Hackaday Links: April 25, 2021

There’s much news from the Jezero Crater on Mars this week, and all of it was good. Not only did the Ingenuity helicopter make history by making the first powered, controlled flight of an aircraft on another planet, it made a second longer, more complex flight just a couple of days later. This time, the autonomous rotorwing craft flew to a higher altitude than the maiden flight, hovered for a bit longer, and made a lateral move before landing safely again on the surface. Three more flights of increasing complexity (and risk) are scheduled over the next two weeks, with the next set to happen early Sunday morning. I have to admit that even though the Ingenuity tech demonstration seemed a little like a publicity stunt when I first heard about it, especially when compared to the Perseverance’s main mission of searching for evidence of life on Mars, the Ingenuity team’s successes have made a believer out of me.

Speaking of technology demonstrations, NASA fired up the MOXIE experiment aboard Perseverance for the first time. Intended to explore the possibility of producing oxygen from the thin carbon dioxide-rich Martian atmosphere, the Mars Oxygen In-Situ Resource Utilization Experiment made about 5.4 grams of oxygen total at a rate of about 6 grams an hour. We detailed the technology MOXIE uses, called solid-oxide electrolysis, which depends on a scandium-stabilized zirconium oxide ceramic electrolyte to strip the oxygen from superheated carbon dioxide using an electric current. Should the technology prove itself over the planned total of ten MOXIE runs over the next few months, a scaled up version of the device could someday land on Mars and produce the estimated 55 metric tons of oxygen needed to fuel a return trip from a crewed mission.

By now we’ve all heard about the global semiconductor shortage, or perhaps felt the pinch ourselves while trying to procure parts for a build. It’s easy to count the crunch as yet another follow-on from the COVID-19 shutdowns and the logistics woes the pandemic begat, so one might have hope that with lockdowns easing up around the world, the shortage will soon be over as manufacturers ramp up production. But not so fast — it looks like the machines needed to make the chips are the latest victims of the shortage. According to Nikkei Asia, wire bonding machines, wafer dicers, and laser drilling machines are all in short supply, with orders for new machines booked out for a year. Like toilet paper this time last year, chip makers are hoarding machines, ordering 50 or 100 of them at a time, in the hopes of having enough to meet production goals. And when machines are available, travel restrictions are making it difficult to get on-site installation and support from factory reps. The bottom line — this isn’t over yet, not by a long shot.

We all know the Stack Overflow memes, and few of us who are being honest haven’t squirmed a bit when thinking about just how screwed we’d be without being able to copy a bit of code to get us past that rough part in a project. But just how often do people copy code from Stack Overflow? Quite a lot, actually, if SO’s analysis of the use of copy commands on their pages is to be believed. For two weeks, SO monitored the number of times the Ctrl-C (or Command-C, if that’s your jam) key combination was pressed. They toted up over 40 million copies, most often from the answers to questions and almost always from the code blocks within them. We suppose none of this is exactly unexpected — memes are memes for a reason, after all — but what we found surprising is that one in four visitors to Stack Overflow copied something within five minutes of loading a page. Being charitable, we’d say the speed with which coders accept someone else’s work is an indication that maybe they were almost at an answer themselves and just needed a little reminder. On the other hand, it could be a sign of separation driving them to get something working.

And finally, while we know we’ve recommended videos from Grady at Practical Engineering recently, we couldn’t help but plug another of his videos as a must-watch. This time, Grady tackles the Suez Canal blockage, and he presents it in the same dispassionate, informed way that he previously handled the engineering roots of the Texas blackouts. If you think the Ever Given grounding was just a case of poor seamanship, think again — Grady makes a compelling case for possible hydrodynamic causes of the incident, including “squatting” and the bank effect. He also speculates on the geotechnical forces that held the ship fast, in the process of which he helpfully introduces the concept of dilatancy and how it explains the way your feet seem to “dry out” a zone around them as you walk across the beach.

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Is This The World’s Smallest Computer?

How small could you make a computer? In a way, that’s a question that requires that a computer be defined, because you could measure the smallest computer simply in terms of the smallest area of silicon required to create a microprocessor. So perhaps it’s better to talk about a smallest working computer. Recent entries in the race for the smallest machine have defined a computer as a complete computer system which holds onto its program and data upon power-down, but this remains one that is hotly debated. You might for instance debate as to whether that definition would exclude machines such as the crop of 1980s home computers that didn’t store their programs and data, was your Sinclair Spectrum not a computer?

At the University of Michigan they have opted for the simpler definition with their latest entry in the race to be the tiniest. Their latest machine packs an ARM Cortex M0 into a 0.3mm cube, along with photoreceptors and LEDs for programming, data throughput, and power. It is designed to be a temperature sensor and logger for medical implantation, but it stands more as a demonstration of technological prowess than as a usable product.

Pictures of a tiny computer “dwarfed by a grain of rice” make for good mass media consumption but where’s the relevance for us? The interesting part comes from the tantalizing glimpse of its construction: this is a hybrid device upon which we can see the optoelectronic components have been wire-bonded. Unfortunately the paper, catchily titled “A 0.04mm3 16nW Wireless and Batteryless Sensor System with Integrated Cortex-M0+ Processor and Optical Communication for Cellular Temperature Measurement” does not appear to be free-to-view online, so we don’t have any more information. We wish that such feats were possible within our community, but suspect those days are still pretty far away.

The Mystery Behind The Globs Of Epoxy

When Sparkfun visited the factory that makes their multimeters and photographed a mysterious industrial process.

We all know that the little black globs on electronics has a semiconductor of some sort hiding beneath, but the process is one that’s not really explored much in the home shop.  The basic story being that, for various reasons , there is no cheaper way to get a chip on a board than to use the aptly named chip-on-board or COB process. Without the expense of encapsulating  the raw chunk of etched and plated silicon, the semiconductor retailer can sell the chip for pennies. It’s also a great way to accept delivery of custom silicon or place a grouping of chips closely together while maintaining a cheap, reliable, and low-profile package.

As SparkFun reveals, the story begins with a tray of silicon wafers. A person epoxies the wafer with some conductive glue to its place on the board. Surprisingly, alignment isn’t critical. The epoxy dries and then the circuit board is taken to a, “semi-automatic thermosonic wire bonding machine,” and slotted into a fixture at its base. The awesomely named machine needs the operator to find the center of the first two pads to be bonded with wire. Using this information it quickly bonds the pads on the silicon wafer to the  board — a process you’ll find satisfying in the clip below.

The final step is to place the familiar black blob of epoxy over the assembly and bake the board at the temperature the recipe in the datasheet demands. It’s a common manufacturing process that saves more money than coloring a multimeter anything other than yellow.

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Thermosonic Wedge Bonding

hot

In the past, if we’ve been doing smd soldering, we’ve used pretty basic hot plates. This project takes that idea a bit further.  Since [kc6qhp] will be using parts that aren’t conducive to soldering, he has to use wire bonding. After locating a fairly cheap wire bonding machine and microscope, he built the heated stage to fit perfectly with his other tools.  You’ll notice that he has machined a lip around the heat plate for small custom C-clamps as well as made it adjustable height. Very nice work [kc6qhp].