阅读说明：本技术 一种背钻深度测量基板及背钻深度测量方法 (Back drilling depth measuring substrate and back drilling depth measuring method ) 是由 宋明哲 于 2021-10-14 设计创作，主要内容包括：本发明公开了一种背钻深度测量基板,当检测到背钻过孔与一测量过孔之间的电阻为无穷大时,表明当前背钻参数所对应的背钻深度已经达到了该测量过孔所对应的金属层；而当检测到电阻与一测量过孔之间电连接时,表明当前背钻参数所对应的背钻深度未达到了该测量过孔所对应的金属层。因此测量电阻与各个测量过孔之间是否连通,可以确定当前背钻参数所对应的背钻深度是否达到预设深度。并且上述结构非常简单,可以集成在设置有功能线路的基板中,避免再另行设置测量板,同时使上述结构与功能线路共用一块基板,可以避免不同板材各个板层之间的差异,使得测量结果更加准确。本发明还提供了一种背钻深度测量方法,同样具有上述有益效果。(The invention discloses a back drilling depth measuring substrate, which indicates that the back drilling depth corresponding to the current back drilling parameter reaches a metal layer corresponding to a measured via hole when the resistance between the back drilling via hole and the measured via hole is detected to be infinite; and when the electrical connection between the resistor and a measured via hole is detected, the back drilling depth corresponding to the current back drilling parameter does not reach the metal layer corresponding to the measured via hole. Therefore, whether the measuring resistor is communicated with each measuring through hole or not can be determined, and whether the back drilling depth corresponding to the current back drilling parameter reaches the preset depth or not can be determined. The structure is very simple, can be integrated in a substrate provided with a functional circuit, avoids additionally arranging a measuring plate, simultaneously enables the structure and the functional circuit to share one substrate, can avoid the difference between the plate layers of different plates, and enables the measuring result to be more accurate. The invention also provides a back drilling depth measuring method, which also has the beneficial effects.)

1. The back drilling depth measurement substrate is characterized by comprising a substrate provided with a functional circuit and at least three through holes arranged on the substrate, wherein the through holes comprise a back drilling through hole and at least two measurement through holes, and the back drilling through hole is a through hole subjected to back drilling from the back side of the substrate;

the metal wire layer on the side, farthest away from the back of the substrate, of the plate layer in the preset back drilling depth in the substrate, and the metal wire layer on the side, closest to the back of the substrate, of the plate layer in the substrate, which is not in the preset back drilling depth, are provided with connecting wires; the connecting wires are in one-to-one correspondence with the measuring via holes, and the connecting wires are electrically connected with the back drilling via holes and the corresponding measuring via holes.

2. The backdrill depth measurement substrate of claim 1, wherein the number of measurement vias is equal to the number of metal line layers within the substrate.

3. The substrate according to claim 2, wherein the measuring vias correspond to the metal wire layers one to one, and each of the metal wire layers has a connecting wire disposed therein, and the connecting wires electrically connect the back-drilled vias and the corresponding measuring vias.

4. The substrate of claim 3, wherein the measurement vias are distributed in a ring shape, and the backdrilled vias are located inside the measurement vias that are distributed in a ring shape.

5. The backdrilled depth measurement substrate of claim 1, wherein the backdrilled via is electrically connected to a resistor.

6. The backdrill depth measurement substrate of claim 5, wherein the resistor is connected to the backdrill via on a side of the front surface of the substrate.

7. The backdrilling depth measurement substrate of claim 6, wherein the resistance value of the resistor is not less than 50 Ω.

8. The backdrilling depth measurement substrate of claim 6, further comprising measurement points, wherein the measurement points correspond to the vias one to one; the resistor is electrically connected with the measuring point corresponding to the back drilling through hole, and the measuring through hole is electrically connected with the corresponding measuring point.

9. A method of backdrilling depth measurement, comprising:

back drilling the back drilled through hole from the back side of the substrate according to preset back drilling parameters; the substrate is provided with a functional circuit and at least three via holes, wherein the via holes comprise a back-drilled via hole and at least two measuring via holes; the metal wire layer on the side, farthest away from the back of the substrate, of the plate layer in the preset back drilling depth in the substrate, and the metal wire layer on the side, closest to the back of the substrate, of the plate layer in the substrate, which is not in the preset back drilling depth, are provided with connecting wires; the connecting lines are in one-to-one correspondence with the measuring through holes, and the connecting lines are electrically connected with the back drilled through holes and the corresponding measuring through holes;

after back drilling is carried out, measuring the on-off relation between the back drilling through holes and each measured through hole, and determining whether the back drilling depth corresponding to the back drilling parameters reaches the preset back drilling depth.

