I am computer technician with more then 25 years of experience. This is best video I saw on the net which practically explains thermal grease application. And why you should apply only very little paste on the surfaces so you will not get the effect of insulation. Unfortunately many pc technicians don't understand this or for that matter any electronics or physics .
It really depends on the current on how hot the semi conductor gets. You don't need to use that much paste at all. Most modern pastes are better today. I have worked on many older amplifiers that use older germanium transistors which don't like heat where i have taken them out and there was never any sign of thermal paste application. The insulator and large heatsink was enough. But i always like to use a dot size dab of paste.
Short but informative, Great video! Ive a hard time with the silicone ones shorting due to snugging to tight.. The plastic / grease appear to work better although the silicon is cleaner.
I like the idea of the mica because I am a bit of a 'purist' when it comes to retro stereo equipment. Of course as long as you don't compromise function like in selecting components for recapping etc.
I just repaced 4 high hat transistors on a Kenwood KA2500 output.(2SD160) There wasnt any grease or Silicone on none of the transostors or Mica for that matter. and unbelievable the transistors still tested good. So apparently through time i guess the dielectric grease or paste must evaporate threw transformation i guess.
Thank you for your videos! Simply put, they are the best out there! I notice Nichicon has a few different Gold series capacitors. Could I ask which ones you are installing? Thanks.
Which sections on the datasheet for a heat sink compoud or silicon pad should I look at to se how non-conductive and thermally conductive it is? And if higher or lower value on respective parameter is better or worse?
I am sure the insulator reduces the heat transfer dramatically. What if we use a silicone pad with a silicone thermal paste. Maybe this will the best thermal solution for all type of heatsinks.
How about showing us your tools you take on site for fixing equipment? Various screw drivers, wrenches, ratchets etc? My dad was an old school computer repair tech and had a wonderful tool kit and oscilloscope, at least in the eyes of a 12 year old.
Is it worth investing in a torque screwdriver? Don't see torque spec listed on data sheets, but some application notes specify a range of 4-7 inch-lbs.
That would be a good idea, especially with the silicon pads. The mica pads are really durable, so I just snug the two screws down and let it go at that. Never really had a problem, at least with the old '70s receivers.
I know this is an older vid Tony, but did you mention insulator bushings on the mounting screws? Without them, the collector is essentially grounded to the heatsink!
When using this type of socket, there is a bushing on the socket itself that spaces the screw away from the heatsink. The screw provides the connection between the collector (attached to the TO-3 case) and the socket. There is no contact with the heatsink. TO-220 transistors will use the bushing sometimes on the tab, as the middle pin is also connected to the collector.
Dumb question for you -- how does heat transfer through the grease when there's an insulator between the grease? I've never understood that I guess even though I've replaced transistors in cb/ham radios. Just trying to learn some.
Since no one has answered, in the perfect world the metal case of the transistor is in perfect mechanical contact with as thin an insulator as possible for electrical insulation and the insulator is in perfect mechanical contact with the heat sink. The major impediment to heat transfer would be the insulator. However, in the real world, there is no perfect mechanical contact. There are ridges and voids and these have air in them. Air is a one of the worst mediums for conducting heat. The compound replaces the air with a better thermal conductor.
I bought some very, very expensive what you may refer to as a kind of heat sink product. It is called liquid metal.When you dispense it , it looks just like liquid solder.I hope no one will ever use this type of product for any type of electrical application.
uhm... did i missed something here ?!? why do i need mica or rubber thermal insulator sheets when i am bolting down the metal housing to the metal heatsink using metal screws ?!? where does that make sense ? btw: never ever seen these TO3 "sockets" as you called them. most often i see these tranies soldered to wires or PCBs. however.... now back to my question. how to properly mount/assemble these tranies to a heatsink, so it does not short out ? is this video covering just the half story ?
The front face of the socket is made of non-conductive high temperature plastic. It has two bushings the protrude out where the screw holes are. These bushings fit into the mounting holes of the heatsink and prevent the screws from contacting it. The rear face of the socket has a metal plate that the screw threads into. The screws then become the conductor from the case of the transistor (which is the collector) to the back plate, which has the terminal for the collector. They work very well. never had any issues except for when someone overtightened the screws and stripped them out.
