JP5787605B2 - Multilayer board - Google Patents

Description

  The present invention relates to a multilayer substrate.

  2. Description of the Related Art A multilayer board that can be used for high-speed signal transmission has been known that includes a conduction hole (for example, referred to as a via (VIA)) that is electrically connected to a conductor of a desired layer. In general, the conduction hole is formed as a through hole having a metal film on the inner surface and opening on the surface of the substrate. Particularly in high-speed signal transmission applications, it is desired to suppress transmission loss due to impedance mismatch between a conductor of a desired layer and a conduction hole connected to the conductor as much as possible.

  Patent document 1 discloses the component which is inserted in the hole of a multilayer substrate, and reduces impedance mismatching. This component includes a conductive ground core, a dielectric layer surrounding the conductive ground core, and a signal conductor layer surrounding the dielectric layer. The impedance of the component can be adjusted by selecting the dielectric layer material and the distance between the conductive ground core and the signal conductor layer. Impedance mismatch can be reduced by connecting conductors of arbitrary layers using components whose impedance is appropriately adjusted.

JP 2006-191018 A

  In a multilayer board having a conduction hole opening on the surface of the board, electromagnetic radiation from the conduction hole caused by impedance mismatch between the conductor of the desired layer and the conduction hole during high-speed signal transmission contributes to transmission loss. It may become. Therefore, it is desired to suppress electromagnetic radiation from the conduction hole in the multilayer substrate toward the outside of the substrate.

As one aspect of the present invention, a ground layer formed on the surface of the substrate, a signal layer formed inside the substrate, and a substrate electrically connected to the signal layer and adjacent to the ground layer in a non-contact manner. A multi-layer substrate having a conduction hole that opens on the surface, and a shielding member that is installed on the substrate surface while shielding the conduction hole and is electrically connected to the ground layer while being insulated from the signal layer and the conduction hole. The shielding member includes a metal plate fixed to the grounding layer, and air having a dimension to eliminate impedance mismatch between the signal layer and the conduction hole between the metal plate and the opening end of the conduction hole on the substrate surface. A multilayer substrate is provided in which layers are formed .

The present invention also provides a ground layer formed on the substrate surface, a signal layer formed inside the substrate, an electrical connection to the signal layer, and an opening on the substrate surface at a position adjacent to the ground layer in a non-contact manner. A multi-layer substrate having a conduction hole that shields the conduction hole and is provided on the substrate surface and is electrically insulated from the signal layer and the conduction hole and electrically connected to the ground layer, and is shielded member comprises an insulating adhesive to be fixed to the substrate surface to cover the through hole, and a conductive adhesive to be secured to the ground layer is disposed on the outer surface of the insulating adhesive, the insulating adhesive but having a mass to eliminate impedance mismatch between introducing hole and the signal layer, that provides a multi-layer substrate.

  The multi-layer substrate described above includes a second ground layer formed on the back surface of the substrate opposite to the front surface of the substrate, and the conduction hole opens on the back surface of the substrate at a position adjacent to the second ground layer in a non-contact manner. It can also be. In this configuration, a second shielding member that shields the conduction hole and is installed on the back surface of the substrate and is electrically connected to the second ground layer while being insulated from the signal layer and the conduction hole can be provided. .

  Since the multilayer substrate according to one embodiment of the present invention includes a shielding member that shields the conduction hole and is installed on the substrate surface and is electrically connected to the ground layer, the shielding member functions as a shield similarly to the ground layer. Is exerted to suppress electromagnetic radiation from the conduction hole toward the outside of the substrate. As a result, signal transmission loss due to electromagnetic radiation from the conduction hole toward the outside of the substrate can be prevented in advance.

1A and 1B are diagrams showing a multilayer substrate according to a first embodiment of the present invention, wherein FIG. 1A is a cross-sectional view taken along line II, and FIG. It is a figure which shows the multilayer substrate by a modification, (a) Sectional drawing along line II-II, (b) Plan view. It is a figure which shows the multilayer substrate by the 2nd Embodiment of this invention, (a) Sectional drawing along line III-III, (b) Plan view.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.

