Laminated substrate and manufacturing method of the laminated substrate

Abstract

To provide a laminated substrate capable of ensuring a long-term reliability by preventing stress from being applied to a conductive paste for electrical connection when the laminated substrate is manufactured by laminating a plurality of multilayer substrates.SOLUTION: In a laminated substrate 100 formed by laminating a plurality of multilayer substrates 10, in each multilayer substrate 10, a through hole 30 penetrating through each multilayer substrate 10 and having an inner wall surface plated and filled with a resin 32 therein, and bonding lands 34 electrically connected to the through hole 30 are formed on an upper surface and a lower surface of the through hole 30. An insulating adhesive layer 40 and a conductive paste via 50 for electrically connecting the bonding lands 34 of the opposed multilayer substrates to each other by a conductive paste filled in a through hole 46 formed in the insulating adhesive layer 40 are provided between the multilayer substrates 10, and the conductive paste via 50 is provided at a position different from the position where the through hole 30 is formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated substrate and a method for manufacturing a laminated substrate. [Background technology]

[0002] 2. Description of the Related Art Conventionally, circuit boards such as printed wiring boards have been widely used in general to incorporate electronic components into electronic devices in a compact manner. On the other hand, along with the demand for smaller, higher performance, and lower prices for electronic devices, the electronic circuits on circuit boards have rapidly become finer, more multilayered, and the electronic components have become more densely mounted, and there has been active research into multilayer boards that use printed wiring boards in a multilayer structure.

[0003] When forming through holes in a multilayer board, the more layers there are and the thicker the board, the larger the drill diameter required to drill the through holes. This makes it impossible to accommodate finer pitches, so a method has been studied in which multilayer boards with a small number of layers are prepared with through holes formed using drills with as small a diameter as possible, and then multiple such multilayer boards are stacked together to finally produce a multilayer laminate board.

[0004] For example, Patent Document 1 discloses a laminated substrate in which an adhesive layer is laminated on the top surface of one multilayer substrate, through holes are drilled in the adhesive layer, the through holes are filled with a conductive paste, and the other multilayer substrate is laminated on top of the adhesive layer and the conductive paste. The layers of each multilayer board are connected to each other by through holes whose inner walls are plated, and the upper and lower surfaces of these through holes are provided with bonding lands made of metal layers. The conductive paste described above electrically connects these bonding lands together. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-258779 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned Patent Document 1 discloses a configuration in which bonding lands of through holes that penetrate each multilayer board and connect the layers are electrically connected to each other by a conductive paste.

[0007] However, the through holes formed in each multilayer board are filled with resin to bond the layers that make up the multilayer board together, and so if conductive paste is placed directly on top of the through holes, the thermal expansion of the resin will place stress on the conductive paste when the multilayer boards are joined together by thermocompression, posing a problem that could impair the long-term reliability of the conductive paste.

[0008] Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to provide a laminated substrate and a method for manufacturing a laminated substrate that can ensure long-term reliability when manufacturing a laminated substrate by stacking multiple multilayer substrates, by preventing stress from being applied to the conductive paste that electrically connects them to each other. [Means for solving the problem]

[0009] According to the laminated board of the present invention, the laminated board is formed by stacking a plurality of multilayer boards, and each multilayer board has a through hole that penetrates the multilayer board, the inner wall surface of which is plated and the interior of which is filled with resin, and a bonding land that is electrically connected to the through hole on the upper and lower surfaces of the through hole, and an insulating adhesive layer and a conductive paste via that electrically connects the bonding lands of opposing multilayer boards to each other by a conductive paste filled in the through hole formed in the insulating adhesive layer are provided between each multilayer board, and the conductive paste via is provided at a position different from the position where the through hole is formed. By adopting this configuration, even if the resin in the through hole expands due to heat, the conductive paste via is located in a different position from the through hole, so it is not subjected to stress caused by the effects of thermal expansion and long-term reliability can be maintained.

