TWI727651B - Multilayer circuit board - Google Patents

Abstract

A multilayer circuit board includes a first circuit layer, a second circuit layer, a circuit structure, and an inclined conductive structure. The first circuit layer extends in a first reference plane and includes a first pad. The second circuit layer extends in a second reference plane and includes a second pad. The circuit structure is located between the first circuit layer and the second circuit layer. The circuit structure includes at least one inner circuit layer. Furthermore, the first reference plane and the second reference plane are parallel to each other. The inclined conductive structure connects to the first pad and the second pad, and the inclined conductive structure passes through the circuit structure. Moreover, an axis of the inclined conductive structure is not perpendicular to the first reference plane.

Description

Multilayer circuit board

The invention relates to a multilayer circuit board, in particular to a multilayer circuit board with an inclined conductive structure.

At present, some electronic devices are heading toward the development trend of increasing output power to improve performance. Take the network server as an example. In order to meet the current network transmission requirements, the output power of the existing network server is increasing, so that the motherboard circuit design in the network server also needs to be changed to improve performance and stability. degree. However, the housing for accommodating the motherboard has limited accommodating space, so that the area and shape of the motherboard are not easy to change. Secondly, the existing method of changing the circuit design of the motherboard is usually to directly change the layout of the multilayer circuit layer in the motherboard, that is, to change the number, distribution position and shape of the traces and pads of each layer of the circuit layer. . Therefore, the circuit design of the entire motherboard may need to be redesigned, so that the original circuit design will be discarded entirely, which requires a lot of research and development time and cost.

The invention provides a multilayer circuit board, which uses an inclined conductive structure to electrically connect two circuit layers separated from each other.

The multilayer circuit board provided by the present invention includes a first circuit layer, a second circuit layer, a circuit structure and an inclined conductive structure. The first circuit layer extends on the first reference plane and includes a first pad. The second circuit layer extends on the second reference plane and includes a second pad. The circuit structure is located between the first circuit layer and the second circuit layer, and includes at least one inner circuit layer, wherein the first reference plane and the second reference plane are parallel to each other. The inclined conductive structure connects the first pad and the second pad and passes through the circuit structure, wherein the axis of the inclined conductive structure is not perpendicular to the first reference plane.

In an embodiment of the present invention, the above-mentioned first pad and the second pad do not overlap at all.

In an embodiment of the present invention, the above-mentioned inclined conductive structure is electrically isolated from the inner circuit layer.

In an embodiment of the present invention, the above-mentioned inclined conductive structure The inclined conductive structure includes a metal cylinder.

In an embodiment of the present invention, the above-mentioned inclined conductive structure further includes a filling material, and the metal barrel has a through hole, and the filling material fills the through hole.

In an embodiment of the present invention, the above-mentioned inclined conductive structure has an outer diameter ranging from 8 mils to 17 mils on a cross section, and the cross section is parallel to the first reference plane.

In an embodiment of the present invention, the number of the above-mentioned inclined conductive structures is multiple.

In an embodiment of the present invention, the above-mentioned circuit structure includes a plurality of inner circuit layers.

In an embodiment of the present invention, the above-mentioned circuit structure includes a plurality of insulating layers.

Based on the foregoing, the multilayer circuit board of the present invention includes more than three circuit layers (for example, the first and second circuit layers and at least one inner circuit layer) and at least one inclined conductive structure, wherein the inclined conductive structure connects two of them. Layer circuit layer, and through another layer of circuit layer. Using the above-mentioned inclined conductive structure can increase the flexibility and flexibility of circuit design of the circuit board, so that the present invention has the opportunity to not change the area and shape of the multilayer circuit board and the premise of not greatly changing the wiring of these circuit layers. Design a multilayer circuit board that can meet the needs of existing electronic equipment.

In order to make the above-mentioned features and advantages of the present invention more comprehensible and understandable, the following specific examples are given in conjunction with the accompanying drawings, which are described in detail as follows.

Please refer to FIG. 1, which is a schematic cross-sectional view of a multilayer circuit board according to an embodiment of the present invention. The multilayer circuit board 10 includes a first circuit layer 11 and a second circuit layer 12. The first circuit layer 11 extends on the first reference plane P1, and the second circuit layer 12 extends on the second reference plane P2, wherein the first reference plane P1 and the second reference plane P2 are parallel to each other. In detail, the first reference plane P1 and the second reference plane P2 are two virtual planes parallel to each other, and the first circuit layer 11 and the second circuit layer 12 are substantially along the first reference plane P1 and the second reference plane P1 and the second reference plane respectively. It extends with reference to the plane P2, so the first circuit layer 11 and the second circuit layer 12 are substantially parallel to each other. In detail, under the premise that the multilayer circuit board 10 can operate normally, the above-mentioned "substantially parallel to each other" includes the slight non-parallelism between the first circuit layer 11 and the second circuit layer 12, that is, the first circuit layer 11 and the second circuit layer 11 are not parallel. The distance between the two circuit layers 12 may be slightly uneven, and the first circuit layer 11 and the second circuit layer 12 may have slightly uneven thicknesses.

