In our final installment of Tools of the Trade (with respect to circuit board assembly), we’ll look at how the circuit board is tested and programmed. At this point in the process, the board has been fully assembled with both through hole and surface mount components, and it needs to be verified before shipping or putting it inside an enclosure. We may have already handled some of the verification step in an earlier episode on inspection of the board, but this step is testing the final PCB. Depending on scale, budget, and complexity, there are all kinds of ways to skin this cat.
In the last episode, we put our circuit boards through the reflow process. Unfortunately, it’s not 100% accurate, and there are often problems that can occur that need to be detected and fixed. That’s what the inspection step is for. One could insert an inspection step after paste, after placement, and after reflow, but the first two are icing on the cake — the phase where most mistakes can be caught is after reflow.
There are a number of problems typical with a surface mount reflow process: Continue reading “Tools of the Trade – Inspection”
Like the fictitious invention of the Hula Hoop in Hudsucker Proxy, [David Spinden]’s big idea is small and obvious once you’ve seen it. And we’re not saying that’s a bad thing at all. What he’s done is to make a new kind of prototyping connector; one that hooks into a through-plated hole like a pogo pin, but in the horizontal direction.
This means that your test-points can do double duty as header connectors, when you need to make something more permanent, or vice-versa. That’s a lot of flexibility for a little wire, and it takes one more (mildly annoying) step out of prototyping — populating headers.
[David] makes them out of readily available header pins that already have the desired spring-like profile, and simply cuts them out and connects them to a standard Dupont-style hookup wire. Great stuff.
When we opened up the “Anything Goes” category for the Hackaday Prize, we meant it. We’re excited to see people entering large and small ideas that improve the world, even if it’s just the world of hackers.
A few days ago, we mentioned the new ARM-powered Teensy 3.0 project on Kickstarter. The creator, [Paul Stoffregen], decided to share the trials of building a test fixture along with a shocking comparison of the accuracy of different PCB manufacturers in an update to his Kickstarter.
Because [Paul]’s Teensy 3.0 has more IO pins than should be possible on such a small board, the test fixture to verify if a board is defective or not is fairly complex. To test each board, a Teensy is placed on dozens of spring-loaded contacts arranged like a bed of nails. From there, another Teensy (this time a Teensy 2.0) performs a few tests by cycling through all the pins with several patterns.
Because the spring-loaded contacts require rather precise drill holes in the PCB of his test fixture, [Paul] thought it would be neat to compare the accuracy of several board houses. In the title pic for this post (click to embiggen), [Paul] demonstrates the capabilities of OSH Park, Seeed Studio, and iTead Studio. The lesson here is probably going with a US company if quality drill work is a necessary requirement of your next project.