CN112312648A

CN112312648A - Circuit board and manufacturing method thereof

Info

Publication number: CN112312648A
Application number: CN201910703333.3A
Authority: CN
Inventors: 李智; 韩雪川; 崔荣; 刘振波
Original assignee: Shennan Circuit Co Ltd
Current assignee: Shennan Circuit Co Ltd
Priority date: 2019-07-31
Filing date: 2019-07-31
Publication date: 2021-02-02

Abstract

The application provides a circuit board and a manufacturing method thereof, wherein the circuit board comprises: the circuit board comprises a plurality of core boards which are arranged in a stacked mode, wherein at least part of the surfaces of the core boards comprise circuit layers; the circuit board is provided with a groove penetrating through part of the core boards, and a conductive substance is formed in the groove and used for connecting the circuit layers in at least two core boards; the dimension of the first direction in the cross section of the tank is larger than the dimension of the second direction, so that the plating solution can contact any part in the tank to carry out plating to form the conductive substance. This application is through the shape that changes the groove to improve the hole and when electroplating the not enough problem in liquid medicine exchange space, and then promote the electroplating ability in hole, expand the depth ratio in hole.

Description

Circuit board and manufacturing method thereof

Technical Field

The invention relates to the technical field of circuit boards, in particular to a circuit board and a manufacturing method thereof.

Background

As an important electronic connector, a PCB (Printed Circuit Board) is used in almost all electronic products, and is considered as a "mother of electronic system products". Electronic products currently show two obvious trends, namely, lightness, thinness, shortness, High speed and High frequency, and accordingly drive downstream PCBs to develop towards High Density, High integration, encapsulation, miniaturization and multilayering, and the demand for High Density Interconnect (HDI) boards and High Density Interconnect (HDI) boards is increasing day by day. The high-speed multilayer board has short wiring length, low circuit impedance, high-frequency and high-speed work, stable performance and more complex functions, and is a necessary trend of the electronic technology towards high-speed, high-frequency, multifunctional and high-capacity development. Especially, the deep application of large scale integrated circuit will further drive the PCB to have high precision and high layer.

The HDI wiring density has obvious advantages compared with the common multilayer board, and the HDI wiring density is more and more applied to backbone networks in the communication field. Communication network switches, routing products and the like have higher and higher densities, less and less wiring spaces, and the requirement of limited space for transmitting more signals is difficult for common multilayer boards to meet the requirements. The high density interconnection circuit board (HDI) adopts a lamination method to manufacture a board, common multilayer boards are used as core boards to be laminated, and the connection function among the circuits of each layer is realized by utilizing the processes of drilling and metallization in holes. Compared with a common multilayer board only provided with through holes, the HDI accurately sets the blind holes and the buried holes to reduce the number of the through holes, saves the wiring area of a PCB, and greatly improves the density of components.

Currently HDI technology can realize cross-layer connection, such as connection of L1-3 layer and L1-4 layer. The general HDI in the industry can realize the depth ratio of electroplating capability of about 1:1, and can individually reach 1.2:1, but due to the limitation of electroplating liquid exchange capability of blind holes, when the depth ratio exceeds 1.2:1, the electroplating metallization of the blind holes is a bottleneck, so that the HDI technology is restricted to realize more levels of interconnection under a relatively simple process flow.

Disclosure of Invention

The invention mainly provides a circuit board, which improves the wiring density of products of the printed circuit board.

