Method for forming conductive holes in circuit board and circuit board

Abstract

The invention belongs to the technical field of circuit board manufacturing, and particularly relates to a forming method of a conductive hole in a circuit board and the circuit board. The invention discloses a forming method of a conductive hole in a circuit board. The forming method comprises the steps of obtaining the circuit board; drilling a base hole in a to-be-drilled area on the circuit board along the thickness direction of the to-be-drilled area; forming a conductive layer on the hole wall of the base hole; and removing part of the material of the conductive layer along the thickness direction of the circuit board to obtain a plurality of conductive wires which are mutually spaced along the circumferential direction of the base hole and extend along the thickness direction of the circuit board so as to prepare the conductive hole. According to the invention, a part of material of a circle of conductive layer of a common whole conductive hole is removed to obtain a plurality of conductive wires which are mutually spaced, and one conductive wire can transmit one signal, so that one conductive hole can be connected with a plurality of signals, the utilization rate is high, and the number of conductive holes can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit board manufacturing, and in particular relates to a method for forming a conductive hole on a circuit board and a circuit board. Background Art

[0002] A printed circuit board (PCB) includes multiple circuit layers stacked together. In order to connect different circuit layers, conductive holes (VIA holes) are provided on the circuit board to achieve signal transmission.

[0003] On existing circuit boards, the conductive holes are a whole, either connected to the power layer, or connected to GND (short for the ground terminal of the wire), or connected to a specific signal. The application density of the circuit board is very high, and the number of circuit layers is also large, resulting in a large number of conductive holes, which greatly reduces the strength of the circuit board, and the circuit board is prone to failure under stress and external force. Moreover, too many conductive holes will cause excessive loss of conductive copper foil on the circuit layer, resulting in a weakened current carrying capacity of the circuit layer. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the problem that the number of conductive holes in the existing circuit board is large, a method for forming conductive holes on the circuit board and a circuit board are provided.

[0005] In order to solve the above technical problems, on the one hand, an embodiment of the present invention provides a method for forming a conductive hole on a circuit board, the forming method comprising: Obtain a circuit board; drill a base hole in the area to be drilled on the circuit board along the thickness direction thereof; forming a conductive layer on the hole wall of the base hole; Part of the material of the conductive layer is removed along the thickness direction of the circuit board to obtain a plurality of conductive traces that are spaced from each other along the circumference of the base hole and extend along the thickness direction of the circuit board, so as to obtain a conductive hole.

[0006] Optionally, part of the material of the conductive layer is removed along the thickness direction of the circuit board to obtain a plurality of conductive traces spaced from each other along the circumference of the base hole and extending along the thickness direction of the core board to obtain a conductive hole, comprising: At least two segmentation holes are processed along the thickness direction of the circuit board. In the process of forming the segmentation holes, part of the material of the conductive layer is removed to obtain a plurality of conductive traces that are spaced apart from each other and extend along the thickness direction of the core board.

[0007] Optionally, the segmentation holes are processed by laser cutting or drilling.

[0008] On the other hand, an embodiment of the present invention provides a circuit board, on which a conductive hole is provided, the conductive hole comprising a base hole and a plurality of conductive traces, the base hole penetrates at least a portion of the circuit board along the thickness direction of the circuit board, a plurality of the conductive traces are arranged around the base hole on the hole wall of the base hole at intervals, the conductive traces extend along the thickness direction of the circuit board, and each of the conductive traces can electrically connect at least two circuit layers of the circuit board.

[0009] Optionally, at each of the conductive holes, a partition hole is provided between any two adjacent conductive traces, and the partition hole penetrates the hole wall of the base hole along the thickness of the circuit board.

[0010] Optionally, the cross-sectional shape of the base hole is circular, and all the segmented holes are distributed at equal intervals along the circumferential direction of the base hole.

[0011] Optionally, the cross-sectional shape of the base hole is an equilateral triangle or a square, and all the segmentation holes are respectively arranged at the vertices of the base hole.