  FIG. 1 shows a multilayer substrate 10 according to a first embodiment of the present invention. The illustrated multilayer substrate 10 has a multilayer (four-layer) printed circuit board configuration that can be used for high-speed signal transmission.

  The multilayer substrate 10 is electrically connected to the ground layer 12 formed on the substrate surface 10a, the signal layers 14 and 16 formed inside the substrate, and the signal layers 14 and 16, and is not in contact with the ground layer 12 And a conduction hole 18 opened to the substrate surface 10a at a position adjacent to the substrate surface 10a. The multilayer substrate 10 further includes a second ground layer 20 formed on the substrate back surface 10b opposite to the substrate surface 10a, and the back surface of the substrate is located at a position adjacent to the second ground layer 20 in a non-contact manner. Open to 10b. Note that the names of the substrate front surface 10 a and the substrate back surface 10 b are for convenience, and do not necessarily mean the front and back in the usage pattern of the multilayer substrate 10.

  In the illustrated configuration, the signal layers 14 and 16 are different from the first signal layer 14 located on the side close to the substrate surface 10a and the first signal layer 14, and the signal layers 14 and 16 are located on the side close to the substrate back surface 10b. 2 signal layers 16. The conduction hole 18 has a metal coating 22 such as a plating layer on the inner surface, and the first and second signal layers 14 and 16 are electrically connected to each other via the metal coating 22. Note that the names of the first and second signal layers 14 and 16 are for convenience, and do not necessarily mean priority in the usage pattern of the multilayer substrate 10 (the same applies to other components). Further, the conduction hole 18 is for conducting the first and second signal layers 14 and 16 and does not have a function of a through hole for mounting an electronic component.

  The substrate structure of the multilayer substrate 10 is formed by laminating three dielectric layers 24, 26, and 28 with each other. In the central dielectric layer 24, first and second signal layers 14 and 16 are formed in a predetermined pattern on both surfaces 24a and 24b, respectively. A dielectric layer 26 is fixed to one surface (upper surface in the figure) 24 a of the dielectric layer 24 with, for example, an adhesive (not shown) sandwiching the first signal layer 14, and the outer surface of the dielectric layer 26. That is, the ground layer 12 is formed in a predetermined pattern on the substrate surface 10a. On the other surface (lower surface in the figure) 24b of the dielectric layer 24, the dielectric layer 28 is fixed by, for example, an adhesive (not shown) with the second signal layer 16 interposed therebetween, and the outer surface of the dielectric layer 28 In other words, the second ground layer 20 is formed in a predetermined pattern on the substrate back surface 10b. The conduction hole 18 has a form of a through hole that continuously penetrates the dielectric layers 24, 26, and 28 and penetrates the first and second signal layers 14 and 16.

  In the multilayer substrate 10, the first and second signal layers 14 and 16 are formed as layers different from each other in the laminated structure described above, so that signal lines can be patterned with high density. The ground layer 12 formed on the substrate front surface 10a and the ground layer 20 formed on the substrate back surface 10b are located on both outer sides of the first and second signal layers 14 and 16, and thereby the first and second signal layers are formed. Serves as a shield for layers 14 and 16. The multilayer substrate 10 having such a configuration is suitable for high-speed signal transmission.

  In the illustrated configuration, the ground layer 12 has a pattern that surrounds the conduction hole 18 that opens in the substrate surface 10a. More specifically, the conduction hole 18 is formed in a circular shape on the substrate surface 10a, and the opening end 18a is formed to be exposed on the substrate surface 10a as an annular layer integrally connected to the metal coating 22 on the inner surface. . The ground layer 12 has a circular inner edge 12a at a uniform distance from the annular opening end 18a of the metal coating 22 of the conduction hole 18, and surrounds the opening end 18a of the conduction hole 18 in a non-contact manner. To do. As a result, an annular exposed region 10 c of the substrate surface 10 a is formed around the open end 18 a of the conduction hole 18.

