Hi All,
Could anyone please advise me if these thermal insulators from Digi-Key are OK to use for the Transistors on the Honey Badger.
For Q10-Q15 TO-126 & TO-220 Digi-Key Pn= Electronic Components and Parts Search | DigiKey Electronics
and for Q16-Q21 TO-3P Digi-Key Pn= Electronic Components and Parts Search | DigiKey Electronics
Any advise would be appreciated.
Thanks
Could anyone please advise me if these thermal insulators from Digi-Key are OK to use for the Transistors on the Honey Badger.
For Q10-Q15 TO-126 & TO-220 Digi-Key Pn= Electronic Components and Parts Search | DigiKey Electronics
and for Q16-Q21 TO-3P Digi-Key Pn= Electronic Components and Parts Search | DigiKey Electronics
Any advise would be appreciated.
Thanks
So Sorry
The first PN should be - 56-77-11G-ND
The second PN should be - 4180G-ND
If you want good thermal conductivity, then use 1mil/thou, or 1.5mil Kapton with a thin adhesive layer.
If you need tough insulation, then go up to 6mil/thou. But this is not at all good for a thermal conductor.
If you need tough insulation, then go up to 6mil/thou. But this is not at all good for a thermal conductor.
Thanks prasi 🙂
Thanks Andrew 🙂
I appreciate your input. I have done a web search found this 1 Mil Kapton® Tapes and I just wanted to confirm this is what you talking about before I order it.
If you wouldn't mind confirming I will go ahead and order some.
https://www.kaptononline.com/kapton_tape.php
or
https://www.kaptontape.com/1_Mil_Kapton_Tapes.php
Thanks again.
yes thats correct. Go for 30mm width, you will be able to accommodate any package from to-126, mt-200 and to-264.
use heat sink paste on back side of transistor.
there are cheaper options on ebay, but not know the quality.
reg
Prasi
A few of us bought "koptan" tape on eBay a little while back. It appears to be good, and I believe a couple of members use it successfully on a regular basis. It is much cheaper!
Yes, I bought the spelling error (Koptan) version and it is surprisingly good value.
It does not curl/shrivel in contact with a 290egrees C soldering iron tip.
And it is thin enough to compare to thin mica for heat transfer.
I could not recommend it for continuous use at that high a temperature, but I suspect it could have a long life at 100degrees C for an overheated amplifier that has heatsink temperature cut-out.
If you can get 10mm, or 12mm without adhesive in 6thou, that would be good for insulating toroid transformers.
An update, since I did a partial dismantle recently.
The adhesive does migrate from high pressure areas to lower pressure areas when heated in the longer term.
That means the adhesive will gradually reduce in average thickness with time improving the heat transfer. But this may require re-tightening of the clamps to ensure adequate pressure at the interface.
It does not curl/shrivel in contact with a 290egrees C soldering iron tip.
And it is thin enough to compare to thin mica for heat transfer.
I could not recommend it for continuous use at that high a temperature, but I suspect it could have a long life at 100degrees C for an overheated amplifier that has heatsink temperature cut-out.
If you can get 10mm, or 12mm without adhesive in 6thou, that would be good for insulating toroid transformers.
An update, since I did a partial dismantle recently.
The adhesive does migrate from high pressure areas to lower pressure areas when heated in the longer term.
That means the adhesive will gradually reduce in average thickness with time improving the heat transfer. But this may require re-tightening of the clamps to ensure adequate pressure at the interface.
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Thanks Guys for your input really appreciate it. 
Now I fell like I am on the right track. 🙂
So for my Transistors I am going to take your advise "Thanks prasi" and get the 1 1/4" Kapton Tape.
Just to confirm, I checked the spec sheet and it say that this tape has a
Film Thickness of 1.2 Mil & Adhesive Thickness of 1.5 Mil.
So I install that Adhesive side onto my heat-sink and then place the thermal heat sink paste on back side of transistor?
What about where the mounting screw for the transistor goes?
What do you guy's recommend for that?
Do you some how drill a hole in the tape? 😕
Andrew If you don't mind could you please give me some more detail on this.
Are you saying that I should place a layer of non insulated tape. I think they refer to it as film. (non sure) under the toroidal transformer. So it adds another layer of insulation between it and the amplifiers chassis?
If film is what your talking about I think I found some 5 Mil here.
https://www.kaptontape.com/Kapton_Films.php
Is this what you are talking about?
Thanks again guys for all the positive & informative input. it really helps a lot.
Now I fell like I am on the right track. 🙂
So for my Transistors I am going to take your advise "Thanks prasi" and get the 1 1/4" Kapton Tape.
