Material Library

Edit: Edit LayoutMaterials

The dialog box is also available via Navigation Tree: Technology Materials.  A  right mouse click on Materials opens a drop-down menu where the user is able to call the Edit dialog box. It  shows a list of all available materials. The icons on the top of the dialog box enable the following actions:

 

There are two different types of materials: conductor and dielectric. Each material requires a unique name that has to be assigned in the field Identifier. The type of the material can be set in the field Material. Materials of type conductor are characterized by their conductivity which has to be set inside the field Conductivity. The Skin effect of a conductive material is modeled by using this conductivity value in combination with the 2D cross-section shape of the corresponding conductor.

In case of material type dielectric, there are three further parameters. The field Permittivity enables the definition of the relative permittivity and the field Loss angle tan() enables the definition of the dielectric loss angle. If the Loss angle differs from zero a specific Frequency has to be specified where the given Permittivity is valid. The  loss angle will be assumed as constant over the whole frequency range (see Model valid up to frequency).

 

 

Ohmic loss modeling

The program approximates the increase in ohmic resistance and the decrease in internal inductance over the specified frequency range, from DC up to a maximum frequency, which is specified via the parameter Model valid up to frequency (see Model valid up to frequency). The way that the impedance changes over frequency depends on the general shape of the conductor. On a PCB the typical shape type is a flat rectangle. In general, the program distinguishes between thin rectangle (strips) and circular wire shapes. For both shape types CST PCB STUDIO provides a solution for the two different kinds of model interpretation during the circuit simulation (see Circuit Simulation Aspects)

 

In case of a Dispersive model interpretation, an analytic expression is used to describe the Skin effect over the frequency range:

 

 

In case of a Standard model interpretation, a multi-order R/L ladder circuit approach is used to approximate the characteristic behavior given by the analytic expression:

 

 

Reference:

"Experimental Researches on Skin Effect in Conductors", A.E. Kennelly; P.H. Pierce, Panama-Pacific Convention of the American Institute of Electrical Engineers, San Francisco, September 16.th 1915

"Digital Signal Integrity", B. Young, Prentice Hall, 200, chapters: 7.4 and 10.3

 

Dielectric loss modeling

The program approximates a constant loss angle over the specified frequency range, from DC up to a maximum frequency (see Model valid up to frequency). The crucial point in dielectric loss modeling is to keep the model causal. CST PCB STUDIO provides a solution for the two different kinds of model interpretations during the circuit simulation (see Circuit Simulation Aspects)

 

In case of a Dispersive model interpretation, an analytic expression is used to describe the relationship between the increase of conductance and the decrease of capacitance over the frequency range. At the frequency, specified in the material definition dialog box, the capacitance corresponds to the permittivity, also specified in the material definition dialog box.

 

 

In case of a Standard model interpretation, a multi-order Debye approach is used to approximate the characteristic behavior by the analytic expression:

 

 

Reference:

"Time-Domain Modeling of Lossy Substrates with Constant Loss Tangent", A.E. Engin; W. Mathis; W. John; G. Sommer; H. Reichl, Signal Propagation on Interconnects, Proceedings. 8th IEEE Workshop; 9-12 May 2004, pp 151-154