[0010] The conductive paste via may be provided in plural at positions away from the through holes for each pair of the bonding lands. With this configuration, even when a relatively large current flows through a through hole for a power supply, the provision of multiple conductive paste vias reduces the resistance value and prevents an increase in heat generation. By preventing an increase in heat generation, the risk of melting can be eliminated.

[0011] The bonding land may be formed to a size that allows the plurality of conductive paste vias to be arranged thereon.

[0012] The bonding land may be formed in a substantially rectangular shape with the through hole at its center so that the conductive paste vias are provided at four locations around the through hole.

[0013] The bonding land may be substantially elliptical or oval in shape, connecting the position where the conductive paste via is provided and the position of the through hole. According to this configuration, for through holes that require noise countermeasures, such as signal lines, the area of ​​the bonding lands can be made as small as possible to reduce noise.

[0014] The bonding land may also be characterized in that it has a shape in which a first circular portion surrounding the through hole and a second circular portion surrounding the position where the conductive paste is to be applied are connected. In this configuration as well, noise can be reduced by making the area of ​​the bonding land as small as possible for through holes that require noise countermeasures, such as signal lines.

[0015] According to the method for manufacturing a laminated substrate of the present invention, there is provided a method for manufacturing a laminated substrate by stacking a plurality of multilayer substrates each having a through hole whose inner wall surface is plated and filled with resin, and a bonding land on the upper and lower surfaces of the through hole that is electrically connected to the through hole, the method comprising the steps of: laminating an insulating adhesive layer on the upper surface of one of the multilayer substrates; forming a through hole that penetrates the insulating adhesive layer at a position different from the position where the through hole is formed, so that the bonding lands of the one multilayer substrate and another multilayer substrate facing the one multilayer substrate can be electrically connected to each other; filling the through hole with a conductive paste to form a conductive paste via; and thermocompressing the plurality of multilayer substrates together to harden the insulating adhesive layer and the conductive paste, thereby integrating the plurality of multilayer substrates. According to this method, even if the resin in the through-hole expands due to heat, the conductive paste via is located in a different position from the through-hole, so that a laminated substrate can be obtained that is not subjected to stress caused by thermal expansion and can maintain long-term reliability.

[0016] Furthermore, the method may include a step of filling recesses between the bonding land and another metal layer or another bonding land on the upper surface of the first multilayer substrate and the lower surface of the other multilayer substrate with insulating resin before the step of laminating an insulating adhesive layer on the upper surface of the first multilayer substrate and the lower surface of the other multilayer substrate, and polishing the surface to flatten the surface facing the other multilayer substrate so that there are no irregularities. According to this method, the flatness of the laminated substrate can be maintained, and the electrical connection layer formed by the conductive paste vias can be made uniform over the entire substrate, thereby preventing the occurrence of abnormal resistance values. [Effects of the Invention]

[0017] According to the present invention, when manufacturing a laminated substrate by stacking a plurality of multilayer substrates, stress is not applied to the conductive paste that establishes electrical connection between the substrates, thereby ensuring long-term reliability. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a laminated substrate. [Figure 2] FIG. 10 is a schematic plan view of a bonding land showing an example in which a plurality of conductive paste vias are arranged for one through hole. [Figure 3] FIG. 10 is a schematic plan view of a bonding land showing an example in which one conductive paste via is arranged for one through hole. [Figure 4] 1 is a schematic cross-sectional view (part 1) illustrating an example of a method for manufacturing a multilayer substrate according to the present embodiment. [Figure 5] 4 is a schematic cross-sectional view (part 2) illustrating an example of a method for manufacturing a multilayer substrate according to the present embodiment. [Figure 6] 10 is a schematic cross-sectional view (part 3) illustrating an example of a method for manufacturing a multilayer substrate according to the present embodiment. [Figure 7] 10 is a schematic cross-sectional view (part 4) illustrating an example of a method for manufacturing a multilayer substrate according to the present embodiment. [Figure 8] 5 is a schematic cross-sectional view (part 5) illustrating an example of a method for manufacturing a multilayer substrate according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] (Laminated substrate) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. Figure 1 shows a schematic cross-sectional view of a laminated substrate. In this embodiment, for convenience, the "top surface" or "bottom surface" may be described based on the top-bottom direction in the drawings, but the top and bottom surfaces of the laminated substrate 100 or the multilayer substrate 10 may not be aligned with the actual top-bottom direction. Furthermore, the laminated substrate 100 or the multilayer substrate 10 may be described as a "side surface," but the side surface means the side surface in contrast to the top and bottom surfaces described above.