It depends on the circuit. "Metal housing connected to a metal heatsink using metal screws" will electrically connect the heatsink to the collector of the transistor. If the heatsink itself is bolted to ground (for support), you nearly always have to have insulation since there aren't too many "grounded collector" circuit designs. Also, many the transistors share a heatsink, but the collectors are connected to different parts of the circuit (such as in a push-pull output.)
Aren't they missing a point here with these type of transistors most of the heat is in the bowl of the transistor wouldn't it be better to have fins round the outside? you can buy heat sinks that are tubular in their construction surely this is better to dissipate heat than just relying on the base what meanie is insulated by the Mica to transfer heat I'd be curious to see if you had one of these transistors with one of these circular heatsinks and you measure the heat on the different transistors of the same type! And it's performance in a working environment? Not seen it done on RUclips anywhere. If you have washers on the bolts would help for couplings and transfer of heat and stop it warping when you tighten the screws, you get a high spot at this area, but putting washers should eliminate this further especially if it's a thick washer or hard steel if you can get it
The round dome on the top is just a protective cover for the transistor element inside. The actual transistor is fused to the oval-shaped metal base. The base is then thermally coupled to the heatsink. Just do a search for "TO3 Transistor inside" and you can see what it looks like. Thanks for watching!
xraytonyb so why have them in that sort of manner why don't you just have the transistor open what's the point of the cover!? And the Heat would still be transmitted to the casing more than it would to the body of the transistor because it's thiner metal if you can dissipate this heat even quicker helps
I believe the cap is just to seal the transistor. The transistor would be destroyed if it came in contact with the air, so it has to have a air-tight container. I don't think there's any connection between the transistor and the cap, so heatsinking the cap doesn't help. Besides, that thick base has a purpose - it's part of the heatsink. It's conducting the heat away from the silicon. It all comes down to using the transistor the way it was designed to be used. Sure, it could have been done a different way, but that's not the direction the original designers took.
Russell Hltn of course it's going to be beneficial to take the heat away from the cap! it is a thin piece of metal so it heat will transfer to that first
Since the silicon (which is the actual transistor) is connected only to the base, then the cap won't heat up until the base does. And because it's so thin, it's not going to conduct the heat from the base as well as the heatsink because it lacks the cross-sectional area to do so. (Thin pipe) CPU chips are constructed completely different. For them, the cap is the heatsink. Take a look at this page. There's no connection between the cap and the chip. www.diystompboxes.com/smfforum/index.php?topic=109306.0
One forum,, they love the Silicone Pads for TO3, I love the Mica (they don't like it and make me think I'm doing some thing wrong ) But every now and they talk People into using the gray Silicone Pads and Guess what happens? They over tighten the screws and they short the Amp out and Blow fuses. That's why I use the Mica! Thanks Tony for showing me the Paint Bruch Trick, its easier than ever to do w less mess and it also easier to install, sines the grease will holds the Transistor in place before install the screws.
They only need to be firm tight. Those blue modern silicone insulators are great for low current devices that don't run too hot. They are more practical because you don't have to add any thermal compound. It is optionable. But for devices that run hotter, it is best to use the old silver micas with a light smear of thermal grease.
I am computer technician with more then 25 years of experience. This is best video I saw on the net which practically explains thermal grease application. And why you should apply only very little paste on the surfaces so you will not get the effect of insulation. Unfortunately many pc technicians don't understand this or for that matter any electronics or physics .
It really depends on the current on how hot the semi conductor gets.
You don't need to use that much paste at all. Most modern pastes are better today.
I have worked on many older amplifiers that use older germanium transistors which don't like heat
where i have taken them out and there was never any sign of thermal paste application.
The insulator and large heatsink was enough.
But i always like to use a dot size dab of paste.
Not so long ago I made that mistake, used pasta with silver where it was not possible. So an instructive video Tony
Very informative video.ive always used Dielecric grease. But both work good.
