4 ms·

A Tale of Two Mice: Sustainable Electronics Design and Prototyping [pdf]

21 points by mkj 4y ago

mkj 4y ago
The biodegradable PCB material looks interesting, https://www.jivamaterials.com https://www.jivamaterials.com Seems at an early stage of development (fairly low accuracy surface?), but seems it would simplify recycling a lot. Just need waterproof enclosures for more things!
- hulitu 4y ago
  Until it starts failing in the field and causes fire.
  - atoav 4y ago
    I mean this has to be tested. "Biodegradable" can come in many flavours. For a single use product it would make sense to rot within months. For a PCB it would make sense to rot within multiple decades to a century. If you manage to get a PCB that has all the properties of a regular PCB, but rots after a century that would probably also make recycling the other materials on that PCB less energy intensive.
wingrime 4y ago
You will buy new mouse every month or you will use non-recyclable casing on top
- adrianN 4y ago
  Why do you think that recyclable plastic only lasts a month? You could also use something made of metal, or wood (arguably biodegradable is better than recyclable given the awful recycling rates).
  - benj111 4y ago
    I quite like the idea of a wooden mouse.
- atoav 4y ago
  I mean it depends. It would already be a huge improvement if we created plastics that rot after 200 years instead of basically never. I am not going to be 200 years old and something other in that mouse will fail first, so that would be ok.
avian 4y ago
One interesting thing is they used a lead-free bismuth-based solder. I was not aware that this is a thing. Apparently it has some history of use in IBM and Motorola [1] for soldering sensitive parts in mainframes. A quick search shows it's about 3 times the price of common Sn60/Pb40 lead solder in small quantities: 0.3 EUR/g vs. 0.1 EUR/g. Typical lead-free tin-copper-silver solder you find in factory mass-produced electronics is hard to work/rework manually because of its high melting point. That is the reason most hand-made and low-volume circuits still use lead solder. [1] https://en.wikipedia.org/wiki/Solder_alloys https://en.wikipedia.org/wiki/Solder_alloys
- atoav 4y ago
  I am teaching art students with Sn96,5Ag3,0Cu0,5 (Felder iso-core clear) solder. They all tend to do pretty good after a few hours. Soldering temperature needs to be higher, and using one of those fancier soldering stations where the temperature sensing element is directly in the tip instead of somewhere in the shaft makes a ton of sense (to avoid temperature dips). I think soldering with lead free can indeed be harder, but for teaching that means the people will have to learn the right technique. It is much easier to do it wrong and still get something that looks ok using leaded solder. And if they don't have the comparison they won't complain ; ) I will have to check out the bismuth solder nonetheless.
  - avian 4y ago
    I'm an electrical engineer and I just spend the whole day yesterday reworking some factory-made Sn/Cu/Ag boards in the lab. What kind of parts are you soldering? Thru-hole parts are easy. Surface-mount parts can go quickly from annoying to very hard/nearly impossible to work with Sn/Cu/Ag, depending on their size and thermal sinking ability. Sn/Cu/Ag solder has a narrow window where the solder is melted and wets pads but the FR4 substrate isn't yet degrading. If you have sensitive plastic parts like connectors, etc. the window is even narrower. This is doable in an industrial reflow owen. However when doing hand work or repair, it's impossible to control the temperature this well. For example, after years of experience, I'm still unable to desolder large BGA or PGA parts without visibly degrading the board (i.e. there's usually a brown mark left on it - unfortunately the boards I commonly work with these days use white soldermask, which makes this even more obvious). That's with a temperature controlled pre-heater and a hot-air station. I won't even attempt to solder such parts manually with Sn/Cu/Ag.

21 points by mkj 4y ago

mkj 4y ago

The biodegradable PCB material looks interesting, https://www.jivamaterials.com https://www.jivamaterials.com Seems at an early stage of development (fairly low accuracy surface?), but seems it would simplify recycling a lot. Just need waterproof enclosures for more things!

hulitu 4y ago
Until it starts failing in the field and causes fire.
- atoav 4y ago
  I mean this has to be tested. "Biodegradable" can come in many flavours. For a single use product it would make sense to rot within months. For a PCB it would make sense to rot within multiple decades to a century. If you manage to get a PCB that has all the properties of a regular PCB, but rots after a century that would probably also make recycling the other materials on that PCB less energy intensive.

wingrime 4y ago

You will buy new mouse every month or you will use non-recyclable casing on top

adrianN 4y ago
Why do you think that recyclable plastic only lasts a month? You could also use something made of metal, or wood (arguably biodegradable is better than recyclable given the awful recycling rates).
- benj111 4y ago
  I quite like the idea of a wooden mouse.
atoav 4y ago
I mean it depends. It would already be a huge improvement if we created plastics that rot after 200 years instead of basically never. I am not going to be 200 years old and something other in that mouse will fail first, so that would be ok.

avian 4y ago

One interesting thing is they used a lead-free bismuth-based solder. I was not aware that this is a thing. Apparently it has some history of use in IBM and Motorola [1] for soldering sensitive parts in mainframes. A quick search shows it's about 3 times the price of common Sn60/Pb40 lead solder in small quantities: 0.3 EUR/g vs. 0.1 EUR/g. Typical lead-free tin-copper-silver solder you find in factory mass-produced electronics is hard to work/rework manually because of its high melting point. That is the reason most hand-made and low-volume circuits still use lead solder. [1] https://en.wikipedia.org/wiki/Solder_alloys https://en.wikipedia.org/wiki/Solder_alloys

atoav 4y ago
I am teaching art students with Sn96,5Ag3,0Cu0,5 (Felder iso-core clear) solder. They all tend to do pretty good after a few hours. Soldering temperature needs to be higher, and using one of those fancier soldering stations where the temperature sensing element is directly in the tip instead of somewhere in the shaft makes a ton of sense (to avoid temperature dips). I think soldering with lead free can indeed be harder, but for teaching that means the people will have to learn the right technique. It is much easier to do it wrong and still get something that looks ok using leaded solder. And if they don't have the comparison they won't complain ; ) I will have to check out the bismuth solder nonetheless.
- avian 4y ago
  I'm an electrical engineer and I just spend the whole day yesterday reworking some factory-made Sn/Cu/Ag boards in the lab. What kind of parts are you soldering? Thru-hole parts are easy. Surface-mount parts can go quickly from annoying to very hard/nearly impossible to work with Sn/Cu/Ag, depending on their size and thermal sinking ability. Sn/Cu/Ag solder has a narrow window where the solder is melted and wets pads but the FR4 substrate isn't yet degrading. If you have sensitive plastic parts like connectors, etc. the window is even narrower. This is doable in an industrial reflow owen. However when doing hand work or repair, it's impossible to control the temperature this well. For example, after years of experience, I'm still unable to desolder large BGA or PGA parts without visibly degrading the board (i.e. there's usually a brown mark left on it - unfortunately the boards I commonly work with these days use white soldermask, which makes this even more obvious). That's with a temperature controlled pre-heater and a hot-air station. I won't even attempt to solder such parts manually with Sn/Cu/Ag.