Re: [volt-nuts] PCBs with ceramic substrates

When the glass fibre bunch periodicity approaches a significant fraction of a wavelength the periodic spatial modulation of the substrate dielectric constant under or surrounding transmission lines has interesting effects on the properties of the transmission line. At even higher frequencies

Re: [volt-nuts] PCBs with ceramic substrates

There's little out there on the frequency dependence of dielectric constant at audio and sub audio frequencies. A bit more for 10MHz and above like: http://www.edn.com/design/analog/4398951/2/What-PCB-material-do-I-need-to-use-for-RF-

Re: [volt-nuts] PCBs with ceramic substrates

That's quite a difference from what I knew, thanks! On Mon, 17 Apr 2017 05:17 Andy Bardagjy, wrote: > Synthetic sapphire has come down in price quite a bit, a 25mm dia 5mm thick > sapphire window can be had for just $71 > >

Re: [volt-nuts] PCBs with ceramic substrates

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 ◉ +1-404-964-1641 On Sun, Apr 16, 2017 at 12:03 PM, Scott Stobbe

Re: [volt-nuts] PCBs with ceramic substrates

Hi David, You could perhaps send some of that white material to Mike's Electric Stuff, he has a mass spectrogram, which could tell you what it is. On Mon, 17 Apr 2017 04:31 cheater00 cheater00, wrote: > Thank you. Do you have a plot of the effect on impedance due to hook

Re: [volt-nuts] PCBs with ceramic substrates

Thank you. Do you have a plot of the effect on impedance due to hook out into high frequencies, measured on a real world material? It would tell me a lot. On Mon, 17 Apr 2017 04:19 Bruce Griffiths, wrote: > Hook is merely a manifestation of the variation of

Re: [volt-nuts] PCBs with ceramic substrates

Are conformal coatings the right way to handle this? I understand there are kinds of FR4 and G10 that don't have hook. What does one do about hook - how are those substrates improved? How does hook manifest in circuits? On Mon, 17 Apr 2017 03:48 David, wrote: > FR4 has

Re: [volt-nuts] PCBs with ceramic substrates

FR4 has problems with consistency. Samples can have problems with hook, dielectric absorption, leakage, and sensitivity to humidity. On Sun, 16 Apr 2017 12:08:07 +0100, you wrote: >Hi Chuck > >But the context is "PCBs with ceramic substrates". Are any of *those* >tough? They may well be,

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

> > > > On Sun, 16 Apr 2017 13:17 Poul-Henning Kamp, wrote: > In message <87inm44nl4@devereux.me.uk>, John Devereux writes: > > > There is also the question of exactly what properties of FR4 are > > limiting for "metrology" use. > > FR4 are certainly not without its own

Re: [volt-nuts] PCBs with ceramic substrates

Hi John, I am not advocating ceramics in place of FR4, or vice versa. That was someone else wondering why ceramics weren't used in metrology... As to what you can use that isn't brittle, that is up to your imagination. Unlike common FR4 materials, ceramics don't do well with the usual FR4

Re: [volt-nuts] PCBs with ceramic substrates

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