Laminated substrate and method for manufacturing the same

Abstract

To prevent occurrence of resistance value abnormality by maintaining flatness of a substrate so as not to concentrate load into a portion and uniformizing a conductive layer between terminal parts over the entire substrate when laminating substrates while pressurizing / heating them.SOLUTION: A multilayer substrate comprises: a first substrate A; a first terminal part 28 formed at the side of a first surface 1A of the first substrate A; a second substrate B disposed so as to be opposed with the side of the first surface 1A of the first substrate A; a second terminal part 38 formed at the side of a first substrate 1B in the second substrate B opposed with the first terminal part 28; a regulation member 50 which is interposed between the first substrate A and the second substrate B, in which a through hole 51 is formed for communicating the first terminal part 28 and the second terminal part 38, and which regulates an interval between the first substrate A and the second substrate B; and conductive paste 46 which is disposed in the communication hole 51 and electrically connects the first terminal part 28 and the second terminal part 38.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 miniaturization, 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 research into multilayer wiring boards, which have a multilayer structure based on printed wiring boards, has become more active.

[0003] Conventional methods for electrically connecting and stacking multilayer wiring boards, which are circuit boards with a multilayer structure, include forming them into BGA or LGA and connecting them to a motherboard with solder bumps, and electrically connecting them with wire bonding or stud bumps. Furthermore, as shown in Patent Document 1 (Japanese Patent Laid-Open Publication No. 2003-243797), a method has been proposed in which multilayer wiring boards are fixed together with fixing pins or the like, and terminals are brought into contact with each other to provide an electrical connection.

[0004] Furthermore, Patent Document 2 (JP 2007-335701 A) discloses a method for manufacturing a laminated substrate, in which a first substrate and a second substrate are laminated with an insulating layer interposed therebetween, an adhesive sheet made of a thermosetting resin having through holes formed in positions corresponding to the terminal portions of the first substrate is adhered so that the terminal portions are positioned within the through holes, the through holes are filled with a conductive paste containing a hardener and a filler formed by plating the surfaces of metal particles having a first melting point with solder having a second melting point that is lower than the first melting point, and the first substrate and the second substrate are heated and pressurized to thermally harden the adhesive sheet and conductive paste to integrate them. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-243797 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-335701 Summary of the Invention [Problem to be solved by the invention]

[0006] In the manufacturing method disclosed in the aforementioned Patent Document 1, in which multilayer wiring boards are fixed together with fixing pins and terminals are mechanically contacted to form an electrical connection, there are problems with the reliability of the joint surfaces being unstable due to design variations in the fixing pins and other mounting jigs, variations in the design dimensions of the assembled parts, etc. Also, there is a problem that assembly is done manually, which requires a lot of labor.

[0007] Furthermore, the manufacturing method disclosed in Patent Document 2 solves the problems of Patent Document 1, and the filler in the bonding ink is integrated with the solder as it melts, and is firmly bonded to the terminal portion, forming a columnar conductive member, which provides good electrical properties and also increases the bonding strength. However, when substrates are generally stacked, the laminated substrate tends to have a raised central portion and a lowered edge portion. Under these circumstances, when attempting to stack substrates by applying pressure and heat using the manufacturing method of Patent Document 2, the load is concentrated in the protruding central portion, which causes the conductive paste to easily overflow from the terminals in the central portion where the load is concentrated, resulting in a thinner conductive layer between the terminals in the central portion, which may result in an abnormal resistance value. [Means for solving the problem]

[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 the laminated substrate, which can maintain the flatness of the substrate by preventing the load from concentrating on one part when stacking substrates under pressure and heat, and can make the conductive layer between terminal portions uniform over the entire substrate, thereby preventing the occurrence of abnormal resistance values.