[0012] Optionally, three sections of the conductive traces with the same width are arranged on the hole wall of the base hole, and the three conductive traces are respectively a first conductive trace, a second conductive trace and a third conductive trace, the first conductive trace is used to connect the first signal of the differential pair signal, the second conductive trace is used to connect the second signal of the differential pair signal, and the third conductive trace is used to connect the ground signal, so that one conductive hole can realize the layer change of the differential pair signal.

[0013] Optionally, N segments of the conductive traces are arranged in the base hole, and the conductive traces are used to connect single-ended signals. One conductive hole can transmit N single-ended signals at most; wherein N≥2.

[0014] Optionally, the circuit board comprises a first signal layer, a second signal layer and a third signal layer which are spaced apart and distributed along a thickness direction of the circuit board, the first signal layer is located on a top layer of the circuit board, and the third signal layer is located on a bottom layer of the circuit board; The base hole passes through from the first signal layer to the third signal layer, and four sections of the conductive traces are arranged in the base hole, and the conductive traces are used to connect single-ended signals; on the first signal layer, the four sections of the conductive traces are respectively connected to the four single-ended signals on the first signal layer, and on the second signal layer, two sections of the conductive traces are respectively connected to the two single-ended signals on the second signal layer, and on the third signal layer, the other two sections of the conductive traces are respectively connected to the two single-ended signals on the third signal layer.

[0015] Compared with the prior art in which a conductive hole is an integral whole and one conductive hole is either connected to a power source, a GND, or a specific signal, the method for forming a conductive hole on a circuit board of the present invention removes part of the material of a circle of conductive layer on a common entire conductive hole to obtain a plurality of conductive traces spaced from each other, so that one conductive hole can be connected to a plurality of signals, so that one conductive hole can realize the layer change of a plurality of signals at the same time, with a high utilization rate, and can reduce the number of conductive holes, reduce costs, improve the strength of the circuit board, reduce the space occupied by the conductive holes, thereby reducing the degree of damage to the copper foil layer on the circuit board caused by drilling, and improving the current carrying capacity of each circuit layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of step S2 in a method for forming a conductive hole on a circuit board provided in one embodiment of the present invention; Figure 2 is a schematic diagram of step S3; Figure 3 is a schematic diagram of step S4; Figure 4 is a schematic diagram of step S2 when the base hole is a blind hole; Figure 5 is a schematic diagram of step S3 when the base hole is a blind hole; Figure 6 It is a plan view diagram when four conductive traces are arranged in the base hole; Figure 7 yes Figure 6 Cross-sectional view of the conductive vias at three signal layers; Figure 8 It is the plane diagram of the conductive hole when the base hole is an equilateral triangle; Fig. 9 It is the plan view of the conductive hole when the base hole is square.

[0017] The reference numerals in the specification are as follows: 1. Circuit board; 11. Base plate; 12. Circuit layer; 2. Conductive hole; 21. Base hole; 22. Conductive layer; 23. Conductive trace; 3. Partition hole. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] like Figures 1 to 3 As shown, an embodiment of the present invention provides a method for forming a conductive hole on a circuit board, the forming method comprising: S1: Get circuit board 1; S2: Figure 1 As shown, a base hole 21 is drilled in the area to be drilled on the circuit board 1 along its thickness direction; S3: Figure 2 As shown, a conductive layer 22 is formed on the hole wall of the base hole 21; S4: Figure 3 As shown, part of the material of the conductive layer 22 is removed along the thickness direction of the circuit board 1 to obtain a plurality of conductive traces 23 which are spaced from each other along the circumference of the base hole 21 and extend along the thickness direction of the circuit board 1 to obtain the conductive hole 2.

[0020] In step S3, an integrally connected conductive layer 22 is formed on the hole wall of the base hole 21. This is a process of electroplating and copper deposition for metallized holes commonly used in the field of circuit board manufacturing technology, which will not be described in detail here.

[0021] It can be seen from steps S3 and S4 that the forming method of the conductive hole 2 of the present invention is to remove part of the material of a circle of conductive layer 22 on a common entire conductive hole to obtain a plurality of conductive traces 23 spaced apart from each other. One end of the conductive trace 23 extending along the thickness direction of the circuit board 1 can be connected to an input signal on a circuit layer 12 of the circuit board 1, and the other end can output the signal to another circuit layer 12 to realize the signal layer switching operation.