10. The method of claim 9, wherein backdrilling the backdrilled via from the back side of the substrate according to the predetermined backdrilling parameters comprises:

back drilling the back drilled through holes from the back surface of the substrate according to the sequence from shallow to deep and preset back drilling parameters; the number of the measuring through holes is equal to that of the metal wire layers in the substrate, the measuring through holes correspond to the metal wire layers one by one, connecting wires are arranged in the metal wire layers, and the connecting wires are electrically connected with the back drilling through holes and the corresponding measuring through holes;

after back drilling, measuring the on-off relationship between the back drilling via hole and each measured via hole, and determining whether the back drilling depth corresponding to the back drilling parameter reaches a preset back drilling depth comprises:

after each back drilling, measuring the on-off relation between the back drilling through hole and each measured through hole, and determining the back drilling depth corresponding to the back drilling parameters.

Technical Field

The invention relates to the technical field of back drilling, in particular to a back drilling depth measuring substrate and a back drilling depth measuring method.

Background

With the continuous promotion of the information-based industry, the transmission speed of digital signals is faster and faster, and the frequency is higher and higher, so that the traditional design of a PCB (printed circuit board) cannot meet the requirement of the high-frequency circuit. The research on the integrity transmission of signals becomes an increasingly important core technology. When the frequency of a circuit signal is increased to a certain height, redundant copper plating of a useless hole copper part in a through hole PTH (plated through hole) in the PCB is equivalent to that of an antenna, signal radiation is generated to cause interference on other surrounding signals, the normal work of a circuit system is affected when the interference is serious, and the back drilling technology is used for drilling away the redundant copper plating in a back drilling mode, so that the EMI (electromagnetic interference) problem is eliminated. The cost is reduced, and the high-frequency and high-speed performance is met. In other words, the back drilling is to drill away the PCB through hole section that does not have any connection or transmission function, so as to avoid reflection, scattering, delay and the like of high-speed signal transmission, and the study of "distortion" brought to the signal shows that: the main factors influencing the signal integrity of the signal system include design, PCB material, transmission lines, connectors, chip packaging and the like, and the through holes have great influence on the signal integrity.

However, in the prior art, the back drilling depth is not easy to control, and in an actual situation, due to the fact that the multilayer board has thickness tolerance, drill parameters and other factors, the back drilling process generally has an error of 2-14 mil. If the tolerance is too long to remain above the upper limit, the signal will be affected to some extent. Therefore, how to measure the back drilling depth quickly and accurately is an urgent problem to be solved by the technical personnel in the field.

Disclosure of Invention

The invention aims to provide a back drilling depth measuring substrate which can quickly and accurately measure the back drilling depth; another object of the present invention is to provide a method for measuring back drilling depth, which can quickly and accurately measure the back drilling depth.

In order to solve the technical problem, the invention provides a back-drilled depth measuring substrate, which comprises a substrate provided with a functional circuit and at least three through holes arranged on the substrate, wherein the through holes comprise a back-drilled through hole and at least two measuring through holes, and the back-drilled through hole is a through hole subjected to back drilling from the back surface of the substrate;

the metal wire layer on the side, farthest away from the back of the substrate, of the plate layer in the preset back drilling depth in the substrate, and the metal wire layer on the side, closest to the back of the substrate, of the plate layer in the substrate, which is not in the preset back drilling depth, are provided with connecting wires; the connecting wires are in one-to-one correspondence with the measuring via holes, and the connecting wires are electrically connected with the back drilling via holes and the corresponding measuring via holes.

Optionally, the number of the measurement vias is equal to the number of the metal line layers in the substrate.

Optionally, the measuring via holes correspond to the metal wire layers one by one, connecting wires are arranged in the metal wire layers, and the connecting wires are electrically connected with the back drilling via holes and the corresponding measuring via holes.

Optionally, the measurement via hole is annularly distributed, and the back-drilled via hole is located to be annularly distributed the measurement via hole is inboard.

Optionally, the back-drilled via is electrically connected to a resistor.

Optionally, the resistor and the back-drilled via hole are located on one side of the front surface of the substrate and connected.

