Weird ceramic board origins?

[daqq]

Hi guys,

I got this from a gold scrap harvester guy... I don't know what it's from, or anything. Does anyone have a clue? The processor is a Siemens 186. The real puzzle is the board - it's a ceramic square, with at least 3 layers. There's no high frequency stuff going on there as far as I can see - why would someone go to all that trouble. Doesn't exactly seem to be better suited for space/mil stuff than, well, anything... if anything, it looks more fragile.

The only other thing I know about it is that it was a part of a larger system (duh!) with more boards like this (in terms of size, interface, not content) around.

So... any clues?

Thanks,

David

[daqq]

Oh, and don't mind the crystal frequency, I soldered that on there because the old one wasn't in any useful state, being only legs and part of the package... I tried powering it just out of curiosity.

[SArepairman]

possible for high temperature use

that board might be able to sink alot of heat too

[hagster]

It's thick film technology.
http://en.m.wikipedia.org/wiki/Thick_film_technology

Lots of reasons for it.
High temp,high reliability,low loss substrate etc. Also the substrate needs to be ceramic to withstand the kiln firing to sinter the inks.

They often print the resistors directly and laser trim for accuracy.

[daqq]

Thanks. Seems overkill though for a control board. But maybe they were doing all of the boards that way and decided to do it in one run.

[Kjelt]

Looks familiar, I have seen these kinds of sub-boards for PIP (picture in picture) also from Siemens I believe made for Philips in tv sets begin/half 90's must still have a couple of them somewhere. For the PIP unit it had pins attached (where your board has gold fingers) to stick it in a standard female header sockets.
I also have seen a couple of this kind of boards in their older VCR's same brand.

[senso]

Even more amazing is the TI chips marked Portugal, now thats a rare thing.