How it's made,Oil Pressure Sensors: video, includes screenprinted PCB tracks

[codeboy2k]

I just came across this video and I thought I would share it

It's about the construction of oil-pressure sensors, which to my surprise, reads the pressure directly on the silicon chip.  There's a portion where they screen print a silver-palladium alloy onto a ceramic carrier, and then pick and place some passives on the pads.  I thought that was pretty cool to see the screen-printing and it was a very quick way to get dozens of little circuits printed.  Why isn't that a home-process yet I'd certainly pick screen printing over chemical etching, but it's probably still too expensive even with the reduction in steps.

[Tandy]

What is this soddering they speak of?

[rs20]

Thanks for sharing, that's a really elegant process -- I especially liked the way the o-rings and pushed down, and then the whole thing is crimped in that state to maintain the preload. Lovely stuff.

[T3sl4co1l]

It's called hybrid construction.  You can do PCB stuff and IC packaging stuff, all in one place.

I'd suspect the screened connections are lower tolerance than photo-etched (compare the tolerance on PCB silkscreen to soldermask or copper).  But certainly good enough for placing some chip components on.

Other methods include direct nichrome (or other resistive alloy) deposition, followed by photochemical or laser etching, to get precise shapes and controlled resistances.  Laser drilling to apply vias on the ceramic substrate; alternating layers of enamel and metal paste to get multilayer construction; etc.

No idea what the typical NRE is, but I'm sure it's not small.  When you're making a billion of a thing, like automakers do, you can negotiate astonishingly low prices even for things like this.

Tim

[codeboy2k]

Yeah, I've seen some of the multilayer hybrids used in some HP gear, and others as well. 

This oil pressure sensor is not a complex hybrid, but I've never seen the construction in a video before.  I'm sure there's one out there somewhere showing the process for a more complex hybrid as you described.

Post a link if anyone has one

Cheers