes loose,it seems to do better if it soaks a little then I used a paper towel to get it clean,
NS
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Kapton is the trade name for Polyimide of DuPont.
According to my knowledge only one type of polyimide films are available.
For sure they are available in different thicknesses, with or w/o adhesive for many different applications.
For me it is less the thermal performance (0.24W/m*K vs Mica 0.53W/m*K) without thermal grease.
It is more the ease of handling and the good mechanical stability which make it for me and many others more desirable for the DIY application as insulator at the assembly of power transistors on heatsinks.
In addition I personally prefer the finished discs with thermal grease on both sides and with the mounting hole raedy to use.
If others like to use different types of material and do tayloring these to their special use, it is ok for me.
I come from the electronic industry and am used to work with established and well experienced materials to reduce the risk at my DIY work.
According to my knowledge only one type of polyimide films are available.
For sure they are available in different thicknesses, with or w/o adhesive for many different applications.
For me it is less the thermal performance (0.24W/m*K vs Mica 0.53W/m*K) without thermal grease.
It is more the ease of handling and the good mechanical stability which make it for me and many others more desirable for the DIY application as insulator at the assembly of power transistors on heatsinks.
In addition I personally prefer the finished discs with thermal grease on both sides and with the mounting hole raedy to use.
If others like to use different types of material and do tayloring these to their special use, it is ok for me.
I come from the electronic industry and am used to work with established and well experienced materials to reduce the risk at my DIY work.
I'll state my interest in thermal interface alternatives as a simple combination of ease of use and cost. It's not so much re-inventing as it is experimenting with different approaches. The 1 mil mica that Andrew likes should be the inexpensive standard, IMHO - but it's application requires more practice on my part. The pads the store is selling appear to be the easiest to use but are also the most expensive.
So since as a retired dude, I have more time than money and good sense - I don't mind a little trial and hopefully not too much error. However, I am aware of that "Don't trip over a dollar to pick up a dime" thing. The pre-cut Kapton disks may well prove to be the sweet spot.
So since as a retired dude, I have more time than money and good sense - I don't mind a little trial and hopefully not too much error.
However, I am aware of that "Don't trip over a dollar to pick up a dime" thing. The pre-cut Kapton disks may well prove to be the sweet spot.
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Keratherm red 86/83 is a glassfiber reinforced, alumina (aluminum oxyd) filled silicone rubber from a German manufacturer.
In our company we have tested it as a thermal conductive insulators for large heat think attachment.
It is a good alternative product to Kapton tapes.
But the thermal conductivity with 8W/m*K is much too high. In our company we have re-checked these data and found 2.6 W/m*K, still a very good value.
According to the manufacturer his data are not measured data, they were calculated from the thermal conductivity of alumina.
In Germany we can get it as pre-cutted parts for TO247 but quite expensive, the reason why I use thermal grease coated Kapton.
In our company we have tested it as a thermal conductive insulators for large heat think attachment.
It is a good alternative product to Kapton tapes.
But the thermal conductivity with 8W/m*K is much too high. In our company we have re-checked these data and found 2.6 W/m*K, still a very good value.
According to the manufacturer his data are not measured data, they were calculated from the thermal conductivity of alumina.
In Germany we can get it as pre-cutted parts for TO247 but quite expensive, the reason why I use thermal grease coated Kapton.
Interestingly, I experienced something similar last weekend with the micas. I found absolutely no continuity on any FET leg before I applied the power. Once heated the shorts appeared. There is a good possibility I over-tightened the bolts on the bars and some compression of the mica occurred with heat. I'm not sure if that's a characteristic of that material.
Try aluminum oxide ceramic insulators and a little goo, no problems with thermal breakdown or peacing; they may not be the best thermal conductor but they are certainly good enough; a good compromise I think.