Phase 2: Tooling up for SMT components


If I learned anything on the Arcsin project, I learned that through hole circuit boards require a lot of assembly time. So, I set out to learn about SMT parts and get used to dealing with much smaller components and boards. Hopefully, this will lead to some form of automated assembly if the Modus ever makes it to production.

So, I started out by making a few adapter boards to familiarize myself with SMT components, how to solder them, how to deal with them, and how to see them! The first board I built was the PIC microcontroller board that will carry the PIC, crystal, and ICSP (In-Circuit Serial Programming) header. This will make it super easy to program and use the PIC micro that I have chosen for this project. Here you can see the board right after I transfered the toner to the copper clad and peeled away the paper.


After a swim in the acid jacuzzi with the crazy chemical etchant pump throwing Ferric Chloride everywhere, the board emerges perfect!


The next board is the H-bridge carrier board that carries both the high-side and low-side mosfets. I won't state the details of the parts that I'm using here because I'm not sure if this config is going to work or not, so stay tuned for details on how this design plays out. So how do you solder mosfets to a large copper heat sink on the PCB? Good question. After fiddling with the soldering iron for a while, I realized that there was no way that I was going to get enough heat. So, I fluxed up the spot where I wanted the FET to live, laid down some solder, put the FET on top of it all, and then blasted it with my heat gun. The solder melted and the FET attached itself to both the pads and the heat sink quite nicely.


The assembled PIC carrier board ready to program...or so I thought. After a frustrating hour trying to figure out why the ICSP wasn't working, I realized that my programmer only suppors PIC16 devices! Time to hit Spark Fun and order a new programmer.


Here you can see the assembled H-bridge and PIC carrier boards. As soon as I get my programmer and a few other SMT parts, I'll wire this thing up and see if I can let the magic smoke out of something.


Plenty of room on the old breadboard with these two cool adapter boards installed. The other circuit on the board is the current limiter that I've been playing with. Details to follow.


A slightly different angle.


All of the glue logic for the Modus will be using SOIC SMT packages so I had to make a few adapter boards so I could use the SOIC parts on the breadboard.


After the swim.


The smallest circuit board that I've made to date. Slightly smaller than 1" square, or roughly the size of the tip of my thumb!