Especially for small chips, you can substantially increase the dissipation rating by adding solid copper pour to the terminals.
You're still limited by rated temperature, which means you must qualify the result. No time and money for testing the prototype = don't do it. You also don't save much space, because you need at least as much copper area as a larger part would occupy anyway.
Tim
I don't think it is hot enough to reach rated temperature. I am just passing <3A which is <0.15W. What caused me to think of fixing it is the original shunt there has a bad temp-co. It is giving me reading (mV drop) of +- 2% (perhaps 3%) between cold verses fully warm up at that current.
So if I have a 2A fluctuation at say in the low single digit seconds, current is changing faster than the temperature of the shunt can change, the reading becomes a bit wild.
This shunt is about 6mm long and about 3mm wide. Hard to measure given limited access and solder already on the ends. I have some 3W shunts (400ppm/1C) that hardly made a difference at that current with the mildest of air flow cooling. This shunt is giving me 1-2% or 1-3% change.
I was thinking along these lines:
1. Try to find some way to fit my 3W shunts through-hole that I can cool better
2. Try to get a shunt with better tempco
I was leaning toward #1 - Solder the 3W shunt to the underside somehow. I have the 3W shunts at hand and also because I am not sure of the size until I remove the SMD to measure, plus the order then wait.
This idea of mounting the original shunt on the side occurred to me in the mean time hence the post to solicit your views. That is something I can also do without having to remove-measure-order and then wait.