The invention adopts a technical scheme that: provided is a wiring board including:

the circuit board comprises a plurality of core boards which are arranged in a stacked mode, wherein at least part of the surfaces of the core boards comprise circuit layers;

the circuit board is provided with a groove penetrating through part of the core boards, and a conductive substance is formed in the groove and used for connecting the circuit layers in at least two core boards;

the dimension of the first direction in the cross section of the groove is larger than the dimension of the second direction, so that the plating solution can contact any part in the groove to carry out plating to form the conductive substance.

the circuit board comprises a circuit board and a circuit layer, wherein a concave hole is formed in one surface of the circuit board, and a conductive substance is formed in the hole and used for connecting the circuit layer in at least two core boards;

the diameter of the hole in the axial vicinity of the opening is larger than the diameter of the hole in the axial vicinity of the opening, so that there is enough space in the hole to perform electroplating to form the conductive substance.

the circuit board is provided with holes in the thickness direction, and conductive substances are formed in the holes and used for connecting the circuit layers in at least two core boards;

the cross section of the hole has different sizes in two different directions or different sizes in the axial space, so that the electroplating liquid enters a position with a larger size and a position with a larger axial space from a position with a smaller size to form the conductive substance.

the circuit board is provided with a hole penetrating through part of the core boards, and a conductive substance is formed in the hole and used for connecting the circuit layers in at least two core boards;

wherein the dimension of the cross section of the hole in the first direction is larger than the dimension in the second direction, and the ratio of the depth of the hole to the dimension in the first direction is less than 1.2; or

The dimension of the cross section of the hole in the first direction is equal to the dimension of the hole in the second direction, and the ratio of the depth of the hole to the dimension of the first direction or the dimension of the hole in the second direction is less than 2.

The invention adopts a technical scheme that: the method for manufacturing the circuit board comprises the following steps:

providing a plurality of core boards which are arranged in a stacked mode, wherein the surface of each core board comprises a circuit layer;

a groove penetrating through part of the core board is arranged on the circuit board;

forming a conductive substance in the groove to connect the circuit layers in at least two of the core boards;

wherein a dimension in the first direction in a cross section of the groove is larger than a dimension in the second direction.

The circuit board provided by the invention comprises: the circuit board comprises a plurality of core boards which are arranged in a stacked mode, wherein at least part of the surfaces of the core boards comprise circuit layers; the circuit board is provided with a groove penetrating through part of the core boards, and a conductive substance is formed in the groove and is used for connecting the circuit layers in at least two core boards; the size of the first direction on the cross section of the groove is larger than the size of the second direction, compared with the traditional circular via hole, the depth ratio of the groove is reduced, electroplating liquid medicine can be enabled to contact any part in the groove, and electroplating capacity is improved.

Drawings

FIG. 1a is a schematic structural view of a first embodiment of a wiring board of the present invention;

FIG. 1b is a schematic structural view of a cross section of a slot of a wiring board of the present invention;

FIG. 2 is a schematic structural view of a second embodiment of the wiring board of the present invention;

FIG. 3a is a schematic structural view of a second embodiment of the wiring board of the present invention;

FIG. 3b is a schematic structural diagram of a third embodiment of the wiring board of the present invention;

FIG. 4a is a schematic structural diagram of a fourth embodiment of the wiring board of the present invention;

FIG. 4b is a schematic structural diagram of a fifth embodiment of the wiring board of the present invention;

FIGS. 5-6 are schematic flow charts of a first embodiment of a method for manufacturing a circuit board according to the present invention;

fig. 7 is a schematic flow chart of a manufacturing method of the circuit board according to a second embodiment of the invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.

The terms "first," "second," "third," and the like in the description and in the claims, and in the above-described drawings, are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, system, article, or apparatus.

When the depth ratio (the degree of depth of blind hole than the diameter of blind hole opening part) of blind hole is bigger, when letting in electroplating liquid medicine in the blind hole, the blind hole bottom forms vacuum environment easily, lead to electroplating liquid medicine unable circulation in the blind hole bottom, make the blind hole bottom unable conductive material that fills, it is incomplete to metalize, this application provides following scheme to this to improve the blind hole and electroplate time liquid medicine exchange problem, promote the blind hole and electroplate the ability, make the blind hole still can completely electroplate under the condition of high depth ratio.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

Referring to fig. 1a, a schematic structural diagram of a circuit board according to a first embodiment of the present invention includes: the circuit board comprises a plurality of

core boards

11 and 12 which are arranged in a stacked mode, wherein at least part of the surfaces of the

core boards

11 and 12 comprise

circuit layers

111 and 121; wherein, there are troughs 13 penetrating some said

core boards

11, 12 on the said breadboard, there are conducting substances in the trough 13, are used for connecting the

said circuit layers

111, 121 in at least two said

core boards

11, 12.

