Patent ID: 7603645

Claim:
A calibration method of insulating washer in a circuit board, wherein an insulating washer is disposed around a metal via, the calibration method comprising the steps of: (a) establishing an equivalent circuit model corresponding to the metal via, and storing the same in a computer; (b) with computer software run on the computer; (i) depicting an electric characteristic curve corresponding to the equivalent circuit model; (ii) calculating a capacitance equation and an inductance equation corresponding to the electric characteristic curve; (iii) substituting parameter values of the equivalent circuit model, the capacitance equation, and the inductance equation into a characteristic impedance expression for being calculated, so as to obtain a first radius length value of the insulating washer for the metal via; (iv) making a temporary insulating washer by employing the first radius length value; (v) reestablishing an equivalent circuit model corresponding to the metal via according to the temporary insulating washer; (c) repeating steps (i), (ii), (iii), (iv), and (v) until the first radius length value is converged to be a fixed value; and (d) when the first radius length value is converged to the fixed value in step (c), determining the fixed value as an optimum value for designing the insulating washer.