Jo Hincliffe shares their latest robotics adventure:
Lil’ Lights, Adventures in PCB’s, FLIR and high power LED’s
After designing the MTV robot I’ve been slowly tinkering with numerous add ons. I wanted to add some high power LED lights and so I bought some 1 watt white LED’s in an SMD package. They offered a lot of light and I’d read that the 1 watt LED didn’t need heatsinks to keep the running temperature within the datasheet operational temperature range.
Testing them on the bench they get hot enough to be uncomfortable on the fingers so I decided that a PCB breakout that enabled them to be easily mounted but also acted as a slight heatsink was desirable. I quickly whipped up a design using the fabulous inkscape plugin SVG2Shenzhen and finished the design off in KiCAD . The PCB has a large pad that interfaces with the LED “slug” and in the PCB pad there are some via’s connecting that pad to the large copper flood on the back of the PCB. This flood is under the mask so heat doesn’t dissipate massively but I wanted it to just slightly reduce the temperature of the LED. When soldering on the LED I’ve added a small spot of thermal grease between the LED slug and the PCB pad. Finally I made sure that the M3 mount hole (3.2mm diameter for clearance) wasn’t copper plated so that hopefully the heat in the LED and PCB wouldn’t wick into mounting bolts etc.
I got some of the PCB made by the fantastic OSHpark and mounted up some LED. Driving them at 1 watt is made simpler by using one of the cheap constant current capable DC-DC buck driver boards that are readily available now. They certainly are bright!
OSH Park 