The multilayer wiring board 10 also includes a wiring structure 13. The circuit structure 13 is located between the first circuit layer 11 and the second circuit layer 12 and includes at least one inner circuit layer 130. Taking FIG. 1 as an example, the circuit structure 13 includes an inner circuit layer 130, and the multilayer circuit board 10 is a circuit board with three circuit layers, but in other embodiments, the inner circuit layer 130 included in the circuit structure 13 The number can be multiple layers, that is, the multilayer circuit board 10 can be a circuit board with more than three circuit layers. In addition, in the embodiment shown in FIG. 1, the first circuit layer 11 and the second circuit layer 12 may be outer circuit layers, and the inner circuit layer 130 may be the middle circuit layer of the multilayer circuit board 10, but in other implementations In an example, at least one of the first circuit layer 11 and the second circuit layer 12 may also be an inner circuit layer, and the inner circuit layer 130 may not be an intermediate circuit layer. Therefore, FIG. 1 does not limit that the first circuit layer 11 and the second circuit layer 12 must be outer circuit layers, and the inner circuit layer 130 must be an intermediate circuit layer. In addition, the inner circuit layer 130 can be used to transmit signals, such as digital signals. For example, the inner circuit layer 130 may have a high-speed signal line, which may be a PCIE (PCI Express) signal line. Alternatively, the inner circuit layer 130 may also be a ground plane.

The circuit structure 13 further includes a plurality of insulating layers 131 (two layers are shown in FIG. 1 ), and the inner circuit layer 130 is sandwiched between the insulating layers 131. Each insulating layer 131 can be made of glass fiber cloth (prepreg or core), so the constituent material of the insulating layer 131 can include resin and glass fiber. In addition, in this embodiment, the inner circuit layer 130 may use conductive vias, blind vias or buried vias (none of which are shown) to electrically connect to other circuit layers, such as the first circuit layer 11 and the second circuit layer 12. At least one layer, so that the inner circuit layer 130 can be electrically connected to other circuit layers (for example, the first circuit layer 11 or the second circuit layer 12). Of course, the inner circuit layer 130 may not be electrically connected to other circuit layers. For example, when the inner circuit layer 130 is a ground plane, the inner circuit layer 130 may not electrically connect the first circuit layer 11 and the second circuit layer 12.

The multilayer circuit board 10 further includes at least one inclined conductive structure 14. The first circuit layer 11 includes a first pad 110, and the second circuit layer 12 includes a second pad 120, wherein the inclined conductive structure 14 connects the first pad 110 and the second pad 120 and passes through the circuit structure 13 , So that the first circuit layer 11 and the second circuit layer 12 can be electrically connected to each other by using the inclined conductive structure 14 to allow current to pass between the first circuit layer 11 and the second circuit layer 12. In addition, in the embodiment shown in FIG. 1, the inclined conductive structure 14 may be electrically isolated from the inner circuit layer 130, that is, the inclined conductive structure 14 is not directly electrically connected and electrically conductive with the inner circuit layer 130. In this way, part or all of the electrical signals can be transmitted between the first circuit layer 11 and the second circuit layer 12 through the inclined conductive structure 14, but will not enter the inner circuit layer 130.

In this embodiment, both the first pad 110 and the second pad 120 are used to connect the inclined conductive structure 14, but the electronic components may not be mounted, that is, the electronic components are not directly soldered to the first connection. The pad 110 and the second pad 120. However, each of the first circuit layer 11 and the second circuit layer 12 may further include a plurality of traces (not shown), and each of the traces may be connected to both the first pad 110 and the second pad 120 One of them and the others have pads for mounting electronic components. Using these wires, at least one of the first pad 110 and the second pad 120 can be electrically connected to a pad equipped with electronic components, so that the first pad 110 and/or the second pad 120 can be electrically connected. This electronic component is connected sexually, where the above-mentioned electronic component can be a passive component or an active component, such as an inductor, a resistor, or a processor (such as a microprocessor or a central processing unit).