The

core plates

11 and 12 are copper-clad plates, the copper-clad plates are base materials for manufacturing the circuit board and comprise base material plates and copper foils covered on the base materials, the base material plates are made by soaking materials such as paper substrates, glass fiber cloth substrates, synthetic fiber cloth substrates, non-woven fabric substrates and composite substrates with resin to prepare bonding sheets, the bonding sheets are combined to prepare the copper-clad plates, the copper foils are covered on one side or two sides of the prepared base material plates, and then hot-pressing solidification is carried out to prepare the copper-clad plates. The wiring layers 111, 121 are provided on the copper foils on the surfaces of the

core boards

11, 12.

In the prior art, the holes connecting the wiring layers are generally circular, and in this embodiment, the conventional circular holes are stretched in one direction to change the shape of the holes to the shape of the slots 13 as shown in fig. 1 b. Specifically, the dimension in the first direction in the cross section of the groove 13 is larger than the dimension in the second direction. In an embodiment, the cross-section of the groove 13 may also be oval or the like, as long as the electroplating solution can contact any part in the groove 13 to perform electroplating when entering the groove 13. In particular, in an embodiment, the ratio of the depth of the groove 13 to the dimension in the first direction in the cross section of said groove 13 is less than 1.2.

In the present embodiment, when the shape of the groove 13 is changed, the cross-sectional area of the groove 13 is increased as much as possible, and further, under the condition of the same depth, the depth ratio (the ratio of the depth of the groove to the long axis of the groove) is decreased to improve the electroplating capability, so that the groove 13 can contact with the electroplating solution at any position during electroplating to form a conductive substance, in one embodiment, the conductive substance is copper.

In this embodiment, the opening position of the groove 13 is located on the circuit layer 111 on the surface of the circuit board, the bottom of the groove 13 overlaps with the circuit layer 121 in the middle layer of the circuit board, the groove 13 is filled with a conductive material, and the groove 13 connects the circuit layer 111 on the surface of the circuit board with the circuit layer 121 in the middle layer of the circuit board.

In the present embodiment, the opening position of the groove 13 is located on the wiring layer 111 on the surface of the wiring board, the bottom is located in the middle of the wiring board, and overlaps with the wiring layer 121 of the core board 12 in the middle of the wiring board, so that the wiring layer 111 and the wiring layer 121 are electrically connected by the conductive substance in the groove 13. In the present embodiment, the number of the grooves for connecting the wiring layers formed by the groove 13 is one, and thus the wirings on the wiring layers 111 and 121 are each conducted.

In one embodiment, the slot 13 is located in the middle of the circuit board. Specifically, as shown in fig. 2, it is a schematic structural diagram of a second embodiment of the circuit board of the present invention. The opening position of the groove 13 overlaps with the circuit layer 112, the bottom of the groove 13 overlaps with the circuit layer 122, and the groove 13 is filled with a conductive material to electrically connect the circuit layer 112 of the core board 11 with the circuit layer 122 of the core board 12.

When the conductive material is filled in the groove 13 by electroplating, the conductive material is flush with the opening of the groove 13.

As in the first embodiment, the bottoms of the slots 13 are located on one of the circuit layers of the core 12, specifically, the bottoms of the slots 13 are all overlapped with the circuit layer 122, and the circuits on the circuit layer 122 are connected to each other, that is, the circuits on the circuit layer 122 are electrically connected. In one embodiment, the lines on the line layer 122 may also be disconnected from each other, as shown in fig. 4 b.

