CN-122002686-A - PCB structure for nondestructively measuring back drilling depth

CN122002686ACN 122002686 ACN122002686 ACN 122002686ACN-122002686-A

Abstract

The invention discloses a PCB structure for nondestructively measuring back drilling depth, relates to a multilayer PCB back drilling technology, and provides a scheme for solving the problem that a test sample must be damaged in the prior art. An electric area is arranged in a process edge of a production board formed by stacking N layers of boards, a surface layer alignment sheet, a plurality of second surface layer electric measurement sheets and a pair of first surface layer electric measurement sheets are respectively arranged on the surface of a first layer board, a first inner layer alignment sheet and a pair of first inner layer electric measurement sheets are arranged on the surface of an nth layer board, the first inner layer electric measurement sheets are in one-to-one correspondence with the first surface layer electric measurement sheets and are communicated with the first inner layer alignment sheets, a second inner layer alignment sheet and a plurality of second inner layer electric measurement sheets are arranged on the surface of an n+1 layer board, and the second inner layer alignment sheets are in one-to-one correspondence with the second surface layer electric measurement sheets and are communicated with the second inner layer alignment sheets. The method has the advantage that whether the back drilling depth meets the depth requirement can be known without irreversible slicing operation on the production plate.

Inventors

CHANG XUANWEI
XU WEILIAN
CHEN SHIJIN
ZENG TIECHENG
ZHOU GUOYUN
XU HUAN

Assignees

博敏电子股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260130

Claims (6)

1. A PCB structure for nondestructively measuring back drilling depth is characterized in that an electric area is arranged in a process edge of a production board formed by stacking N layers of boards; The surface of the first laminate (L1) is provided with a surface layer alignment sheet (13), a plurality of second surface layer electrical measurement sheets (12) and a pair of first surface layer electrical measurement sheets (11) respectively, the plurality of second surface layer electrical measurement sheets (12) are annularly distributed around the surface layer alignment sheet (13), and the pair of first surface layer electrical measurement sheets (11) are arranged at the periphery of the second surface layer electrical measurement sheets (12) respectively; The electrical measurement area is provided with a first inner layer alignment sheet (22) and a pair of first inner layer electrical measurement sheets (21) on the surface of an nth layer plate (Ln), wherein the first inner layer alignment sheet (22) corresponds to the surface layer alignment sheet (13) in the vertical direction, and the first inner layer electrical measurement sheets (21) correspond to the first surface layer electrical measurement sheets (11) one by one in the vertical direction and are conducted in a crossing way through metal through holes; The electric area is provided with a second inner layer alignment sheet (32) and a plurality of second inner layer electric measurement sheets (31) on the surface of the n+1th laminate (Ln+1), wherein the second inner layer alignment sheet (32) corresponds to the surface layer alignment sheet (13) in the vertical direction, and the second inner layer electric measurement sheets (31) correspond to the second surface layer electric measurement sheets (12) one by one in the vertical direction and are conducted in a crossing way through metal through holes; wherein N and N are both positive integers, and N is more than or equal to 4,1< N < N.
2. A PCB structure for non-destructive measurement of back drilling depth according to claim 1, characterized in that the first skin electrical measurement (11) and the second skin electrical measurement (12) are not shaped the same.
3. A PCB structure for non-destructive measurement of back drilling depth according to claim 2, characterized in that the first skin electrical measurement (11) is rectangular or square.
4. A PCB structure for non-destructive measurement of back drilling depth according to claim 3, characterized in that the second skin electrical measurement (12) is circular.
5. A PCB structure for non-destructive measurement of back drilling depth according to claim 4, characterized in that the number of second skin electrical measurement pads (12) is four.
6. A PCB structure for non-destructive measurement of back drilling depth according to claim 5, wherein N = 4 and N = 2.

Description

PCB structure for nondestructively measuring back drilling depth Technical Field The invention relates to a multi-layer PCB back drilling technology, in particular to a PCB structure for nondestructively measuring back drilling depth. Background The printed circuit board backdrill design is normal and is sliced in a destructive manner to measure backdrill depth. The common production mode is that the back drilling depth is confirmed for the first piece of the slice, and the first piece of the slice is produced in batch after no problem exists. The quality of the back drilling cannot be monitored by plates produced in subsequent batch, in order to achieve the back drilling quality which meets the specification as much as possible, the thickness uniformity of production is generally controlled, the plates are piled according to thickness before production, and the plates are sliced and subjected to spot measurement in the production process. However, the detection method has difficult monitoring and high scrapping cost caused by slicing, and the production department is always plagued by how to effectively reduce the cost and gain. Disclosure of Invention The present invention is directed to a PCB structure for nondestructively measuring back drilling depth, which solves the above-mentioned problems of the prior art. According to the PCB structure for nondestructively measuring the back drilling depth, an electric area is arranged in a process edge of a production board formed by stacking N layers of boards; The electrical measurement area is provided with a surface layer alignment sheet, a plurality of second surface layer electrical measurement sheets and a pair of first surface layer electrical measurement sheets on the surface of the first laminate respectively, wherein the second surface layer electrical measurement sheets are annularly distributed around the surface layer alignment sheet, and the pair of first surface layer electrical measurement sheets are arranged on the periphery of the second surface layer electrical measurement sheets respectively; The electrical measurement area is provided with a first inner layer alignment sheet and a pair of first inner layer electrical measurement sheets on the surface of the nth laminate, wherein the first inner layer alignment sheet corresponds to the surface layer alignment sheet in the vertical direction, and the first inner layer electrical measurement sheets correspond to the first surface layer electrical measurement sheets one by one in the vertical direction and are conducted in a crossing way through metal through holes; The electric area is provided with a second inner layer alignment sheet and a plurality of second inner layer electric measurement sheets on the surface of the n+1 layer plate, wherein the second inner layer alignment sheet corresponds to the surface layer alignment sheet in the vertical direction, and the second inner layer electric measurement sheets correspond to the second surface layer electric measurement sheets one by one in the vertical direction and are conducted in a crossing way through metal through holes; wherein N and N are both positive integers, and N is more than or equal to 4,1< N < N. The PCB structure for nondestructively measuring the back drilling depth has the advantage that whether the back drilling depth meets the depth requirement can be known by respectively carrying out back drilling electric measurement on the first surface layer electric measurement piece and the second surface layer electric measurement piece. Irreversible slicing operation is not required to be carried out on the production board, and the back drilling test area is positioned in the non-production area of the production board, so that the PCB unit is not interfered and damaged. Drawings Fig. 1 is a schematic view of the structure of a production plate according to the present invention. Fig. 2 is a schematic structural view of the electric area according to the present invention. Fig. 3 is a graph of the explosive effect of the electrical zone described in the present invention. FIG. 4 is a schematic diagram showing the electrical connection of each electrical measurement chip in the electrical area according to the present invention. Fig. 5 is a schematic view of the state when the electrical measurement area is back drilled. Reference numerals: an A-process zone, a B-process side and a C-electric zone; L1-first layer plate, ln-N layer plate, ln+1-n+1 layer plate, LN-N layer plate; 11-a first surface layer electrical measurement piece, 12-a second surface layer electrical measurement piece and 13-a surface layer alignment piece; 21-a first inner layer electrical measurement piece and 22-a first inner layer alignment piece; 31-second inner layer electrical measurement pieces and 32-second inner layer alignment pieces; 90-bit. Detailed Description As shown in fig. 1 to 4, one PCB structure for non-destructive measurement of back drillin