Short but informative, Great video! Ive a hard time with the silicone ones shorting due to snugging to tight.. The plastic / grease appear to work better although the silicon is cleaner.
I never realized that there are different grades of heat sink compounds thanks for the information.
Good job, very good practical advice. Thanks for sharing!
Well, that certainly answered my question on the subject! Thank you.
Great tutorial Tony.
thanks for the info!
I like the idea of the mica because I am a bit of a 'purist' when it comes to retro stereo equipment. Of course as long as you don't compromise function like in selecting components for recapping etc.
I just repaced 4 high hat transistors on a Kenwood KA2500 output.(2SD160) There wasnt any grease or Silicone on none of the transostors or Mica for that matter. and unbelievable the transistors still tested good. So apparently through time i guess the dielectric grease or paste must evaporate threw transformation i guess.
Thank you for this useful video.
Thank you for your videos! Simply put, they are the best out there! I notice Nichicon has a few different Gold series capacitors. Could I ask which ones you are installing? Thanks.
very informative
Which sections on the datasheet for a heat sink compoud or silicon pad should I look at to se how non-conductive and thermally conductive it is? And if higher or lower value on respective parameter is better or worse?
I am sure the insulator reduces the heat transfer dramatically. What if we use a silicone pad with a silicone thermal paste. Maybe this will the best thermal solution for all type of heatsinks.
I'm about to try and change my first one. But how do you remove the old one? Just pull it out, or is it soldered in?
How about showing us your tools you take on site for fixing equipment? Various screw drivers, wrenches, ratchets etc? My dad was an old school computer repair tech and had a wonderful tool kit and oscilloscope, at least in the eyes of a 12 year old.
Is it worth investing in a torque screwdriver? Don't see torque spec listed on data sheets, but some application notes specify a range of 4-7 inch-lbs.
That would be a good idea, especially with the silicon pads. The mica pads are really durable, so I just snug the two screws down and let it go at that. Never really had a problem, at least with the old '70s receivers.
So do I have to let the paste set or can I start playing music right after install?
The paste never hardens. You can use the device right away.
Just for reference sake , the silicone is type z9 .
where on the web do I buy this heatsink.
Why I would have to isolate a transistor with an isolating pad? Shouldn't the 3rd pin of the transistor to be connected to ground?
Those transistors only have 2 pins
I know this is an older vid Tony, but did you mention insulator bushings on the mounting screws? Without them, the collector is essentially grounded to the heatsink!
When using this type of socket, there is a bushing on the socket itself that spaces the screw away from the heatsink. The screw provides the connection between the collector (attached to the TO-3 case) and the socket. There is no contact with the heatsink. TO-220 transistors will use the bushing sometimes on the tab, as the middle pin is also connected to the collector.
Does the "Thermal Grizzly Minus Pad 8" 0.5mm thick thermal pad work better than mica and thermal grease?
It will short when it gets hot.
@@raymundmendoza3405 which will short when it gets hot?
Dumb question for you -- how does heat transfer through the grease when there's an insulator between the grease? I've never understood that I guess even though I've replaced transistors in cb/ham radios. Just trying to learn some.
Since no one has answered, in the perfect world the metal case of the transistor is in perfect mechanical contact with as thin an insulator as possible for electrical insulation and the insulator is in perfect mechanical contact with the heat sink. The major impediment to heat transfer would be the insulator. However, in the real world, there is no perfect mechanical contact. There are ridges and voids and these have air in them. Air is a one of the worst mediums for conducting heat. The compound replaces the air with a better thermal conductor.
@@johnhodgson5313 Thank you very much!
I bought some very, very expensive what you may refer to as a kind of heat sink product. It is called liquid metal.When you dispense it , it looks just like liquid solder.I hope no one will ever use this type of product for any type of electrical application.