The shape of groove 13 is passed through in this embodiment, increases groove 13's cross sectional area, and then reduces the depth ratio to promote the electroplating ability of blind hole, expand the depth ratio of blind hole, and then improve the wiring density of printed wiring board's product.

Referring to fig. 3a, which is a schematic structural diagram of a third embodiment of the circuit board of the present application, a boss 14 is provided at the bottom of a groove 13 of the circuit board, a blind hole is formed between the boss 14 and a side wall of an opposite groove 13, in order to prevent incomplete plating at other positions (such as the blind hole) than the boss 14 at the bottom of the groove 13 from contacting conductive materials, the thickness of the boss 14 is limited within a range of a preset threshold value, that is, a ratio between the height of the boss 14 and the diameter of the blind hole is smaller than a preset threshold value, where the preset threshold value is a value that an electroplating solution can enter the groove 13 and contact any position of the groove 13 including a hole wall of the blind hole, that is, a depth ratio threshold value that the electroplating solution can just enter any position of the groove 13. In particular, in one embodiment, the ratio between the height of the boss 14 and the diameter of the blind hole is less than 1.

In this embodiment, the boss 14 is located on one side of the bottom of the groove 13 and connects the side walls of the groove 13, the portion of the other side of the bottom of the groove 13 without the boss 14 forms a blind hole with the boss side wall, and the rest positions of the bottom of the groove 13 except the position of the boss 14 are overlapped with the circuit layer 121. After the groove 13 is plated to fill the groove 13 with a conductive material, the conductive material is flush with the opening of the groove 13, and the conductive material contacts the circuit layer 121 on the bottom surface of the groove 13, so as to electrically connect the circuit layer 111 at the opening of the groove 13 with the circuit layer 121 at the bottom of the groove 13.

In this embodiment, the number of the bosses 14 is one, in other embodiments, the number of the bosses 14 may also be multiple, as shown in fig. 3b, which is a schematic structural diagram of a fourth embodiment of the circuit board of the present invention, the bosses 14 include 141 and 142, the

bosses

141 and 142 are located at two sides of the bottom of the groove 13 and connected to the side wall of the groove 13, and the

bosses

141 and 142 are not connected to each other. As in the second embodiment, the bottom of the groove 13 in this embodiment overlaps the wiring layer 121 except for the positions of the

lands

141 and 142.

In the embodiments shown in fig. 1a, fig. 2, fig. 3a and fig. 3b, the slot 13 forms one hole for connecting the circuit layers 111 and 121 or the circuit layers 112 and 122, so that the circuits on the circuit layers 111, 121, 112 and 122 are connected to each other. Note that, the groove 13 and the groove having the boss 14 in the above embodiments may be located in the middle of the circuit board, for example, as shown in fig. 2.

Fig. 4a is a schematic structural diagram of a circuit board according to a fifth embodiment of the present invention. In this embodiment, the protrusion 143 is located in the middle of the bottom of the groove 13, and connects the side wall of the groove in one direction and the side wall of the groove in another direction, an insulating material is formed above the protrusion 143 to divide the groove 13 into the first blind via 131 and the second blind via 132 that are not electrically connected, and a conductive material is located in the first blind via 131 and the second blind via 132.

In the present embodiment, the bottom of the groove 13 is located on one of the wiring layers 121 on the core 12, and at least partially overlaps with the wiring layer 121. Specifically, the bottoms of the first blind via 131 and the second blind via 132 in the trench 13 are both located on the circuit layer 121.

In the present embodiment, the network of first blind vias 131 and second blind vias 132 is broken to form two separate holes. Furthermore, the circuit layer 121 includes

circuits

1211 and 1212 that are not electrically connected to each other, the conductive material at the bottom of the first via hole 131 contacts the circuit 1211, and the conductive material at the bottom of the second via hole 132 contacts the circuit 1212. In an embodiment, the circuit layer 111 at the opening position of the slot 13 may not be conducted to the circuits at the positions corresponding to the first blind via 131 and the second blind via 132.

