Anyway, there was no concensus that a SOT23 cannot be allowed to dissipate more than 150mW.
So here is the reasoning behind it...which I am sure you may agree with?.........
..........regarding the allowable dissipation of an sot23 device...
Comparing it with SMD resistors is helpful..
A sot23 (3mmx1.3mm) body size is slightly smaller than a 1206 resistor (3.2mmx1.6mm).
A SOT23's pad contact area is, however, a mere 1.2mmx0.4mm.
A 1206's pad contact area is 1.6mm x1mm....much more than a sot23.
...so we can say that a sot23 wouldn't be expected to have a power rating as much as a 1206 resistor (250mW)
In fact, the pad area for a 0805 resistor (1.25mm x 0.8mm) is more than for a sot23.
An 0805 resistor, does however have a smaller body area(2mm x 1.25mm) than a sot23.
So I would say that a sot23 could dissipate no more than an 0805 resistor, i.e. 125mW.
At my last company, a Consultant Engineer, who runs his own electronics consultancy, has a range of lighting electronics products on sale to the commercial lighting world, and has completed a number of electronics projects for the military, plus used to design the neon lights for picadilly circus, plus used to design audio amplifiers for commercial sale, told me never to dissipate more than 100mW in a SOT23 package. (He was referring to my use of SOT23 BJTs in a battery charge circuit., for one of his sister companies)
Is there concurrence with the 100mW maximum for a sot23?
Is there at least concurrence that a sot 23 is at most, equivalent to an 0805 resistor in terms of dissipation allowance.?
Its worth noting that resistors don't ever come in SOT23 packages....and this suggests that the SOT23 package is not as good at dissipating heat as a SMD chip resistor package.?