Hi,

We wish to mount INN3675C (inSOP-24D) across the isolation  barrier as ever.

Its a 20W, 90-265VAC flyback...but its in CCM at 105VAC, so we need to heatsink it well.

We have it on a daughter board,  which is resting on two kind of PCB "pieces" which have castellated pads so that we can bring the signals/power up to the innoswitch on the little PCB.......so we can put a gap pad to the bottom  of this little PCB , and then gap pad it to the underlying earthed heatsink. However, its obviously across the isolation barrier, so do you know any gap pads that we can use for this.?

So we have the INN3675C mounted on a small PCB (just a bit bigger then the innoswitch)....and this little PCB has thermal vias to bottom copper, and then this is mounted on the main PCB via the PCB "Pieces"....so the innoswitch is kind of the other-way-round (upside down) to the usual way, and so this means we can gap pad the thermal via'd bottom copper   of the little PCB to the earthed heatsink which is 4mm below the main PCB.

So do you know of gap pad which is good for this isolated purpose...where the gap pad will span the isolation barrier under the innoswitch's little PCB?

We are also thinking of a "liquorice allsort" heatsink approach, where we have a  little (2mm thick) square of aluminium in between 2 gap pad pieces....and this "allsort" will be in the gap between the little PCB and the below earthed heatsink.  Do you know of gap pads that can do this without needing a "harder"  electrical  insulator piece?