In the present embodiment, the bottom of the slot 13 is located on one of the circuit layers 121 of the core 12, and the bottoms of the first blind via 131 and the second blind via 132 are located on one of the circuit layers 121 of the core 12. In another embodiment, the slot 13 includes staggered multi-layer bottoms that are respectively positioned on multiple wiring layers of several core boards. Specifically, please refer to fig. 4b, which is a schematic structural diagram of a circuit board according to a sixth embodiment of the present invention. In the present embodiment, the multilayer bottom portions in which the slots 13 are staggered are located in the two

wiring layers

121, 122 of the wiring board, respectively. Further, the bottom of the first blind via 131 overlaps the circuit layer 121, the bottom of the second blind via 132 overlaps the circuit layer 122, and the conductive material in the first blind via 131 contacts the circuit layer 121, so as to electrically connect the circuit layer 111 at the opening position of the first blind via 131 with the circuit layer 121 at the bottom of the first blind via 131, and the conductive material in the second blind via 132 contacts the circuit layer 122, so as to electrically connect the circuit layer 111 at the opening position of the second blind via 132 with the circuit layer 122 at the bottom of the second blind via 132. In an embodiment, the circuits in the circuit layer 111 at the opening positions of the first blind via 131 and the second blind via 132 corresponding to the positions of the first blind via 131 and the second blind via 132 may also be disconnected from each other.

In the third to sixth embodiments, the groove 13 may be located in the middle of the circuit board as in the second embodiment, and in the first to sixth embodiments of the present application, the shape of the conventional hole is changed from a circular shape to a shape with an elongated cross section, so that the size of the cross section in the first direction is larger than that in the second direction, and the cross section area is increased to a certain extent, thereby achieving the purposes of reducing the depth ratio and improving the plating capability.

In another embodiment of the present application, the hole may not be changed in shape, but may still be provided in a circular shape, and have a diameter at the position of the axial opening larger than the diameter at the position away from the opening, but in this embodiment, the diameter of the hole needs to be increased as much as possible to have enough space in the hole for plating, and specifically, the ratio of the depth of the hole to the diameter at the position of the opening of the hole is smaller than 2.

In an embodiment, if the hole is circular and the cross-sectional area is large enough, in order to further ensure that the electroplating solution can have enough exchange space, the bottom of the hole may be provided with the boss as described in the above embodiments two to five, so as to reduce the depth ratio of the hole at the bottom of the hole, and further enable any part in the air to contact with the conductive material during electroplating.

The present application further provides a method for manufacturing a circuit board according to the first to sixth embodiments, please refer to fig. 5, which is a schematic flow chart of the manufacturing method according to the first to fourth embodiments of the present application, including:

step S41: a number of core boards are provided in a stacked arrangement, and a surface of the core boards includes a wiring layer.

The manufactured circuit board is provided, generally, the circuit board is usually composed of core boards which are arranged in a stacking mode, and the surface of each core board is provided with a circuit layer, wherein the core board is a copper-clad board, the copper-clad board is a base material for manufacturing the circuit board and comprises a base material board and a copper foil covered on the base material board, the base material board is made by soaking materials such as a paper base board, a glass fiber cloth base board, a synthetic fiber cloth base board, a non-woven fabric base board, a composite base board and the like with resin to manufacture bonding sheets, the bonding sheets are made by combining a plurality of bonding sheets, the single face or double faces of the manufactured base material board are covered with. The circuit layer is arranged on the copper foil on the surface of the core plate. And carrying out high-temperature pressing on the core board through the prepregs during lamination to manufacture the circuit board.

Step S42: and a groove penetrating through part of the core board is arranged on the circuit board.

