Manufacturing method for multilayer substrates

Abstract

This maintains the flatness of the laminated substrate and ensures that the electrical connection layer using conductive paste vias is uniform across the entire substrate, preventing the occurrence of abnormal resistance values. [Solution] A laminated substrate 100 is formed by stacking multiple multilayer substrates 10, and each multilayer substrate 10 has a through-hole 30 that penetrates the multilayer substrate 10, has its inner wall surface plated and is filled with resin 32, and bonding lands 34 that are electrically connected to the through-hole 30 are formed on the upper and lower surfaces of the through-hole 30, and between each multilayer substrate 10 there is an insulating adhesive layer 40 and conductive paste vias 50 that electrically connect the bonding lands 34 of opposing multilayer substrates by conductive paste filled in through-holes 46 formed in the insulating adhesive layer 40, and insulating resin 42 is filled in the recess between the bonding lands 34 and other metal layers 38 or other bonding lands 34.

Description

Technical Field

[0001] The present invention 、 relates to a method for manufacturing a laminated substrate.

Background Art

[0002] Conventionally, circuit boards such as printed wiring boards have been widely used in general in order to compactly incorporate electronic components into electronic devices. On the other hand, with the demands for miniaturization, high performance, and low cost of electronic devices, the miniaturization, multilayerization of electronic circuits on circuit boards, and high-density mounting of electronic components have rapidly progressed, and studies on multilayer substrates with a multilayer structure of printed wiring boards have become active.

[0003] When forming through-holes in a multilayer substrate, the drill diameter for drilling the through-holes must be increased as the number of layers increases and the board thickness increases. Then, since it is impossible to cope with fine pitch, it has been considered to prepare a multilayer substrate in which through-holes are formed with a drill having as thin a diameter as possible in a state where the number of layers is not too large, and to stack a plurality of these multilayer substrates to finally obtain a multilayer laminated substrate.

[0004] For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-258779) discloses a laminated substrate in which an adhesive layer is laminated on the upper surface of one multilayer substrate, through-holes are drilled in this adhesive layer, conductive paste is filled in these through-holes, and the other multilayer substrate is laminated on the adhesive layer and the conductive paste. Further, each multilayer substrate is interlayer-connected by through-holes whose inner walls are plated, and bonding lands formed of metal layers are formed on the upper and lower surfaces of these through-holes. The above-described conductive paste electrically connects these bonding lands to each other.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In the aforementioned Patent Document 1, an adhesive layer is provided between the multilayer substrates when joining them together. However, since a bonding land, which is a metal layer, is formed on the opposing surfaces of the multilayer substrates, even if an adhesive layer is provided, the overall flatness of the laminated substrate formed by stacking the multilayer substrates may deteriorate. If the overall flatness of the laminated substrate deteriorates, there is a risk that abnormal resistance values ​​may occur at the electrical connection points made by conductive paste vias.

[0007] Therefore, the present invention has been made to solve the above problems, and its objective is to prevent abnormal resistance values ​​in the conductive paste used to electrically connect multiple multilayer substrates when manufacturing a laminated substrate by stacking multiple multilayer substrates, thereby ensuring long-term reliability. The product The objective is to provide a method for manufacturing layered substrates. [Means for solving the problem]

[0009] The present invention relates to a method for manufacturing a laminated substrate, which involves stacking multiple multilayer substrates, each having through-holes with plated inner walls and resin-filled interiors, and bonding lands electrically connected to the through-holes on the upper and lower surfaces of the through-holes, comprising the steps of: laminating an insulating adhesive layer onto the upper surface of one multilayer substrate; forming through-holes through the insulating adhesive layer so as to electrically connect the bonding lands of one multilayer substrate and other multilayer substrates facing the one multilayer substrate; filling the through-holes with conductive paste to form conductive paste vias; and thermocompressing the multiple multilayer substrates to cure the insulating adhesive layer and the conductive paste and integrate the multiple multilayer substrates, wherein, prior to the step of laminating the insulating adhesive layer onto the upper surface of the one multilayer substrate, the upper surface of the one multilayer substrate and Opposite the upper surface of the first multilayer substrate The lower surface of the other multilayer substrate eachThe present invention is characterized by including a step of filling the recess between the bonding land and another metal layer or another bonding land with insulating resin and polishing the surface to flatten it so that there are no irregularities on the surface facing other multilayer substrates. This method maintains the flatness of the laminated substrate and ensures that the electrical connection layer using conductive paste vias is uniform across the entire substrate, preventing the occurrence of abnormal resistance values. [Effects of the Invention]