[0009] A laminated substrate according to the present invention includes a first substrate, a first terminal portion formed on a first surface side of the first substrate, a second substrate disposed so as to face the first surface side of the first substrate, a second terminal portion formed on the second substrate on the first surface side facing the first terminal portion, a restricting member interposed between the first substrate and the second substrate, communicating between the first terminal portion and the second terminal portion, having a through hole formed in a location where the first terminal portion and the second terminal portion are provided, and disposed in a location where the first terminal portion and the second terminal portion are not provided to restrict a gap between the first substrate and the second substrate, and a conductive paste disposed in the through hole and electrically connecting the first terminal portion and the second terminal portion. The regulating member is fixed between the first substrate and the second substrate by a first adhesive that adheres to the first surface side of the first substrate and a second adhesive that adheres to the first surface side of the second substrate, and the insulating material that constitutes the first substrate, the insulating material that constitutes the second substrate, and the regulating member are made of insulating materials that have the same thermal expansion, and the thickness of the regulating member is set so that the sum of the thickness of the first terminal portion, the thickness of the second terminal portion, and the thickness of the conductive paste that has hardened and reliably ensured conductivity after pressure and heat application is equal to the sum of the thickness of the regulating member and the thickness of the first adhesive and the second adhesive after pressure and heat application. It is characterized by the following. By adopting this configuration, the thickness between the first substrate and the second substrate can be determined by the thickness of the regulating member, thereby maintaining flatness and creating a laminated substrate in which the conductive layer between the terminal portions is uniform across the entire substrate. Furthermore, with this configuration, even if there are variations in plating thickness between the first terminal portion and the second terminal portion, or if the pattern shapes of the intermediate layers of the first and second substrates are different for each layer, resulting in unevenness in some locations, such variations in thickness and unevenness can be absorbed by the first adhesive and second adhesive applied to the upper and lower surfaces of the regulating member. Therefore, flatness can be maintained more reliably. Furthermore, with this configuration, the regulating member is reliably fixed between the first and second substrates. Furthermore, with this configuration, the first substrate, the second substrate, and the regulating member have the same thermal expansion, so that distortion and dimensional deviation can be prevented from occurring when stacking.

[0010] The restricting member may be made of an unclad material.

[0013] According to the method for manufacturing a laminated substrate of the present invention, a first substrate has a first terminal portion on a first surface side, and a second substrate has a second terminal portion on a first surface side opposite to the first surface of the first substrate, and the first terminal portion and the second terminal portion are electrically connected via a conductive paste, the method including the steps of applying the conductive paste onto the first terminal portion of the first substrate, forming through holes at locations where the first terminal portion and the second terminal portion are provided, and applying a first adhesive to adhere to the first surface side of the first substrate and a second adhesive to adhere to the first surface side of the second substrate, thereby regulating the distance between the first substrate and the second substrate. Therefore, the thickness is set so that the sum of the thickness of the first terminal portion, the thickness of the second terminal portion, and the thickness of the conductive paste that has hardened and ensured conductivity after pressure and heat application is equal to the sum of the thickness of the regulating member and the thickness of the first adhesive and the second adhesive after pressure and heat application. the step of using a restricting member to place the restricting member at a location between the first substrate or the second substrate where the first terminal portion and the second terminal portion are not provided so that the first terminal portion or the second terminal portion is positioned in the through hole; the step of positioning and stacking the first substrate and the second substrate with the restricting member interposed and the first terminal portion and the second terminal portion facing each other; and the step of applying heat and pressure to the laminate of the first substrate and the second substrate to harden the conductive paste and harden the first adhesive and the second adhesive, thereby integrating the first substrate and the second substrate so that the distance between them is the same as the thickness of the restricting member. The insulating material constituting the first substrate, the insulating material constituting the second substrate, and the regulating member are made of insulating materials having the same thermal expansion coefficient. 1. A method for manufacturing a laminated substrate comprising: By adopting this method, the thickness between the first and second substrates can be determined by the thickness of the regulating member during pressure and heat application, thereby maintaining flatness and making the conductive layer between the terminal portions uniform across the entire substrate, resulting in a laminated substrate. Furthermore, even if there are variations in plating thickness between the first and second terminal portions, or if the pattern shapes in the intermediate layers of the first and second substrates are different for each layer and therefore there are unevenness in some locations, such variations in thickness and unevenness can be absorbed by the first adhesive and second adhesive applied to the top and bottom surfaces of the regulating member. [Effects of the Invention]

[0014] According to the present invention, when stacking substrates by applying pressure and heat, the load is not concentrated in one area, thereby maintaining the flatness of the substrate, and the conductive layer between the terminal portions is made uniform over the entire substrate, preventing the occurrence of abnormal resistance values. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a laminated substrate. [Figure 2] 1A to 1C are schematic cross-sectional views showing an example of a method for manufacturing a laminated substrate. DETAILED DESCRIPTION OF THE INVENTION

[0016] (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. 1 has a configuration in which a substrate A and a substrate B are electrically connected and laminated. In this embodiment, both the substrate A and the substrate B are multilayer substrates, and each of the substrates A and B has an insulating layer made of a plurality of insulating base materials 22. The insulating base material 22 of the substrate A and the substrate B may be, for example, prepreg (a nonwoven or woven base material such as glass fiber impregnated with epoxy resin or the like).