[0022] Moreover, the multiple conductive traces 23 in a conductive via 2 are independent of each other, and each conductive trace 23 can be connected to a power layer, GND or a specific signal, so that a conductive via 2 can transmit multiple signals and complete the layer switching operation of multiple signals. The signal connected by the conductive trace 23 can be a normal signal or a differential signal.

[0023] Compared with the prior art in which the conductive layer in the conductive hole is a full circle, and a conductive hole is either connected to a power supply, a GND, or a specific signal, a conductive hole 2 in the present invention can be connected to multiple signals through multiple independent conductive traces 23, so that one conductive hole 2 can simultaneously realize the layer change of multiple signals, with a high utilization rate, and can reduce the number of conductive holes 2, reduce costs, improve the strength of the circuit board, and reduce the space occupied by the conductive hole 2, thereby reducing the degree of damage to the copper foil layer on the circuit board caused by punching and improving the current carrying capacity of each circuit layer 12.

[0024] In addition, the line width of the conductive trace 23 can be controlled by controlling the cross-sectional shape of the base hole 21 and the spacing between adjacent conductive traces 23, thereby controlling the impedance of the conductive trace 23. Compared with the whole cylindrical conductive hole 2 in the prior art, the impedance of the conductive trace 23 is relatively small, which is conducive to satisfying the condition of continuous impedance when the conductive hole 2 is used for layer switching of differential pair signals.

[0025] The conductive holes 2 of the circuit board 1 are used to connect different layers of the circuit layer 12 to achieve cross-layer signal transmission. The specific application of the circuit board 1 with the conductive holes 2 can be a single-layer PCB board or a multi-layer PCB board, which can be an HDI (High Density Interconnector) for connecting electronic components and transmitting signals, or a substrate for packaging chips.

[0026] In one embodiment, in step S1, the circuit board 1 is a single-layer board, including a substrate 11 and circuit layers 12 disposed on two opposite sides of the substrate 11 in the thickness direction. Figure 1 As shown, the base hole 21 passes through the entire circuit board 1 , and the conductive trace 23 can connect the circuit layers 12 on both sides of the circuit board 1 .

[0027] or, The circuit board 1 is a multi-layer board, which is formed by laminating a plurality of single-layer boards. Figure 4 and Figure 5 As shown, at this time, the base hole 21 can be a through hole, which passes through the entire circuit board 1; the base hole 21 can also be a blind hole or a buried hole, and the base hole 21 passes through a certain depth from one side surface of the circuit board 1.

[0028] It should be noted that when the base hole 21 is a buried hole or a blind hole, it is necessary to first laminate multiple single-layer boards through which the base hole 21 passes to form a transition board, and then process the conductive hole 2 on the transition board through steps S2 to S4, and then laminate the transition board with other single-layer boards to obtain a circuit board 1 with the required number of layers, so that the conductive hole 2 forms a buried hole or a blind hole style on the circuit board 1.

[0029] In one embodiment, the single-layer board is a copper-clad board, and a copper foil layer is provided on the surface of the substrate 11 in the thickness direction. The copper foil layer is subsequently etched with a circuit pattern by development to form a circuit layer 12 .

[0030] In one embodiment, in step S2, the base hole 21 may be processed by laser drilling or mechanical drilling.

[0031] In one embodiment, in step S4, at least two split holes 3 are processed along the thickness direction of the circuit board 1. In the process of forming the split holes 3, part of the material of the conductive layer 22 is removed to obtain a plurality of conductive traces 23 that are circumferentially spaced from each other in the base hole 21 and extend along the thickness direction of the circuit board 1.

[0032] Part of the material of the conductive layer 22 is removed by machining the dividing holes 3 to divide the entire circle of the conductive layer 22 into a plurality of spaced conductive traces 23 . The machining method is simple and the amount of material removal is easy to control.

[0033] In one embodiment, the dividing holes 3 are processed by laser cutting or drilling, wherein the drilling is performed by laser drilling or mechanical drilling.

