Printed circuit board, and method and apparatus for drilling printed circuit board

An apparatus for drilling a printed circuit board, the printed circuit board comprising a plurality of conductive layers and insulation layers isolating the conductive layers, the apparatus comprising:

• a main unit, a first drill bit, and a second drill bit whose aperture is smaller than that of the first drill bit;
• wherein the main unit comprises a controller, wherein:
• the controller comprises a control circuit and a sensor;
• the control circuit controls the first drill bit to drill down in an initial position until a superficial conductive layer of a test Coupon zone of the printed circuit board is drilled through;
• when the first drill bit contacts the superficial conductive layer, the sensor acquires a first electrical signal to determine a first conductive position and acquires a first height difference between the initial position and the first conductive position;
• the control circuit controls the second drill bit to drill onward in a position where the first drill bit drills through the superficial conductive layer;
• and when the second drill bit contacts another conductive layer of the test Coupon zone of the printed circuit board, the sensor acquires a second electrical signal to determine a second conductive position and acquires a second height difference between the initial position and the second conductive position;
• and
• wherein the main unit calculates a difference between the second height difference and the first height difference to obtain a third height difference, and controls a back-drilling drill bit to perform back-drilling, according to the third height difference, in a position that corresponds to the test Coupon zone and needs back-drilling,
• wherein the first drill bit is configured to drill through the superficial conductive layer of the test Coupon zone to acquire a first blind via with its aperture being a first diameter;
• and
• the second drill bit is configured to drill a second blind via with its aperture being a second diameter under the superficial conductive layer, wherein the bottom of the second blind via is positioned on a surface of, inside, or under another conductive layer,
• wherein when the first drill bit contacts the live superficial conductive layer of the test Coupon zone of the printed circuit board, the 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:
• 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, 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.

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 third loop through a wire led out from the another conductive layer to generate the second electrical signal.

An apparatus for drilling a printed circuit board, the printed circuit board comprising a plurality of conductive layers and insulation layers isolating the conductive layers, the apparatus comprising:

• a main unit, a first drill bit, and a second drill bit whose aperture is smaller than that of the first drill bit;
• wherein the main unit comprises a controller, wherein:
• the controller comprises a control circuit and a sensor;
• the control circuit controls the first drill bit to drill down in an initial position until a superficial conductive layer of a test Coupon zone of the printed circuit board is drilled through;
• when the first drill bit contacts the superficial conductive layer, the sensor acquires a first electrical signal to determine a first conductive position and acquires a first height difference between the initial position and the first conductive position;
• the control circuit controls the second drill bit to drill onward in a position where the first drill bit drills through the superficial conductive layer;
• and when the second drill bit contacts another conductive layer of the test Coupon zone of the printed circuit board, the sensor acquires a second electrical signal to determine a second conductive position and acquires a second height difference between the initial position and the second conductive position;
• and
• wherein the main unit calculates a difference between the second height difference and the first height difference to obtain a third height difference, and controls a back-drilling drill bit to perform in back-drilling, according to the third height difference, in a position that corresponds to the test Coupon zone and needs back-drilling,
• wherein the first drill bit is configured to drill through the superficial conductive layer of the test Coupon zone to acquire a first blind via with its aperture being a first diameter;
• and
• the second drill bit is configured to drill a second blind via with its aperture being a second diameter under the superficial conductive layer, wherein the bottom of the second blind via is positioned on a surface of, inside, or under another conductive layer,
• wherein when the first drill bit contacts the live superficial conductive layer of the test Coupon zone of the printed circuit board, the 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:
• 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 third loop through a wire led out from the another conductive layer to generate the second electrical signal.