[0020] The laminated substrate 100 shown in Figure 1 is, as an example, configured by stacking two multilayer substrates 10 in the vertical direction and electrically connecting them to each other, but is not limited to stacking two multilayer substrates 10 and can be applied to stacking two or more multiple multilayer substrates 10. Moreover, the laminated substrate 100 shown in FIG. 1 is described as an example in which both are MLBs (multilayer printed wiring boards).

[0021] Each multilayer substrate 10 has an insulating layer 20 made of a plurality of insulating base materials and a metal layer (not shown) formed on the upper or lower surface of each insulating layer 20, and has through holes 30 formed therethrough in the vertical direction.

[0022] The insulating layer 20 is not particularly limited as long as it is an insulating layer used in a multilayer substrate, and can be appropriately selected depending on the purpose. For example, an inorganic base material such as an inorganic woven fabric or inorganic nonwoven fabric using glass cloth or the like, or a base material whose hardness is reinforced by an organic base material such as an organic woven fabric or organic nonwoven fabric can be used.

[0023] More specifically, for example, the insulating layer 20 may be made of a glass epoxy substrate (a glass woven fabric substrate impregnated with epoxy resin, a glass nonwoven fabric substrate impregnated with epoxy resin), a glass woven fabric substrate impregnated with bismaleimide triazine resin, an aramid nonwoven fabric substrate impregnated with epoxy resin, or a glass woven fabric substrate impregnated with modified polyphenylene ether resin.

[0024] The inner walls of the through holes 30 are plated with a metal such as copper to form a plating layer 35, and the hollow portion further inside the plating layer 35 is filled with resin 32. Resin 32 is filled to bond the layers that make up each multilayer board together so that they do not separate.

[0025] On the upper and lower surfaces of each multilayer substrate 10, bonding lands 34 for electrically connecting to the through holes 30 of other multilayer substrates 10 or to semiconductor elements or the like (not shown) are formed to close the through holes 30. The bonding lands 34 are electrically connected to the plating layers 35 of the through holes 30, and can be made of a metal such as copper.

[0026] An adhesive layer 40 is interposed between the multilayer substrates 10. A thermosetting resin can be used as the adhesive layer 40, and as an example, a glass epoxy prepreg can be used.

[0027] 1, the bonding lands 34 on the upper surface of the lower multilayer substrate 10 and the bonding lands 34 on the lower surface of the upper multilayer substrate 10 are electrically connected by vias. These vias are conductive paste vias 50 made of conductive paste. The conductive paste may contain a conductive filler and a binder resin.

[0028] The conductive paste vias 50 are provided at positions different from the through holes 30, i.e., positions that are not directly above or directly below the through holes 30. In other words, the through holes 30 of the two multilayer substrates 10 are arranged in a straight line in the vertical direction, but the conductive paste vias 50 are provided at positions that are not aligned with this straight line.

[0029] In other words, if the conductive paste vias 50 are located directly above and directly below the through holes 30, if the resin 32 in the through holes 30 thermally expands due to thermocompression bonding when joining the multilayer substrates 10 together, stress will be applied to the conductive paste vias 50, which may hinder the long-term reliability of the conductive paste vias 50. Therefore, by locating the conductive paste via 50 in a position that is not directly above or directly below the through hole 30, the conductive paste via 50 is not subjected to stress due to thermal expansion of the resin 32 in the through hole 30, thereby ensuring long-term reliability.

