Mitra,

A buried resistor is a method
of using a laminated material 
made up as follows:

copper
resistive material film (ie. nickel)
substrate

which then can be subtractively processed
to yield planar resistors.

This allows you to add resistors without
putting them on the surface and without 
adding substantial thickness since the layer
is 0.1-0.4 microns thick for the resistive material.

My facility designs and fabricates using this 
technique for designs where the density is too
great to use surface components.

--
Robert Blomstrom            Advanced Interconnection Technology, Inc. - Atlanta
Phone: 404-938-9387 x226    3289 Montreal Industrial Way, Tucker, Ga. 30084
fax:   404-934-9885         e-mail address: [log in to unmask]