Screws for mounting stars and wiring

[flyfish]

Evil and others,

 

My parts are starting to arrive and I am getting ready to mark drill and tap my heat sink. Any suggestions on screw size. I looked at some 6-32 that I had in stock but they were too large as they covered the solder terminals on both sides of the screw on the UV stars from KAI. Don't have the Cree's yet so don't know if I will have the same problem with those.

 

Am I correct in assuming that I should wire these stars in series? Buck puck+ to +led-,+led-,+led-,+led-,+led-, -buck puck. Are both sets of solder terminals active and connected through the PCB. Also, with respect to these UV leds from KAI. Is the back side of these stars electric neutral?

 

Thanks in advance. I will send some pics along as I make some real progress!

[evilc66]

Use 4-40 or 3mm screws to hold down the stars. The heads of the screws can come close to the solder pads, but it changes from one pcb manufacturer to the next as to how close. You can use nylon or phenolic washers to isolate the screws if need be.

 

Connecting in series is the way to go. Half of the pads will be positive and the other half will be negative. It will be marked on each side, but not each pad. All the stars are electrically isolated. If you want to make sure, test continuity between the back of the star and each solder pad. I haven't seen one yet that isn't isolated.