| 摘要 |
PURPOSE:To set a highly reliable criterion speedily and automatically, by performing statistical processing of measured values of electrostatic capacities of signal lines of every substrate and updating their mean electrostatic capacity and deviation, and using a distribution function for an automatic decision on a reference electrostatic capacity and a permissible value. CONSTITUTION:Electrostatic capacities of signal lines of every substrate are measured by a measuring instrument 1 under the control of a control part 5, and through the accumulator and distributor 6 and counter 7 of a limited value generating device 2', the mean electrostatic capacity and deviation, and the number of times of measurement, etc., after statistical operation are updated and stored in the accumulating storage device 8. On the basis of those updated value an up-to-date distribution function is read out of a distribution function generator 9 and a reference value operating device 10 calculates the reference electrostatic capacity and permissible value automatically to set them in a comparator 3. The maximum and minimum values of the electrostatic capacities are stored in a limit value storage device 11 through the storage device 8 and when the electrostatic capacity which is not within a normal applicable distribution is obtained, a decision function monitoring device 12, etc., performs abnormal warning display. This constitution allows the automatic, speedy setting of a highly reliable criterion without the intervention of an operator's judgement to improve the reliability of decision. |