In addition, it should be noted that in other embodiments, the first pad 110 and the second pad 120 may also be used for mounting electronic components. Alternatively, each of the first circuit layer 11 and the second circuit layer 12 may further include a metal layer with a larger area, such as a copper foil with a larger area, and electronic components may be mounted on this metal layer, wherein the metal layer is connected The first pad 110 or the second pad 120. In this way, by using this metal layer, at least one of the first pad 110 and the second pad 120 can also be electrically connected to electronic components.

The inclined conductive structure 14 is inclined relative to the first circuit layer 11 and the second circuit layer 12. In other words, the axis X of the inclined conductive structure 14 is not perpendicular to the first reference plane P1, and certainly not perpendicular to the second reference plane P2. In detail, in the embodiment of FIG. 1, the center lines (not shown) of the first pad 110 and the second pad 120 are obviously not different from both the first reference plane P1 and the second reference plane P2. The normal line (ie, the vertical line) is collinear, and the axis X of the inclined conductive structure 14 is not collinear with the normal lines of both the first reference plane P1 and the second reference plane P2. Therefore, the inclined conductive structure 14 is inclined relative to the first circuit layer 11 and the second circuit layer 12. In addition, the inclined conductive structure 14 has an outer diameter R ranging from 8 mils (mils) to 17 mils on the cross section, wherein the cross section is parallel to the double arrow horizontal line representing the outer diameter R in FIG. 1, and from From Fig. 1, the above-mentioned cross-section is parallel to the first reference plane P1.

The inclined conductive structure 14 may include a metal barrel 141, and the metal barrel 141 has a through hole (not labeled). The inclined conductive structure 14 is connected to the first pad 110 and the second pad 120. In detail, the first pad 110 has a first opening 111, and the second pad 120 has a second opening 121, wherein the first opening 111, the second opening 121 and the above-mentioned through hole of the metal cylinder 141 communicate with each other. In addition, the metal cylinder 141 also has an inner wall, and the first opening 111 and the second opening 121 also have inner walls, and the inner wall of the first opening 111 and the inner wall of the second opening 121 are respectively the same as the inner wall of the metal cylinder 141. Chopped. The inclined conductive structure 14 further includes a filling material 142, and the filling material 142 fills the above-mentioned through holes. The filling material 142 is, for example, ink, solder paste, copper paste, or epoxy resin. Therefore, the filling material 142 can be a conductor or an insulator, but The present invention is not limited to these materials. After the through hole of the metal cylinder 141 is filled with the filling material 142, it is not easy to form a cavity composed of gas (such as air) in the through hole, so that the multilayer circuit board 10 will not explode when it enters a high temperature environment. In the case of boards, the aforementioned high-temperature environment is provided by, for example, a reflow furnace or a high-temperature furnace for deterioration test.

The multilayer circuit board 10 can be made by an additive method, a subtractive method, a semi-additive method, or a stacking method, and the inclined conductive structure 14 can also be made by a drilling and plating through-hole process, wherein the aforementioned drilling can be Laser drilling or mechanical drilling is used, and a Plating Through Hole (PTH) process can form the metal cylinder 141. In addition, in the embodiment shown in FIG. 1, the inclined conductive structure 14 includes a hollow metal cylinder 141, but in other embodiments, the inclined conductive structure 14 may also be a solid metal pillar filling the through hole. For example, the inclined conductive structure 14 may be a solid metal pillar formed by electroplating. Therefore, the inclined conductive structure 14 may not include the filling material 142, and the inclined conductive structure 14 shown in FIG. 1 is only one example of the present invention, and is not intended to limit the present invention.

Please refer to FIG. 2, which is a schematic cross-sectional view of a multilayer circuit board according to another embodiment of the present invention. Similar to the foregoing embodiment, the multilayer circuit board 20 in this embodiment also includes an inclined conductive structure, and the manufacturing method thereof may be the same as the manufacturing method of the inclined conductive structure 14. In this embodiment, the multilayer circuit board 20 includes a plurality of inclined conductive structures 24a and 24b, and the multilayer circuit board 20 has more than three circuit layers. The multilayer circuit board 20 further includes a first circuit layer 21, a second circuit layer 22 and a circuit structure 23, wherein the circuit structure 23 is located between the first circuit layer 21 and the second circuit layer 22. The circuit structure 23 includes a plurality of inner circuit layers 232 to 235 and a plurality of insulating layers 131, and one of the inner circuit layers 232 to 235 is sandwiched between two adjacent insulating layers 131.