[0034] In other embodiments, part of the material of the conductive layer 22 may be removed by chemical etching.

[0035] In addition, the present invention can process a circuit board through a method for forming a conductive hole on a circuit board provided by any of the above-mentioned embodiments.

[0036] like Figure 2 and Figure 3 As shown, the circuit board 1 is provided with a conductive hole 2, which includes a base hole 21 and a plurality of conductive traces 23. The base hole 21 penetrates at least a portion of the circuit board 1 along the thickness direction of the circuit board 1, and a plurality of conductive traces 23 are arranged around the base hole 21 at intervals on the hole wall of the base hole 21. The conductive traces 23 extend along the thickness direction of the circuit board 1. Each conductive trace 23 can electrically connect at least two circuit layers 12 of the circuit board 1 to realize the transmission of a signal, so that the same conductive hole 2 can transmit multiple signals.

[0037] The conductive hole 2 is processed by electroplating and copper deposition, which are commonly used in the field of circuit board manufacturing technology, and will not be described in detail here.

[0038] The multiple conductive traces 23 in a conductive via 2 are independent of each other, and each conductive trace 23 can be connected to a power layer, GND or a specific signal, so that a conductive via 2 can transmit multiple signals and complete the layer switching operation of multiple signals. The signal connected by the conductive trace 23 can be a normal signal or a differential signal.

[0039] Compared with the prior art in which a full circle of conductive layers is provided in a conductive hole, and a conductive hole is either connected to a power supply, a GND, or a specific signal, a conductive hole 2 in the present invention can be connected to multiple signals through multiple independent conductive traces 23, so that a conductive hole 2 can simultaneously realize the layer change of multiple signals, with a high utilization rate, and can reduce the number of conductive holes 2, reduce costs, improve the strength of the circuit board, and reduce the space occupied by the conductive hole 2, thereby reducing the degree of damage to the copper foil layer on the circuit board caused by punching, and improving the current carrying capacity of each circuit layer 12.

[0040] The conductive holes 2 of the circuit board 1 are used to connect different layers of the circuit layer 12 to achieve cross-layer signal transmission. The specific application of the circuit board 1 with the conductive holes 2 can be a single-layer PCB board or a multi-layer PCB board, which can be an HDI (High Density Interconnector) for connecting electronic components and transmitting signals, or a substrate for packaging chips.

[0041] In one embodiment, if Figure 2 As shown, the circuit board 1 is a single-layer board, including a substrate 11 and circuit layers 12 arranged on two opposite side surfaces of the substrate 11 in the thickness direction.

[0042] or, like Figure 4 and Figure 5 As shown, the circuit board 1 is a multi-layer board formed by laminating a plurality of single-layer boards.

[0043] In one embodiment, at each conductive hole 2, a split hole 3 is provided between any two adjacent conductive traces 23, and the split hole 3 passes through the hole wall of the base hole 21 along the thickness of the circuit board, so that a full circle of conductive layer can be processed on the hole wall of the base hole 21 first, and then part of the material of the conductive layer is removed by processing the split hole 3 to obtain a plurality of conductive traces 23 arranged at intervals. The processing method is simple and it is easy to control the amount of material removed and the line width of the conductive trace 23.

[0044] In one embodiment, the cross-sectional shape of the partition hole 3 is square or circular, and the center of the partition hole 3 is located on the side wall of the ring where the plurality of conductive traces 23 are located.

[0045] In one embodiment, the dividing holes 3 are processed by laser cutting or drilling, wherein the drilling is performed by laser drilling or mechanical drilling.

[0046] In other embodiments, chemical etching may be performed at multiple locations of the entire circle of the conductive layer 22 to obtain a plurality of conductive traces 23 distributed at intervals.

[0047] In one embodiment, if Figure 3 As shown, the cross-sectional shape of the base hole 21 is circular, and all the segmented holes 3 are evenly spaced along the circumferential direction of the base hole 21. The circular base hole 21 is more common, and is relatively easy to achieve whether by laser processing or drilling processing.

