CO2 laser cutting ceramic sheet under water film

Water Is The Secret Ingredient When Laser Cutting Ceramics To Make Circuits

[Ben Krasnow] over at Applied Science was experimenting with cutting inexpensive ceramic sheets with his cheap CO2 laser cutter when he found that (just as expected) the thermal shock of the CO2 beam would cause cracking and breaking of the workpiece. After much experimentation, he stumbled upon a simple solution: submersion under a thin layer of water was sufficient to remove excess heat, keeping thermal shock at bay, and eventually cutting the material. Some prior art was uncovered, which we believe is this PHD thesis (PDF) from Manchester University in the UK. This is a great read for anyone wanting to dig into this technique a little deeper.

The CO2 laser cutter is a very versatile tool, capable of cutting and etching a wide range of materials, many of natural origin, such as cardboard, leather and wood, as well as certain plastics and other synthetic materials. But, there are also materials that are generally a no-go, such as metals, ceramics and anything that does not absorb the laser wavelength adequately or is too reflective, so having another string in one’s bow is a good thing. After all, not everyone has access to a fibre laser.

After dispensing with the problem of how to cut ceramic, it got even more interesting. He proceeded to deposit conductive traces sufficiently robust to solder to. A mask was made from vinyl sheet and a squeegee used to deposit a thick layer of silver and glass particles 1 um or less in size. This was then sintered in a small kiln, which was controlled with a Raspberry Pi running PicoReFlow, and after a little bit of scrubbing, the surface resistance was a very usable 2 mΩ/square. Holes cut with the laser, together with some silver material being pushed through with the squeegee formed through holes with no additional effort. That’s pretty neat!

Some solder paste and parts were added to the demo board, and with an added flare for no real reason other than he could, reflowed by simply applying power direct to the board. A heater trace had been applied to the bottom surface, rendering the board capable of self-reflowing. Now that is cool!

Continue reading “Water Is The Secret Ingredient When Laser Cutting Ceramics To Make Circuits”

Hackaday Prize Entry: DIY Ceramic PCBs

We’ve seen hundreds of ways to create your own PCBs at home. If you have a laser printer, you can put traces on a piece of copper clad board. If you have some hydrogen peroxide and acid, you can etch those traces. Don’t have either? Build a tiny mill and cut through the copper with a Dremel. Making your own PCBs at home is easy, provided your boards are made out of FR4 and copper sheets.

Printed circuit boards can be so much cooler than a piece of FR4, though. Ceramic PCBs are the height of board fabrication technology, producing a very hard board with near perfect electrical properties, high thermal conductivity, and a dielectric strength similar to mineral transformer oil. Ceramic PCBs are for electronics going to space or inside nuclear reactors.

For his entry into this year’s Hackaday Prize, [Chuck] is building these space grade PCBs. Not only is he tackling the hardest challenge PCB fabrication has to offer, he’s building a machine to automate the process.

The basic process of building ceramic PCBs is to create a sheet of alumina, glass powder, and binder. This sheet is first drilled out, then silver ink is printed on top. Layers of these sheets are stacked on top of each other, and the whole stack is rammed together in a press and fired in a furnace.

Instead of making his own unfired ceramic sheets, he’s just buying it off the shelf. It costs about a dollar per square inch. This material is held down on a laser cutter/inkjet combo machine with a vacuum table. It’s just a beginning, but [Chuck] has everything he needs to start his experiments in creating truly space grade PCBs.

The HackadayPrize2016 is Sponsored by: