CN116261280A

CN116261280A - High-precision back drilling method and circuit board

Info

Publication number: CN116261280A
Application number: CN202310155092.XA
Authority: CN
Inventors: 李秋梅; 王俊; 蓝春华; 张霞
Original assignee: Kinwong Electronic Technology Longchuan Co Ltd
Current assignee: Kinwong Electronic Technology Longchuan Co Ltd
Priority date: 2023-02-22
Filing date: 2023-02-22
Publication date: 2023-06-13

Abstract

The application relates to the technical field of printed circuit boards, and discloses a drilling method of a high-precision back drill and a circuit board, wherein the drilling method of the high-precision back drill comprises the following steps: providing a substrate, wherein the substrate comprises a target metal layer, a first metal layer and a second metal layer, a test hole is further formed in the substrate, one surface of the target metal layer, facing the first metal layer, is a target surface, and one surface of the first metal layer, facing away from the target metal layer, is a reference surface; acquiring a distance M between a target surface and a reference surface in a test hole; drilling a first hole in the substrate; etching to remove the target metal layer in the first hole; drilling a second hole with the aperture of d2 on the substrate; carrying out copper deposition electroplating on the substrate; a third hole with a diameter d4 is drilled in the substrate. The application provides a drilling method and a circuit board of a high-precision back drill, which can better control the back drill precision and avoid influencing signal transmission due to overlong back drill residual piles.

Description

High-precision back drilling method and circuit board

Technical Field

The application relates to the technical field of printed circuit boards, in particular to a drilling method of a high-precision back drill and a circuit board.

Background

The metallized holes of the circuit board serve to connect the transmission of the electrical signals of the layers, but at the same time connect unnecessary signal transmission. With the continuous development of circuit board technology, when the requirements of high-frequency and high-speed signal transmission are involved, the integrity of information transmission of a connecting layer is affected by the existence of a non-connecting interlayer metallized hole, and therefore, the metal layer in the non-connecting interlayer metallized hole needs to be removed.

The traditional removing method is to remove the metal layer in the metalized hole of the non-connecting layer by a back drilling mode, and high-precision back drilling cannot be achieved because the precision of the back drilling depth is influenced by the precision of equipment and the thickness precision of the laminated plate. The control of the back drilling precision mainly has the influence that the back drilling is too deep or too shallow, the back drilling is too deep, the metal layer in the metallized hole between the effective connection layers can be removed, the circuit connection is invalid, the back drilling is too shallow, the metal layer (back drilling stub) in the metallized hole between the residual non-connection layers can be too long, the integrity of signal transmission is influenced, and the normal operation of a circuit system is influenced in severe cases.

Disclosure of Invention

The application provides a drilling method and a circuit board of a high-precision back drill, which can better control the back drill precision and avoid influencing signal transmission due to overlong back drill residual piles.

In a first aspect, an embodiment of the present application provides a drilling method of a high-precision back drill, including:

providing a substrate, wherein the substrate comprises a target metal layer, a first metal layer and a second metal layer which are respectively overlapped on two opposite sides of the target metal layer, a test hole penetrating through the first metal layer, the target metal layer and the second metal layer is also formed in the substrate, one surface of the target metal layer, which faces the first metal layer, is a target surface, and one surface of the first metal layer, which faces away from the target metal layer, is a reference surface;

acquiring a distance M between the target surface and the reference surface in the test hole;

drilling a first hole on the substrate from one side of the first metal layer far away from the target metal layer, wherein the aperture of the first hole is d1, and the depth of the first hole is equal to the distance M;

etching to remove the target metal layer in the first hole;

drilling a second hole with the aperture d2 on the substrate from one side of the second metal layer far away from the target metal layer, wherein the second hole is coaxially arranged with the first hole and penetrates through the bottom surface of the first hole;

carrying out copper deposition electroplating on the substrate to enable the hole wall of the first hole, the hole bottom surface and the hole wall of the second hole to form a conductive metal layer, wherein the conductive metal layer positioned on the hole wall of the first hole forms a hole ring with an inner hole diameter d 3;

drilling a third hole with the aperture of d4 on the substrate from one side, far away from the target metal layer, of the second metal layer, wherein the third hole is coaxially arranged with the first hole and penetrates through the conductive metal layer positioned at the bottom surface of the first hole, and d4 satisfies: d1> d3> d4> d2.

In some of these embodiments, the distance between the first well and the test well is 3mm-5mm.

In some embodiments, before a first hole is drilled in the substrate from a side of the first metal layer away from the target metal layer, a plurality of sets of drilling data are preset in drilling equipment, and drilling depths corresponding to the sets of drilling data are different; drilling a first hole in the substrate from a side of the first metal layer remote from the target metal layer includes: selecting the drilling data with the drilling depth closest to the distance M for the drilling equipment; the first hole is drilled in the substrate from a side of the first metal layer remote from the target metal layer using the drilling apparatus.

In some embodiments, the substrate further comprises a plurality of intermediate metal layers, a part of the intermediate metal layers are located between the first metal layer and the target metal layer, the rest of the intermediate metal layers are located between the target metal layer and the second metal layer, a position avoidance hole is formed in the intermediate metal layers, and the projection of the test hole on the reference plane is located inside the projection of the position avoidance hole on the reference plane.

In some embodiments, the acquiring the distance M between the target surface and the reference surface in the test hole includes:

providing a measuring device provided with a measuring probe;

contacting the measurement probe with the datum surface;

and extending the measuring probe into the test hole and contacting with the target surface to obtain the distance M.

In some embodiments, after the measurement probe extends into the test hole and contacts with the target surface to obtain the distance M, the measurement probe extends into the test hole and contacts with a surface of the second metal layer away from the target metal layer to obtain the board thickness of the substrate.

In some embodiments, a first dielectric layer is disposed between the first metal layer and the target metal layer, and a second dielectric layer is disposed between the second metal layer and the target metal layer.

In some embodiments, the method of drilling a high precision back drill further comprises, prior to providing a substrate;

sequentially stacking and pressing the second metal layer, the second dielectric layer, the target metal layer, the first dielectric layer and the first metal layer together to form a pressing plate;

and drilling the test hole in the laminated plate to obtain the substrate.

In some embodiments, after a first hole is drilled in the substrate from a side of the first metal layer away from the target metal layer and before etching to remove the target metal layer in the first hole, the reference surface and a side of the second metal layer away from the target metal layer are covered with a dry film, and the dry film is provided with an open window exposing the first hole.

In a second aspect, an embodiment of the present application provides a circuit board, which is manufactured by the drilling method of the high-precision back drill according to the first aspect.

The drilling method of the high-precision back drill provided by the embodiment of the application has the beneficial effects that: the distance M between the target surface and the reference surface in the test hole is firstly obtained, then the first hole with the depth of d1 is drilled on the substrate from one side of the first metal layer far away from the target metal layer, and the target metal layer in the first hole is etched and removed, so that the depth of the first hole can be accurately controlled, the problem of burrs and copper scraps generated during subsequent drilling of the second hole can be avoided, meanwhile, after the second hole with the aperture of d2 is drilled on the substrate from one side of the second metal layer far away from the target metal layer, copper deposition electroplating is carried out on the substrate, so that a conductive metal layer is formed on the hole wall, the hole bottom surface and the hole wall of the second hole, a hole ring with the inner aperture of d3 is formed on the metal layer positioned on the hole wall of the first hole, and finally, a third hole with the aperture of d4 is drilled on the substrate from one side of the second metal layer far away from the target metal layer, d1> d3> d4> d2, after the third hole is drilled, the second hole is completely removed, and the signal transmission pile can be completely removed, and the signal transmission integrity is completely influenced.

The circuit board that this application provided compares in prior art's beneficial effect, compares in prior art's beneficial effect with the drilling method that this application provided for high accuracy back of body bores, and this is unnecessary here.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required for the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method of drilling a high precision back drill in one embodiment of the present application;

FIG. 2 is a schematic view of a substrate according to one embodiment of the present application;

FIG. 3 is a schematic view of the structure of the substrate shown in FIG. 2 after a first hole is drilled in the substrate;

FIG. 4 is a schematic view of a structure of the substrate shown in FIG. 3 after etching the target metal layer in the first hole of the substrate;

fig. 5 is a schematic view of the structure of the substrate shown in fig. 4 after a second hole is drilled in the substrate;

FIG. 6 is a schematic view of a structure of the substrate shown in FIG. 5 after copper deposition plating;

FIG. 7 is a schematic illustration of a third hole drilled in the substrate shown in FIG. 6;

fig. 8 is a schematic view of the substrate shown in fig. 6 after a third hole is drilled in the substrate.

The meaning of the labels in the figures is:

100. a substrate; 10. a target metal layer; 11. a target surface; 20. a first metal layer; 21. a reference surface; 30. a second metal layer; 40. a test well; 50. a first hole; 60. a second hole; 61. a third hole; 70. a conductive metal layer; 80. an intermediate metal layer; 81. a clearance hole; 90. a first dielectric layer; 91. and a second dielectric layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings, i.e. embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

Reference in the specification to "one embodiment," "some embodiments," or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," and the like in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

For the purpose of illustrating the technical aspects of the present application, reference is made to the following description taken in conjunction with the accompanying drawings and examples.

In the related art, besides the influence of the precision of back drilling equipment, the thickness of a circuit board product after lamination and the thickness between layers can be influenced by factors such as lamination parameters, plate characteristics, lamination and the like, certain difference exists in the thickness after lamination, the difference data between the thickness and the layers often can be measured by taking samples to carry out slicing after lamination, but on one hand, the thickness data of the taken samples can only be measured due to slicing measurement, the consistency of the thickness of laminated products in the same batch or different batches can not be ensured, on the other hand, the working efficiency of the slicing measurement method is low, on the other hand, the samples are required to be wasted for data measurement, the accuracy of the thickness between layers of each product before back drilling can not be ensured, and the waste of the products is caused.

Referring to fig. 1 and 2, in a first aspect, an embodiment of the present application provides a drilling method for a high-precision back drill, including:

s100: a substrate 100 is provided, where the substrate 100 includes a target metal layer 10, and a first metal layer 20 and a second metal layer 30 stacked on opposite sides of the target metal layer 10, and a test hole 40 penetrating the first metal layer 20, the target metal layer 10 and the second metal layer 30 is further provided on the substrate 100, a surface of the target metal layer 10 facing the first metal layer 20 is a target surface 11, and a surface of the first metal layer 20 facing away from the target metal layer 10 is a reference surface 21.

Specifically, a first dielectric layer 90 may be disposed between the first metal layer 20 and the target metal layer 10, and a second dielectric layer 91 may be disposed between the second metal layer 30 and the target metal layer 10. The first metal layer 20 and the second metal layer 30 may each be a copper layer.

Alternatively, the substrate 100 may be fabricated as follows: first, the second metal layer 30, the second dielectric layer 91, the target metal layer 10, the first dielectric layer 90 and the first metal layer 20 are sequentially stacked and pressed together to form a laminated plate; then, test holes 40 were drilled in the laminate to obtain a substrate 100.

It will be appreciated that the test wells 40 are disposed in the non-circuit area of the substrate 100.

S200: the distance M between the target surface 11 and the reference surface 21 in the test hole 40 is acquired.

Specifically, a measuring device provided with a measuring probe may be employed to acquire the distance M between the target surface 11 and the reference surface 21 in the test hole 40. For example, the distance M may be obtained by first bringing the measurement probe into contact with the reference surface 21, and then inserting the measurement probe into the test hole 40 and into contact with the target surface 11.

It should be noted that, the structure and principle of the measurement device provided with the measurement probe are mature prior art, and will not be described herein.

Alternatively, after the measurement probe is inserted into the test hole 40 and brought into contact with the target surface 11, the measurement probe may be inserted into the test hole 40 and brought into contact with the surface of the second metal layer 30 facing away from the target metal layer 10, and the board thickness of the substrate 100 may be obtained.

In this embodiment, the thickness of the substrate 100 is 2.0mm and the distance M is 1.0mm.

S300: referring to fig. 3, a first hole 50 is drilled in the substrate 100 from a side of the first metal layer 20 away from the target metal layer 10, wherein the aperture of the first hole 50 is d1 and the depth of the first hole 50 is equal to the distance M.

Specifically, a CCD ((Charge Coupled Device, a charge coupled device image sensor) drilling device may be used to drill a first hole 50 with a depth of a distance M on the substrate 100 from a side of the first metal layer 20 away from the target metal layer 10, and when the first hole 50 is drilled, the drilling device performs a drilling depth of a distance from the reference surface 21 to the target surface 11 because the data fed back by the measurement probe is a distance between the target surface 11 and the reference surface 21, and after the drilling is stopped, there is a certain delay due to the drilling device, and the drilling depth is on the basis of touching the target surface 11, and the target metal layer 10 is damaged by drilling but the target metal layer 10 is not penetrated.

It will be appreciated that the measuring device provided with the measuring probe may be integrated in a CCD drilling device.

It should be noted that, in order to ensure the accuracy of drilling the first hole 50, the distance between the first hole 50 and the test hole 40 should not be too large.

In this embodiment, the distance between the first well 50 and the test well 40 is 3mm-5mm, such as 3mm, 4mm, 5mm, or the like.

S400: referring to fig. 4, the target metal layer 10 in the first hole 50 is etched away.

Specifically, the target metal layer 10 in the first hole 50 may be removed by etching, exposing the second dielectric layer 91. The reference surface 21 and the side of the second metal layer 30 facing away from the target metal layer 10 may be covered with a dry film prior to etching, the dry film being provided with an open window exposing the first hole 50.

S500: referring to fig. 5, a second hole 60 with a hole diameter d2 is drilled in the substrate 100 from a side of the second metal layer 30 away from the target metal layer 10, the second hole 60 is disposed coaxially with the first hole 50, and the second hole 60 penetrates through a bottom surface of the first hole 50.

Specifically, the second hole 60 is drilled with respect to the bottom surface of the first hole 50, and the depth of the drilled hole is not required to be strictly controlled, and the depth of the drilled hole is only required to be larger than the difference between the thickness of the substrate 100 and the distance M, so as to ensure that the second hole 60 penetrates through the bottom surface of the first hole 50, for example, in this embodiment, the depth of the second hole 60 is larger than 1.0mm.

It will be appreciated that since the target metal layer 10 in the first hole 50 has been etched away before, the bottom of the first hole 50 will not have a flash problem when the second hole 60 is drilled, and the uniformity of the hole copper in the subsequent copper deposition plating will be better ensured.

S600: referring to fig. 6, the substrate 100 is subjected to copper deposition plating, such that the hole wall, the hole bottom surface of the first hole 50 and the hole wall of the second hole 60 form a conductive metal layer 70, and the conductive metal layer 70 located on the hole wall of the first hole 50 forms a hole ring with an inner hole diameter d 3.

Specifically, the conductive metal layer 70 may be a hole copper, a thin copper layer may be deposited in all holes including the back hole by chemical deposition, and then the conductive metal layer 70 is formed on the hole wall of the first hole 50, the hole bottom surface and the hole wall of the second hole 60 by electrochemical deposition.

Optionally, after copper deposition plating is performed on the substrate 100, an outer layer circuit may be formed on the substrate 100 by pattern transfer and etching according to design requirements.

S700: referring to fig. 7 and 8, a third hole 61 with a hole diameter d4 is drilled in the substrate 100 from a side of the second metal layer 30 away from the target metal layer 10, the third hole 61 is coaxially disposed with the first hole 50, and the third hole 61 penetrates the conductive metal layer 70 located at the bottom surface of the first hole 50, where d4 satisfies: d1> d3> d4> d2.

Specifically, since d1> d3> d4> d2, the conductive metal layer 70 in the second hole 60 can be effectively removed after the third hole 61 is drilled, and the conductive metal layer 70 on the wall of the first hole 50 is not damaged, thereby realizing the effect of zero back drilling of the stub in the second hole 60.

In this example, d1 is 0.30mm, d3 is 0.25mm, d4 is 0.23mm, and d1 is 0.15mm.

According to the high-precision back drilling method provided by the embodiment of the invention, the distance M between the target surface 11 and the reference surface 21 in the test hole 40 is firstly obtained, then the first hole 50 with the depth of M and the aperture of d1 is drilled on the substrate 100 by one side of the first metal layer 20 far away from the target metal layer 10, and the target metal layer 10 in the first hole 50 is removed by etching, so that the depth of the first hole 50 can be precisely controlled, the measurement efficiency is improved, the problems of burrs and copper scraps generated during the subsequent drilling of the second hole 60 can be avoided, meanwhile, the second hole 60 with the aperture of d2 is drilled on the substrate 100 by one side of the second metal layer 30 far away from the target metal layer 10, and then the substrate 100 is subjected to copper deposition electroplating, so that the conductive metal layer 70 is formed by the hole wall of the first hole 50, the hole bottom surface and the hole wall of the second hole 60, the metal layer with the aperture of d3 is formed by etching, and finally the third hole 61 is drilled on the substrate 100 by one side of the second metal layer 30 far away from the target metal layer 10, the third hole 61 with the aperture of d3 is formed by d3, and the third hole 61 is completely removed by d1, and the signal transmission of the third hole 61 is completely removed after the third hole 60 is drilled, and the signal transmission of the third signal is completely affected by d1 d is completely drilled by d4 d and the third hole is completely d 4.

The drilling method of the high-precision back drill solves the problems that the small back drilling residual pile is difficult to remove and the scrapped residual pile is caused by the difficulty in removing the Gao Houjing ratio back drill residual pile of a line to be etched.

Alternatively, after the third hole 61 having the aperture d4 is drilled in the substrate 100 from the side of the second metal layer 30 away from the target metal layer 10, the following steps may be sequentially performed on the substrate 100:

AOI (Automated Optical Inspection ) inspection: and (3) producing the cable in a conventional manner, and overhauling the bad points of the cable.

Welding prevention: besides the original anti-welding design of customers, the anti-welding layer is manufactured.

Characters: and (5) producing in a conventional manner to obtain the text mark and curing at a high temperature.

Surface treatment: produced in a conventional manner to give a surface treatment.

And (3) forming: and (5) producing the finished product in a conventional manner to obtain the appearance of the finished product.

And (3) electric measurement: through the electric test, the leakage of the tin short circuit and other open short circuit problems is prevented.

FQC (Final Quality Control, shipment detection) and FQA (Factory Quality Assurance ): and (5) checking the machine and manually and visually, and preventing abnormal products of the continuous tin short circuit from flowing out again.

Referring to fig. 3, in some embodiments, before a first hole 50 is drilled in a substrate 100 from a side of a first metal layer 20 away from a target metal layer 10, a plurality of sets of drilling data are preset in a drilling device, and drilling depths corresponding to the sets of drilling data are different; drilling the first hole 50 in the substrate 100 from the side of the first metal layer 20 remote from the target metal layer 10 includes: selecting drilling data with the closest corresponding drilling depth and distance M for the drilling equipment, namely, drilling data with the smallest absolute value of the difference value between the corresponding drilling depth and the distance M; a first hole 50 having a depth of a distance M is drilled in the substrate 100 from a side of the first metal layer 20 remote from the target metal layer 10 using a drilling apparatus.

For example, the substrate 100 has a plate thickness H of 2.0mm, a theoretical depth h1=1.0 mm of the first hole 50, a drilling depth of h1=1.0 mm of the conventionally designed drilling data, and a plurality of sets of drilling data needs to be added on the basis of the conventional drilling data design, and the drilling depth of the plurality of sets of drilling data may be any value of h1=0.8 mm to h1=1.2 mm, such as h1=0.8 mm, h2=0.81 mm, h3=0.82 mm, h4=1.1 mm, h5=1.11 mm, h6=1.12 mm.

By adopting the above scheme, corresponding drilling data can be rapidly selected according to different drilling depths, and the first hole 50 with the depth of M is drilled on the substrate 100, so that the drilling efficiency is improved.

It will be appreciated that the drill depth corresponding to the drill band data selected for the drilling apparatus may be equal to the distance M.

It should be noted that, even if the drill depth corresponding to the drill band data selected for the drilling apparatus is not equal to the distance M, the difference between the two is within an acceptable error.

Optionally, drilling the first hole 50 in the substrate 100 from a side of the first metal layer 20 remote from the target metal layer 10 includes:

judging whether the drilling depth corresponding to the drilling data currently selected by the drilling equipment is the same as the distance M or whether the difference value is within an error allowable range or not:

if the difference or the difference is not within the error allowable range, firstly selecting drilling data with the drilling depth closest to the distance M for the drilling equipment, and then drilling a first hole 50 with the depth of the distance M on the substrate 100 from one side of the first metal layer 20 far away from the target metal layer 10 by using the drilling equipment;

if the same or a difference is within the tolerance, a first hole 50 having a depth of M is directly drilled in the substrate 100 from a side of the first metal layer 20 remote from the target metal layer 10 using a drilling apparatus.

By adopting the scheme, the drilling efficiency can be further improved.

Referring to fig. 2, in some embodiments, the substrate 100 further includes a plurality of intermediate metal layers 80, a portion of the intermediate metal layers 80 is located between the first metal layer 20 and the target metal layer 10, the rest of the intermediate metal layers 80 are located between the target metal layer 10 and the second metal layer 30, the intermediate metal layers 80 are provided with the avoidance holes 81, and the projections of the test holes 40 on the reference surface 21 are located inside the projections of the reference surface 21 of the avoidance holes 81.

By adopting the above scheme, the measurement probe can be prevented from mistakenly touching the middle metal layer 80 when the distance M between the target surface 11 and the reference surface 21 in the test hole 40 is obtained while carrying out high-precision back drilling on the multilayer circuit board, so that the middle metal layer 80 causes interference to the obtained M value.

It can be understood that the first dielectric layer 90 is disposed between the first metal layer 20 and the intermediate metal layer 80, the second dielectric layer 91 is disposed between the second metal layer 30 and the intermediate metal layer 80, and the first dielectric layer 90 or the second dielectric layer 91 is disposed between two adjacent intermediate metal layers 80. In this embodiment, the substrate 100 is an 8-layer board, and the substrate 100 may be obtained by cutting, inner-layer circuit and lamination.

The substrate 100 may be manufactured as follows: first, the second metal layer 30, the second dielectric layer 91, a part of the intermediate metal layer 80 (the second dielectric layer 91 is arranged between the two connected intermediate metal layers 80), the second dielectric layer 91, the target metal layer 10, the first dielectric layer 90, another part of the intermediate metal layer 80 (the first dielectric layer 90 is arranged between the two connected intermediate metal layers 80), the first dielectric layer 90 and the first metal layer 20 are sequentially stacked and pressed together to form a laminated plate; then, test holes 40 were drilled in the laminate to obtain a substrate 100.

