| 摘要 |
An automatic thickness analyzer is provided which automatically measures the thickness of a metallic film deposited on an insulating substrate e.g. plated through holes of printed circuits. A direct current increasing at a constant rate 125, 150 is applied to the conductors of a plated-through hole 350. If the metallic film burns out before the maximum output of the analyzer is achieved, the value of the current corresponding to the burn-out current is captured and held by circuit 200 and the held valve applied to a display meter 250 until it is manually reset by 325. An empirical relationship allows automatic conversion of the burnout current to the corresponding thickness of the metallic film. Burn-out shutdown circuit 275 responsive to the burn-out current inhibits the sample and hold circuit 200 and inactivates the current generator 150. If the metallic film does not burn out before the maximum current capacity of the analyzer is reached, current limit shutdown circuitry 300 is automatically activated. <IMAGE> |