In general, when the outermost layer of the wiring board is connected, a through hole penetrating through the wiring board is provided in the outermost layer of the wiring board, and when the outer layer and the inner layer of the wiring board are to be connected or the inner layer and the inner layer are to be connected, a blind hole penetrating from the outer layer to a specified inner layer is provided in the wiring board, or a blind hole penetrating from a specified inner layer to another specified inner layer is provided in the wiring board, and then the blind hole is plated to have conductivity. Because the bottom of blind hole is confined, when the circuit layer that needs to switch on is darker if the blind hole, because the restriction of depth ratio, when electroplating, liquid medicine can't get into the blind hole bottom, consequently change the circular blind hole commonly used into the groove in order to overcome this problem in this application, just the size of the first direction on the cross section of groove is greater than the size of second direction. In an embodiment, the depth of the groove and the dimension in the first direction in the cross-section of the groove are less than 1.2.

Step S43: forming a conductive substance in the groove to connect the wiring layers in at least two of the core boards.

After the grooves are provided, a conductive material needs to be provided in the grooves in order to electrically connect the lines connected to the grooves. Specifically, plating is performed in the tank, so that the plating liquid enters the tank and contacts any portion of the tank, thereby forming a conductive substance. In one embodiment, the groove may be filled with a conductive material, and in another embodiment, only the sidewall of the groove may have a conductive material.

Referring to fig. 6, step S42 specifically includes:

step S421: and a groove is formed in the circuit board, and the bottom of the groove is not communicated with the circuit layer to be connected.

And the groove is formed in the circuit board by using a mechanical drilling or milling mode, and the mechanical drilling or milling precision is low, so that the circuit layer is prevented from being damaged in the groove forming process, the bottom of the groove is not communicated with the circuit layer when the groove is formed by using the mechanical drilling or milling, and the circuit layer and the bottom of the groove have certain thickness.

Step S422: and treating the bottom of the groove to ensure that the bottom part of the groove is communicated to the circuit layer to be connected, and the other part of the groove forms a boss.

And processing the bottom of the groove in a laser drilling mode to enable the bottom of the groove to be communicated with the circuit layer to be connected, in the process, enabling the bottom of the groove to be communicated with the circuit layer to be connected, and enabling the other part of the groove to form a boss, so that the depth ratio of the bottom of the groove can be further reduced through the boss, and the boss can be removed.

In this embodiment, the number of the fabricated grooves is one, and the grooves are used for connecting two different circuit layers, and the circuits on each circuit layer are electrically connected.

Referring to fig. 7, a method for manufacturing a circuit board according to embodiments three to four of the present application is different from fig. 6 in that the method preferably includes, after step S43:

step S431: and covering a protective layer on the surface of the conductive substance.

Specifically, after filling the conductive material in the groove by electroplating, electroplating is performed on the surface of the conductive material exposed on the surface of the groove to form a protective layer covering the conductive material, and in this embodiment, the material of the protective layer is tin.

Step S432: and removing the protective layer on the surface of the conductive substance at the position corresponding to the boss.

And removing the protective layer corresponding to the boss on the surface of the conductive substance in a laser mode to expose the conductive substance corresponding to the boss.

Step S433: and removing the conductive substance exposed above the boss so as to divide the groove into a first blind hole and a second blind hole.

The conductive substance exposed above the boss is removed by alkaline etching, so that the groove is divided into the first blind hole and the second blind hole, the conductive substance is filled in the first blind hole and the second blind hole, the conductive substance above the boss is removed at the moment, the protective layer can protect the integrity of the conductive substance in the first blind hole and the second blind hole, and the conductive performance of the first blind hole and the second blind hole cannot be influenced.

Step S434: and filling an insulating substance above the boss so as to electrically disconnect the first blind hole and the second blind hole.

And filling an insulating material above the boss to further electrically disconnect the first blind hole and the second blind hole.

