Assembling prototype PCBs

A couple of years ago, I was completely new to electronics and never soldered a thing in my life. Fast forward to the previous week, I was soldering the 5th generation prototypes of the Ultimate Hacking Keyboard. It's been quite a journey and although I am by no means perfect at this stuff, upon reflecting on it I realized that I was able to push my PCB assembly productivity to the next level several times in a row, so let me show you what I learned.

Given that you asked for panels from the fab everything starts with depanelization. Even though this is a no brainer and doesn't require any skills or equipment other than a flash cutter, I decided to show it because I'm sure a lot of people have never seen it in action.

Next up, PCB assembly follows, so it's time to heat up the soldering iron.

Some words of advice:

• You can notice at the beginning of the video that it takes me about 4 minutes to find the MCUs which is exactly what you want to avoid. A while ago, I purchased way too many AVRs, put them into a drawer and didn't take the time to organize them properly which causes me a time penalty every time I search for a specific AVR. I have yet to solve this problem but regarding passive components I already solved it by buying a resistor and capacitor book and a blank SMT storage book. The productivity boost is incredible.
• It's easier to solder large components first. It's not a coincidence that I started with the AVRs.
• After soldering large components, it's worth progressing by the descending number of components used per type. In order to generate such a list I ended up writing a node module (and its dependencies) to extract this information from KiCad files.
• For passive components that have two or three pads it's worth pre-tinning a pad per component before actually soldering them, then soldering the components using the pre-tinned pads, then soldering the rest of the pads. You only have to grab the soldering 3 times this way instead of hundreds of times.
• Adding easily readable reference designators and component values to the silk screen can be a major productivity booster. Component values are especially handy.
• There is no such thing as too much flux and a flux pen is the best choice to deploy flux. I use a Circuitworks CW8100 pen which does a great job.
• DRC is your friend so use it extensively. Even better if your fab provides you a state-of-the-art PCB visualizer that checks your gerbers, like in the case of Eurocircuits.

Often times, it comes very handy to salvage SMD parts from previous prototypes which can be hard to desolder but with Chip Quik it's so much easier. On the video below it takes me 21 seconds to desolder a TSSOP 20 after starting to heat up the Chip Quik with my soldering iron.

Reusing PTH parts is usually much simpler but it can still be a pain. A desoldering station to the rescue! I purchased my ZD-985 desoldering station for about $100, probably the best bang for the bucks ever.

I'm pretty sure that I missed a lot of things but this is a very broad topic and I mostly wanted to give a glimpse into the world of PCB hand assembly. You're welcome to correct me, add suggestions and ask questions!