[SI-LIST] Re: Use of Ceramic substrates at High Frequencies
- From: "Raymond W. Waugh" <ray_waugh@xxxxxxxxxxx>
- To: <APANNIKK@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 17 Sep 2001 17:00:16 -0700
Anil...
Of the commonly used microwave and RF boards, FR4 and other cheap materials
have the highest dielectric loss. Ceramics such as 99.4% alumina are in the
middle, and certain organics such as Teflon based boards have the lowest.
Dielectric losses dominate the total loss picture at microwave frequencies.
The reason ceramics are used (so called MIC or microwave integrated
circuits) is twofold. First, they are sometimes chosen for high temperature
processing (die attach, wire bond). This permits semiconductors to be used
without packages, greatly reducing parasitic reactances and permitting wider
bandwidths. There is no way one can make a 6 - 18 GHz GaAs FET amplifier
using packaged FETs. Second, the high dielectric constant of alumina
(around ten) shrinks the size of distributed transmission line structures
such as backward wave couplers.
Ray
------------------------------------------------------
Raymond W. Waugh - WSD Applications Engineering
E-mail: ray_waugh@xxxxxxxxxxx
USPS : Wireless Semiconductor Division
39201 Cherry Street, MS NK20
Newark, California 94560
------------------------------------------------------
-----Original Message-----
From: Anil Pannikkat <APANNIKK@xxxxxxxxxx>
To: si-list@xxxxxxxxxxxxx <si-list@xxxxxxxxxxxxx>
Date: Monday, September 17, 2001 4:43 PM
Subject: [SI-LIST] Re: Use of Ceramic substrates at High Frequencies
Hello
This might be a very naive question, but can anyone please tell me as to
why ceramic substrates are used so much in the microwave world as compared
to organic substrates. I know the dielectric loss in ceramic substrates is
much lower than the organic substrates, but the skin resistance in ceramic
substrates (due to W metallization) is much higher. So why is the dielectric
loss more important than skin R?. Or is the choice more due to other factors
such as cost?
Thanks
Anil
Anil Pannikkat
MTS Package Development Ph : 408-544-7542
Altera Corporation Fax: 408-544-6419
101, Innovation Drive, M/S 4101 Email: apannikk@xxxxxxxxxx
San Jose, CA 95134 WWW: http://www.altera.com
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
