Circuit module

Abstract

A circuit module (1) comprises: substrate (10) having one principal surface (10a) and another principal surface (10b); and a connection terminal (30) disposed on the one principal surface (10a) side of the substrate (10). The circuit module (1) is characterized in that: a first electrode (11) is provided to the one principal surface (10a) of the substrate (10); on the one principal surface (10a) side of the substrate (10), the connection terminal (30) has one end bonded to the first electrode (11); a portion of the first electrode (11) bonded to the connection terminal (30), when the first electrode is viewed from the thickness direction, is a first portion (11a), a portion surrounding the outer periphery of the first portion (11a) is a second portion (11b), and a portion surrounding the outer periphery of the second portion (11b) is a third portion (11c); a plating film (23) is provided to the surface of the second portion (11b); and a ceramic protective film (70) made of a ceramic material is provided to the surface of the third portion (11c).

Description

Circuit Module

[0001] The present invention relates to a circuit module.

[0002] 2. Description of the Related Art Components mounted in electronic devices include circuit modules in which electronic components are mounted on a substrate such as an LTCC substrate and sealed with resin.

[0003] When mounting a circuit module having electronic components mounted on both sides of the substrate on another substrate (mounting substrate) such as a motherboard, electrodes (external connection terminals or connection terminals) that penetrate the resin layer in the thickness direction are required to connect the circuit module substrate to the mounting substrate.

[0004] For example, Patent Document 1 discloses a circuit module including a substrate having a first electrode and a second electrode provided on one main surface thereof, a first electronic component connected to the first electrode, and a first resin layer provided on one main surface of the substrate, in which the second electrode is composed of a second electrode base connected to the substrate, a metal pillar made of sintered metal powder and having one end directly connected to the second electrode base and the other end located inside the outer surface of the first resin layer, a plating layer covering the second electrode base and the side surfaces of the metal pillar, and a covering portion having one main surface connected to the other end of the metal pillar and the plating layer and the other main surface located outside the outer surface of the first resin layer.

[0005] Patent document 1 discloses that by providing a plating film that is compatible with the resin layer on the side of the metal pillar that constitutes the second electrode that serves as the external connection terminal, it is possible to improve adhesion between the metal pillar and the resin layer and suppress peeling.

[0006] Patent No. 6791352

[0007] In recent years, there has been an increasing demand for miniaturization and high reliability of electronic components. However, due to miniaturization, cracks are more likely to occur at the interface between the metal posts and the substrate due to thermal cycles and impacts when the housing is dropped.

[0008] Patent Document 1 discloses that a plating film is provided at the interface between the metal post, which is the connection terminal, and the resin layer to improve adhesion between the metal post and the resin layer, but does not disclose anything about suppressing cracks that occur between the substrate and metal post that constitute the circuit module.

[0009] Generally, in heterogeneous joints such as those between a ceramic substrate and a metal pillar, it is possible to suppress thermal stress by reducing the size of the metal pillar, which has a large thermal expansion coefficient. However, the area, shape, position, etc. of the connection terminal (metal pillar) on the mounting surface are determined by the specifications of the mounting destination (customer).

[0010] The mounting specifications include the position and shape of the connection terminals for the circuit module on the mounting board on which the circuit module is mounted. When mounting the circuit module on the mounting board, the position and shape of the metal posts that connect to the mounting board must match the position and shape of the connection terminals on the mounting board. Therefore, once the area, shape, position, etc. of the connection terminals (metal posts) have been determined as the mounting specifications, they cannot be changed for the circuit module's convenience in order to improve thermal cycle characteristics or connection reliability.

[0011] For these reasons, there has been a demand for improved thermal cycle characteristics and connection reliability without being affected by the specifications of the mounting destination.

[0012] The present invention has been made to solve the above problems, and aims to provide a circuit module that can improve thermal cycle characteristics and connection reliability without being affected by the specifications of the mounting destination.

[0013] The circuit module of the present invention is a circuit module comprising a substrate having one main surface and another main surface, and a connection terminal arranged on the one main surface side of the substrate, wherein a first electrode is provided on the one main surface of the substrate, and on the one main surface side of the substrate, one end of the connection terminal is joined to the first electrode, and when the first electrode is viewed from the thickness direction, a portion of the first electrode joined to the connection terminal is defined as a first portion, a portion surrounding the outer periphery of the first portion is defined as a second portion, and a portion surrounding the outer periphery of the second portion is defined as a third portion, and a plating film is provided on the surface of the second portion, and a ceramic protective film made of a ceramic material is provided on the surface of the third portion.