Optionally, the resistance of the resistor is not less than 50 Ω.

Optionally, the device further comprises measuring points, wherein the measuring points correspond to the via holes one to one; the resistor is electrically connected with the measuring point corresponding to the back drilling through hole, and the measuring through hole is electrically connected with the corresponding measuring point.

The invention also provides a back drilling depth measuring method, which comprises the following steps:

back drilling the back drilled through hole from the back side of the substrate according to preset back drilling parameters; the substrate is provided with a functional circuit and at least three via holes, wherein the via holes comprise a back-drilled via hole and at least two measuring via holes; the metal wire layer on the side, farthest away from the back of the substrate, of the plate layer in the preset back drilling depth in the substrate, and the metal wire layer on the side, closest to the back of the substrate, of the plate layer in the substrate, which is not in the preset back drilling depth, are provided with connecting wires; the connecting lines are in one-to-one correspondence with the measuring through holes, and the connecting lines are electrically connected with the back drilled through holes and the corresponding measuring through holes;

after back drilling is carried out, measuring the on-off relation between the back drilling through holes and each measured through hole, and determining whether the back drilling depth corresponding to the back drilling parameters reaches the preset back drilling depth.

Optionally, the back drilling the back drilled via from the back side of the substrate according to the preset back drilling parameters includes:

back drilling the back drilled through holes from the back surface of the substrate according to the sequence from shallow to deep and preset back drilling parameters; the number of the measuring through holes is equal to that of the metal wire layers in the substrate, the measuring through holes correspond to the metal wire layers one by one, connecting wires are arranged in the metal wire layers, and the connecting wires are electrically connected with the back drilling through holes and the corresponding measuring through holes;

after back drilling, measuring the on-off relationship between the back drilling via hole and each measured via hole, and determining whether the back drilling depth corresponding to the back drilling parameter reaches a preset back drilling depth comprises:

after each back drilling, measuring the on-off relation between the back drilling through hole and each measured through hole, and determining the back drilling depth corresponding to the back drilling parameters.

The invention provides a back-drilled depth measuring substrate which comprises a substrate provided with a functional circuit and at least three through holes arranged on the substrate, wherein the through holes comprise a back-drilled through hole and at least two measuring through holes; the metal wire layer on the side farthest from the back of the substrate in the plate layer in the preset back drilling depth in the substrate and the metal wire layer on the side closest to the back of the substrate in the plate layer not in the preset back drilling depth in the substrate are both provided with connecting wires; the connecting wires are in one-to-one correspondence with the measuring through holes, and the connecting wires are electrically connected with the back drilling through holes and the corresponding measuring through holes.

In a specific measurement process, when the resistance between the back drilling through hole and a measured through hole is detected to be infinite, the back drilling depth corresponding to the current back drilling parameter is shown to reach the metal layer corresponding to the measured through hole; and when the electrical connection between the resistor and a measured via hole is detected, the back drilling depth corresponding to the current back drilling parameter does not reach the metal layer corresponding to the measured via hole. Therefore, whether the measuring resistor is communicated with each measuring through hole or not can be determined, and whether the back drilling depth corresponding to the current back drilling parameter reaches the preset depth or not can be determined. The structure is very simple, can be integrated in a substrate provided with a functional circuit, avoids additionally arranging a measuring plate, simultaneously enables the structure and the functional circuit to share one substrate, can avoid the difference between the plate layers of different plates, and enables the measuring result to be more accurate.

The invention also provides a back drilling depth measuring method, which has the beneficial effects and is not repeated herein.

Drawings

In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a back-drilling depth measurement substrate according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a specific back-drilling depth measurement substrate according to an embodiment of the present invention;

FIG. 3 is a schematic top view of the structure of FIG. 2;

fig. 4 is a flowchart of a back drilling depth measuring method according to an embodiment of the present invention.

In the figure: 1. the device comprises a substrate, 2. back drilling through holes, 3. measuring through holes, 4. connecting wires and 5. resistors.

Detailed Description

The core of the invention is to provide a back drilling depth measurement substrate. In the prior art, the back drilling depth is not easy to control, and in an actual situation, due to the fact that the multilayer board has thickness tolerance, drill parameters and other factors, the back drilling process generally has an error of 2-14 mil. If the tolerance is too long to remain above the upper limit, the signal will be affected to some extent.