Just to confirm, I checked the spec sheet and it say that this tape has a
Film Thickness of 1.2 Mil & Adhesive Thickness of 1.5 Mil.
So I install that Adhesive side onto my heat-sink and then place the thermal heat sink paste on back side of transistor?
What about where the mounting screw for the transistor goes?
What do you guy's recommend for that?
Do you some how drill a hole in the tape? 😕
Andrew If you don't mind could you please give me some more detail on this.
Are you saying that I should place a layer of non insulated tape. I think they refer to it as film. (non sure) under the toroidal transformer. So it adds another layer of insulation between it and the amplifiers chassis?
If film is what your talking about I think I found some 5 Mil here.
https://www.kaptontape.com/Kapton_Films.php
Is this what you are talking about?
Thanks again guys for all the positive & informative input. it really helps a lot.
Thanks Guys for your input really appreciate it.
Now I fell like I am on the right track. 🙂
So for my Transistors I am going to take your advise "Thanks prasi" and get the 1 1/4" Kapton Tape.
Just to confirm, I checked the spec sheet and it say that this tape has a
Film Thickness of 1.2 Mil & Adhesive Thickness of 1.5 Mil.
So I install that Adhesive side onto my heat-sink and then place the thermal heat sink paste on back side of transistor?
What about where the mounting screw for the transistor goes?
What do you guy's recommend for that?
Do you some how drill a hole in the tape? 😕
have a read here ESP - Heatsink design and transistor mounting
my procedure is like this.
carefully mark the center of transistor mtg holes on heatsink. use a center punch to make an indentation.
drill 2.5 mm holes in heatsink. countersink it with a bigger drill 5 -6mm for about 1mm depth. clean heatsink with pressurized air or water to get rid of the burrs.
use a M3 tap with a handle /wrench and some tap oil (5-6 drops per hole, put some oil on tap too) and very carefully tap the heatsink. 1 to 1-1/2 rotation in, then 1/2-3/4 rotation out.
once all holes are tapped, again clean heatsink with water and nylon brush. be thorough in this and take your time.. there should be no burrs whatsoever.
dry the heaksink, put kapton tape on it so that it covers whole area where the transistor will make contact with heatsink. start from one end carefully put the kapton and see that there are no air bubbles and folds.
with small precision screw driver /pin, pop the kapton over the tapped portion.
apply h/s paste on back side of transistor, mount transistor with M3 bolts and with a metal washer.
this is applicable for all power transistors to-3p, to-247, mt-200, to-264 and also for to-126.
for to-220, use a plastic bush and appropriately sized tapping and screw.
This is OK for heat transfer.
Yes. The adhesive excludes air from the sink to Kapton interface and the thermal compound excludes air from the device to Kapton interface.
The really important part is excluding ALL the air from the joint. Next up is making the "no air" joint as thin as possible.
the area around the hole rises above the flat face of the sink. This needs to be taken down to the same level as the flat plat. I use 600grit "wet or dry" silicon carbide rubbing down paper for this. Place a piece on a FLAT holder and wrap the sides up to be gripped by your fingers. Rub over the holed area and gradually you will reduce the hills down to the flat level. If your heatsink has a rough finish you will see it becoming flatter as well. 600grit does not get to a mirror finish but it can be very much better than the finish on most aluminum from the factory.
I prefer the clamping method where a thick bar across the device is held down with two bolts/screws inserted close to the device. This gives a much more even pressure between the device and sink. It also allows a bigger bolt/screw to be used and you have two of them. Overtightening a single through bolt deforms the interface "flatness" and can lead to poor heat transfer. Clamping is better.
If you ever remove the insulation from a toroid you will find it has a few nicks in it. When you come to rewarap the insulation it will tear at these nicks. Starting with a fresh roll of undamaged Kapton is better, You will have to guesstimate the length you will need to completely wrap the whole winding. That has to be wrapped around a shuttle that can easily pass through the toroid.Andrew If you don't mind could you please give me some more detail on this.
Are you saying that I should place a layer of non insulated tape. I think they refer to it as film. (non sure) under the toroidal transformer. So it adds another layer of insulation between it and the amplifiers chassis?
If film is what your talking about I think I found some 5 Mil here.
https://www.kaptontape.com/Kapton_Films.php
Is this what you are talking about?
Thanks again guys for all the positive & informative input. it really helps a lot.
A little bit of sticky tape at the start and a bit more to hold the end. The stickyness of this end fixing tape must last for years. Many tapes have a "stick" that fails within a few months/years. You NEED a long life sticky tape.