Same as the foregoing embodiment, the first circuit layer 21 extends on the first reference plane P1, and the second circuit layer 22 extends on the second reference plane P2, wherein the first reference plane P1 and the second reference plane P2 are parallel to each other. Secondly, from FIG. 2, the inclined conductive structures 24a and 24b each include a metal tube (not labeled), so the inclined conductive structures 24a and 24b are formed on the first pads 210a, 210b and the second pads 220a, 220b. Two openings (not labeled), in which the filling material 142 fills the through holes of these metal cylinders.

In this embodiment, the multilayer circuit board 20 can be a motherboard in a network server. The first circuit layer 21 and the second circuit layer 22 can be used for power supply or transmission of electrical signals to electronic components, such as microprocessors. Or a central processing unit, and the above-mentioned electronic components can be installed on the first circuit layer 21, that is, the first circuit layer 21 can be installed for one or more electronic components. For example, two central processing units can be installed on the first circuit layer 21. The inner circuit layer 232 may have a ground plane, and the inner circuit layer 233 may have multiple traces for transmitting high-speed signals. It must be noted that although the multilayer circuit board 20 of this embodiment can be a motherboard in a network server, in other embodiments, the multilayer circuit board 20 can also be a motherboard of other electronic devices, such as a notebook type. The motherboard in a computer, desktop computer, smart phone, tablet computer, or industrial computer.

The first circuit layer 21 includes two first pads 210a and 210b, and the second circuit layer 22 also includes two second pads 220a and 220b. The inclined conductive structure 24a connects the first pad 210a and the second pad 220a, and the inclined conductive structure 24b connects the first pad 210b and the second pad 220b, and the inclined conductive structures 24a and 24b pass through the circuit structure. twenty three. In this way, the first circuit layer 21 and the second circuit layer 22 can be electrically connected to each other by the inclined conductive structures 24a and 24b, so that the second circuit layer 22 can transmit power or electrical signals through the inclined conductive structures 24a and 24b at least One and the first circuit layer 21 are transferred to the electronic component. For example, after the second pads 220a and 220b are electrically connected to an external power source, the inclined conductive structures 24a and 24b can respectively transmit power to the two central processing units installed on the first circuit layer 21, so as to enable the network server working normally. In addition, in the embodiment of FIG. 2, the inclined conductive structure 24b can be further connected to a part of the inner circuit layer 233, so the above inclined conductive structure is not limited to only two circuit layers.

In the embodiment shown in FIG. 2, the first pad 210a and the second pad 220a do not overlap at all, and the first pad 210b and the second pad 220b do not overlap at all. That is, the first pads 210a, 210b and the second pads 220a, 220b are along the normal line of the first reference plane P1, and the projection areas on the first reference plane P1 do not overlap with each other. From FIG. 2, there are some inner circuit layers 233 to 235 directly below the first pads 210a and 210b and directly above the second pads 220a and 220b. In other words, the first pads 210a and 210b and the second pads 220a and 220b overlap a part of the inner circuit layers 233 to 235.

Secondly, the second circuit layer 22 also includes a conductive layer 221. Although the conductive layer 221 overlaps the first pad 210a, the second pads 220a and 220b are electrically isolated from the conductive layer 221, so that when the second pads 220a and 220b are electrically connected to an external power source, the conductive layer 221 is not It will be electrically connected to an external power source. Therefore, if the inclined conductive structure 24a is not connected to the second pad 220a, but is connected to the conductive layer 221 directly below, the operation of the multilayer circuit board 20 may be abnormal or even fail to operate.

Although the first pads 210a, 210b and the second pads 220a, 220b overlap part of the inner circuit layers 233 to 235, and the conductive layer 221 overlaps the first pad 210a, the inclined conductive structures 24a and 24b can avoid The inner circuit layers 233 to 235 and the conductive layer 221 are opened, and the first pad 210a and the second pad 220a are directly electrically connected, and the first pad 210b and the second pad 220b are directly electrically connected. In this way, basically without changing the positions of the first pads 210a, 210b and the second pads 220a, 220b and the wiring of the inner circuit layers 233 to 235, the inclined conductive structures 24a and 24b can realize the first connection. The electrical connection between the pad 210a and the second pad 220a and the electrical connection between the first pad 210b and the second pad 220b. Therefore, the use of the above-mentioned inclined conductive structures 24a and 24b can increase the flexibility and flexibility of the network server motherboard in terms of circuit design, so as to help the current network server meet the trend of increasing output power and promote the network The performance and stability of the road server are improved, thereby helping to reduce the cost of the network server.

