[volt-nuts] PCBs with ceramic substrates

Chuck Harris cfharris at erols.com
Mon Apr 10 09:37:02 EDT 2017

Yes, there have been enhancements, but ceramics have
been tough since long before the 70's and 80's.  Think
about the insulator on your common spark plug.  The
platinum variety are sitting out in an explosive inferno
with no support.

Think about your gob ordinary Corning Corell ceramic
plate, or corning casserole dish.  They get wacked around,
and just take it.  Sure, you can break them, but not
through casual use.

Ceramic hybrids have not been known to be very fragile
by anyone I know.  They can be tiny, and tiny things have
problems when forced around by big clumsy things.  They
certainly would be more fragile made from an equivalent
dimensioned piece of FR4.  FR4 would flex, breaking all
of the thin film printed resistors, and traces.  Ceramic
won't flex, which is largely why it is used in hybrid

I have been working around tektronix scopes for most of
my life, and the early scopes all have ceramic terminal
boards.  I have never seen one broken.  That includes
50 lb scopes that have been tossed into a scrap pile.

I have been repairing and calibrating 2465 scopes for
at least a decade, and I have never, ever, ever, seen
a ceramic based hybrid that has been broken.  Never.
There are more than a half dozen such ceramic substrates
in each scope.

Ever seen a ceramic DIP package EPROM that spontaneously
broke?  A ceramic DIP packaged 68000 microprocessor?  That
is a heck of a big piece of ceramic!  You really have to
work to break these things.

Google is your friend.  Do some research on ceramics.

-Chuck Harris

cheater00 cheater00 wrote:
> Interesting, good to know! I assume those materials were not available in
> the 70s and 80s? Hybrids from those decades are known to be very fragile.
> On Mon, 10 Apr 2017 04:08 Chuck Harris, <cfharris at erols.com> wrote:
>> There are modern ceramics that are among the toughest things you
>> will ever see in your life.
>> A ceramic gun is entirely of ceramic.  There are automotive
>> engines made entirely of ceramic.  As are some turbines used
>> in turbochargers for engines.
>> One of the things that can make ceramic extremely tough is
>> to put it in a mold, and compress it to many tons per square
>> inch, while in the green state.  After that, it is already
>> tough.  Then fire it to sinter everything together.
>> Google is your friend.
>> Again, it isn't your mother's teapot.
>> -Chuck Harris
>> cheater00 cheater00 wrote:
>>> 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?
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