Ask Hackaday: How Hard Is It To Make A Bad Solder Joint?

When you learn to solder, you are warned about the pitfalls of creating a solder joint. Too much solder, too little solder, cold joints, dry joints, failing to “wet” the joint properly, a plethora of terms are explained  if you read one of the many online guides to soldering.

Unsurprisingly it can all seem rather daunting to a novice, especially if they are not used to the dexterity required to manipulate a tool on a very small-scale at a distance. And since the soldering iron likely to be in the hands of a beginner will not be one of the more accomplished models with fine temperature control and a good tip, it’s likely that they will experience most of those pitfalls early on in their soldering career.

As your soldering skills increase, you get the knack of making a good joint. Applying just the right amount of heat and supplying just enough solder becomes second nature, and though you still mess up from time to time you learn to spot your errors and how to rework and fix them. Your progression through the art becomes a series of plateaux, as you achieve each new task whose tiny size or complexity you previously thought rendered it impossible. Did you too recoil in horror before your first 0.1″ DIP IC, only to find it had been surprisingly easy once you’d completed it?

A few weeks ago we posted a Hackaday Fail of the Week, revolving around a soldering iron failure and confirmation bias leading to a lengthy reworking session when the real culprit was a missing set of jumpers. Mildly embarrassing and something over which a veil is best drawn, but its comments raised some interesting questions about bad solder joints. In the FoTW case I was worried I’d overheated the joints causing them to go bad, evaporating the flux and oxidising the solder. This was disputed by some commenters, but left me with some curiosity over bad solder joints. We all know roughly how solder joints go wrong, but how much of what we know is heresay? Perhaps it is time for a thorough investigation of what makes a good solder joint, and the best way to understand that would surely be to look at what makes a bad one.

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A Very Tidy Circular Saw Bench

If your parents had a workshop as you grew up, the chances are it harbored some tools you came to know and love as you used them for your formative projects. Our reader [Joerg]’s father for instance has a circular saw bench that [Joerg] sorely misses, now living over 500km away. Our subject today is his response to this problem, now needing to cut aluminium he set about creating a  saw bench of his own, and the result is a rather nice build.

table-sawHe put together a variety of CAD models to formulate his ideas, and arrived at a structure in 18mm waterproof plywood with moving table linear bearings. The saw blade itself was mounted on a 5mm aluminum plate, though he doesn’t tell us what motor it uses. All the wooden parts came from a single sheet of plywood, and the result is a very tidy creation indeed.

Power saws are among the more hazardous tools in your workshop arsenal, whatever their type. If this was a commercial saw it would probably have a guard over the top of its blade, but even without that its sturdy construction and relatively low profile blade make this one stand above some of the more basic home-made saws we’ve seen. Building a power saw is something you have to take seriously.

We’ve featured quite a few home-made saws over the years. At least one other large table saw, a rather powerful but surprisingly tiny saw bench, this scroll saw using a sewing machine mechanism, or how about this simple jigsaw table?

Tools of the Trade – Inspection

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”

Reverse Engineering The OWON SDS7102 Oscilloscope

It is something of a rite of passage for an electronics enthusiast, the acquisition of a first oscilloscope. In decades past that usually meant a relatively modest instrument, maybe a 20MHz bandwidth and dual trace if you were lucky. Higher spec devices were eye-wateringly expensive monsters, not for the Common People.

We are fortunate that like most other areas of technology the world of test equipment has benefited in the last few years both from developments in digital technology and from the growth in Chinese manufacturing. If your first ‘scope is that second-hand 20MHz CRT you will probably secure it for pennies, and the first ‘scope you buy new will probably have a spec closer to those unattainable super-scopes of yesteryear. Gone is the CRT and timebase generator, in its place a TFT, system-on-chip, and super-fast A to D converter.

[Christer Weinigel] has just such an entry-level modern digital ‘scope, an OWON SDS7102. He comments that it’s got an impressive spec for its price, though the input is noisier than you’d expect on a more expensive device, and the software has one or two annoying bugs. Having owned it for a while, he’s now subjected it to a lengthy teardown and reverse engineer, and he’s posted his findings in a succession of blog posts.

[Christer]’s interest lay mainly in the OWON’s digital section, it seems there is already a substantial community paying attention to its analog front end. He’s deduced how its internals are connected, ported Linux to its Samsung SoC in the scope, succeeded in getting its peripherals working, and set to work programming the Xilinx FPGA that’s responsible for signal processing.

The series of posts is a fascinating read as a run through the process of reverse engineering , but he points out that it’s quite a lot of information. If you are just interested in how a cheap modern oscilloscope works, he says, he suggests reading his post in which he recaps on all its different components.

He also makes a plea for help, he’s no slouch on the ‘scope’s software but admits he’s a bit out of his depth on some aspects of the FPGA. If you’re an FPGA wizard with an interest in ‘scopes, he’d like to hear from you.

This isn’t the first time we’ve featured ‘scope reverse engineering here at Hackaday, though it may be more in-depth than others. In the past we’ve seen a Uni-T screen grab protocol laid bare, and an investigation of a Rigol 1054Z.

