Mail*Link(r) SMTP               FWD>Questions about PCB#180#s

Urban,

The "size" of printed board conductive patterns for most requirements are
based on the capability of a large group of manufacturers to manufacturer
acceptable printed boards, and also on the functional (and sometimes
regulatory) electrical / electronic requirements.

For electrical signal conductors, the requirements are based on "electrical
signal integrity" which means the signal must propagate from Point "A" to
Point "B" with as acceptable level of distortion.  For low frequency
applications (rule of thumb <   1 MHz) the electrical resistance (which is a
function of material resistivity, cross-sectional area, and conductor length)
are the key requirements.  For higher operating speed/frequencies (rule of
thumb >1 MHz) conductor impedance becomes more critical.  For impedance
evaluations DO NOT FORGET TO INCLUDE THE RESISTANCE OF THE CONDUCTOR in your
model, you do not wany any supprises with "lossy" transmission lines.  The
last major concern is be the impedance of the power and ground distrubution
system, it's got to be low in order to maintain electrical signal integrity.

The other problem you will have is electrical spacings, you will need to
eliminate all contaminants that will have an effect on insulation resistance
and dielectric strength.

Lastly, if you are using copper conductive materials, there may be a problem
with the use of traditional tin/lead solders.  In theory, solid state
diffusion of the Cu/Sn intermetallic could consume all of the Cu and I'm not
sure what happens to the adhesion of the remaining intermetallic of the
conductors to the base material.

I hope these few thoughts help you out,

Ralph Hersey
[log in to unmask]

--------------------------------------
Date: 8/14/96 5:35 AM
From: Urban Stromback - Kretselektro

-------------------------------------
E-mail: [log in to unmask]
Date: 1996-08-14
Time: 12.15.46

Serious Question to IPC TechNet Forum

In a soon future it will be possible to produce Printed Circuit Boards 
with tarackwith and distance < 10 um
If i should be able to produce Boards with trackwith of 1 um, 3 um, 5 um 
and 10 um.
How thick must the copper be and how thich is it allowed to be ?

With hope waiting for answers.

Urban Stromback
at Kretselektronik Sweden AB
Tel +46 92366640
Fax +46 92314557
E-mail [log in to unmask]

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