heatsink paste

[mike409]

Hi,

I jsut fixed my Mitsuhishi rear projection tv. 5 out of 18 pins on one of the convergence modules had "desoldered" themselves from the board. I have resolded the pins and the TV works fine. The two STK's are vertical and "pasted" onto a large heat sink. Who ever put this thing together used a large amout of heat sink paste and I have noticed that some has run down the heat sink and pooled against the circuit board. It is not touching the pins. The TV is back together. Should I take it apart and clean the paste off the circuit board? If so, then with what - 70% rubbing alcohol?

thanks

mike

 

[fingaz]

Hi,

To be honest, if it was me, I'd clean it up and re-apply new paste. TOO MUCH thermal transfer paste can actually REDUCE thermal conductivity (because it causes a gap between the metal surfaces).
You only need enough to form a very thin layer between the component and the heatsink, just to fill the imperfections in the two surfaces.

I would use a clean dry cloth to remove most of the paste. The residue can be removed with a cloth soaked in isopropanol.

You only need apply enough paste so that it just appears at the edges of the component when the heatsink is fastened properly.

BE SURE to take precautions when dealing with ESD sensitive parts.

BE SURE to let the isopropanol evaporate before applying new paste.