I wanted to make a post about thermal interfaces since I have had some experience and have had the chance to use it in holography. Anyone with corrections, clarifications or additions please post a follow up. It is very difficult to make two rigid surfaces make contact. When it is desirable to conduct heat through a junction of materials it is wise to use a thermal interfacing compound. I have experience with five types. They all work best when the surfaces mate as closely as possible. 1. Silicone based thermal grease. It is the cheapest and most available product. It is available at Radio Shack or any good electronics store. It is not a very good conductor of heat. .735 W/mK 2. Non silicone based thermal grease. AL2O3. It is difficult to spread and has a slightly better conductivity at 2.0 W/mK . 3. Silver based thermal grease. Don't be fooled by cheep imitations. Real silver based grease has 80% to 85% silver content. It is by far the best conductor and the most expensive grease I have found. I get mine from subzeropc.com. 8.4 W/mK 4. Adhesive interface pads. This is a good choice when you can't bolt the parts together. They are very easy to work with and have a reasonable conductivity at 1.7 W/mK for AL2O3 based products. I use the melcore.com product but I believe the product from digikey.com is the same thing. 5. Thermal epoxy. I have only used the Silver based epoxy. I get it from subzeropc.com. It is not a very strong epoxy as far as glue goes but it is perfect for bonded fin heat sinks. 7.5 W/mK. ------ When applying thermal products it is important to make the parts fit as well as possible. Also the surfaces must be perfectly clean. The ideal thickness of grease is .001" to .003". To maintain these tolerances it is important to not allow any dust or grit from any lapping operations to remain on the part. I clean both surfaces with alcohol before applying any grease. I use a printers ink roller to apply a very thin film on the parts. ------ I have used these techniques to assemble laser diodes to housings, make bonded fin heat sinks for laser housings and to attach the heat sink to the D&S chip in the D&S laser power supply. ----- I hope someone finds this information useful.
Colin - Wed, Jun 06, 01 10:51:10 PM
I hope this is easier to read. :-)
I wanted to make a post about thermal interfaces since I have had some experience and have had
the chance to use it in holography. Anyone with corrections, clarifications or additions please post a
follow up.
It is very difficult to make two rigid surfaces make contact. When it is desirable to conduct
heat through a junction of materials it is wise to use a thermal interfacing compound. I have
experience with five types. They all work best when the surfaces mate as closely as possible.
1. Silicone based thermal grease. It is the cheapest and most available product. It is available at
Radio Shack or any good electronics store. It is not a very good conductor of heat. .735 W/mK
2. Non silicone based thermal grease. AL2O3. It is difficult to spread and has a slightly better
conductivity at 2.0 W/mK .
3. Silver based thermal grease. Don't be fooled by cheep imitations.
Real silver based grease has 80% to 85% silver content. It is by far the best conductor and the most
expensive grease I have found. I get mine from subzeropc.com. 8.4 W/mK
4. Adhesive interface pads. This is a good choice when you can't bolt the parts together. They are very easy to work with
and have a reasonable conductivity at 1.7 W/mK for AL2O3 based products. I use the melcore.com
product but I believe the product from digikey.com is the same thing.
5. Thermal epoxy. I have only used the Silver based epoxy. I get it from subzeropc.com. It is not a very strong epoxy as far as
glue
goes but it is perfect for bonded fin heat sinks. 7.5 W/mK.
When applying thermal products it is important to make the parts fit as well as possible. Also the surfaces must be perfectly
clean. The
ideal thickness of grease is .001" to .003". To maintain these tolerances it is important to not allow
any dust or grit from any lapping operations to remain on the part. I clean both surfaces with alcohol
before applying any grease. I use a printers ink roller to apply a very thin film on the parts.
I have used these techniques to assemble laser diodes to housings, make bonded fin heat sinks for
laser housings and to attach the heat sink to the D&S chip in the D&S laser power supply.
I hope someone finds this information useful.
64.170.192.178
John Klayer - Thu, Jun 07, 01 06:24:01 PM
I used the NVG housing of the D&S laser inserted into a 75 Ohm TV coaxial coupler. Take the TV coupler, push the center conductor and insulation out, open the "crimped" end with a drill and expand the center diameter slightly with a drill or rat tail file. Put the NVG housing in it. Then mount the coupler in a heat sink. I used a piece of flat aluminum 1 inch by 3 inch by 1/8 inch. I don't remember if I used any kind of thermal grease, it has been a long time since I built it. But once I forgot to turn it off and it ran for more than two days with no damage to the diode and the assembly was only a little warm. 216.46.36.49
Khurshid Khan - Tue, Dec 31, 02 07:21:35 PM
I need to know how it applies to installing a CPU with heatsink on a Computer motherboard. I am thinking about building my own PC and I have heard some horror stories where someone applied too much of the grease and burnt the CPU? Why/how is it applied. Some pictorials would help. 170.224.224.102