Referring to fig. 1 to 8, in a second aspect, a circuit board is provided, and the circuit board is manufactured by the drilling method of the high-precision back drilling according to the first aspect.

According to the circuit board provided by the embodiment of the invention, the distance M between the target surface 11 and the reference surface 21 in the test hole 40 is firstly obtained when back drilling is carried out, then the first hole 50 with the depth of the distance M and the aperture of d1 is drilled on the substrate 100 by one side of the first metal layer 20 far away from the target metal layer 10, and the target metal layer 10 in the first hole 50 is removed by etching, so that the depth of the first hole 50 can be accurately controlled, the problems of burrs and copper scraps generated during subsequent drilling of the second hole 60 can be avoided, meanwhile, copper deposition electroplating is carried out on the substrate 100 after the second hole 60 with the aperture of d2 is drilled on one side of the second metal layer 30 far away from the target metal layer 10, the conductive metal layer 70 is formed on the wall of the first hole 50, the bottom surface of the hole and the wall of the second hole 60, the metal layer with the inner aperture of d3 is formed, and finally the third hole 61 d4 is formed on the substrate 100 by one side of the second metal layer 30 far away from the target metal layer 10, the third hole 61 d4 is drilled on the substrate 100, the quality of d3 is completely improved, and the quality of the third hole 61 is completely drilled is completely removed, and the signal transmission can be completely removed after the third hole 61 is drilled, and the quality of the third hole is completely removed, and the signal is completely removed.

The above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims

1. A method of drilling a high precision back drill, comprising:

etching to remove the target metal layer in the first hole;

2. The method of drilling a high precision back drill according to claim 1, wherein the distance between the first hole and the test hole is 3mm-5mm.

3. The drilling method of the high-precision back drill according to claim 1, wherein a plurality of sets of drilling data are preset in a drilling device before a first hole is drilled in the substrate from one side of the first metal layer away from the target metal layer, and drilling depths corresponding to the sets of drilling data are different; drilling a first hole in the substrate from a side of the first metal layer remote from the target metal layer includes: selecting the drilling data with the drilling depth closest to the distance M for the drilling equipment; the first hole is drilled in the substrate from a side of the first metal layer remote from the target metal layer using the drilling apparatus.

4. The method of drilling a high precision back drill according to claim 1, wherein the substrate further comprises a plurality of intermediate metal layers, a part of the intermediate metal layers are located between the first metal layer and the target metal layer, the rest of the intermediate metal layers are located between the target metal layer and the second metal layer, a clearance hole is formed in the intermediate metal layers, and a projection of the test hole on the reference plane is located inside a projection of the clearance hole on the reference plane.

5. The method of drilling a high-precision back drill according to claim 4, wherein the obtaining the distance M between the target surface and the reference surface in the test hole comprises:

providing a measuring device provided with a measuring probe;

contacting the measurement probe with the datum surface;

6. The method according to claim 5, wherein after the measurement probe is inserted into the test hole and brought into contact with the target surface to obtain the distance M, the measurement probe is inserted into the test hole and brought into contact with a surface of the second metal layer facing away from the target metal layer to obtain the board thickness of the substrate.

7. The method of any one of claims 1 to 6, wherein a first dielectric layer is disposed between the first metal layer and the target metal layer, and a second dielectric layer is disposed between the second metal layer and the target metal layer.

8. The method of drilling a high-precision back drill according to claim 7, wherein prior to providing a substrate, the method of drilling a high-precision back drill further comprises;

and drilling the test hole in the laminated plate to obtain the substrate.

9. The drilling method of a high-precision back drill according to any one of claims 1 to 6, wherein after a first hole is drilled in the substrate from a side of the first metal layer away from the target metal layer and before etching to remove the target metal layer in the first hole, the reference surface and a side of the second metal layer facing away from the target metal layer are covered with a dry film provided with an opening window exposing the first hole.

10. A wiring board manufactured by the high-precision back drilling method according to any one of claims 1 to 9.