PinJig Soldering Clamp has Pins Seized by Airport Security

There’s an old adage that when performing a live demo, previously working hacks will mysteriously go awry. In this case, the hardware demo was doomed before it ever arrived at the conference.

PinJig is an interesting take on though-hole soldering. As its name indicates, it’s a jig which holds through-hole components in place as the board is flipped on its side (or even upside down). This is accomplished by 2000 steel pins which are locked in place after being nestled around all of the board’s components. Unfortunately, carrying this prototype onto an international flight didn’t work out. [Niall Barrett] told us that on his way from Ireland to Bay Area Maker Faire he was required to ditch the 3-inch steel pins that make up the jig, or not get on the plane.

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The Politest Patent Discussion, OSHW v. Patents

We’ve covered [Vijay] refreshable braille display before. Reader, [zakqwy] pointed us to an interesting event that occured in the discussion of its Hackaday.io project page.

[Vijay] was inspired by the work of [Paul D’souza], who he met at Makerfaire Bangalore. [Paul] came up with a way to make a refreshable braille display using small pager motors. [Vijay] saw the light, and also felt that he could make the vibrating motor display in such a way that anyone could make it for themselves at a low cost.

Of course, [Paul], had patented his work, and in this case rightly so. As jaded as we have become with insane patent trolls, our expectation on receiving the tip was that [Paul] had sued [Vijay] out of house and home and kicked his dog while he was at it. A short google search shows that [Paul] is no patent troll, and is a leader in his field. He has done a lot to help the visually impaired with his research and inventions.

Instead we were greeted by a completely different conversation. [Paul] politely mentioned that his lawyer informed him that in order to protect his IP he needed to let [Vijay] know exactly how the information could be used. No cease and desist, in fact he encouraged [Vijay] to continue his open research as long as he made it clear that the methods described could not be used to make a marketable product without infringing on [Paul]’s patents. They’d need to get in touch with [Paul] and work something out before doing such.

[Vijay] responded very well to this information. His original goal was to produce a cheap braille display that could be made and sold by anyone. However, he did use [Paul]’s work as a basis for his variation. Since [Paul]’s commercial interests relied on his patent, there was a clear conflict, and it became obvious to [Vijay] that if he wanted to meet his goal he’d have to pick a new direction. So, he released his old designs as Creative Commons, since the CERN license he was using was invalidated by [Paul]’s patent. He made it very clear that anyone basing their work off those designs would have to get in touch with [Paul]. Undaunted by this, and still passionate about the project, [Vijay] has decided to start from scratch and see if he can invent an entirely new, unprotected mechanism.

Yes, the patent system is actually encouraging innovation by documenting prior work while protecting commercial and time investments of beneficial inventors. Well. That’s unexpected.

Kudos to [Paul] for encouraging the exploration of home hackers rather than playing the part of the evil patent owner we’ve all come to expect from these stories. Also [Vijay], for acting maturely to [Paul]’s polite request and not ceasing his work.

Crowdfunding: A Wireless Oscilloscope

One of the most ingenious developments in test and measuring tools over the last few years is the Mooshimeter. That’s a wireless, two-channel multimeter that can measure voltage and current simultaneously. If you’ve ever wanted to look at the voltage drop and power output on a souped up electrified go-kart, the Mooshimeter is the tool for you.

A cheap, wireless multimeter was only the fevered dream of a madman a decade ago. We didn’t have smartphones with Bluetooth back then, so any remote display would cost much more than the multimeter itself. Now this test and measurement over Bluetooth is bleeding over into the rest of the electronics workbench with the Aeroscope,  a wireless Bluetooth oscilloscope.

[Alexander] and [Jonathan], the devs for the Aeroscope got the idea for this device while debugging a mobile robot. The robot would work on the bench, but in the field the problem would reappear. The idea for a wireless troubleshooting tool was born out of necessity.

The specs for the Aeroscope are about equal to the quite capable ‘My First Oscilloscope’ Rigol DS1052E. Analog bandwidth is 100MHz, sample rate is 500 Msamples/second, and the memory depth is 10k points. Resolution per division is 20mV to 10V, and the Aeroscope “Deluxe Package” that includes a few leads, tip, clip, USB cable, and case is about the same price as the Rigol 1052E. The difference, of course, is that the Aeroscope is a single channel, and wireless. That’s fairly impressive for two guys who aren’t a team of Rigol engineers.

As is the case with all Bluetooth test and measurement devices, the proof is in the app. Right now, the Aeroscope only supports iOS 9 devices, but according to the crowdfunding campaign, Android support is coming. Since the device is Open Source, you can always bang something out in Python if you really need to.

While this is a crowdfunding campaign, it’s hosted on Crowd Supply. Crowd Supply isn’t Indiegogo or Kickstarter; there are people at Crowd Supply vetting projects. The campaign still has a month to go, but the first few pledges are putting the Aeroscope right on track to a successful campaign.