[SI-LIST] Effects of steam?

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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