Patent ID: 9426902
Filing Date: 2016-08-23
CPC Classification: B23B,H05K,Y10T

Claim Text:
1. A method for drilling a printed circuit board, the method comprising: drilling down, by a first drill bit of a driller, in an initial position; and when contacting a live superficial conductive layer of a test Coupon zone of a printed circuit board, acquiring, by the driller, a first electrical signal to determine a first conductive position and acquiring a first height difference between the initial position and the first conductive position; drilling onward, by a second drill bit, after the first drill bit of the driller drills through the superficial conductive layer; and when contacting another conductive layer of the test Coupon zone of the printed circuit board, acquiring, by the driller, a second electrical signal to determine a second conductive position and acquiring a second height difference between the initial position and the second conductive position; calculating a difference between the second height difference and the first height difference to obtain a third height difference; and performing back-drilling, according to the third height difference, in a position that corresponds to the test Coupon zone and needs back-drilling, wherein acquiring, by the driller, the first electrical signal comprises: when the first drill bit contacts the live superficial conductive layer of the test Coupon zone of the printed circuit board, the live superficial conductive layer, a through hole, a control circuit of the driller, and the first drill bit form a first loop to generate the first electrical signal, and wherein acquiring, by the driller, the second electrical signal comprises: when the second drill bit contacts the another conductive layer of the test Coupon zone of the printed circuit board, the another conductive layer, the superficial conductive layer, the through hole, the control circuit of the driller, and the second drill bit form a second loop through a conductive layer on the inner wall of the through hole to generate the second electrical signal.