[0048] In other embodiments, Figure 8 and Fig. 9 As shown, the cross-sectional shape of the base hole 21 is an equilateral triangle or a square, and all the segmentation holes 3 are respectively arranged at the vertices of the base hole 21. All the segmentation holes 3 are respectively arranged at the vertices of the conductive holes 2, so as to facilitate the positioning of the segmentation holes 3 when processing the segmentation holes 3.

[0049] Of course, the cross-sectional area of ​​the base hole 21 may also be other polygonal shapes, such as a square, an isosceles triangle, a regular hexagon, etc.

[0050] In one embodiment, if Figure 3As shown, three sections of conductive traces 23 of the same width are arranged on the hole wall of the base hole 21. The three conductive traces 23 are respectively a first conductive trace, a second conductive trace and a third conductive trace. The first conductive trace is used to connect the first signal of the differential pair signal, the second conductive trace is used to connect the second signal of the differential pair signal, and the third conductive trace is used to connect the GND line, so that one conductive hole 2 can realize the layer change of the differential pair signal.

[0051] The circuit board of the prior art requires four conductive holes 2 to complete a differential pair signal layer change, wherein two conductive holes 2 are connected to the differential pair signals and the other two conductive holes 2 are connected to the GND lines. However, in the present invention, only one conductive hole 2 is required to achieve the layer change of the differential pair signal. It can be seen that the structure of the conductive hole 2 in the present invention can reduce the number of drilling holes, improve the space utilization of the circuit board, and is very competitive in high-density applications.

[0052] In order to meet the impedance control of the differential signal, the line width and line spacing of the first conductive trace and the second conductive trace in the base hole 21 are simulated according to the impedance value of the differential signal, and the spacing requirements of the GND line connected to the third conductive trace are obtained to control the processing dimensions of each conductive trace, so that the forming dimensions of the first conductive trace, the second conductive trace and the third conductive trace meet the impedance requirements of the line width, line spacing and distance to the GND line. The so-called "line width" refers to the circumferential dimension of the conductive trace 23 along the base hole 21.

[0053] In other embodiments, Figure 6 As shown, N segments of conductive traces 23 are arranged in the base hole 21, and the conductive traces 23 are used to connect single-ended signals to achieve layer switching of single-ended signals, and one conductive hole 2 can transmit N single-ended signals at most; wherein N≥2.

[0054] For general signals that are not differential signals, the transmission speed is very slow and the control of signal impedance is not so strict. Therefore, there is no need to set one of the conductive traces 23 to connect to GND, and all the conductive traces 23 in a conductive hole 2 can be used to connect general signals.

[0055] In one embodiment, if Figures 5 to 7 As shown, when the circuit board 1 to be processed is a multi-layer board, the circuit board 1 includes a first signal layer, a second signal layer and a third signal layer which are spaced apart along the thickness direction of the circuit board 1, the first signal layer is located on the top layer of the circuit board 1, and the third signal layer is located on the bottom layer of the circuit board 1.

[0056] The base hole 21 passes through from the first signal layer to the third signal layer, and four sections of conductive traces 23 are arranged in the base hole 21, and the conductive traces 23 are used to connect single-ended signals; in the first signal layer, the four sections of conductive traces 23 are respectively connected to the four single-ended signals on the first signal layer, and in the second signal layer, two sections of the conductive traces 23 are respectively connected to the two single-ended signals on the second signal layer, so as to switch two of the signals input from the first signal layer to the second signal layer, and in the third signal layer, the other two sections of the conductive traces 23 are respectively connected to the two single-ended signals on the third signal layer, so as to switch the other two signals input from the first signal layer to the third signal layer.

[0057] Among them, the "first signal layer", "second signal layer" and "third signal layer" are definitions of the circuit layer 12 used to transmit signals. When a circuit layer 12 is used as a power source, it is called a power layer, and when a circuit layer 12 is used as a ground, it is called a GND layer, and the GND line is set on the GND layer.

[0058] Of course, in other embodiments, the connection mode of the conductive traces 23 can be adjusted according to the actual circuit board application function. For example, the first signal layer inputs four signals, the second signal layer outputs three signals, and the third signal layer outputs one signal.

