DIY Surface-Mount Circuit Boards

James Lyman, an engineer with degrees in Aerospace, Electrical Engineering, and Systems Design, has more than 35 years of design experience but says he was “dragged” over the past decade into using surface-mount devices (SMD) in his prototypes. He had a preference for using through-hole technology whenever possible.

“The reasons are simple,” he says in an article appearing in the June issue of Circuit Cellar magazine. “It’s much easier to use traditional components for building and reworking prototype circuits than it is to use wire to make the connections. Plus, the devices are large and easy to handle. But time and technology don’t leave anyone at peace, so my projects have gradually drifted toward surface-mount design.”

In his article, Lyman shares the techniques he developed for designing prototypes using SMD components. He thought sharing what he learned would make the transition less daunting for other designers.

This accompanying photo shows one of his completed circuit board designs.

Lyman’s techniques developed out of trial and error. One trial involved keeping small components in place during the building of his prototype.

“When I built my first few surface-mount boards, I did what so many amateurs and technicians do. I carefully placed each minute component on the circuit board in its correct position, and then spent several minutes playing ‘SMD hockey,’ ” Lyman says. “With nothing holding the component in place, I’d take my soldering iron and heat the pad component while touching the solder to the junction. Just as the solder was about to melt, that little component would turn into a ‘puck’ and scoot away. Using the soldering iron’s tip as a ‘hockey stick,’ I’d chase the little puck back to its pads and try again, which was maddening. Finally, I’d get a drop of solder holding one end of the puck in place, usually with the other end sticking away from its pad. Then I could reheat the solder joint while holding the puck and position it correctly. I would have to start over with the next component, all the while yearning for that wonderful old through-hole technology.

“It slowly occurred to me that I needed something to hold each part in place while soldering—something that would glue them in place. Commercial houses glue the components down on the boards and then use a wave soldering machine, which does all the soldering at once. That’s exactly what I started doing. I use J-B Weld, a common off-the-shelf epoxy.”

Using an easy-to-get epoxy is just one of the tips in Lyman’s article. For the rest, check out his full article in the June issue of Circuit Cellar.



11 thoughts on “DIY Surface-Mount Circuit Boards

  1. Hey, come on guys! JB Weld is a steel reinforced epoxy – what are we trying to do here, build a bridge?

    If you must use epoxy then the cheapest fast setting epoxy from Poundland will do the trick.

    Personally, I’ve always used a tiny spot of cheapo CA superglue, which gives you 20 – 60 seconds to position the component. If there are a lot of smds on the board you might want to use an accelerant spray to reduce the CA cure to 5 or 10 seconds – if you can’t afford proper CA accelerant then isoprop or a gentle waft above the board with a cloth soaked in a little household ammonia will do the trick.

    Breadboarding is not quite dead yet.

    Cheers, Bill

  2. crikey, epoxying all the components first is a bit brutal, what if you want to change one? melt the solder and twist, all at the same time?
    much easier to tin one pad, then place the part on it with tweezers and touch it with the iron, one end soldered fine, now solder the other end.

  3. Very few PCBs that are SMD are wave soldered. It’s true that wave soldered PCBs are glued, but the vast majority of SMD PCB’s go thru an IR oven. Solder paste is used to hold components in place which is also the solder when it is melted in the IR oven. If the IR oven does a one pass, then components on the bottom would be glued, but the glue step is added cost and the vast majority of PCB’s make a second trip flipped over to do the other side.

  4. Playing hockey with SMD parts is what you do with the very first SMD – resistor. After that you should know better.
    My method: use solder paste. It is sticky to hold all parts at place. Then solder everything with a hot air gun.
    I do prototypes in SMD by very intention: only SMD resistors allow to stack several on top of each other to adjust the required value. Nothing is easier.


  5. Pingback: Interesting Projects |

Comments are closed.