[0030] Although Figure 1 illustrates multiple conductive paste vias 50 provided for one through hole 30, the number of conductive paste vias 50 for one through hole 30 is not limited to any particular number, and one or multiple conductive paste vias 50 can be provided for one through hole 30.

[0031] In addition, the placement position of the conductive paste via 50 must be a distance away from the resin 32 that is sufficient to avoid being affected by the thermal expansion of the resin 32 in the through hole 30, and is set appropriately based on the type of resin 32 and the diameter of the through hole 30.

[0032] In addition, insulating resin 42 for flattening the surface of the multilayer substrate 10 is arranged between the bonding land 34 on the top surface of the lower multilayer substrate 10 and the adjacent metal layer 38 (or the bonding land 34 in an adjacent position), and between the bonding land 34 on the bottom surface of the upper multilayer substrate 10 and the adjacent metal layer 38 (or the bonding land 34 in an adjacent position).

[0033] That is, since the multilayer substrate 10 has a metal layer 38 including bonding lands 34 on its upper and lower surfaces that protrude from the surface of the insulating layer 20, the metal layer 38 is arranged to fill the step, and the upper surface of the multilayer substrate 10 arranged on the lower side and the lower surface of the multilayer substrate 10 arranged on the upper side can be flattened.

[0034] 2 and 3 show schematic plan views of the bonding land portion. 2, the bonding land 34 is sized so that multiple conductive paste vias 50 can be arranged on the bonding land 34 of one through hole 30. Specifically, the planar shape of the bonding land 34 is roughly rectangular. The through hole 30 is arranged approximately in the center of this rectangular shape, and the conductive paste vias 50 are arranged at four locations around the through hole 30 (at the corners of the rectangle). In FIG. 2, the through holes 30 are shown by dashed lines.

[0035] As an example, if the diameter of the through hole 30 is 250 μm and the diameter of the conductive paste via 50 is 180 μm, and the length of one side of the bonding land 34 is 720 μm, four conductive paste vias 50 can be placed within one bonding land 34 for one through hole 30 in positions that do not overlap with the through hole 30.

[0036] In FIG. 2, four conductive paste vias 50 are arranged for the bonding land 34 of one through hole 30, but the number of conductive paste vias 50 is not limited to four, and two or three conductive paste vias 50 may be arranged. Furthermore, when a plurality of conductive paste vias 50 are arranged for the bonding land 34 of one through-hole 30, the planar shape of the bonding land 34 is not limited to a substantially rectangular shape.

[0037] 2, a case where multiple conductive paste vias 50 are arranged for the bonding land 34 of one through hole 30 can be considered, for example, when a relatively large current flows through the through hole 30 for a power supply. By providing multiple conductive paste vias 50 for the through hole 30 through which a large current flows, the resistance value is reduced, and it is possible to prevent an increase in the amount of heat generated. In this way, by preventing an increase in the amount of heat generated, it is possible to eliminate the risk of melting at the stacking points of the multilayer substrates 10.

[0038] FIG. 3 shows an example in which one conductive paste via 50 is arranged for the bonding land 34 of one through hole 30. In this case, the planar shape of the bonding land 34 is a gourd or a potbelly shape with a large circle and a small circle partially overlapping each other. Specifically, the bonding land 34 has a shape in which a first circular portion 34a surrounding the through hole 30 and a second circular portion 34b surrounding the conductive paste via 50 are connected.

[0039] As an example, when the diameter of the through hole 30 is 250 μm and the diameter of the conductive paste via 50 is 180 μm, the diameter of the first circular portion 34a can be 500 μm and the diameter of the second circular portion 34b can be 340 μm.

