I am working on an application that switches a high power (15 W typical, 100 W maximum) resistive load at 230 VAC (RMS) from a 5 VDC control line. For this I plan to use a Solid State Relay. I am currently planning to use the AQH3213A from Panasonic, but I am concerned about the heat dissipation of the part. The load will be switched on regularly anywhere from a few seconds to a few minutes. I performed the following calculation for power dissipation under maximum load conditions:
$$ P = I_{Load}\bullet V_{TM} $$ $$ = 0.435 A \bullet 2.5 V $$ $$ =1.09 W $$
However the datasheet (or any other information I've been able to find from Panasonic) does not list any thermal resistance values for the DIP package the SSR uses.
How can I figure out how hot the SSR will get under maximum conditions, and whether I need a heatsink? Furthermore how could I effectively heatsink a DIP 8?