In this embodiment, the first blind via and the second blind via are independent vias, and it should be noted that, if the bottoms of the first blind via and the second blind via are through the same circuit layer, the circuit in contact with the conductive material at the bottom of the first blind via and the circuit in contact with the conductive material at the bottom of the second blind via are not connected to each other, and if the bottoms of the first blind via and the second blind via are through the different circuit layers, the circuit layers in contact with the conductive materials at the bottoms of the first blind via and the second blind via are different layers.

In this embodiment, only a part of the related structures of the circuit board are described, and other structures are the same as those of the circuit board in the prior art, and are not described herein again.

The invention reduces the depth ratio by changing the depth ratio of the holes for connecting the circuit layers, particularly, on one hand, changing the shape of the holes to ensure that the size of the cross section in the first direction is larger than that in the second direction, forming the grooves, and ensuring that the ratio of the depth of the grooves to the size in the first direction is less than 1.2, so that the bottom of the grooves has enough space for electroplating, and electroplating liquid medicine can contact any position in the grooves. On the other hand, the shape of the hole is not changed, the hole is made circular, but the ratio of the depth of the hole to the diameter of the hole is made smaller than 2, so that the hole has enough space to be plated to form the conductive substance. The invention can improve the electroplating capability of the blind hole on one hand and can also improve the product wiring density of the printed circuit board on the other hand.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A circuit board, comprising:

2. The wiring board of claim 1,

the bottom of the groove is positioned on one of the circuit layers on the plurality of core boards and at least partially overlaps with the circuit layer.

3. The wiring board of claim 1,

the slots include staggered multi-layer bottoms, wherein the staggered multi-layer bottoms are respectively located on a plurality of circuit layers of a plurality of core boards.

4. The wiring board according to claim 2 or 3, wherein the groove is a blind groove, the bottom of the groove has a boss, a blind hole is formed between the boss side wall and the opposite groove side wall, the ratio between the height of the boss and the diameter of the blind hole is smaller than a preset threshold, and the preset threshold is a value at which the plating liquid can enter the groove and contact any position of the groove including the wall of the blind hole.

5. The wiring board of claim 4,

the number of the bosses is one, the bosses are positioned on one side of the bottom of the groove and connected with the side wall of the groove, so that a blind hole is formed on the other side of the bottom of the groove; or

The number of the bosses is two, the bosses are positioned on two sides of the bottom of the groove and are respectively connected with two side walls of the groove, so that a blind hole is formed in the middle of the bottom of the groove;

the number of the bosses is one, the bosses are positioned in the center of the bottom of the groove, the bosses are connected with the side wall of the groove in one direction and are not connected with the side wall of the groove in the other direction, and therefore a first blind hole and a second blind hole are formed in the bottom of the groove.

6. The wiring board of claim 5, wherein the conductive substance covers the bosses and is flush with the open ends of the slots.

7. The wiring board of claim 5,

the conductive substance is positioned in the first blind hole and the second blind hole, and an insulating substance is formed above the boss so as to electrically insulate the first blind hole from the second blind hole;

the conductive substances on the bottom surfaces of the first blind hole and the second blind hole contact the same circuit layer; or

And the conductive substances on the bottom surfaces of the first blind hole and the second blind hole contact different layers of circuit layers.

8. Wiring board according to claim 1 or 4,

the ratio of the depth of the groove to the dimension in the first direction over the cross-section of the groove is less than 1.2;

the ratio of the height of the boss to the diameter of the blind hole is less than 1.

9. A circuit board, comprising:

10. The wiring board of claim 9,

the bottom of the hole is provided with a boss, and the side wall of one side of the boss is connected with the hole wall, so that the diameter of the hole is subjected to sudden change in the axial direction.

11. The wiring board of claim 10,

and a blind hole is formed between the side wall of the boss and the opposite side wall of the hole, the ratio of the height of the boss to the diameter of the blind hole is smaller than a preset threshold value, and the preset threshold value is a value which can enable electroplating liquid to enter the hole and contact with any position of the hole including the hole wall of the blind hole.

