This is a PCB Mount SSR for Control of a Small AC load like a Lamp or a Contacter. It has Optical Isolation and has a Thyristor for output. This was in the I/O Module Standard.
The MOC3041 A zero crossover optical triac driver is used here. The footprint is very small, many can be stacked in one small PCB.
Read More – PCB AC Load SSR with DC control.
You can see in the PCBs below the distance between the input and output tracks is more than 5mm. The opto is itself a few kilovolts of isolation and we should take care of the creepage distance on the PCB and surface.
This thing is Hermetically Sealed using a Alumina Powder filled Epoxy. This combination gives good thermal conductivity and Excellent Insulation.