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silicone rubber sheet

Posted by: rambabupotluri on

Dear Sir,

we designed with TOP258Y for 100W output power.the temp beween  case to heatsink is more than 30Deg.C

we feel silicone rubber sheet is not good,how to select silicone rubber sheet and suggest some make with model.

and also suggest heatsink compund with make and model .

Thanks&Regards 

Comments

Submitted by PI-Cochrane on 04/01/2014

I understand that you are struggling on the thermal issue.For our part, because the heatsink is connected to source, you can connect the case to heatsink directly, but place the silicon grease between the heatsink and part. The part number of the grease is 120-SA.

You can test the thermal without the rubber sheet first,. If the temperature difference is around 30 degree too. I guess the 30 degress may not be true. 30 degree difference is a lot for me.

 

And normally you have to make sure that the part is connected tight with the heatsink.

 

regards

 

 

Submitted by rambabupotluri on 04/02/2014

Dear Sir,

as per your seggession we tried without silicon rubber sheet the unit performance is ok.

but we need to isolate the heatsink for safety reasons,so suggest the better thermal & insulated silicon rubber sheet for which meet 2kv isolation & 4kv surge as per IEC & better thermal conductivity.

Thanks&Regards 

Submitted by PI-Cochrane on 04/02/2014

As you know, most of parts (Such as TI part or Mosfet from different vendors) connect switching node drain pin to heatsink, and thus insulation is must.

 

But for TOPSWITCH, the heatsink actually is connected to S pin or primary side return. Because of the above reason, I do not think you really need the insulation between heatsink and part.

 

regards

 

Submitted by rambabupotluri on 04/02/2014

Dear Sir,

the heatsink is mounted common for O/P diode and TOPswitch,then we have to use the insulator between topswitch and heatsink.So suggest the better thermal & insulated silicon rubber sheet for which meet 2kv isolation & 4kv surge as per IEC & better thermal conductivity.

Thanks&Regards 

Submitted by PI-Cochrane on 04/03/2014

Actually we do not have a lot of experience for silicon rubber sheet, especially at PI, since we do not use it. You have to discuss with vendors of silicon rubber sheet, and search from website.

 

Sorry about that