The back-drilled depth measuring substrate comprises a substrate provided with a functional circuit and at least three through holes arranged on the substrate, wherein the through holes comprise a back-drilled through hole and at least two measuring through holes, and the back-drilled through hole is a through hole subjected to back drilling from the back side of the substrate; the metal wire layer on the side farthest from the back of the substrate in the plate layer in the preset back drilling depth in the substrate and the metal wire layer on the side closest to the back of the substrate in the plate layer not in the preset back drilling depth in the substrate are both provided with connecting wires; the connecting wires are in one-to-one correspondence with the measuring through holes, and the connecting wires are electrically connected with the back drilling through holes and the corresponding measuring through holes.

In a specific measurement process, when the resistance between the back drilling through hole and a measured through hole is detected to be infinite, the back drilling depth corresponding to the current back drilling parameter is shown to reach the metal layer corresponding to the measured through hole; and when the electrical connection between the resistor and a measured via hole is detected, the back drilling depth corresponding to the current back drilling parameter does not reach the metal layer corresponding to the measured via hole. Therefore, whether the measuring resistor is communicated with each measuring through hole or not can be determined, and whether the back drilling depth corresponding to the current back drilling parameter reaches the preset depth or not can be determined. The structure is very simple, can be integrated in a substrate provided with a functional circuit, avoids additionally arranging a measuring plate, simultaneously enables the structure and the functional circuit to share one substrate, can avoid the difference between the plate layers of different plates, and enables the measuring result to be more accurate.

In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a back drilling depth measurement substrate according to an embodiment of the present invention.

Referring to fig. 1, in the embodiment of the present invention, the back-drilled depth measurement substrate includes a substrate 1 provided with a functional circuit and at least three via holes provided in the substrate 1, where the via holes include a back-drilled via hole 2 and at least two measurement via holes 3, and the back-drilled via hole 2 is a via hole back-drilled from the back surface of the substrate 1; the metal wire layer on the side farthest from the back of the substrate 1 in the plate layer within the preset back drilling depth in the substrate 1 and the metal wire layer on the side closest to the back of the substrate 1 in the plate layer not within the preset back drilling depth in the substrate 1 are both provided with connecting wires 4; the connecting wires 4 correspond to the measuring via holes 3 one by one, and the connecting wires 4 are electrically connected with the back drilling via holes 2 and the corresponding measuring via holes 3.

The substrate 1 is a PCB substrate 1, and the substrate 1 is generally formed by laminating a plurality of board layers. The composite plate layer is generally formed by alternately stacking a metal layer and a glass fiber layer. For the specific structure of the PCB substrate 1, reference may be made to the prior art, and details thereof are not repeated herein. The substrate 1 is provided with a functional circuit, which is a circuit capable of playing a preset function, that is, in the embodiment of the present invention, the PCB substrate 1 is not a separate substrate 1 without any electronic component, but is provided with an electronic component to constitute a functional circuit, which can also play a preset function, that is, in the embodiment of the present invention, the via hole for measuring the back drilling depth subsequently is integrated with the functional circuit actually needing back drilling on the same PCB substrate 1, so that the via hole for measuring the back drilling depth subsequently can accurately measure the specific depth of back drilling performed when back drilling is performed on the functional circuit. The specific structure of the related functional circuit may be set according to the actual situation, and is not limited specifically herein.

The substrate 1 is provided with at least three via holes for measuring the back drilling depth, and the via holes comprise a back drilling via hole 2 and at least two measuring via holes 3. The via holes only comprise a back-drilled via hole 2, and the rest of the via holes are measuring via holes 3. Specifically, the back-drilled via hole 2 is a via hole back-drilled from the back surface of the substrate 1, that is, in an actual manufacturing process, a manufacturer back-drills the back-drilled via hole 2 according to back-drilling parameters used for back-drilling the functional circuit, so that a conductive structure with a preset depth at the back surface of the back-drilled via hole 2 is drilled.

In the back drilling process, the back drilling through hole 2 is drilled from the back side of the substrate 1 so as to remove the partial plating layer in the through hole, namely, only the plating layer corresponding to a partial plate layer is removed from the back side of the substrate 1 in the back drilling process, and meanwhile, the plating layer corresponding to a partial plate layer is remained. Specifically, the plate layer in the back drilling depth corresponding to the back drilling is the plate layer which needs to be removed with the plating, and the plate layer corresponding to the back drilling depth exceeding the back drilling depth is the plate layer which needs to retain the plating in the through hole. In the embodiment of the present invention, the metal line layer farthest from the back surface of the substrate 1 in the board layer within the preset back drilling depth in the substrate 1, and the metal line layer closest to the back surface of the substrate 1 in the board layer not within the preset back drilling depth in the substrate 1 are both provided with the connecting line 4, that is, each metal line layer is provided with the connecting line 4, and the connecting lines 4 correspond to the measuring vias 3 one by one, and the connecting lines 4 are electrically connected to the back drilling vias 2 and the corresponding measuring vias 3.