Good vid but i think the hardware for these is the most confusing part and that wasnt very detailed.
uhm... did i missed something here ?!? why do i need mica or rubber thermal insulator sheets when i am bolting down the metal housing to the metal heatsink using metal screws ?!? where does that make sense ? btw: never ever seen these TO3 "sockets" as you called them. most often i see these tranies soldered to wires or PCBs. however.... now back to my question. how to properly mount/assemble these tranies to a heatsink, so it does not short out ? is this video covering just the half story ?
The front face of the socket is made of non-conductive high temperature plastic. It has two bushings the protrude out where the screw holes are. These bushings fit into the mounting holes of the heatsink and prevent the screws from contacting it. The rear face of the socket has a metal plate that the screw threads into. The screws then become the conductor from the case of the transistor (which is the collector) to the back plate, which has the terminal for the collector. They work very well. never had any issues except for when someone overtightened the screws and stripped them out.
It depends on the circuit. "Metal housing connected to a metal heatsink using metal screws" will electrically connect the heatsink to the collector of the transistor. If the heatsink itself is bolted to ground (for support), you nearly always have to have insulation since there aren't too many "grounded collector" circuit designs. Also, many the transistors share a heatsink, but the collectors are connected to different parts of the circuit (such as in a push-pull output.)
Morning sir..can it regulate voltage? For vintage motorcycle for example? Thank you sir 🙏
Aren't they missing a point here with these type of transistors most of the heat is in the bowl of the transistor wouldn't it be better to have fins round the outside? you can buy heat sinks that are tubular in their construction surely this is better to dissipate heat than just relying on the base what meanie is insulated by the Mica to transfer heat I'd be curious to see if you had one of these transistors with one of these circular heatsinks and you measure the heat on the different transistors of the same type! And it's performance in a working environment? Not seen it done on RUclips anywhere. If you have washers on the bolts would help for couplings and transfer of heat and stop it warping when you tighten the screws, you get a high spot at this area, but putting washers should eliminate this further especially if it's a thick washer or hard steel if you can get it
The round dome on the top is just a protective cover for the transistor element inside. The actual transistor is fused to the oval-shaped metal base. The base is then thermally coupled to the heatsink. Just do a search for "TO3 Transistor inside" and you can see what it looks like.
Thanks for watching!
xraytonyb so why have them in that sort of manner why don't you just have the transistor open what's the point of the cover!?
And the Heat would still be transmitted to the casing more than it would to the body of the transistor because it's thiner metal if you can dissipate this heat even quicker helps
I believe the cap is just to seal the transistor. The transistor would be destroyed if it came in contact with the air, so it has to have a air-tight container. I don't think there's any connection between the transistor and the cap, so heatsinking the cap doesn't help. Besides, that thick base has a purpose - it's part of the heatsink. It's conducting the heat away from the silicon. It all comes down to using the transistor the way it was designed to be used. Sure, it could have been done a different way, but that's not the direction the original designers took.
Russell Hltn of course it's going to be beneficial to take the heat away from the cap! it is a thin piece of metal so it heat will transfer to that first
Since the silicon (which is the actual transistor) is connected only to the base, then the cap won't heat up until the base does. And because it's so thin, it's not going to conduct the heat from the base as well as the heatsink because it lacks the cross-sectional area to do so. (Thin pipe) CPU chips are constructed completely different. For them, the cap is the heatsink. Take a look at this page. There's no connection between the cap and the chip. www.diystompboxes.com/smfforum/index.php?topic=109306.0
Silicon, or silicone?
Unless you know the difference, you won't know the difference ;)
Depends if your British or American.
One forum,, they love the Silicone Pads for TO3, I love the Mica (they don't like it and make me think I'm doing some thing wrong ) But every now and they talk People into using the gray Silicone Pads and Guess what happens? They over tighten the screws and they short the Amp out and Blow fuses. That's why I use the Mica! Thanks Tony for showing me the Paint Bruch Trick, its easier than ever to do w less mess and it also easier to install, sines the grease will holds the Transistor in place before install the screws.
They only need to be firm tight. Those blue modern silicone insulators are great for low current devices that don't run too hot.
They are more practical because you don't have to add any thermal compound. It is optionable.
But for devices that run hotter, it is best to use the old silver micas with a light smear of thermal grease.