Method for implementing high-precision backdrilling stub length control

Patent metadata

Field	Value
Publication number	US-9827616-B2
Application number	US-201414553942-A
Country	US
Kind code	B2
Filing date	Nov 25, 2014
Priority date	Aug 28, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

The present invention relates to a PCB drilling method including: performing a drilling motion from an initial location, and generating a first electrical signal when coming into contact with a first conductive layer of the PCB, determining a first conductive location according to the first electrical signal, and obtaining first Z-coordinate information continuing to perform the drilling motion after drilling through the first conductive layer, and generating a second electrical signal when coming into contact with a second conductive layer, determining a second conductive location according to the second electrical signal, and obtaining second Z-coordinate information; continuing to perform the drilling motion and drilling through the PCB to obtain a through hole; and performing backdrilling in the location of the through hole according to a preset depth, and the preset depth is a medium thickness between the second conductive layer and the first conductive layer plus a compensation depth.

First claim

What is claimed is:

1. A printed circuit board drilling method comprising:
in a process of drilling a through hole, performing the following:
controlling, by a drill, a drill bit to perform a drilling motion from an initial location;
generating, by the drill, a first electrical signal when the drill bit comes into contact with a first conductive layer of a printed circuit board;
determining a first conductive location according to the first electrical signal;
obtaining a first Z-coordinate information corresponding to the first conductive location;
continuing to control the drill bit to perform the drilling motion after drilling through the first conductive layer;
generating, by the drill, a second electrical signal when the drill bit comes into contact with a second conductive layer of the printed circuit board;
determining a second conductive location according to the second electrical signal;
obtaining a second Z-coordinate information corresponding to the second conductive location; and
continuing to control the drill bit to perform the drilling motion until the drill bit drills through the printed circuit board to obtain a the through hole; and

after forming the through hole, performing the following:
controlling the drill bit to perform a backdrilling motion in a location of the through hole according to a preset depth, wherein the preset depth is a medium thickness between the second conductive layer and the first conductive layer plus a compensation depth, and wherein the medium thickness is obtained by calculating an absolute value of a difference between the first Z-coordinate information and the second Z-coordinate information.

2. The printed circuit board drilling method according to claim 1 , wherein, when the first conductive layer is a backdrill-side conductive layer and the second conductive layer is a conductive layer between a signal layer and the backdrill-side conductive layer, controlling the drill bit to continue to perform the drilling motion until the drill bit drills through the printed circuit board to obtain the through hole comprises: after the drill bit drills through the second conductive layer, continuing to control the drill bit to perform the drilling motion until the printed circuit board is drilled through and the through hole is obtained, and
wherein, when the first conductive layer is the conductive layer between the signal layer and the backdrill-side conductive layer and the second conductive layer is the backdrill-side conductive layer, controlling the drill bit to continue to perform the drilling motion until the drill bit drills through the printed circuit board to obtain the through hole comprises: stopping the drilling motion after the drill bit drills through the second conductive layer and the through hole is obtained.

3. The printed circuit board drilling method according to claim 2 , wherein the first Z-coordinate information and the second Z-coordinate information identify coordinate values of the drill bit in a vertical direction.

4. The printed circuit board drilling method according to claim 2 , wherein generating the first electrical signal when the drill bit comes into contact with the first conductive layer of the printed circuit board comprises:
when the drill bit comes into contact with the first conductive layer of the printed circuit board, detecting, by the drill using an internal sensor, that a first loop is formed among the first conductive layer, a control circuit of the drill, and the drill bit; and
generating the first electrical signal.

5. The printed circuit board drilling method according to claim 2 , wherein generating the second electrical signal when the drill bit comes into contact with the second conductive layer of the printed circuit board comprises:
when the drill bit comes into contact with the second conductive layer of the printed circuit board, detecting, by the drill using an internal sensor, that a second loop is formed among the second conductive layer, a control circuit of the drill, and the drill bit; and
generating the second electrical signal.

6. The printed circuit board drilling method according to claim 1 , wherein the first Z-coordinate information and the second Z-coordinate information identify coordinate values of the drill bit in a vertical direction.

7. The printed circuit board drilling method according to claim 1 , wherein generating the first electrical signal when the drill bit comes into contact with the first conductive layer of the printed circuit board comprises:
when the drill bit comes into contact with the first conductive layer of the printed circuit board, detecting, by the drill using an internal sensor, that a first loop is formed among the first conductive layer, a control circuit of the drill, and the drill bit; and
generating the first electrical signal.

8. The printed circuit board drilling method according to claim 1 , wherein generating the second electrical signal when the drill bit comes into contact with the second conductive layer of the printed circuit board comprises:
when the drill bit comes into contact with the second conductive layer of the printed circuit board, detecting, by the drill using an internal sensor, that a second loop is formed among the second conductive layer, a control circuit of the drill, and the drill bit; and
generating the second electrical signal.

9. A printed circuit board drilling apparatus configured to drill a through hole on a printed circuit board, the printed circuit board drilling apparatus comprising:
a drill coupled to a drill bit, the drill comprising a main body that includes a control circuit and a sensor, wherein the control circuit is configured to control the drill bit to perform a drilling motion from an initial location,
wherein the drill is configured to, while drilling the through hole, perform the following:
generate a first electrical signal when coming into contact with a first conductive layer of the printed circuit board, to determine a first conductive location according to the first electrical signal, and to obtain a first Z-coordinate information corresponding to the first conductive location;
control the drill bit to continue performing the drilling motion after the drill bit drills through the first conductive layer, to generate a second electrical signal when the drill bit comes into contact with a second conductive layer of the printed circuit board, to determine a second conductive location according to the second electrical signal, to obtain a second Z-coordinate information corresponding to the second conductive location;
control the drill bit to continue performing the drilling motion until the drill bit drills through the printed circuit board and obtains the through hole; and

wherein the drill is further configured to, after drilling the through hole, perform the following:
control the drill bit to perform backdrilling in a location of the through hole according to a preset depth,

wherein the preset depth is a medium thickness between the second conductive layer and the first conductive layer plus a compensation depth, and
wherein the medium thickness is obtained by calculating an absolute value of a difference between the first Z-coordinate information and the second Z-coordinate information.

10. The printed circuit board drilling apparatus according to claim 9 , wherein, when the first conductive layer is a backdrill-side conductive layer and the second conductive layer is a conductive layer between a signal layer and the backdrill-side conductive layer, the drill is further configured to: after the drill bit drills through the second conductive layer, control the drill bit to continue the drill

Assignees

• Huawei Tech Co Ltd

Inventors

• Yang Yongxing
• Zhang Jian
• Liu Shandang

Classifications

• B23B2270/32

  Use of electronics · CPC title

• B23B41/00

  Boring or drilling machines or devices specially adapted for particular work {(surgical drilling machines A61B17/16)}; Accessories specially adapted therefor · CPC title

• B23B2270/48

  Measuring or detecting · CPC title

• Y10T408/173

  Responsive to work · CPC title

• B23B2228/36

  Multi-layered · CPC title