Useful PCB calculators.

Hello All,
I have prepared an useful PCB spreadsheet ,Which contains the following most useful PCB calculators.The calculators have been designed to work the best to our knowledge.
Kindly find the attachment Pcb_calci_satya_20071112.xls.

Please inform if any errors or omissions found.The spreadsheet contains the following PCB calculators:

1.Trace Current Calci-----------------Gives trace width based on the current and temperature rating.
2.Via Current Calci--------------------Gives Via size based on the current and temperature rating.
3.Rise time-Max length Calci--------Gives maximum PCB trace length based on rise time and 
                                                      dielectric constant of material.
4.Trace Spacing Calci-----------------Gives trace spacing based on the voltage rating.
5.Pad Stack Calculator---------------Gives Padstack features based on the Finished hole diameter.
6.FR4 Impedance Distortion Calc---Gives how impedance value distorts based on rise time and 
                                                       dielectric constant of material.
7.Thermal Copper Area Calci--------Gives copper surface area to cool a device based on its power 
                                                       dissipation.
8.AT&S PCB Standards---------------Gives AT&S PCB manufacturing Standards.
9.ICE Calculation----------------------Computes ICE and board density.calculation based on the  
                                                       number of pins.
10.Job Quote Calculator--------------In progress.

Your feed backs are most welcome to correct and improve the same.

Regards,
Satya
AT&S Ecad