Micromachining Glass With A Laser — Very, Very Slowly

When it comes to machining, the material that springs to mind is likely to be aluminum, steel, or plastic. We don’t necessarily think of glass as a material suitable for machining, at least not in the chuck-it-up-in-the-lathe sense. But glass is a material that needs to be shaped, too, and there are a bunch of different ways to accomplish that. Few, though, are as interesting as micromachining glass with laser-induced plasma bubbles. (Video, embedded below.)

The video below is from [Zachary Tong]. It runs a bit on the longish side, but we found it just chock full of information. The process, formally known as “laser-induced backside wet-etching,” uses a laser to blast away at a tank of copper sulfate. When a piece of glass is suspended on the surface of the solution and the laser is focused through the glass from the top, some interesting things happen.

The first pulse of the laser vaporizes the solution and decomposes the copper sulfate. Copper adsorbs onto the glass surface inside the protective vapor bubble, which lasts long enough for a second laser pulse to come along. That pulse heats up the adsorbed copper and the vapor in the original bubble, enough to melt a tiny bit of the glass. As the process is repeated, small features are slowly etched into the underside of the glass. [Zachary] demonstrates all this in the video, as well as what can go wrong when the settings are a bit off. There’s also some great high-speed footage of the process that’s worth the price of admission alone.

We doubt this process will be a mainstream method anytime soon, not least because it requires a 50-Watt Nd:YAG fiber laser. But it’s an interesting process that reminds us of [Zachary]’s other laser explorations, like using a laser and Kapton to make graphene supercapacitors.

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Chemistry And Lasers Turn Any Plastic Surface Into A PCB

On the face of it, PCB production seems to pretty much have been reduced to practice. Hobbyists have been etching their own boards forever, and the custom PCB fabrication market is rich with vendors whose capabilities span the gamut from dead simple one-side through-hole boards to the finest pitch multilayer SMD boards imaginable.

So why on Earth would we need yet another way to make PCBs? Because as [Ben Krasnow] points out, the ability to turn almost any plastic surface into a PCB can be really handy, and is not necessarily something the fab houses handle right now. The video below shows how [Ben] came up with his method, which went down a non-obvious path that was part chemistry experiment, part materials science. The basic idea is to use electroless copper plating, a method of depositing copper onto a substrate without using electrolysis.

This allows non-conductive substrates — [Ben] used small parts printed with a Formlabs SLA printer — to be plated with enough copper to form solderable traces. The chemistry involved in this is not trivial; there are catalysts and surfactants and saturated solutions of copper sulfate to manage. And even once he dialed that in, he had to figure out how to make traces and vias with a laser cutter. It was eventually successful, but it took a lot of work. Check out the video below to see how he got there, and where he plans to go next.

You’ve got to hand it to [Ben]; when he decides to explore something, he goes all in. We appreciate his dedication, whether he’s using candles to explore magnetohydrodynamics or making plasma with a high-speed jet of water.

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The (Copper) Crystal Method

One of the staples of kitchen chemistry for kids is making sugar crystals or rock candy. Why not? It is educational and it tastes good, too. [Science with Screens] has a different kind of crystal in mind: copper crystals. You can see the result in the video below.

To grow pure metal crystals, he used copper wire and copper sulfate. He also used a special regulated power supply to create a low voltage to control the current used to form the crystal. The current needed to be no more than 10mA, and an LM317 holds the voltage constant. However, that regulator only goes as low as 1.25V, so diodes cut a volt off the output.

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