First SMD reflow attempt

The LED boards turned up from Seeedstudio today. Here’s one:

My first board!

My first board!

That didn’t turn out too bad. The text for the resistor values is too small, I’ll know next time.

I thought I’d better get on with it to see what happened so I started by testing the board for continuity where I expected it. That seemed fine. Next up was applying solder paste to one of the boards to give this process a trial run. That took a little while and I learned a few more things not to do – like putting your hand on part of the board that you’ve just applied solder paste to 🙄

Here’s timelapse video so it’s not too tedious to watch…

I guess I wasn’t too happy at that point, I seemed to have large variations in the amount of solder paste and none of the components were particularly straight. Still, I wasn’t going to be too disappointed if this one didn’t work out. Time to load up the oven:

Before reflow

Before reflow

Not the best of photos but you can probably get a sense of the general placement of the components. It was time to hack the controller firmware (which I still haven’t got around to finishing properly) and see what happened…

I watched the whole process through the magnifying lens of my desklight. At around 200ºC some of the paste started to melt and turn shiny and, miracle of miracles, the resistors started to rotate into perfect alignment. Surface tension rocks 😆

At around 235ºC all the solder seemed “done” so I shut down the oven and opened the door – the oven is relatively slow to warm up so it had been close to that temperature for a while. I hoped it would be “long enough”.

Cooked and cooling down

Cooked and cooling down

I’ll admit to being gob-smacked at this point. It really looked like everything had gone the way it should. The fairly random amounts of solder paste end up giving fairly similar results at each joint. All looking ok really.

Neat!

Neat!

I’ve got to be pleased with that. But does it work?

Red

Red

Green

Green

Blue
Blue

It works! 😯

I’ve labelled the Blue and Green pins the wrong way around so I’ve maintained tradition by cocking something up. Have to admit to being really pleased with the result – my first ever circuit board, my first ever reflow attempt – and it actually works!

I’ll practice with the rest of the boards at some point and then get around to designing something a bit more useful. Has to be worth chucking 3 transistors (and resistors) into a breadboard and PWMing the nuts off this with an Arduino though.

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