12. The wiring board of claim 11,

the number of the bosses is one, the bosses are positioned on one side of the bottom of the hole and connected with the side wall of the hole, so that a blind hole is formed on the other side of the bottom of the hole; or

The number of the bosses is two, the bosses are positioned on two sides of the bottom of the hole and are respectively connected with two side walls of the hole, so that a blind hole is formed in the middle of the bottom of the hole;

the number of the bosses is one, the bosses are positioned in the center of the bottom of the hole, the bosses are connected with the side wall of the hole in one direction and are not connected with the side wall of the hole in the other direction, and therefore a first blind hole and a second blind hole are formed in the bottom of the hole.

13. The wiring board of claim 12,

the bottom of the hole is positioned on one of the circuit layers on the plurality of core boards and at least partially overlaps with the circuit layer.

14. The wiring board of claim 12,

the holes include staggered multi-layer bottoms, wherein the staggered multi-layer bottoms are respectively located on a plurality of circuit layers of the plurality of core boards.

15. The wiring board of claim 13 or 14, wherein the conductive substance covers the bosses and is flush with the open ends of the slots.

16. Wiring board according to claim 13 or 14,

17. Wiring board according to claim 9 or 11,

the ratio of the depth of the hole to the diameter at the position of the opening of the hole is less than 2;

18. A circuit board, comprising:

19. The wiring board of claim 18,

20. The wiring board of claim 18,

21. The wiring board of claim 19,

the bottom of the hole is at least partially provided with a boss, and the boss is connected with the side wall of one side of the hole; or

The bosses are connected with the side walls on the two sides of the hole, and the bosses connected with the two side walls of the hole are not connected with each other;

the conductive substance covers the boss.

22. The wiring board of claim 19,

the bottom of the hole is at least partially provided with a boss, the boss is positioned in the middle of the bottom of the hole and divides the hole into a first blind hole and a second blind hole which are not connected with each other, the conductive substance is positioned in the first blind hole and the second blind hole, and an insulating substance is formed above the boss so as to electrically insulate the first blind hole from the second blind hole;

23. The wiring board of claim 21 or 22,

the ratio of the height of the boss to the diameter of the hole between the side wall of the boss and the opposite side wall of the hole is smaller than a preset threshold value, and the preset threshold value is a value which enables electroplating liquid to enter the hole and to contact any position of the hole including the hole wall of the blind hole.

24. The wiring board of claim 18 or 23,

the ratio between the dimension of the hole in the thickness direction and the larger dimension of the hole in the cross-section is less than 1.2;

the ratio of the height of the boss to the diameter of the hole between the boss sidewall and the opposing hole sidewall is less than 1.

25. A circuit board, comprising:

26. The wiring board of claim 25, wherein the axial spaces of the holes decrease sequentially from top to bottom; or

The axial space of the holes is the same from top to bottom.

27. A method for manufacturing a circuit board is characterized by comprising the following steps:

28. The method of manufacturing according to claim 27,

the groove for arranging the core plate penetrating through the circuit board specifically comprises:

a groove is formed in the circuit board, and the bottom of the groove is not communicated with a circuit layer to be connected;

and treating the bottom of the groove to ensure that the bottom part of the groove is communicated to the circuit layer to be connected, and the other part of the groove forms a boss.

29. The method of manufacturing according to claim 27,

the step of forming a conductive substance in the groove to connect the circuit layers of at least two of the core boards further comprises the following steps:

covering a protective layer on the surface of the conductive substance;

removing the protective layer on the surface of the conductive substance at the position corresponding to the boss;

removing the conductive substance exposed above the boss to divide the groove into a first blind hole and a second blind hole;

an insulating substance is formed over the boss to electrically insulate the first and second blind vias.