Re: [volt-nuts] PCBs with ceramic substrates

Indeed, someone I asked elsewhere hinted that ceramic filled PTFE is a good idea for curbing hook. On Mon, 17 Apr 2017 06:20 Bruce Griffiths, wrote: > When the glass fibre bunch periodicity approaches a significant fraction > of a wavelength the periodic spatial

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

Re: [volt-nuts] PCBs with ceramic substrates

ril 12, 2017 5:04 PM Subject: Re: [volt-nuts] PCBs with ceramic substrates Simple, ceramic is a generic term, like car. And, ceramic substrates are available in all manner of different thicknesses, densities, and materials. Like every other engineering material, you decide what characteristics ar

[volt-nuts] PCBs with ceramic substrates

Not always.. A guy I worked with was pulling a ceramic 40 pin dip out of a socket when it broke... sliced his finger to the bone. There was initially some concern that it was a BeO ceramic. Checking with the manufacturer showed it was not. I checked the socket afterwards, and it seemed

Re: [volt-nuts] PCBs with ceramic substrates

In message <58eb8a7e.8010...@erols.com>, Chuck Harris writes: >Google is your friend. Do some research on ceramics. We can add that the toughest materials, on pretty much all parameters, is what is becoming known as "metalic glass", which is just a fancy way of saying "ceramics made of

Re: [volt-nuts] PCBs with ceramic substrates

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, wrote: > There are modern ceramics that are among the toughest things you > will ever

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

Some of the best piezoelectric transducers are made from sintered ceramics. Crystalline salts were once used, but they are highly hygroscopic. -Chuck Harris Attila Kinali wrote: > On Fri, 07 Apr 2017 21:30:56 +0200 > Rob Klein wrote: > >> In general, metrology

Re: [volt-nuts] PCBs with ceramic substrates

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

Re: [volt-nuts] PCBs with ceramic substrates

I assume for cost reasons everybody likes to stay as close to FR4 type materials as possible. This goes double if you have a qualified FR4 type of material which does not suffer from hook and other problems which are a good reason to use a better material. I have noticed that special substrates

Re: [volt-nuts] PCBs with ceramic substrates

In general, metrology equipment doesn't get thrown about much ... I know some calibrators have (heated) modules on ceramic substrates, so it's not that it is completely unheard of. ⁣Met vriendelijke groet, Rob Klein verstuurd vanaf mijn smartphone​ Op 7 apr. 2017 20:12, om 20:12, cheater00

Re: [volt-nuts] PCBs with ceramic substrates

We used them in the supercomputer space long long ago. Mount 8 die to ceramic substrate, mount those to Rogers boards. Thermal wasn't really an issue as everything was bathed in Flourinert™. Was an interesting project. The Unix kernel scheduler had to make scheduling decisions based on all the

Re: [volt-nuts] PCBs with ceramic substrates

well, certain Rogers materials have an even higher surface resistance than PTFE, and are the preferred choice in that case. > Gesendet: Donnerstag, 06. April 2017 um 06:38 Uhr > Von: "Attila Kinali" <att...@kinali.ch> > An: volt-nuts@febo.com > Betreff: [volt-nuts]

Re: [volt-nuts] PCBs with ceramic substrates

In message <20170406063848.2bac84ef9bec7c9c55694...@kinali.ch>, Attila Kinali w rites: >I recently wondered, why people around voltage metrology hardly >talk about ceramic substrates (Al2O3, AlN, ...) for PCBs. >They have surface resistivity that is as high as PTFE, have >higher thermal