interesting solder info - thermal,physical,electrical properties

[stinky]

I thought this was interesting

http://www.williams-adv.com/packagingMaterials/lead-free-solder.php

Shows melting point, thermal conductivity, electrical conductivity, tensile strength, etc. Interesting how they don't move hand-in-hand.

They also have an interesting solder selector:

http://www.williams-adv.com/tools/solder-selector.php

I also didn't realize how much better the thermal conductivity of solder is compared to thermal paste.

I also found some info on heat transfer and solder thickness

[FONT=&quot]Effect Of The Thickness Of A Thermal Interface Material (Solder) On Heat Transfer Between Copper Surfaces[/FONT][FONT=&quot] [/FONT]

 

[Justin Case]

Arctic Alumina compound thermal conductivity is advertised as >4 W/m-K.

Arctic Silver 5 compound thermal conductance is advertised as 350000 W/m^2-C for an 0.001 inch thick layer. That calculates to 8.89 W/m-K thermal conductivity.

Ceramique compound thermal conductance is advertised as >200000 W/m^2-C for an 0.001 inch thick layer. That calculates to >5.08 W/m-K thermal conductivity.

Arctic Silver adhesive thermal conductivity is advertised as >7.5 W/m-K.

There is no stated thermal conductivity or conductance data for Arctic Alumina adhesive. However, I would think it is safe to assume that the upper bound has to be the thermal conductivity of AA compound, which is >4 W/m-K. Various references in the literature list the thermal conductivity of epoxy-alumina composites at about 0.5-2.7 W/m-K depending on filler loading.

Plain epoxy thermal conductivity is about 0.2 W/m-K. Air is about 0.026 W/m-K.

So AA adhesive is probably about 75X-100X better than air as a thermal conductor. Arctic Silver adhesive may be about 300X better than air. AA compound is about >150X better. Arctic Silver 5 compound is about >340X better. Ceramique is about 200X better.

 

[stinky]

So good thermal grease / adhesive ranges from around 4-9 W/m-K. Common types of solder range from around 30-60 W/m-K.

This may not effect the choice to use grease. But it does make me wonder about choosing adhesive over solder.

Also, based on the second article, I wonder if a thick layer of grease might make the choice of heatsink material (copper, aluminum, even brass) somewhat moot.