[0010] According to the present invention, the flatness of the laminated substrate can be maintained, and the electrical connection layer using conductive paste vias can be made uniform throughout the substrate, thereby preventing the occurrence of abnormal resistance values. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an example of a multilayer substrate. [Figure 2] This is a schematic cross-sectional view (part 1) showing an example of a method for manufacturing a multilayer substrate in this embodiment. [Figure 3] This is a schematic cross-sectional view (part 2) showing an example of a method for manufacturing a multilayer substrate in this embodiment. [Figure 4] This is a schematic cross-sectional view (part 3) showing an example of a method for manufacturing a multilayer substrate in this embodiment. [Figure 5] This is a schematic cross-sectional view (part 4) showing an example of a method for manufacturing a multilayer substrate in this embodiment. [Figure 6] This is a schematic cross-sectional view (part 5) showing an example of a method for manufacturing a multilayer substrate in this embodiment. [Modes for carrying out the invention]

[0012] (Laminated substrate) Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a schematic cross-sectional view of a laminated substrate. In this embodiment, for the sake of convenience, there may be cases where "upper surface" or "lower surface" is described based on the vertical direction in the drawings. However, the upper and lower surfaces of the stacked substrate 100 or the multilayer substrate 10 include cases where they do not match the actual vertical direction. Further, in the stacked substrate 100 or the multilayer substrate 10, there may be cases where "side surface" is described, and the side surface means the side surface with respect to the above-described upper and lower surfaces.

[0013] The stacked substrate 100 shown in FIG. 1 has a configuration in which, as an example, two multilayer substrates 10 are stacked in the vertical direction and electrically connected to each other. However, it is not limited to the stacking of two multilayer substrates 10 and can be applied to the stacking of two or more multilayer substrates 10. In addition, the stacked substrate 100 shown in FIG. 1 is described by taking the case where both are MLB (multilayer printed wiring boards) as an example.

[0014] 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 surface or the lower surface of each insulating layer 20, and through holes 30 penetrating in the vertical direction are formed.

[0015] 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 according to the purpose. As an example, an inorganic base material such as an inorganic woven fabric using glass cloth or an inorganic non-woven fabric, or a base material hardness-strengthened by an organic base material such as an organic woven fabric or an organic non-woven fabric can be adopted.

[0016] More specifically, as an example, the insulating layer 20 can adopt a glass epoxy base material (a glass woven fabric base material impregnated with an epoxy resin, a glass non-woven fabric base material impregnated with an epoxy resin), a glass woven fabric base material impregnated with a bismaleimide triazine resin, an aramid non-woven fabric base material impregnated with an epoxy resin, a glass woven fabric base material impregnated with a modified polyphenylene ether resin, and the like.

[0017] The through-hole 30 has a plating layer 35 formed by plating the inner wall with a metal such as copper, and the hollow portion further inside the plating layer 35 is filled with a resin 32. When forming the bonding land 34 of the conductive paste on each multilayer substrate 10, if the inside of the through-hole 30 remains hollow, the bonding land 34 cannot be formed. For this reason, the resin 32 is filled inside the plating layer 35 in the through-hole 30.

[0018] 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, semiconductor elements, etc. (not shown) are formed. The bonding land 34 is electrically connected to the plating layer 35 of the through-hole 30 and can be formed of a metal such as copper.

[0019] An adhesive layer 40 is interposed between the multilayer substrates 10. As the adhesive layer 40, a thermosetting resin can be adopted, and as an example, a glass epoxy prepreg can be adopted.

[0020] The bonding land 34 on the upper surface of the lower multilayer substrate 10 and the bonding land 34 on the lower surface of the upper multilayer substrate 10 in FIG. 1 are electrically connected by a via. This via is a conductive paste via 50 made of a conductive paste. As the conductive paste, one containing a conductive filler and a binder resin can be adopted.

[0021] Also, between the bonding land 34 on the upper surface of the lower multilayer substrate 10 and the adjacent metal layer 38 (or the bonding land 34 at an adjacent position), and between the bonding land 34 on the lower surface of the upper multilayer substrate 10 and the adjacent metal layer 38 (or the bonding land 34 at an adjacent position), an insulating resin 42 for flattening the surface of the multilayer substrate 10 is disposed.

[0022] In other words, since the multilayer substrate 10 has metal layers 38 including bonding lands 34 protruding from the surface of the insulating layer 20 on its upper and lower surfaces, it is positioned to fill the step difference and can flatten the upper surface of the lower multilayer substrate 10 and the lower surface of the upper multilayer substrate 10.