  In the illustrated configuration, the second ground layer 20 has a pattern surrounding the conduction hole 18 opened in the substrate back surface 10b. More specifically, on the substrate back surface 10b, the conduction hole 18 is formed in a circular shape, and the opening end 18b is formed on the substrate back surface 10b as an annular layer integrally connected to the metal coating 22 on the inner surface. . The ground layer 20 has a circular inner edge 20a at a uniform distance from the annular opening end 18b of the metal coating 22 of the conduction hole 18, and surrounds the opening end 18b of the conduction hole 18 in a non-contact manner. To do. As a result, an annular exposed region 10 d of the substrate back surface 10 b is formed around the open end 18 b of the conduction hole 18.

  The above configuration is merely an example, and the manufacturing method of the multilayer substrate 10, the number and pattern of the signal layers 14 and 16, the shape and dimensions of the conduction holes 18, the thicknesses of the dielectric layers 24, 26, and 28 are particularly limited. Not. For example, the conduction hole 18 may be formed in a shape that opens only on the substrate surface 10a and does not open on the substrate back surface 10b. In addition, the opening ends 18a and 18b of the conduction hole 18 do not have an annular layer formed on the front and back surfaces 10a and 10b, and portions corresponding to the thickness of the metal coating 22 on the inner surface are directly exposed as the opening ends 18a and 18b. (FIG. 2).

  The multilayer substrate 10 includes a shielding member 30 that shields the conduction hole 18 and is installed on the substrate surface 10a. The shielding member 30 is electrically connected to the ground layer 12 while being insulated from the signal layers 14 and 16 and the conduction hole 18. The shielding member 30 is formed from a dome-shaped metal plate 32 that is fixed to the ground layer 12. The metal plate 32 integrally includes a base end portion 32a that is in contact with the ground layer 12 and a lid portion 32b that bulges in one direction from the base end portion 32a. In the illustrated configuration, the base end portion 32a of the metal plate 32 forming the shielding member 30 has a shape of an annular flange, and is soldered to the outer surface of the ground layer 12 (for example, reflow) at a position close to the inner edge 12a of the ground layer 12. It is fixed by soldering. In a state where the shielding member 30 is properly fixed to the ground layer 12, the lid portion 32b of the metal plate 32 is disposed at a predetermined distance from the exposed region 10c of the substrate surface 10a and the opening end 18a of the conduction hole 18, A space (that is, an air layer) 34 having a predetermined size is formed between the lid portion 32 b of the metal plate 32 and the opening end 18 a of the conduction hole 18.

  The multilayer substrate 10 also includes a second shielding member 36 that shields the conduction hole 18 and is disposed on the substrate back surface 10b. The second shielding member 36 is electrically connected to the second ground layer 20 while being insulated from the signal layers 14 and 16 and the conduction hole 18. The second shielding member 36 is formed of a second dome-shaped metal plate 38 that is fixed to the second ground layer 20. The second metal plate 38 integrally includes a base end portion 38a that comes into contact with the ground layer 20 and a lid portion 38b that bulges in one direction from the base end portion 38a. In the illustrated configuration, the base end portion 38a of the metal plate 38 forming the second shielding member 36 has an annular flange shape and is soldered to the outer surface of the ground layer 20 at a position close to the inner edge 20a of the ground layer 20. It is fixed by (for example, reflow soldering). With the shielding member 36 properly fixed to the ground layer 20, the lid portion 38b of the metal plate 38 is disposed at a predetermined distance from the exposed region 10d of the substrate back surface 10b and the opening end 18b of the conduction hole 18. A space (that is, an air layer) 40 having a predetermined size is formed between the lid portion 38 b of the metal plate 38 and the opening end 18 b of the conduction hole 18.

