[volt-nuts] PCBs with ceramic substrates

[cheater00 cheater00]

Hi Chuck,
I can't talk about most of those applications but in the ones I know of the
ceramics are used for their hardness (ie ability to withstand deformation).
What we want is toughness which is a different thing (ability to withstand
breaking). Compromising hardness and toughness is why in a knife you only
harden the cutting edge, and you specifically watch out that the rest
doesn't harden, or you even reverse the hardening process on that part.
High hardness and low toughness is also why ceramic knives chip more easily
than metal ones. I haven't seen fully ceramic gun parts, interesting idea.
I know very little about gun parts. I wonder if it's just a layer over a
metal. Brake linings will have the benefit of a tough backing which will
enable load bearing. This is what you want from a pcb - toughness for load
bearing, and minimal hardness for reduced fragility. I don't suppose lathe
inserts will be made in the same way a pcb would be. If you know more
please let me know, I'd love to hear more about it. And yeah, I like to
break things when I can :)

On Sun, 9 Apr 2017 18:37 Chuck Harris, <cfharris at erols.com> wrote:

> Why exactly do you think ceramic is delicate?
>
> It is used to make knifes, pistols, internal combustion
> engines, turbines,  brake linings, clutches,... and even
> insert tooling for machining very hard materials.
>
> It isn't your mother's teapot!
>
> Or, are you the proverbial "bull in a china shop" in
> everything you do?
>
> -Chuck Harris
>
> cheater00 cheater00 wrote:
> > Hi Rob, thanks for your email.
> >
> > My take is you want your standards and calibrated equipment to last very
> > long due to increasing stability, and that is in direct opposition to
> > making them out of fragile materials, even if they don't get thrown
> around.
> > Accidents happen, people trip over, this can't really be helped. I'm no
> > metrology expert by any degree, it just seems to me that making it even
> > easier to break your $250k box is a bad idea if it can be wholly avoided
> by
> > using a different material that'll meet requirements too.
> >
> > You're right that it's not unheard of - ceramics were even used in mobile
> > testing equipment eg by tek - but they didn't know better back then, or
> > they didn't care because equipment would be phased out before it had
> chance
> > to break.
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