Anyone making cheap ceramic substrate electronics

[tszaboo]

Now that we have PCB suppliers in China complete the race to the bottom, and making boards practically for free:
Do you know of any supplier that would do ceramic substrates and printed electronics with pooling service?

[ch_scr]

I've taken apart peltier elements to get ceramic carriers with attached copper pads. Can be sawn to size with a diamond disk on a dremel in a water bath. The pitch fits 0805 SMD and even DIL components. Not precisely what you asked for, but if you could find the supplier, I guess that could be a lead?

[dmendesf]

May I ask... why? (It's a genuine question)

[ch_scr]

Mechanical stresses on components can influence their values. For a SMD component on a FR4 substrate (that have no lead to bend and take up the stress), these stresses can come from the difference in thermal expansion between the two materials, but also from the slight swelling when the epoxy of the FR4 takes up humidity. The effect of humidity is on the order of months and follows the seasons with a delay. This also effects e.g. voltage reference in plastic cases, all containing epoxy that reacts to humidity, putting pressure on the die inside. This is in part the reason why precision circuits (think 6 1/2 digits and beyond) might still use THT components and/or use hermetically sealed components or assemblies. Or have slots milled in the PCB to isolate such stresses. Another proposed way to deal with this is to mount the sensitive SMD components on a flex pcb - with it beeing much softer, the forces should be much lower. This points to a potential problem: given ceramics are much harder than FR4, if the ceramics are "too different" between the component and PCB, potentially the forces from thermal expansion could be even higher than with FR4.

[dmendesf]

I remember Telecontrolli used to make very simple 433/315MHz radios over alumina substrate. They even had small coils and resistors made with thick film over it and laser trimmed. For me it seemed too much technology for a cheap product...

[ch_scr]

I remember Telecontrolli used to make very simple 433/315MHz radios over alumina substrate. They even had small coils and resistors made with thick film over it and laser trimmed. For me it seemed too much technology for a cheap product...

If the technology of the time needed multiple trimmed resistors, that was probably still cheaper than having someone tweak multiple potentiometers on every board.

[tszaboo]

May I ask... why? (It's a genuine question)

Custom ultrasound probe, mmwave radar radome and precision measurement sampling head with PT1000 was three applications that I considered doing this recently.

[temperance]

I've used this service to develop some ultra high temperature capable electronics with components glued onto the PCB: (can't tell you what is. NDA)

https://ceramic-pcb.com/

They are located in Belgium but they speak English.

Many options and not expensive.

Some tips:
-Connectors melt during reflow in a "hobby" reflow oven because the PCB can retain quite some heat. The same is probably true for alu capacitors.
-Soldering wires onto such a board is nearly impossible because of the very high thermal conductivity. If you want to do that, you must solder them all at once and you will need some tool to keep the wires in place while they are cooling down. The no brain part is that you must use teflon wire.

Some very experimental stuff:
Soon I will have to make some more revised proto types and I'm thinking about something like this in combination with a solder paste stencil:
https://www.graphene-supermarket.com/products/high-temperature-silver-graphene-conductive-epoxy-g6e-htsg

Curing of the above is done at 150°C/302°F for two hours. I have no idea what kind of mess I'm going to create on the workbench.

I'm now looking into room temperature curing epoxy. It might work for a low temperature application but not for a high temperature application it seems because room temperature curing epoxy starts to become soft at low temperatures.

[tszaboo]

I've used this service to develop some ultra high temperature capable electronics with components glued onto the PCB: (can't tell you what is. NDA)

https://ceramic-pcb.com/

They are located in Belgium but they speak English.

Many options and not expensive.

Some tips:
-Connectors melt during reflow in a "hobby" reflow oven because the PCB can retain quite some heat. The same is probably true for alu capacitors.
-Soldering wires onto such a board is nearly impossible because of the very high thermal conductivity. If you want to do that, you must solder them all at once and you will need some tool to keep the wires in place while they are cooling down. The no brain part is that you must use teflon wire.

Some very experimental stuff:
Soon I will have to make some more revised proto types and I'm thinking about something like this in combination with a solder paste stencil:
https://www.graphene-supermarket.com/products/high-temperature-silver-graphene-conductive-epoxy-g6e-htsg

Curing of the above is done at 150°C/302°F for two hours. I have no idea what kind of mess I'm going to create on the workbench.

I'm now looking into room temperature curing epoxy. It might work for a low temperature application but not for a high temperature application it seems because room temperature curing epoxy starts to become soft at low temperatures.

Right, so these guys ask for about 500 EUR for a sample. I don't have a reference if this is good or not.
I'm guessing for the cables, I would use an SMD vampire contact. Or bond wires welded to the board (no experience with this). Or spring contacts on the host device.

Yes, I've used silver epoxy for mounting ultrasonic transducers. It's priced as gold, despite it's name

[temperance]

I've contacted some other companies in Germany. But they were only interested in high volume production and of course they offer you much more than just an etched ceramic board.

-Embedded components for RF and simple resistors
-Board assembly
-Edge mounted connection
-Environmental protection
...

Yes, I've used silver epoxy for mounting ultrasonic transducers.

How did that go?

Besides, the epoxy I linked too is not that expensive compared with solder paste. What did you use?