  In the multilayer substrate 10, the open end 18 a of the conduction hole 18 due to impedance mismatch between the first and second signal layers 14 and 16 and the conduction hole 18 (metal coating 22) during high-speed signal transmission. There is a tendency to generate electromagnetic radiation from 18b to the outside of the substrate. In this regard, since the multilayer substrate 10 includes the shielding member 30 that is installed on the substrate surface 10 a while shielding the conduction hole 18 and is electrically connected to the ground layer 12, the shielding member 30 is connected to the ground layer 12. Similarly, it exerts a shielding function and acts to suppress electromagnetic radiation from the open end 18a of the conduction hole 18 toward the outside of the substrate. As a result, signal transmission loss due to electromagnetic radiation from the opening end 18a of the conduction hole 18 toward the outside of the substrate can be prevented in advance. At this time, by appropriately selecting the size of the space (air layer) 34 between the lid portion 32b of the metal plate 32 constituting the shielding member 30 and the opening end 18a of the conduction hole 18, the first and second signals are selected. Impedance mismatch between the layers 14 and 16 and the conduction hole 18 (metal coating 22) can also be eliminated.

  Further, since the multilayer substrate 10 includes the second shielding member 36 that shields the conduction hole 18 and is disposed on the substrate back surface 10b and is electrically connected to the second ground layer 20, the shielding member 36 is provided. Like the ground layer 20, it functions as a shield to suppress electromagnetic radiation from the open end 18b of the conduction hole 18 toward the outside of the substrate. As a result, signal transmission loss due to electromagnetic radiation from the opening end 18b of the conduction hole 18 toward the outside of the substrate can be prevented in advance. At this time, the first and second signals can be selected by appropriately selecting the size of the space (air layer) 40 between the lid portion 38b of the metal plate 38 constituting the shielding member 36 and the opening end 18b of the conduction hole 18. Impedance mismatch between the layers 14 and 16 and the conduction hole 18 (metal coating 22) can also be eliminated.

  Depending on the transmission speed of the signal, even if the second shielding member 36 is not used, a certain amount of transmission loss prevention effect can be obtained by the electromagnetic radiation suppressing action by the first shielding member 30. By installing the shielding members 30 and 36 on the both sides 10a and 10b of the substrate, the transmission loss prevention effect is improved. Further, when the conduction hole 18 does not open in the substrate back surface 10b, it is not necessary to use the second shielding member 36.

In the multilayer substrate 10, metal plates 32 and 38 having a dome-shaped outer shape are used as the shielding members 30 and 36. According to this configuration, according to the dimensions (diameter) of the opening ends 18a, 18b of the conduction holes 18 and the inner edges 12a, 20a of the ground layers 12, 20, the dimensions of the required spaces (air layers) 34, 40, etc. since the shielding member 30, 3 6 of the pre-optimum shape and dimensions can be prepared while simplifying the installation work of the shielding member 30 and 36, to optimize the electromagnetic radiation suppressing effect and transmission loss prevention effect by the blocking member 30, 36 be able to.

  In the multilayer substrate 10, the base end portions 32 a and 38 a of the metal plates 32 and 38 constituting the shielding members 30 and 36 can be fixed to the outer surfaces of the ground layers 12 and 20 by reflow soldering. According to this configuration, since the shielding members 30 and 36 can be installed simultaneously with the mounting process of the electronic components on the substrate front surface 10a and the substrate back surface 10b of the multilayer substrate 10, the installation work of the shielding members 30 and 36 can be further simplified.

  The method for fixing the metal plates 32 and 38 constituting the shielding members 30 and 36 to the ground layers 12 and 20 is not limited to soldering. For example, as shown in FIG. 2 as a modified example, a pair of fixings are made in the through holes 42 provided in advance in the base end portions 32a and 38a of the metal plates 32 and 38, the ground layers 12 and 20 and the dielectric layers 24, 26 and 28. The metal plates 32 and 38 can be fixed to the ground layers 12 and 20 by press-fitting the pins 44 from the metal plates 32 and 38 side, respectively. Alternatively, like a so-called DIP component, a pin-shaped leg portion (not shown) is formed in advance on the base end portions 32a and 38a of the metal plates 32 and 38, and the leg portion is inserted into the through hole 42 and soldered. The metal plates 32 and 38 can be fixed to the ground layers 12 and 20 by fixing by the above.