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There's a lot of bad information on the internet for tapping aluminum. As long as there is something on the tap where it contacts the aluminum the aluminum won't stick to the cutter. Everyone blames tapping procedures for broken taps, but the cause is usually incorrect drilling methods that cause the aluminum to become warm and annealed(mush). Annealed aluminum will stick to a tap and cause it to break. This is not the fault of the tap quality, its the drill operator.
Use a sharp drill bit and cool it. If there is sufficient material depth, follow drilling with a proper chamfer to make chipping of the first tooth of the tap less likely to happen. Sanding a square edge isn't ideal, but will work if the material isn't very thick.
When tapping, use a spiral flute tap designed for aluminum for best results. These taps are easily available from any machine shop supply and are the same price as a steel tap. This will draw the aluminum chip out the top of the hole as you cut which will eliminate the need to stop and back up the cut. If you watch a tapping head on a milling machine operate you will see the cut continues in one motion until the cut is finished, then it reverses out of the hole.
In my experience tapping aluminum (which I've done many times daily for 20+ years) a tap handle is a bad choice of tools. It is too hard to keep the tap square with a tap handle. A drill press chuck (turned by hand) or tapping fixture are much better, or my personal favorite is a cordless drill in low range. The long length of the drill give you a much better sense of squareness than a tap handle. Any reasonable quality 6063-T6 heat sink will tap with ease this way. If you are using low quality extrusions, you are likely going to break a tap no matter what you do as the material you are cutting will likely be sticky mush.
Use a sharp drill bit and cool it. If there is sufficient material depth, follow drilling with a proper chamfer to make chipping of the first tooth of the tap less likely to happen. Sanding a square edge isn't ideal, but will work if the material isn't very thick.
When tapping, use a spiral flute tap designed for aluminum for best results. These taps are easily available from any machine shop supply and are the same price as a steel tap. This will draw the aluminum chip out the top of the hole as you cut which will eliminate the need to stop and back up the cut. If you watch a tapping head on a milling machine operate you will see the cut continues in one motion until the cut is finished, then it reverses out of the hole.
In my experience tapping aluminum (which I've done many times daily for 20+ years) a tap handle is a bad choice of tools. It is too hard to keep the tap square with a tap handle. A drill press chuck (turned by hand) or tapping fixture are much better, or my personal favorite is a cordless drill in low range. The long length of the drill give you a much better sense of squareness than a tap handle. Any reasonable quality 6063-T6 heat sink will tap with ease this way. If you are using low quality extrusions, you are likely going to break a tap no matter what you do as the material you are cutting will likely be sticky mush.
Nice idea, I really like that. I will do this for sure. 🙂
Thank you for that advice, I will do this for sure.
Andrew, so sorry to ask the same question again as you have given me such detailed responses, but is is this Kapton film suitable for wrapping / re wrapping the Toroidal?
https://www.kaptontape.com/Kapton_Films.php
Thanks
It looks like they only do Kapton tape with adhesive.
That is very difficult to work with for rewrapping a toroid.
Plain Kapton tape that is strong in tension is needed.
Ask if they do Kapton with no adhesive for wrapping. 6thou/mil to 10thou thickness is about right.
Two advantages of the clamping method:
a.) no hole is needed for a screw to pass through leaving an intact film for more reliable insulation.
b.) the pull up around the drilled hole is not under the device. After de-burring it does not need to be flattened.
That is very difficult to work with for rewrapping a toroid.
Plain Kapton tape that is strong in tension is needed.
Ask if they do Kapton with no adhesive for wrapping. 6thou/mil to 10thou thickness is about right.
Two advantages of the clamping method:
a.) no hole is needed for a screw to pass through leaving an intact film for more reliable insulation.
b.) the pull up around the drilled hole is not under the device. After de-burring it does not need to be flattened.
Hi Andrew. No to be rude.... are you sure that you are looking at the Kapton Film?
I just doubled checked the spec sheet for it and it doesn't mention adhesive.
5 Mil Kapton® Film, RoHS Compliant
Technical Datasheet
5 Mil Kapton Film
5 Mil Kapton® Film also known as Polyimide Film, Heat Resistant Film or a High Temperature Film, is ideal for insulating circuit boards, high temperature powder coating and transformers manufacturing.
Sent from my SM-G920I using Tapatalk
I just doubled checked the spec sheet for it and it doesn't mention adhesive.
5 Mil Kapton® Film, RoHS Compliant
Technical Datasheet
5 Mil Kapton Film
5 Mil Kapton® Film also known as Polyimide Film, Heat Resistant Film or a High Temperature Film, is ideal for insulating circuit boards, high temperature powder coating and transformers manufacturing.
Sent from my SM-G920I using Tapatalk