[0059] In other embodiments, the depth of the base hole 21 of the conductive via 2 can be adjusted so that the conductive via 2 can be applied to a multilayer board having circuit layers of different layers.

[0060] In other embodiments, the diameter of the base hole 21 , the number of conductive traces 23 in the base hole 21 , and the spacing between adjacent conductive traces 23 may be adjusted according to actual needs.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for forming a conductive hole on a circuit board, characterized in that: The molding method comprises: Get the circuit board; Drilling a base hole in the area to be drilled on the circuit board along the thickness direction thereof; forming a conductive layer on the hole wall of the base hole; Part of the material of the conductive layer is removed along the thickness direction of the circuit board to obtain a plurality of conductive traces that are spaced from each other along the circumference of the base hole and extend along the thickness direction of the circuit board, so as to obtain a conductive hole.

2. The method for forming a conductive hole on a circuit board according to claim 1, characterized in that: The method of removing part of the conductive layer material along the thickness direction of the circuit board to obtain a plurality of conductive traces spaced from each other along the circumference of the base hole and extending along the thickness direction of the circuit board to obtain a conductive hole comprises: At least two segmentation holes are processed along the thickness direction of the circuit board. In the process of forming the segmentation holes, part of the material of the conductive layer is removed to obtain a plurality of conductive traces that are spaced from each other along the circumference of the base hole and extend along the thickness direction of the circuit board.

3. The method for forming a conductive hole on a circuit board according to claim 2, characterized in that: The segmentation holes are processed by laser cutting or drilling.

4. A circuit board, characterized in that: The circuit board is provided with a conductive hole, and the conductive hole includes a base hole and a plurality of conductive traces. The base hole penetrates at least a portion of the circuit board along the thickness direction of the circuit board, and a plurality of conductive traces are arranged around the base hole at intervals on the hole wall of the base hole. The conductive traces extend along the thickness direction of the circuit board, and each of the conductive traces can electrically connect at least two circuit layers of the circuit board.

5. The circuit board according to claim 4, characterized in that: At each of the conductive holes, a partition hole is provided between any two adjacent conductive traces, and the partition hole penetrates the hole wall of the base hole along the thickness of the circuit board.

6. The circuit board according to claim 5, characterized in that: The cross-sectional shape of the basic hole is circular, and all the segmented holes are distributed at equal intervals along the circumferential direction of the basic hole.

7. The circuit board according to claim 5, characterized in that: The cross-sectional shape of the base hole is an equilateral triangle or a square, and all the segmentation holes are respectively arranged at the vertices of the base hole.

8. The circuit board according to any one of claims 4 to 7, characterized in that: Three sections of the conductive traces with the same width are arranged on the hole wall of the base hole, and the three conductive traces are respectively a first conductive trace, a second conductive trace and a third conductive trace. The first conductive trace is used to connect the first signal of the differential pair signal, the second conductive trace is used to connect the second signal of the differential pair signal, and the third conductive trace is used to connect the ground signal, so that one conductive hole can realize the layer change of the differential pair signal.

9. The circuit board according to any one of claims 4 to 7, characterized in that: N segments of the conductive traces are arranged in the base hole, and the conductive traces are used to connect single-ended signals. One conductive hole can transmit N single-ended signals at most; wherein N≥2.

10. The circuit board according to any one of claims 4 to 7, characterized in that: The circuit board comprises a first signal layer, a second signal layer and a third signal layer which are spaced apart and distributed along the thickness direction of the circuit board, the first signal layer is located at the top layer of the circuit board, and the third signal layer is located at the bottom layer of the circuit board; The base hole passes through from the first signal layer to the third signal layer, and four sections of the conductive traces are arranged in the base hole, and the conductive traces are used to connect single-ended signals; On the first signal layer, four sections of the conductive traces are respectively connected to four single-ended signals on the first signal layer; on the second signal layer, two sections of the conductive traces are respectively connected to two single-ended signals on the second signal layer; and on the third signal layer, the other two sections of the conductive traces are respectively connected to two single-ended signals on the third signal layer.

Images