At the moment, when the actual back drilling depth accurately reaches the preset back drilling depth, the plating layer which is electrically connected with the metal wire layer at the side farthest from the back side of the substrate 1 in the back drilling through hole 2 and the plate layer in the preset back drilling depth in the substrate 1 is just removed, so that the back drilling through hole 2 is disconnected with the measuring through hole 3 corresponding to the connecting wire 4 in the metal wire layer; and meanwhile, a plating layer which is electrically connected with the metal wire layer closest to the back side of the substrate 1 in the board layer which is not at the preset back drilling depth in the back drilling through hole 2 is just reserved, so that the back drilling through hole 2 is electrically connected with the measuring through hole 3 corresponding to the connecting wire 4 in the metal wire layer. Therefore, whether the actual back drilling depth reaches the preset back drilling depth or not can be measured by measuring whether the back drilling through hole 2 and the metal through hole are electrically communicated or not. When the actual back drilling depth is exactly equal to the preset back drilling depth, the resistance value between one measured via hole 3 and the back drilling via hole 2 is infinite, and a certain resistance value is provided between the other measured via hole 3 and the back drilling via hole 2; when the actual back drilling depth is smaller than the preset back drilling depth, a certain resistance value is formed between the two measurement via holes 3 and the back drilling via hole 2; when the actual back drilling depth is greater than the preset back drilling depth, the resistance values between the two measurement via holes 3 and the back drilling via hole 2 are infinite.

It should be noted that the metal line layer is isolated from the non-corresponding measurement via 3, that is, the connection line 4 in the metal line layer only connects the back-drilled via 2 and the corresponding measurement via 3, and the non-corresponding measurement via is not electrically connected.

The back-drilled depth measuring substrate provided by the embodiment of the invention comprises a substrate 1 provided with a functional circuit and at least three through holes arranged on the substrate 1, wherein the through holes comprise a back-drilled through hole 2 and at least two measuring through holes 3, and the back-drilled through hole 2 is a through hole subjected to back drilling from the back surface of the substrate 1; the metal wire layer on the side farthest from the back of the substrate 1 in the plate layer in the preset back drilling depth in the substrate 1 and the metal wire layer on the side closest to the back of the substrate 1 in the plate layer not in the preset back drilling depth in the substrate 1 are both provided with connecting wires 4; the connecting wires 4 correspond to the measuring via holes 3 one by one, and the connecting wires 4 are electrically connected with the back drilling via holes 2 and the corresponding measuring via holes 3.

In the specific measurement process, when the resistance between the back drilling via hole 2 and a measured via hole 3 is detected to be infinite, the back drilling depth corresponding to the current back drilling parameter is indicated to reach the metal layer corresponding to the measured via hole 3; and when the electrical connection between the back-drilled via 2 and a measured via 3 is detected, it indicates that the back-drilled depth corresponding to the current back-drilled parameter does not reach the metal layer corresponding to the measured via 3. Therefore, whether the measurement back drilling through holes 2 are communicated with the measurement through holes 3 or not can be determined, and whether the back drilling depth corresponding to the current back drilling parameters reaches the preset depth or not can be determined. The structure is very simple, and can be integrated in the substrate 1 provided with the functional circuit, so that a measuring plate is not required to be additionally arranged, and meanwhile, the structure and the functional circuit share one substrate 1, so that the difference between the plate layers of different plates can be avoided, and the measuring result is more accurate.

The details of the back-drilling depth measurement substrate provided by the present invention will be described in detail in the following embodiments of the invention.

Referring to fig. 2 and fig. 3, fig. 2 is a schematic structural diagram of a specific back-drilling depth measurement substrate according to an embodiment of the present invention; fig. 3 is a schematic top view of fig. 2.

Different from the above embodiments of the invention, the embodiments of the invention further limit the back drilling depth measurement substrate on the basis of the above embodiments of the invention, and the rest of the contents are described in detail in the above embodiments of the invention and are not described again here.

