Searching insulator type for LM4780 chip

[Peter Daniel]

We've been looking with Brian for convenient insulators to use with LM4780 chip package, but it seems like nothing ready made is available. Anybody got any experience with those?

So far it seems like getting bigger sheets from D-K and cutting them to size is the only reasonable way to go, but punching the holes might be a hassle.

 

[Upupa Epops]

I am using fot it folie named Sarcon, typ 30U, dia 0.3 mm ( grey ), Rth = 0.26 °C/W. It is made as belt, so you must cut it yourself.

 

[SheldonD]

Peter I was planning on usin TO3 insulator with a bit of trimming and a hole punch.

It totally covers but for the 2 holes af about 2 mm. for the 2 pins
of the TO3. This area is less than 1 % of total heat sink

 

[Peter Daniel]

To make few insulator for personal needs is not a problem, but I was getting ready for the kits and none of the above is really appealing.

Upupa's suggestion requires punching of the precision holes in the insulator material, and this is something I would prefer to avoid, (maybe not me that much, as Brian )

Sheldon's suggestion, while still workable, will not look professional with the kits supply.

 

[TwoSpoons]

Have you contacted someone like Berquist? They were most helpful when I requested samples of their materials, and they do precut shapes.

 

[carlosfm]

I used isolators for bigger chips (like STK).
I've cut one in half and it did for two 4780s.
But why bother?
I'm makin' another LM4780 amp and will just isolate the heatsink from the chassis.
This chip needs to be properly cooled down, it's two channels in a small package.
If possible, don't use isolators.

 

[Nisbeth]

How about asking National about this?


/U.

 

[Upupa Epops]

TO 3 insulator is nonsens, guys . Much more better is insulated heatsink, as says Carlos, but for many guys it will be big construction problem. Peter, give to the kit stencil on paper - with scissors for nails isn't problem cut it yourself.

 

[Peter Daniel]

Have you contacted someone like Berquist? They were most helpful when I requested samples of their materials, and they do precut shapes.

How about asking National about this?

We did contact them, but receive no answer yet. All in all, if nothing else is found, we will be cutting the pieces. We just thought that could be avoided by finding proper type of insulators, but it doesn't seem like it's been made.

It would be an option to isolate heatsink, but neverthereless, I thin an insulator should be included with a 4780 kit.

 

[carlosfm]

Isolate the heatsink

Screw the heatsink to a piece of wood (MDF of whatever).
Screw the piece of wood to the chassis.
Done.

 

[digi01]

Perhaps it is not a good idea, I have used 35mm film to make the insulations