[0023] (Method of manufacturing a laminated substrate) Next, the manufacturing method of the multilayer substrate will be explained with reference to Figure 2. Note that the multilayer substrate 10 in Figure 2 is the same as that shown in Figure 1, and its structure is denoted by the same reference numerals as in Figure 1, so its explanation is omitted. First, when stacking the multilayer substrates 10, insulating resin 42 is filled into the recesses between the bonding lands 34 and the metal layer 38 (or other adjacent bonding lands 34) in order to make the surface facing the other multilayer substrate 10 flat. Then, the insulating resin 42 is polished to flatten the surface facing the other multilayer substrate 10 so that there are no irregularities. This maintains the flatness of the stacked substrate 100 and makes the electrical connection layer by conductive paste vias 50 uniform throughout the substrate, preventing the occurrence of abnormal resistance values.

[0024] Next, as shown in Figure 3, an adhesive layer 40 is laminated on the surface facing the other multilayer substrates 10 to be laminated. As mentioned above, a thermosetting resin can be used as the adhesive layer 40, and as an example, a glass epoxy prepreg can be used. Furthermore, 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 in the form of a pre-integrated sheet.

[0025] Next, as shown in Figure 4, through holes 46 are formed in the adhesive layer 40 and the resin film 44. The through-hole 46 is a closed-bottomed through-hole 46 that penetrates the adhesive layer 40 and the resin film 44, with the bonding land 34 as its bottom. The through-hole 46 can be made, for example, by laser processing. Examples of laser processing methods include CO2 lasers and YAG lasers, but are not limited to these, and can be appropriately selected depending on the purpose.

[0026] In this case, as shown in Figure 1, a conductive paste via 50 is placed approximately in the center of the bonding land 34 of the through-hole 30, and therefore a through-hole 46 is drilled directly above the position where the through-hole 30 is formed.

[0027] Next, as shown in Figure 5, conductive paste is filled into the through hole 46, 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.

[0028] Next, as shown in Figure 6, another multilayer substrate 10 is laminated onto the multilayer substrate 10 on which the adhesive layer 40 and conductive paste vias 50 are formed. Here, the lower surface of the other multilayer substrate 10 is flattened so that there are no irregularities, by filling the recess between the bonding land 34 and the metal layer 38 (or other adjacent bonding land 34) with insulating resin 42. Then, the multilayer substrates 10 are heat-pressed together. By heat-pressing, the adhesive layer 40 and the conductive paste vias 50 harden, and a laminated substrate 100 is formed by stacking multiple multilayer substrates 10.

[0029] (Other embodiments of multilayer substrates) The specific types of the multilayer substrates 10 and the substrates of the multilayer substrates 10 that make up the laminated substrate 100 are as shown in Figure 1. Both may be MLBs (multilayer printed circuit boards), or the lower multilayer substrate 10 may be an MLB (multilayer printed circuit 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 circuit board) and the upper multilayer substrate 10 may be a CL (coreless semiconductor package substrate). Furthermore, a configuration in which a multilayer substrate 10 that is a CL (coreless semiconductor package substrate) is laminated on both the upper and lower surfaces of the lower multilayer substrate 10 that is an MLB (multilayer printed circuit board).

[0030] The laminated substrate 100 in this embodiment can be used as a motherboard (support substrate) and also as an interposer (relay substrate). In particular, it can be used as a motherboard or interposer for server systems and high-speed communication systems, and can also be used as a circuit board that constitutes semiconductor elements. Furthermore, it can be applied to inspection equipment and probe cards used for determining the quality of semiconductors. [Explanation of symbols]

[0031] 10 Multilayer board 20 Insulating layer 30 through-holes 32 resin 34 Joining Land 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 Multilayer Substrates

Claims

[Claim 1] A method for manufacturing a laminated substrate by stacking multiple multilayer substrates, each having a through-hole with a plated inner wall surface and filled with resin inside, and bonding lands electrically connected to the through-hole formed on the upper and lower surfaces of the through-hole, A step of laminating an insulating adhesive layer onto the upper surface of a multilayer substrate, A step of forming through holes that penetrate the insulating adhesive layer so that the bonding lands of one multilayer substrate and another multilayer substrate facing the first multilayer substrate can be electrically connected to each other, The steps include filling the through-hole with conductive paste to form a conductive paste via, The process includes a step of thermally pressing multiple multilayer substrates together to cure the insulating adhesive layer and the conductive paste, thereby integrating the multiple multilayer substrates, Before the step of laminating an insulating adhesive layer onto the upper surface of the first multilayer substrate, A method for manufacturing a laminated substrate, comprising the steps of filling the recesses between the bonding lands and other metal layers or other bonding lands on the upper surface of one multilayer substrate and the lower surface of the other multilayer substrate facing the upper surface of the one multilayer substrate with insulating resin, and polishing the surface to flatten it so that there are no irregularities on the surface facing the other multilayer substrate.

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