[SI-LIST] Effects of steam?
- From: "John Barrett" <John.Barrett@xxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Mon, 24 Nov 2008 12:08:47 -0000
This one is a bit off the beaten track but I want to operate an organic circuit
board (no devices, just gold conductors on polyimide), in an autoclave with
high pressure (3 bar), high temperature (135C) non-saturated steam. There's no
condensation and so no real water about. What would be the effect of steam
absorption on the dielectric constant and the loss tangent up to 5GHz?
Non-saturated steam, i.e. dry, invisible steam, has dielectric properties very
close to air so, if it were to penetrate a porous material e.g. porous alumina,
then it would just displace the air in the pores and cause little variation in
electrical parameters. With something like polyimide, which I presume absorbs
moisture inter-molecularly, there are measureable shifts in dielectric
properties with variations in moisture content caused by humidity variations at
normal temperatures, and I think that this is caused by the release of extra
charges, but what are the effects in 135C, 3bar steam? I could measure the
effects with resonator test structures and a VNA but I would need to find and
invest in high frequency connectors and cables able to withstand the autoclave
atmosphere - not cheap, I imagine, even if they exist. Perhaps there are
dielectric experts on the list who might be able to speculate from a materials
science viewpoint?
Regards and thanks,
John
Séan de Baróid
Ionad um Raidichórais Inoiriúnaithe
Roinn na hInnealtóireachta Leictreonaí
Institiúd Teicneolaíochta Chorcaí
________________
John Barrett
Centre for Adaptive Wireless Systems
Department of Electronic Engineering
Cork Institute of Technology
"Beidh fáilte roimh freagra as Gaeilge"
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