  FIG. 3 shows a multilayer substrate 50 according to a second embodiment of the present invention. The multilayer substrate 50 has the same configuration as that of the multilayer substrate 10 according to the first embodiment except for the configuration of the shielding member. Accordingly, corresponding components are denoted by the same reference numerals, and description thereof is omitted.

  The multilayer substrate 50 includes a shielding member 52 that shields the conduction hole 18 and is installed on the substrate surface 10a. The shielding member 52 is electrically connected to the ground layer 12 while being insulated from the signal layers 14 and 16 and the conduction hole 18. The shielding member 52 covers the opening end 18a of the conduction hole 18 and is fixed to the exposed region 10c of the substrate surface 10a. The shielding member 52 is disposed on the outer surface 54a of the insulating adhesive 54 and is disposed on the ground layer 12. It is formed from the conductive adhesive 56 to be fixed. With the shielding member 52 properly fixed to the ground layer 12, the conductive adhesive 56 is a distance determined by the amount of the insulating adhesive 54 from the exposed region 10c of the substrate surface 10a and the open end 18a of the conduction hole 18. Spaced apart. The insulating adhesive 54 and the conductive adhesive 56 can be manufactured by a coating process such as potting, but the manufacturing method is not particularly limited.

  The multilayer substrate 50 also includes a second shielding member 58 that shields the conduction hole 18 and is disposed on the substrate back surface 10b. The second shielding member 58 is electrically connected to the second ground layer 20 while being insulated from the signal layers 14 and 16 and the conduction hole 18. The second shielding member 58 covers the opening end 18 b of the conduction hole 18 and is fixed to the exposed region 10 d of the back surface 10 b of the substrate, and the outer surface of the second insulating adhesive 60. The second conductive adhesive 62 is disposed at 60 a and is fixed to the second ground layer 20. In a state where the shielding member 58 is properly fixed to the ground layer 20, the second conductive adhesive 62 is applied from the exposed region 10d of the substrate back surface 10b and the opening end 18b of the conduction hole 18 to the second insulating adhesive 60. Are spaced apart by a distance determined by the amount of. Note that the insulating adhesive 60 and the conductive adhesive 62 can be manufactured by a coating process such as potting, but the manufacturing method is not particularly limited.

  Since the multilayer substrate 50 includes the shielding member 52 (particularly the conductive adhesive 56) that is installed on the substrate surface 10 a while shielding the conduction hole 18 and electrically connected to the ground layer 12, the shielding member 52. (Especially, the conductive adhesive 56) exerts a shielding function similarly to the ground layer 12, and acts to suppress electromagnetic radiation from the opening end 18a of the conduction hole 18 toward the outside of the substrate. As a result, signal transmission loss due to electromagnetic radiation from the opening end 18a of the conduction hole 18 toward the outside of the substrate can be prevented in advance. At this time, impedance mismatch between the first and second signal layers 14 and 16 and the conduction hole 18 (metal coating 22) is eliminated by appropriately selecting the amount of the insulating adhesive 54 constituting the shielding member 52. You can also

  Further, the multilayer substrate 50 is installed on the substrate back surface 10b while shielding the conduction hole 18, and is electrically connected to the second ground layer 20 (particularly the second conductive adhesive). 62), the second shielding member 58 (especially the second conductive adhesive 62) exhibits a shielding function in the same manner as the ground layer 20, and the outside end 18b of the conduction hole 18 is exposed to the outside of the substrate. It acts to suppress the electromagnetic radiation that goes. As a result, signal transmission loss due to electromagnetic radiation from the opening end 18b of the conduction hole 18 toward the outside of the substrate can be prevented in advance. At this time, the impedance of the first and second signal layers 14 and 16 and the conduction hole 18 (metal coating 22) is reduced by appropriately selecting the amount of the second insulating adhesive 60 constituting the shielding member 58. The consistency can also be eliminated.

