If there’s one thing that will bring down the yield of your PCB assembly, it’s your solder paste. Put too much on, and you’ll get bridged leads. If you don’t put enough on, that pad might not make good contact. [ScalarElectric] has an amazing trick that’s sure to astonish and astound. Just use wedges and you’ll get better yield with fine-pitched components.
The trick here is to define the cream/solder paste layer of each package as a wedge on each pad instead of the usual rectangle. This gives a few benefits, the largest being the increased gap between paste shapes. You’re also getting a reduction in the total amount of paste applied, and a subsequent improvement in yield. (Reportedly, we’d love to see some data on this.)
Here at mimicEducationalRobots we farm out most of our production circuit board assembly, but we still assemble all prototypes in house. Most people are surprised to learn how relatively simple the process really is. This blog assumes that a unique PCB of your own design has come out of your wonderful brain, or at least that you’re interested in how we do things here.
Dan Maloney on the Hackaday blog:
To fight the shakes, you can do one of two things: remove the human, or improve the human. Unable to justify a pick and place robot for the former, [Tom] opted to build a quick hand support for surface-mount work, and the results are impressive considering it’s built entirely of scrap.
It’s just a three-piece arm with standard butt hinges for joints; mounted so the hinge pins are perpendicular to the work surface and fitted with a horizontal hand rest, it constrains movement to a plane above the PCB. A hole in the hand rest for a small vacuum tip allows [Tom] to pick up a part and place it on the board — he reports that the tackiness of the solder paste is enough to remove the SMD from the tip.
Timothy Woo has launched a Indiegogo campaign to manufacture his open-source, Arduino-compatible, wireless PCB reflow oven controller:
Reflowduino is the first completely open-source, Arduino-compatible reflow oven controller of its kind that enables practically anyone to assemble their own beautiful circuit boards at home!
Reflowduino comes loaded with features, all in a compact Arduino-compatible package, with full documentation, example code, demo app, and comprehensive wiki on Github.
Reflowduino is designed to be extremely easy to use! The general concept is to switch the power of the appliance on or off with a solid-state relay as shown below, measuring the temperature by placing the thermocouple tip inside the oven during the whole process.
If nothing else, please share this campaign to your friends, family, and anyone who might be interested on social media! Remember that every view counts for me, and I’m depending on you to make this happen!
Sean Hodgins has a great tutorial on surface mount soldering:
I feel like surface mount soldering has a bad reputation. It can seem daunting to someone who has never tried it. Since a lot of my project involve using surface mount components, I thought it would be a good idea to make something to inspire people to try it out (without risking expensive components or their custom project).
Decide how you want to assemble your SMD Challenge Kit (re, the video) you can choose to use a soldering iron, or a reflow oven. They take about the same amount of time but using the soldering iron can be a little more challenging and doesn’t require a cheap toaster oven.
- Bill of Materials for PCB on FindChips.com
- PCB Files on GitHub – or order them on my Tindie Store(soon) or get them by being a Patron.
- Solder Paste (for reflow oven)
- Solder for Hand Soldering
- Flux for Fixing
- CR2032 Battery