[0040] As shown in Fig. 3, a case where one conductive paste via 50 is arranged for one bonding land 34 of one through hole 30 may be the case where the through hole 30 requires noise countermeasures for signal lines, etc. In this case, if the area of ​​the bonding land 34 is large as shown in Fig. 2, the influence of noise may become greater, so it is necessary to make the area of ​​the bonding land 34 as small as possible. Therefore, by making the areas of the bonding land 34a for the through hole 30 and the bonding land 34b for the conductive paste via 50 as small as possible, and by making these two bonding lands 34a and 34b partially overlapping each other, it is possible to eliminate stubs and reduce the effects of noise.

[0041] In addition, when one conductive paste via 50 is placed for the joining land 34 of one through hole 30, the shape of the joining land 34 is not limited to the shape shown in Figure 3, and may be an approximately elliptical or approximately oval shape that connects the position where the through hole 30 is placed and the position where the conductive paste via 50 is placed (not shown).

[0042] (Laminated substrate manufacturing method) Next, a method for manufacturing a multilayer substrate will be described with reference to Fig. 4. The multilayer substrate 10 in Fig. 4 is the same as that shown in Fig. 1, and the same reference numerals as in Fig. 1 are used for the structure, and a description thereof will be omitted. First, when stacking multilayer substrates 10 together, insulating resin 42 is filled into recesses between the bonding lands 34 and the metal layers 38 (or other adjacent bonding lands 34) to make the surface facing other multilayer substrates 10 flat. Then, the insulating resin 42 is polished to flatten the surface facing other multilayer substrates 10 so that there are no irregularities. This maintains the flatness of the laminated substrate 100, makes the electrical connection layer formed by the conductive paste vias 50 uniform across the entire substrate, and prevents abnormal resistance values ​​from occurring.

[0043] 5, an adhesive layer 40 is laminated on the surface facing the other multilayer substrate 10. As described above, a thermosetting resin can be used for the adhesive layer 40, and as an example, a glass epoxy prepreg can be used. In addition, a resin film 44 is laminated on the upper surface of the adhesive layer 40 to protect the surface of the adhesive layer 40 . The adhesive layer 40 and the resin film 44 may be previously integrated into a sheet.

[0044] Next, as shown in FIG. 6, through holes 46 are formed in the adhesive layer 40 and the resin film 44. The through holes 46 are bottomed through holes 46 that penetrate the adhesive layer 40 and the resin film 44 and have the bonding land 34 as the bottom. The through holes 46 can be formed by laser processing, for example. The types of laser processing include CO2 laser, YAG laser, etc., but are not limited to these and can be appropriately selected depending on the purpose.

[0045] As shown in FIG. 1, multiple conductive paste vias 50 are arranged for the bonding land 34 of one through hole 30, and therefore multiple through holes 46 are drilled at positions different from the position where the through hole 30 is formed, and away from the position directly above the through hole 30.

[0046] Next, as shown in FIG. 7, the through holes 46 are filled with a conductive paste, and then the resin film 44 is peeled off. As a result, conductive paste vias 50 are formed, and by peeling off the resin film 44, the conductive paste protrudes above the adhesive layer 40 by the thickness of the resin film 44. Because the conductive paste protrudes from the adhesive layer 40, the conductive paste can be reliably bonded to the bonding lands 34 of other multilayer substrates 10.

[0047] 8, another multilayer substrate 10 is stacked on the multilayer substrate 10 on which the adhesive layer 40 and the conductive paste vias 50 have been formed. Note that the bottom surface of the other multilayer substrate 10 has an insulating resin 42 filled in the recess between the bonding land 34 and the metal layer 38 (or another adjacent bonding land 34), and is flattened to eliminate irregularities. The multilayer substrates 10 are then bonded together by thermocompression. The thermocompression hardens the adhesive layer 40 and the conductive paste vias 50, and a laminated substrate 100 is formed in which a plurality of multilayer substrates 10 are stacked.