Referring to fig. 2 and fig. 3, in the embodiment of the present invention, the number of the measurement vias 3 in the back drilling depth measurement substrate is equal to the number of the metal line layers in the substrate 1. That is, more measurement vias 3 may be provided in the embodiment of the present invention to increase the measurement accuracy. Specifically, measure via hole 3 with the metal cord layer one-to-one, all be provided with connecting wire 4 in the metal cord layer, connecting wire 4 electricity is connected back-drilled hole 2 with correspond measure via hole 3.

That is, in the embodiment of the present invention, each metal line layer in the substrate 1 corresponds to one measurement via 3, and the metal line layer is provided with a connection line 4 to connect the corresponding measurement via 3 with the back-drilled via 2. And then make after the back drilling, through measuring each and measuring the via hole 3 and drilling the via hole 2 and switching on, can measure the present actual back drilling depth and reach that layer of metal wire layer specifically accurately, thus can measure the concrete data of the present actual back drilling depth, also can measure the actual back drilling depth that the present back drilling parameter corresponds.

Specifically, in the embodiment of the present invention, the measurement vias 3 are distributed in a ring shape, and the back-drilled vias 2 are located inside the measurement vias 3 distributed in a ring shape. In order to simplify the arrangement of the connecting lines 4 in the back-drilling depth measuring structure, the measuring via holes 3 are distributed in a substantially circular ring shape, and then the back-drilling via holes 2 are arranged inside the measuring via holes 3 distributed in a circular ring shape, at this time, each connecting line 4 only needs to be connected with the corresponding measuring via hole 3 and the back-drilling via hole 2 in a straight line, so as to simplify the arrangement of the connecting lines 4 in the back-drilling depth measuring structure. Typically, the back-drilled via 2 is located at the center of the measurement via 3 distributed in a ring shape.

Specifically, in the embodiment of the present invention, the back-drilled via 2 is electrically connected to a resistor 5. Normally, the resistor 5 is connected to the back-drilled via 2 on the front side of the substrate 1. In practical situations, the embodiment of the invention specifically determines the on-off relationship between the back-drilled via 2 and the measured via 3 by measuring the resistance values between the back-drilled via 2 and each measured via 3. Since the resistances of the measurement via hole 3 and the back-drilled via hole 2 are too small to be measured, the resistance 5 is specifically arranged in the embodiment of the invention to ensure that the resistance can be measured when the back-drilled via hole 2 and the measurement via hole 3 are electrically connected, so as to detect the on-off relationship between the back-drilled via hole 2 and the measurement via hole 3. Of course, the measured resistance value will be slightly larger than the actual resistance value of the resistor 5.

In addition to the above-mentioned position for setting the resistor 5, it is also possible that each of the above-mentioned measurement vias 3 may be provided with a corresponding resistor 5, and the back-drilled via 2 is electrically connected to the resistor 5 through the measurement via 3. It is sufficient to ensure that the measured path of the measurement via 3 and the back-drilled via 2, which are electrically connected, has the resistance 5 to ensure the measurement, and is not particularly limited herein. Normally, the resistance value of the resistor 5 is not less than 50 Ω to ensure that the resistance value can be measured.

Specifically, in the embodiment of the present invention, the present invention further includes measurement points, where the measurement points correspond to the via holes one to one; the resistor 5 is electrically connected with the measuring point corresponding to the back drilling through hole 2, and the measuring through hole 3 is electrically connected with the corresponding measuring point. The measuring points are usually pads, that is, in the embodiment of the present invention, for convenience of measurement, corresponding pads, that is, measuring points, are specifically set, so as to conveniently measure a specific resistance value between the back-drilled via 2 and the measured via 3 through the measuring points, and thus, an actual back-drilled depth corresponding to a current back-drilled parameter can be quickly identified.

The back drilling depth measuring substrate provided by the embodiment of the invention can measure the actual numerical value of the current back drilling depth, so that the actual back drilling depth corresponding to the current back drilling parameter can be determined.

In the following, a method for measuring a back drilling depth provided by the present invention is described, and the method for measuring a back drilling depth described below and the substrate for measuring a back drilling depth described above can be referred to with each other.

Referring to fig. 4, fig. 4 is a flowchart illustrating a method for measuring a back drilling depth according to an embodiment of the present invention.

