namer of lubricant/grease being used for metallic bond while fixing the fets with h/s

[ch wazir]

hello,
Can one tell the name of lubricant/grease being used while tightening fets/transistors with heat sinks.plz also answer whether one can use the silicon like Harris silicone grease. thanks.

 

[FvM]

It's called thermal grease or heat sink paste. It's usually silicon grease filled with alumina or metal powder and has a white or grey colour. It's thermal conductance is considerably higher than unfilled (clear) silicon grease, but by filling air gaps, the latter still improves thermal conductance.

 

[bigdogguru]

The "grease" you are referring to is a thermal coupling compound, often lithium, zinc or alumina based although there are non-metallic based thermal couplings as well. Whatever you use with your heatsinks you need to ensure it has the proper thermal properties, can withstand constant high temperatures and offers exceptional stability. In short, if the compound is not specifically recommend for use with heatsinks, I would select an alternative.

BigDog

 

[ch wazir]

hello FvM,
plz mention the name of grease if u feel convenient.Thanks

 

[FvM]

See the products from Thermalloy as an example **broken link removed**

 

[bigdogguru]

I came across this interesting comparison of thermal greases/compounds, sometime ago, thought it maybe relevant to this discussion:

Thermal transfer compound comparison

BigDog

 

[ZASto]

Interrestin comparison :smile:

I prefer DOW CORNING|2265931|HEAT SINK COMPOUND, DC340, 100G | Farnell United Kingdom

 

[ch wazir]

hello FvM,
Thanks so much for guidance ,plz also explain whether one can check the conductivity of the grease with Ohm meter.plz also help whether the grease named O-Ring Grease(Harris Silicon Grease) will meet the requirement regarding intrfacing the mosfets like irfp75 with heat sink. thanks for inconvenience.

 

[FvM]

plz also explain whether one can check the conductivity of the grease with Ohm meter.

The parameter of interest is thermal not electrical conductivity. It can't be measured with an ohmmeter.

plz also help whether the grease named O-Ring Grease(Harris Silicon Grease) will meet the requirement regarding intrfacing the mosfets like irfp75 with heat sink.

Sounds like a standard silicone grease. As said, it's better than dry mounting, but not achieving a good thermal interface.

There's however a problem in comparing thermal greases,because a heatsink with perfect flat surface can work with regular grease without much reduction of thermal performance. This problem obviously shows in the benchmark linked by bigdogguru. It should be also clear, that you possibly get good results with unusual compounds like tooth paste. But unfortunately, after the water dried out, they most likely fail.

 

[betwixt]

I think it's time to buy shares in Vegimite, especially if you are in Pakistan.

Brian.

 

[jpanhalt]

I did not see the carbon-based (e.g., diamond dust) materials mentioned, such as this: IC Diamond 7 Carat Thermal Compound - 1.5 gram

They are being pushed by my local DIY computer store. It has presumably been evaluated here: Diamond Thermal Grease Testing | Overclockers

I don't know how much credibility to give to that report, though.

John

 

[FvM]

The criteria applied in the report sound reasonable. It should be considered however, that except for CPU coolers and perhaps high power electronics, applications rarely depend on perfect thermal property. In most standard applications, the share of device packages and heat sinks is making the major part of total thermal resistance.

 

[grizedale]

when i worked at a big electric drive company, my boss told me to not get thermal grease on my hands etc too much..cuzz he said it may cause cancer.

I accidentally got thermal paste on his scope and he went ballistic.

Remember to apply far too much thermal grease, so it seeps out around the fet, then you can actually tell that the assembly staff have bothered to use it...........many assembly staff think that thermal paste is a stupid waste of time, and think that a direct connection of the fet to the heatsink is better for thermal heat flow......so they dont bother to use the thermal paste....because it horrible to work with and difficult to get off your clothes.

i garantee your assembly staff will skimp on thermal paste if they can get away with it.

 

[Tipu606]

name is thermal grease or heat sink grease
go to any electronics shop and they have it in small containers and its made in China

 

[liteon]

In PAKISTAN at city of multan an electronics parts store sells exceptionally good quality thermal compound in tiny containers refiled from a large single container so no name or brand is printed on them.The store keeper told me that he imports it from Germany and the original container costs at whooping high price and contains like 2-KG of the compound so he refills tiny containers to keep the price for hobbyist.I used it and its is of excellent quality.
Another small container i bought from another store is with brand name of "ELCTRO LUBE"
made in japan.I doubt for it to be made in japan yet the quality is good.

 

[ch wazir]

liteon,thanks so much for information.

 

[liteon]

I bought second container with brand name of "ELECTRO LUBE" from a store At Lahore. Ground floor AL KHALIL center 16 Hall road. They sell measurement instruments and soldering accessories.I don't remember the name of store but it is next to Hi-Rise traders shop no 6.
One reason for buying small containers is the life of compound.once original seal of the lid is removed and it can not be stored for longer time and may be for shorter time if the lid is not fitting very tight.The compound may dry up.specially during the summer season in our country when it is killer hot.

 

[ch wazir]

hello dear liteon,
u helped me a lot,i hve no words to thank u.Plz also help me to send some diagrams of charge controller for solar inverter 1000-2000 W if u feel convenient.
Again thnx lot

 

[liteon]

I will love to send you some info for solar charge controller.
What are the ratings of solar panel and specifications of battery to be charged.

 

[ch wazir]

dear liteon,
thanks so much for urs symphethatic help.

---------- Post added at 09:16 ---------- Previous post was at 09:10 ----------

hi liteon,
soler inverte; 2000w,24 volts
batteries 2@12 volts each
capacity;200AH each.
thanking for demanding specification.