[0048] (Another embodiment of the laminated substrate) 1, the multilayer substrates 10 constituting the laminated substrate 100 may both be MLBs (multilayer printed wiring boards), or the lower multilayer substrate 10 may be an MLB (multilayer printed wiring board) and the upper multilayer substrate 10 may be a PKG (semiconductor package substrate). Alternatively, the lower multilayer substrate 10 may be an MLB (multilayer printed wiring board) and the upper multilayer substrate 10 may be a CL (coreless semiconductor package substrate). Alternatively, the lower multilayer substrate 10 may be an MLB (multilayer printed wiring board), and the upper multilayer substrate 10 may be a CL (coreless semiconductor package substrate) laminated on both the top and bottom surfaces of the lower multilayer substrate 10 which is an MLB (multilayer printed wiring board).

[0049] The laminated substrate 100 of this embodiment can be used as a motherboard (support substrate) and also as an interposer (relay substrate). It can be used particularly as a motherboard or interposer for server systems or high-speed communication systems, and can also be used as a circuit board for constituting semiconductor elements. It can also be applied to inspection equipment, probe cards, and the like used to determine the quality of semiconductors. [Explanation of symbols]

[0050] 10 Multilayer board 20 insulating layer 30 through holes 32 Resin 34 Bonding Land 34a First circular section 34b Second circular section 35 plating layer 38 Metal layer 40 Adhesive layer 40 Insulating adhesive layer 42 Insulating resin 44 Resin film 46 Through hole 50 conductive paste vias 100 laminated board

Claims

1. A laminated substrate formed by stacking a plurality of multilayer substrates, Each multilayer board is formed with a through hole that penetrates the multilayer board, has an inner wall surface plated, and is filled with resin, and bonding lands that are electrically connected to the through hole on the upper and lower surfaces of the through hole, Between each multilayer board, an insulating adhesive layer; a conductive paste via that electrically connects the bonding lands of the opposing multilayer substrates to each other by a conductive paste filled in a through hole formed in the insulating adhesive layer, The laminated substrate is characterized in that the conductive paste vias are provided at positions different from positions at which the through holes are formed.

2. 2. The laminated substrate according to claim 1, wherein a plurality of the conductive paste vias are provided for each pair of the bonding lands at positions different from positions at which the through holes are formed.

3. 3. The laminated substrate according to claim 2, wherein the bonding land is formed to a size that allows the plurality of conductive paste vias to be arranged thereon.

4. 4. The laminated substrate according to claim 3, wherein the bonding land is formed in a substantially rectangular shape with the through hole at its center so that the conductive paste vias are provided at four locations around the through hole.

5. 2. The laminated substrate according to claim 1, wherein the bonding land has a generally elliptical or oval shape that connects the position where the conductive paste via is provided and the position of the through hole.

6. 2. The laminated substrate according to claim 1, wherein the bonding land has a shape formed by connecting a first circular portion surrounding the through hole and a second circular portion surrounding the position where the conductive paste is applied.

7. A method for manufacturing a laminated substrate by stacking a plurality of multilayer substrates each having a through hole whose inner wall surface is plated and filled with resin, and bonding lands on the top and bottom surfaces of the through hole that are electrically connected to the through hole, laminating an insulating adhesive layer on the top surface of one multilayer substrate; forming a through hole that penetrates the insulating adhesive layer at a position different from the position where the through hole is formed, so that the bonding lands of one multilayer substrate and another multilayer substrate facing the one multilayer substrate can be electrically connected to each other; filling the through holes with a conductive paste to form conductive paste vias; and a step of thermocompressing a plurality of multilayer substrates together to harden the insulating adhesive layer and the conductive paste, thereby integrating the plurality of multilayer substrates.

8. Before the step of laminating an insulating adhesive layer on the top surface of the first multilayer substrate, 8. The method for manufacturing a laminated substrate according to claim 7, further comprising the steps of filling recesses between the bonding lands and other metal layers or other bonding lands on the upper surface of the first multilayer substrate and the lower surface of the other multilayer substrate with insulating resin, and polishing the surface to flatten the surface facing the other multilayer substrate so that there are no irregularities.

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