Hockey can be fun, unless you’re building a surface-mount device (SMD) prototype and the “puck” is one of the tiny components getting away from your soldering iron. In an article appearing last month in Circuit Cellar, “DIY?Surface-Mount Circuit Boards: Tips and Tricks for Building SMD Prototypes,” engineer James Lyman inadvertently sparked a bit of debate on the magazine’s website. Readers posted various alternatives to Lyman’s approach to the “SMD hockey” challenge. Here’s how Lyman’s article describes the problem and his solution:
“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.’ 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…
“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.”
Here is a sampling of alternative solutions readers posted to circuitcellar.com.
- From Bill: “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 s 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 s. 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.”
- From Trevor: ”I did a lot of hand soldering of SM parts years ago and agree that it is best to fix the parts before soldering.
“I used an adhesive made for SM parts from RS Components, which comes in a syringe and is really easy to use. ” (Trevor’s post provides a link to his preferred Electrolube brand.)
- From Kevin: ”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.”
Feel free to visit circuitcellar.com to weigh in or take some of the advice offered there.