[0017] As for the specific types of substrates, both substrates A and B may be MLBs (multilayer printed wiring boards), or substrate B may be an MLB (multilayer printed wiring board) and substrate A may be a PKG (semiconductor package substrate), or substrate B may be an MLB (multilayer printed wiring board) and substrate A may be a CL (coreless semiconductor package substrate).Furthermore, a configuration may be adopted in which substrate A, which is a CL (coreless semiconductor package substrate), is laminated on both the top and bottom surfaces of substrate B, which is an MLB (multilayer printed wiring board).

[0018] It is preferable that the insulating base material 22 and the insulating base material 22 of substrate B are made of the same insulating material, since the thermal expansion of each material is the same, and therefore distortion and dimensional deviation can be prevented when stacked by applying pressure and heat. However, the invention is not limited to being made of the same insulating material.

[0019] If the surface of substrate A facing substrate B is designated as first surface 1A and the surface opposite to first surface 1A is designated as second surface 2A, a first metal terminal portion 28 is formed on first surface 1A, and a third metal terminal portion 30 is formed on second surface 2A. A via 32 is provided that penetrates the substrate A in the thickness direction and electrically connects the first terminal 28 and the third terminal 30.

[0020] Furthermore, if the surface of substrate B facing substrate A is designated as first surface 1B and the surface opposite first surface 1B is designated as second surface 2B, a second terminal portion 38 made of metal is formed on first surface 1B, and a fourth terminal portion 40 made of metal is formed on second surface 2B. A via 42 is provided that penetrates the substrate B in the thickness direction and electrically connects the second terminal 38 and the fourth terminal 40 together.

[0021] Furthermore, the first terminal portion 28 and the third terminal portion 30 of the substrate A, and the second terminal portion 38 and the fourth terminal portion 40 of the substrate B can be made of a metal such as copper, but are not limited to copper.

[0022] In the laminated substrate 20 in which the substrate A and the substrate B are laminated, the first terminal portion 28 of the substrate A and the second terminal portion 38 of the substrate B are electrically connected by the conductive paste 46 . The conductive paste 46 may contain a conductive filler and a binder resin. Examples of the conductive filler include metal particles of copper, gold, silver, palladium, nickel, tin, bismuth, etc. These metal particles may be used alone or in combination of two or more types. The binder resin may be, for example, an epoxy resin, which is a type of thermosetting resin, but is not limited to epoxy resin and may be a polyimide resin or the like.

[0023] A restricting member 50 is disposed between substrate A and substrate B of laminated substrate 20, which is formed by laminating substrate A and substrate B. Furthermore, through holes 51 are formed in restricting member 50 at locations where first terminal portion 28 and second terminal portion 38 are provided, and restricting member 50 is provided at locations where first terminal portion 28 and second terminal portion 38 are not provided.

[0024] The restricting member 50 is made of an unclad material, which is an insulating resin material for circuit boards that does not have wiring such as copper foil formed thereon. The material of the regulating member 50 may preferably be the same type of insulating material as the insulating base material 22 of the substrates A and B. As with the substrates A and B, the material of the regulating member 50 may be, for example, prepreg (a nonwoven fabric base material such as glass fiber or a woven fabric base material impregnated with epoxy resin or the like). In this way, by constructing the regulating member 50, the insulating base material 22 of substrate A, and the insulating base material 22 of substrate B from the same insulating material, the thermal expansion of each material becomes the same, which makes it possible to prevent distortion and dimensional deviation from occurring when the materials are stacked by applying pressure and heat.

[0025] A first adhesive 52 is provided on the substrate A side of the regulating member 50, and a second adhesive 54 is provided on the substrate B side. The first adhesive 52 adheres and fixes the regulating member 50 to the first surface 1A of the substrate A, and the second adhesive 54 adheres and fixes the regulating member 50 to the first surface 1B of the substrate B. A thermosetting insulating material is used for both the first adhesive 52 and the second adhesive 54. Specifically, a thermosetting insulating film or the like can be used.

[0026] The first adhesive 52 and the second adhesive 54 can be made by using one or more layers of thermosetting insulating film having a thickness of about 10 μm, for example, to allow fine adjustment of the gap between the substrate A and the substrate B. For example, even if there is variation in the plating thickness of the first terminal portion 28 and the second terminal portion 38, or if the pattern shapes in the intermediate layers of each of the substrates A and B are different for each layer and therefore unevenness exists in some locations, such variation in the thickness of each terminal portion and unevenness can be absorbed by the first adhesive 52 and the second adhesive 54.Furthermore, even if there is a large variation in the thickness of each terminal portion and unevenness, the thickness of the laminated substrate can be made uniform by changing the number of first adhesives 52 and second adhesives 54 depending on the location.