Referring to fig. 4, in an embodiment of the present invention, a back drilling depth measurement method includes:

s101: and back drilling the back drilled through hole from the back surface of the substrate according to preset back drilling parameters.

In the embodiment of the invention, the substrate 1 is provided with a functional circuit and at least three via holes, wherein the via holes comprise a back-drilled via hole 2 and at least two measurement via holes 3; the metal wire layer on the side farthest from the back of the substrate 1 in the plate layer within the preset back drilling depth in the substrate 1 and the metal wire layer on the side closest to the back of the substrate 1 in the plate layer not within the preset back drilling depth in the substrate 1 are both provided with connecting wires 4; the connecting wires 4 correspond to the measuring via holes 3 one by one, and the connecting wires 4 are electrically connected with the back drilling via holes 2 and the corresponding measuring via holes 3. The detailed structure of the substrate for measuring the back drilling depth is described in detail in the above embodiments of the present invention, and will not be described herein again.

In this step, or the back-drilled hole 2 is drilled from the back surface of the plate, and a part of the plating layer in the back-drilled hole 2 is removed from the back surface of the substrate 1. At this time, the back drilling depth corresponding to the back drilling via hole 2 is the actual back drilling depth. For the specific operation process of back drilling, reference may be made to the prior art, and details thereof are not repeated herein.

Specifically, the step may specifically be that the back drilling of the back drilling holes 2 is performed from the back side of the substrate 1 sequentially according to a preset back drilling parameter in a sequence from shallow to deep; the quantity of measuring via hole 3 with the quantity of metal line layer equals in 1 base plate, measure via hole 3 with the metal line layer one-to-one, all be provided with connecting wire 4 in the metal line layer, connecting wire 4 electricity is connected back-drilled hole 2 with correspond measure via hole 3. The detailed structure of the substrate 1 for measuring back drilling depth is described in detail in the above embodiments of the invention, and will not be described herein again.

Specifically, in this step, the back-drilled holes 2 may be back-drilled for a plurality of times, and specifically, the back-drilled holes 2 may be back-drilled from the back surface of the substrate 1 with preset back-drilling parameters in sequence from shallow to deep, so as to change the actual back-drilling depth corresponding to each back-drilling parameter for subsequent measurement.

S102: and after back drilling is carried out, measuring the on-off relation between the back drilling through holes and each measured through hole, and determining whether the back drilling depth corresponding to the back drilling parameters reaches the preset back drilling depth.

In this step, after the back drilling of the second back drilling via 2 is performed in S101, the on-off relationship between the back drilling via 2 and each measured via 3 may be specifically measured, and whether the back drilling depth corresponding to the back drilling parameter reaches the preset back drilling depth may be specifically determined according to the on-off relationship. The detailed measurement principle is described in detail in the above embodiments of the present invention, and will not be described herein again.

Specifically, when backdrilling the backdrilled hole 2 for multiple times in S101, the step may specifically be: after each back drilling, measuring the on-off relationship between the back drilling through hole 2 and each measured through hole 3, and determining the back drilling depth corresponding to the back drilling parameters. Namely, after back drilling is carried out on the back drilling through hole 2 every time, the specific on-off relation between the back drilling through hole 2 and each measured through hole 3 is measured, so that the metal wire layer to which each back drilling parameter is specifically and correspondingly drilled is determined, and the specific actual back drilling depth corresponding to each back drilling parameter can be determined.

In the back drilling depth measuring method provided by the embodiment of the invention, in the specific measuring process, when the resistance between the back drilling via hole 2 and a measured via hole 3 is detected to be infinite, it is indicated that the back drilling depth corresponding to the current back drilling parameter has reached the metal layer corresponding to the measured via hole 3; and when the electrical connection between the back-drilled via 2 and a measured via 3 is detected, it indicates that the back-drilled depth corresponding to the current back-drilled parameter does not reach the metal layer corresponding to the measured via 3. Therefore, whether the measurement back drilling through holes 2 are communicated with the measurement through holes 3 or not can be determined, and whether the back drilling depth corresponding to the current back drilling parameters reaches the preset depth or not can be determined. The structure is very simple, and can be integrated in the substrate 1 provided with the functional circuit, so that a measuring plate is not required to be additionally arranged, and meanwhile, the structure and the functional circuit share one substrate 1, so that the difference between the plate layers of different plates can be avoided, and the measuring result is more accurate.

The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The back drilling depth measuring substrate and the back drilling depth measuring method provided by the invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.