[volt-nuts] PCBs with ceramic substrates

[cheater00 cheater00]

That's quite a difference from what I knew, thanks!

On Mon, 17 Apr 2017 05:17 Andy Bardagjy, <andy at bardagjy.com> wrote:

> Synthetic sapphire has come down in price quite a bit, a 25mm dia 5mm thick
> sapphire window can be had for just $71
>
> https://www.thorlabs.com/thorproduct.cfm?partnumber=WG31050
>
> Andy ◉ Bardagjy.com <http://bardagjy.com/> ◉ +1-404-964-1641
>
> On Sun, Apr 16, 2017 at 12:03 PM, Scott Stobbe <scott.j.stobbe at gmail.com>
> wrote:
>
> > As a practical aside regarding surface resistance, ignoring guard
> > amplifiers and guard traces, the historic solution is to point to point
> > wire in air. With some designs using Teflon standoffs for a more rigid
> > approach. Some of this can still be seen today, your smoke-detector
> likely
> > has a one-layer phenonlic PCB with the sense pin of a DIP package IC bent
> > up off board and point-point wired in air to the Ion chamber.
> >
> > On Sun, Apr 16, 2017 at 1:25 PM, fala at gmx.net <fala at gmx.net> wrote:
> >
> > > Possibly Macor (machinable ceramic) from Corning, or the comparable
> > > Vitronit, which are both glass ceramics.
> > >
> > > Comparable to borosilicate glass.
> > > Extremely machinable (HSS or carbide tools, use proper speeds and
> > > coolant), continously stable until 800°C.
> > > No safety concerns or toxic effects. The dust created when machining
> can
> > > be an irritant.
> > >
> > > Available from Corning as standard size maxi slab of 36*36*6 cm.
> > > Price = ?
> > >
> > > Quoting Wikipedia for technical data for Macor:
> > > ---
> > > Density: 2.52 g/cm³
> > > Young's modulus [GPa @ 25°C]: 66.9  (FR4 = 21 - 24, Aluminium = 69,
> Steel
> > > = 200)
> > > Specific stiffness [E6 m²/s²]: 26.55  (Al = 26, Steel = 25 +/- 0.5)
> > > Poisson's Ratio []: 0.29 (FR4 = 0.118 - 0.136, Al = 0.32, Steel =
> > > 0.27-0.31)
> > > Thermal conductivity [W/(m*K)]: 1.46  (FR4 ~ 0.3 - 1, Al ~ 300, Steel ~
> > > 15-50)
> > > compressive strenght [MPa]: ~350
> > > Electrical resistivity [Ohm*cm]: 1 E17 (FR4 = 1 E14, PTFE = 1 E23 to 1
> > E25)
> > > Coefficient of thermal expansion [E-6 m/(m*K)]: 9.3 (FR4 ~ 13 , Copper
> =
> > > 16.6)
> > >
> > > Firat
> > >
> > >
> > > Am 16.04.2017 um 13:08 schrieb John Devereux:
> > >
> > >>
> > >> Hi Chuck
> > >>
> > >> But the context is "PCBs with ceramic substrates". Are any of *those*
> > >> tough? They may well be, perhaps you know of some? It does not help us
> > >> with the subject much if there are ceramics with these amazing
> > >> properties if they are not available as PCBs.
> > >>
> > >> There is also the question of exactly what properties of FR4 are
> > >> limiting for "metrology" use.
> > >>
> > >> John
> > >>
> > >
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