[0027] Furthermore, when substrates A and B are stacked and pressurized and heated, the regulating member 50 regulates the pressure by preventing any further load from being applied, thereby maintaining a constant distance between substrates A and B, thereby ensuring the flatness of the substrates and making the thickness of the conductive paste 46 pressed between the first terminal portion 28 and the second terminal portion 38 uniform across the entire laminated substrate.

[0028] Therefore, the thickness of the regulating member 50 is set so as to be approximately the same as the distance between the substrates A and B after pressure and heat are applied. Specifically, the thickness of the regulating member 50 is set so that the sum of the thickness of the first terminal portion 28, the thickness of the second terminal portion 38, and the thickness of the conductive paste 46 that has hardened and ensured conductivity after pressure and heat application is equal to the sum of the thickness of the regulating member 50 and the thicknesses of the first adhesive 52 and the second adhesive 54 after pressure and heat application.

[0029] In addition, the regulating member 50 also has the function of blocking the outflow of the conductive paste 46, even if the conductive paste 46, which is pressurized and heated between the first terminal portion 28 and the second terminal portion 38 during pressure and heat application, attempts to flow out from the first terminal portion 28 and the second terminal portion 38.

[0030] (Laminated substrate manufacturing method) Next, a method for manufacturing a laminated substrate will be described with reference to Fig. 2. Note that Fig. 2 shows a simplified schematic configuration of each of substrates A and B, omitting vias and the like. 2(a), a metal mask 18 having a conductive paste 46 placed thereon is placed above the second terminal portions 38 of a substrate B having the second terminal portions 38. Then, a squeegee 21 is used to apply the conductive paste 46 from the metal mask 18 to the second terminal portions 38.

[0031] FIG. 2(b) shows a state in which conductive paste 46 is applied onto the second terminal portion 38 of the substrate B. The conductive paste 46 may contain a conductive filler and a binder resin. Examples of the conductive filler include metal particles of copper, gold, silver, palladium, nickel, tin, bismuth, etc. These metal particles may be used alone or in combination of two or more types. The binder resin may be, for example, an epoxy resin, which is a type of thermosetting resin, but is not limited to epoxy resin and may be a polyimide resin or the like.

[0032] Next, as shown in Figure 2(c), a regulating member 50 having a through hole 51 formed in a position corresponding to the first terminal portion 28 of the substrate A is placed on the first surface 1A of the substrate A having the first terminal portion 28 so that the first terminal portion 28 is positioned within the through hole 51. Furthermore, before placing the regulating member 50 on the substrate A, a first adhesive 52 and a second adhesive 54 are applied in advance to both surfaces in the thickness direction of the regulating member 50. As the first adhesive 52 and the second adhesive 54, a thermosetting insulating film can be used, as described above.

[0033] In the above example, the restricting member 50 is disposed on the first surface 1A of the substrate A before stacking, but the restricting member 50 may be disposed on the first surface 1B of the substrate B. In this case, the restricting member 50 has a through hole 51 formed in a position corresponding to the second terminal portion 38 of the substrate B, and is disposed so that the second terminal portion 38 is positioned within the through hole 51. However, it is a preferable step to place the regulating member 50 on the first surface 1A of the substrate A before stacking, as this makes positioning easier.

[0034] Next, as shown in FIG. 2(d), substrate A and substrate B are stacked with the regulating member 50 interposed therebetween, with the first terminal portion 28 and the second terminal portion 38 facing each other, and positioned using a positioning member such as a pin (not shown). Then, the laminate is pressurized and heated in a vacuum press to thermally cure the conductive paste 46, the first adhesive 52, and the second adhesive 54, thereby integrating the laminate and obtaining the desired laminated substrate 20. Furthermore, pressure is applied to enhance bonding between metal particles in the conductive filler in the conductive paste 46, thereby ensuring reliable conductivity. Since the substrates do not have any electronic components such as semiconductor chips mounted thereon, pressure and heat can be applied using a vacuum press.