  Depending on the transmission speed of the signal, even if the second shielding member 58 is not used, a certain amount of transmission loss prevention effect can be obtained by the electromagnetic radiation suppressing action by the first shielding member 52. By installing the shielding members 52 and 58 on the both sides 10a and 10b of the substrate, the effect of preventing transmission loss is improved. Further, when the conduction hole 18 does not open in the substrate back surface 10b, it is not necessary to use the second shielding member 58.

  In the multilayer substrate 50, a laminated body of insulating adhesives 54 and 60 and conductive adhesives 56 and 62 is used as the shielding members 52 and 58. According to this configuration, the amounts of the insulating adhesives 54 and 60 are adjusted with respect to the multilayer substrate 50 having different dimensions (diameters) of the opening ends 18a and 18b of the conduction hole 18 and the inner edges 12a and 20a of the ground layers 12 and 20. As a result, the conductive adhesives 56 and 62 having the optimum shape and size can be appropriately produced. Therefore, the installation work of the shielding members 52 and 58 can be simplified, and the electromagnetic radiation suppressing action and transmission loss prevention by the shielding members 52 and 58 can be achieved. The effect can be optimized.

DESCRIPTION OF SYMBOLS 10, 50 Multilayer board | substrate 12 Ground layer 14 1st signal layer 16 2nd signal layer 18 Conductive hole 20 2nd ground layer 30, 52 Shielding member 32 Metal plate 36, 58 2nd shielding member 38 2nd metal Plate 44 Fixing pin 54 Insulating adhesive 56 Conductive adhesive 60 Second insulating adhesive 62 Second conductive adhesive

Claims (5)

A ground layer formed on the surface of the substrate, a signal layer formed inside the substrate, and electrically connected to the signal layer and open to the surface of the substrate at a position adjacent to the ground layer in a non-contact manner In a multilayer substrate comprising holes,
A shielding member that shields the conduction hole and is installed on the substrate surface and is electrically connected to the ground layer in a state of being insulated from the signal layer and the conduction hole;
The shielding member includes a metal plate fixed to the ground layer ,
A multilayer substrate, wherein an air layer having a dimension that eliminates impedance mismatch between the signal layer and the conduction hole is formed between the metal plate and the opening end of the conduction hole on the substrate surface . A ground layer formed on the surface of the substrate, a signal layer formed inside the substrate, and electrically connected to the signal layer and open to the surface of the substrate at a position adjacent to the ground layer in a non-contact manner In a multilayer substrate comprising holes,
A shielding member that shields the conduction hole and is installed on the substrate surface and is electrically connected to the ground layer in a state of being insulated from the signal layer and the conduction hole;
The shielding member includes an insulating adhesive that covers the conduction hole and is fixed to the surface of the substrate, and a conductive adhesive that is disposed on the outer surface of the insulating adhesive and is fixed to the grounding layer. And
The multilayer substrate , wherein the insulating adhesive has an amount that eliminates impedance mismatch between the signal layer and the conduction hole . 2. A second grounding layer formed on the back surface of the substrate opposite to the front surface of the substrate, wherein the conduction hole opens on the back surface of the substrate at a position adjacent to the second grounding layer in a non-contact manner. The multilayer substrate according to 1 or 2 . A second shielding member that shields the conduction hole and is installed on the back surface of the substrate and is electrically connected to the second ground layer in a state of being insulated from the signal layer and the conduction hole;
The second shielding member includes a second metal plate fixed to the second ground layer ,
Between the open end of the substrate back surface of the second metal plate and the conductive hole, an air layer sized to eliminate an impedance mismatch between the through hole and said signal layer is Ru is formed, in claim 3 The multilayer substrate described. A second shielding member that shields the conduction hole and is installed on the back surface of the substrate and is electrically connected to the second ground layer in a state of being insulated from the signal layer and the conduction hole;
The second shielding member is disposed on the outer surface of the second insulating adhesive so as to cover the conduction hole and to be fixed to the back surface of the substrate. A second conductive adhesive fixed to the formation ,
It said second insulating adhesive, to have the amount to overcome the impedance mismatch between the through hole and the signal layer, multi-layer substrate of claim 3.

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