reccomendation for a glue which is both conducting heat and electricity

[yefj]

Hello,I Have the following PCB shown in the photo below ,which is glued on a heatsink.Is there a good glue you reccomend
which both conduct electricity and heat as best as possible?
Thanks.

 

[BradtheRad]

I've used a silvery fluid in a squeeze tube. Made by CircuitWorks. Also the epoxy formulation.

On the internet I've seen articles about making your own concoction. I'm certain it's tricky to ensure it's conductive... in view of the fact that inductor manufacturers mix a ferrite slurry in the hopes it does not allow eddy currents.

 

[yefj]

Hello, I need to glue two things.
One is the PCB to the heatsink and the other is to connect the transistor to the heat sink.when i removed the transistor i saw this silver stuff.

 

[D.A.(Tony)Stewart]

It is expensive and extremely toxic to skin and vapours to lungs with a short shelf life.

 

[yefj]

Hello Tony , what is the name of this material and what do you recommend ?
Thanks .

 

[D.A.(Tony)Stewart]

Hello Tony , what is the name of this material and what do you recommend ?
Thanks .

I don't have any recommendations, but there are many sources. My photo came from the datasheet using Brad's part.

Although the FET is 10x more $ I would expect $50 to $100/oz.

 

[barry]

Solder conducts both heat and electricity...

 

[yefj]

Hello Tony, what is the name of this material?
Thanks.

--- Updated Wednesday at 5:50 PM ---

I've used a silvery fluid in a squeeze tube. Made by CircuitWorks. Also the epoxy formulation.

On the internet I've seen articles about making your own concoction. I'm certain it's tricky to ensure it's conductive... in view of the fact that inductor manufacturers mix a ferrite slurry in the hopes it does not allow eddy currents.

View attachment 191879

Hello Brad is it better then regular solder? to stick brass and copper?

 

[D.A.(Tony)Stewart]

Hello Tony, what is the name of this material?
Thanks.

View attachment 191889

As I said before it was Brad's post that I used to find the datasheet.

https://www.chemtronics.com/content/msds/TDS_CW2400.pdf

How adhesive was it when removed? It does not look to be a very well-matched surface for heat sinking with many gaps.
Soldering this would need a torch and may damage the FET with a long duration above 210 'C from the mass of the part.
Bolt holes seem to be intended for grease or an adhesive.

 

[yefj]

Hello Tony the board was put on a heating source from below and blower from above till it came off .
So soldering is too high and damage the Fet
How do you know that it would damage it ?
What temperature it could handle ?

 

[D.A.(Tony)Stewart]

IDK about thermal profile. Ask Macom.

Why did you ask for adhesive if you knew it was soldered on with solder paste?
That explains the messy surface.

 

[BradtheRad]

I found the silver liquid to be excellent to attach items that couldn't be soldered. It stayed fluid long enough to be forgiving if I jiggled the work a bit. The manufacturer of your unit evidently felt the same way despite its expense.

As for thermal grease, it does not harden. It is or used to be common to apply thermal grease to fill in gaps between a mica insulator, and transistor, and heat sink. Mechanical fasteners (screws, nuts & bolts) ensured the electrical connection.

 

[G4BCH]

Have you thought about low melting point solder it's more reliable than silver/epoxy with no epoxy filler it has better conductivity.
Tin bismuth is commonly used https://www.farnell.com/datasheets/2000242.pdf, other alloys are available that may be more suitable for your environment, that's for you to investigate.

 

[yefj]

Hello,I was told to use a product called "indium" Is there some more formal name for it?
So i could search for it and order it?
Thanks.

 

[D.A.(Tony)Stewart]

Wikiwand - Indium

Indium is a chemical element; it has symbol In and atomic number 49. It is a silvery-white post-transition metal and one of the softest elements. Chemically, indium is similar to gallium and thallium, and its properties are largely intermediate between the two. It was discovered in 1863 by...

www.wikiwand.com

 

[yefj]

Hello Tony , you said about it that it’s poisonous for touch and breathing
?

 

[D.A.(Tony)Stewart]

Always Read the MSDS or MDS sheets and follow standard safety methods.

 

[FvM]

Are there any manufacturer specifications that requires an electrical conductive compound for mounting of the RF transistor? I don't think so. Also the PCA can be screwed to the heatsink.

 

[D.A.(Tony)Stewart]

electrical conductive compound for mounting of the RF transistor

More unusual is the withholding of any mounting information from MACOM. This tells me MACOM wants to know who is asking for their application info. Torque must have a spec. as well as the plating on the PCB substrate or a reflow solder profile.

Less surprising is MACOM may not have the best advise for adhesives if they prefer to solder them.

Adhesives for Microwave and RF Applications | MasterBond.com

Master Bond adhesives are used for microwave and RF applications.

www.masterbond.com

 

[yefj]

Hello,I was given an answer shown below, could you reccomend me a indium foil product i could order?
Thanks.

"There is a TIM (Thermal Interface Material) in between the bottom of the transistor flange and the top of the heatsink. That material is a, Indium Foil. The device is then screwed in and the leads soldered."