[0035] Furthermore, when the pressure is applied, the regulating member 50 is interposed between the substrates A and B, so the pressure is regulated so that a load greater than the thickness of the regulating member 50 is not applied, thereby maintaining a constant distance between the substrates A and B. In this way, by applying pressure and heat with the regulating member 50 interposed between the substrate A and the substrate B, the flatness of the substrate is ensured, and the thickness of the conductive paste 46 pressed between the first terminal portion 28 and the second terminal portion 38 can be made uniform throughout the entire laminated substrate, thereby preventing the occurrence of abnormal resistance values. Furthermore, even if the conductive paste 46 is about to flow out from the first terminal portion 28 and the second terminal portion 38 due to the application of pressure, the restricting member 50 can block the conductive paste 46.

[0036] In the above-described embodiment, the lamination of two substrates, substrate A and substrate B, has been described, but substrates can be laminated on both surfaces of substrate A or substrate B in the same manner.

[0037] The laminated substrate manufactured by the manufacturing method of this embodiment and the laminated substrate of this embodiment can be used as a motherboard (support substrate) and also as an interposer (relay substrate). In particular, they can be used as motherboards and interposers for server systems and high-speed communication systems, and can also be used as circuit boards that form semiconductor elements. They can also be applied to inspection devices, probe cards, etc. used to determine the quality of semiconductors. [Explanation of symbols]

[0038] 1A 1st surface 2A 2nd surface 1B 1st surface 2B 2nd surface 18 Metal Mask 20. Laminated substrate 21 Squeegee 22 Insulating substrate 28 1st terminal section 30 3rd terminal section 32 Beer 38 2nd terminal section 40 4th terminal section 42 Beer 46 Conductive Paste 50 Regulatory components 51 Through hole 52 First Adhesive 54 Second Adhesive A board B board

Claims

1. a first substrate; a first terminal portion formed on a first surface side of the first substrate; a second substrate disposed to face the first surface side of the first substrate; a second terminal portion formed on a first surface side of the second substrate opposite to the first terminal portion; a restricting member interposed between the first substrate and the second substrate, communicating between the first terminal portion and the second terminal portion, having a through hole formed at a location where the first terminal portion and the second terminal portion are provided, and disposed at a location where the first terminal portion and the second terminal portion are not provided, restricting the gap between the first substrate and the second substrate; a conductive paste disposed in the through hole and electrically connecting the first terminal portion and the second terminal portion, the regulating member is fixed between the first substrate and the second substrate by a first adhesive that adheres to the first surface side of the first substrate and a second adhesive that adheres to the first surface side of the second substrate, an insulating material constituting the first substrate, an insulating material constituting the second substrate, and the regulating member are made of insulating materials having the same thermal expansion coefficient; The thickness of the regulating member is A laminated substrate characterized in that the sum of the thickness of the first terminal portion, the thickness of the second terminal portion, and the thickness of the conductive paste that has hardened and reliably ensured conductivity after pressure and heat application is set to be the sum of the thickness of the regulating member and the thickness of the first adhesive and second adhesive after pressure and heat application.

2. 2. The laminated substrate according to claim 1, wherein the regulating member is made of an unclad material.

3. A method for manufacturing a laminated substrate, comprising: a first substrate having a first terminal portion on a first surface side; and a second substrate having a second terminal portion on a first surface side opposite to the first surface of the first substrate; and electrically connecting the first terminal portion and the second terminal portion via a conductive paste, applying a conductive paste onto the first terminal portion of the first substrate; a step of forming a through hole at a location where the first terminal portion and the second terminal portion are provided, using a restricting member having a first adhesive adhering to the first surface side of the first substrate and a second adhesive adhering to the first surface side of the second substrate, the restricting member having a thickness set so that the sum of the thickness of the first terminal portion, the thickness of the second terminal portion, and the thickness of the conductive paste that has hardened after pressure and heat and has reliably ensured conductivity after pressure and heat is equal to the sum of the thickness of the restricting member and the thickness of the first adhesive and the second adhesive after pressure and heat is applied, and arranging the restricting member at a location where the first terminal portion and the second terminal portion are not provided between the first substrate or the second substrate so that the first terminal portion or the second terminal portion is positioned within the through hole; a step of positioning and stacking the first substrate and the second substrate with the regulating member interposed therebetween and with the first terminal portion and the second terminal portion facing each other; applying heat and pressure to a laminate of the first substrate and the second substrate to harden the conductive paste and harden the first adhesive and the second adhesive, thereby integrating the first substrate and the second substrate so that the gap between them is the same as the thickness of the regulating member; A method for manufacturing a laminated substrate, characterized in that the insulating material constituting the first substrate, the insulating material constituting the second substrate, and the regulating member are made of insulating materials that have the same thermal expansion.

4. 4. The method for manufacturing a laminated substrate according to claim 3, wherein the regulating member is made of an unclad material.

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