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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