Specifically, in the embodiment shown in FIG. 2, the multilayer circuit board 20 has six circuit layers, and the first circuit layer 21 and the second circuit layer 22 may be outer circuit layers, but in other embodiments, The multilayer circuit board 20 may be a semi-finished product, and subsequent addition, subtraction, semi-additive or superposition methods can be used to add at least one circuit layer to one of the first circuit layer 21 and the second circuit layer 22 to The inclined conductive structures 24a and 24b can be not only through holes (as shown in FIG. 2), but also blind holes or buried holes.

Although the inclined conductive structures 24a and 24b in FIG. 2 are both connected to the first circuit layer 21 and the second circuit layer 22, in other embodiments, the circuit layers connected to both ends of the inclined conductive structures 24a and 24b It can be different. For example, the inclined conductive structure 24a connects the first circuit layer 21 and the second circuit layer 22, and the inclined conductive structure 24b can connect the first circuit layer 21 and the inner circuit layer 234, but does not connect the second circuit layer 22. Do not pass through the inner circuit layer 235. In other words, for the multilayer circuit board 20 in other embodiments not shown, the inner circuit layer 234 can be used as the second circuit layer connecting the inclined conductive structure 24b, and the inner circuit layers 232 and 233 can be used as The line structure through which the inclined conductive structure 24b passes. It can be seen from this that, in at least one embodiment of the present invention, the multilayer circuit board may include at least four circuit layers and a plurality of inclined conductive structures, wherein the two ends of each inclined conductive structure are connected to the two circuit layers and pass through at least one layer. The circuit layer, and the circuit layers connected to the same upper end or lower end of these inclined conductive structures may not be the same layer.

In summary, the multilayer circuit board of the present invention includes more than three circuit layers (for example, the first and second circuit layers and at least one inner circuit layer) and at least one inclined conductive structure, wherein the inclined conductive structure is connected therein Two circuit layers, and pass through another circuit layer. Using the above-mentioned inclined conductive structure can increase the flexibility and flexibility of the circuit design of the circuit board, so that the present invention has the opportunity to not change the area and shape of the multilayer circuit board and the premise of not greatly changing the wiring of these circuit layers. Change the circuit of the multilayer circuit board to meet the needs of existing electronic equipment. For example, it helps the current network server to meet the trend of increasing output power and promotes the performance and stability of the network server.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of invention protection shall be subject to the scope of the attached patent application.

10, 20: Multilayer circuit board 11, 21: the first circuit layer P1: the first reference plane 110, 210a, 210b: the first pad 111: The first opening 12, 22: the second circuit layer P2: Second reference plane 120, 220a, 220b: second pad 121: second opening 221: conductive layer 13, 23: Line structure 130, 232~235: inner circuit layer 131: Insulation layer 14, 24a, 24b: inclined conductive structure 141: Metal cylinder 142: Filling Material X: axis R: outer diameter

FIG. 1 is a schematic cross-sectional view of a multilayer circuit board according to an embodiment of the present invention. 2 is a schematic cross-sectional view of a multilayer circuit board according to another embodiment of the invention.

10: Multilayer circuit board

11: The first circuit layer

P1: the first reference plane

110: first pad

111: The first opening

12: The second circuit layer

P2: Second reference plane

120: second pad

121: second opening

13: Line structure

130: inner circuit layer

131: Insulation layer

14: Inclined conductive structure

141: Metal cylinder

142: Filling Material

X: axis

R: outer diameter

Claims (9)

A multilayer circuit board includes: a first circuit layer extending on a first reference plane and including a first pad; a second circuit layer extending on a second reference plane and including a second pad A circuit structure, located between the first circuit layer and the second circuit layer, and includes at least one inner circuit layer, wherein the first reference plane and the second reference plane are parallel to each other; and an inclined conductive structure , Connecting the first pad and the second pad and passing through the circuit structure, wherein the axis of the inclined conductive structure is not perpendicular to the first reference plane. The multilayer circuit board according to claim 1, wherein the first pad and the second pad do not overlap at all. The multilayer circuit board according to claim 1, wherein the inclined conductive structure is electrically isolated from the inner circuit layer. The multilayer circuit board according to claim 1, wherein the inclined conductive structure includes a metal cylinder. The multilayer circuit board according to claim 4, wherein the inclined conductive structure further includes a filling material, and the metal barrel has a through hole, and the filling material fills the through hole. The multilayer circuit board according to claim 1, wherein the inclined conductive structure has an outer diameter ranging from 8 mils to 17 mils on a cross section, and the cross section is parallel to the first reference plane. The multilayer circuit board according to claim 1, wherein the number of the inclined conductive structure is multiple. The multilayer circuit board according to claim 1, wherein the at least one inner layer circuit The number of layers is multiple. The multilayer circuit board according to claim 1, wherein the circuit structure includes a plurality of insulating layers.

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