[0014] According to the present invention, it is possible to provide a circuit module that can improve thermal cycle characteristics and connection reliability without being affected by the specifications of the mounting destination.

[0015] FIG. 1 is a top view schematically illustrating an example of a circuit module of the present invention. FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a diagram illustrating a correspondence between a partial enlargement of FIG. 2 and a schematic diagram of the bonding surface between a connection terminal and a first electrode in the enlarged portion, as viewed from the connection terminal side. FIG. 4 is a diagram illustrating a correspondence between an enlargement of the bonding portion between a connection terminal and a first electrode in another example of a circuit module of the present invention and a schematic diagram of the bonding surface between the connection terminal and the first electrode in the enlarged portion, as viewed from the connection terminal side. FIG. 5 is a cross-sectional view schematically illustrating an example of a constraining layer sheet used in manufacturing a circuit module. FIG. 6 is a cross-sectional view schematically illustrating a step of printing a conductive paste on the surface of the constraining layer sheet shown in FIG. 5. FIG. 7 is a cross-sectional view schematically illustrating a step of forming through holes in the surface of the constraining layer sheet shown in FIG. 5. FIG. 8 is a cross-sectional view schematically illustrating a step of filling the through holes in the constraining layer sheet shown in FIG. 7 with a conductive paste. FIG. 9 is a cross-sectional view schematically illustrating an example of a ceramic green sheet used in manufacturing a circuit module. FIG. 10 is a cross-sectional view schematically showing a step of printing a conductive paste on the surface of the ceramic green sheet shown in FIG. 9 . FIG. 11 is a cross-sectional view schematically showing a step of forming through holes in the surface of the ceramic green sheet shown in FIG. 9 . FIG. 12 is a cross-sectional view schematically showing a step of filling the through holes of the ceramic green sheet shown in FIG. 11 with a conductive paste. FIG. 13 is a cross-sectional view schematically showing a step of printing a conductive paste on the surface of the ceramic green sheet shown in FIG. 12 . FIG. 14 is a cross-sectional view schematically showing a step of printing a conductive paste and a ceramic protective film paste on the surface of the ceramic green sheet shown in FIG. 12 . FIG. 15 is a diagram schematically showing an example of a step of stacking prepared laminate sheets. FIG. 16 is a diagram schematically showing an example of a step of pressing a laminate. FIG. 17 is a diagram schematically showing an example of a step of firing the pressed body. FIG. 18 is a diagram schematically showing an example of a step of removing a constraining layer. FIG. 19 is a diagram schematically showing an example of a step of forming a plating film. Fig. 20 is a diagram schematically showing an example of a process for mounting electronic components on one main surface of a substrate, Fig. 21 is a cross-sectional view schematically showing an example of a process for encapsulating electronic components, and Fig. 22 is a cross-sectional view schematically showing an example of a process for grinding the surface of the encapsulating resin.Fig. 23 is a cross-sectional view schematically showing a step of forming a plating film on the surface of a connection terminal. Fig. 24 is a cross-sectional view schematically showing a step of mounting an electronic board on the other main surface of the substrate. Fig. 25 is a cross-sectional view schematically showing an example of a step of encapsulating an electronic component. Fig. 26 is a cross-sectional view schematically showing an example of a step of grinding the surface of the encapsulating resin.

[0016] The circuit module of the present invention will be described below. However, the present invention is not limited to the following configuration, and can be modified as appropriate within the scope of the present invention. Note that a combination of two or more of the individual desirable configurations of the present invention described below also constitutes the present invention.

[0017] In this specification, terms indicating the relationship between elements (e.g., "parallel," "orthogonal," etc.) are not expressions that only express a strict meaning, but also expressions that include a substantially equal range, for example, a difference of a few percent.

[0018] The drawings shown below are schematic diagrams, and the dimensions, aspect ratios, and other scales may differ from those of the actual product.

[0019] [Circuit Module] A circuit module of the present invention is a circuit module including a substrate having one main surface and another main surface, and a connection terminal arranged on the one main surface side of the substrate, wherein a first electrode is provided on the one main surface of the substrate, and one end of the connection terminal is joined to the first electrode on the one main surface side of the substrate, and when the first electrode is viewed in the thickness direction, a portion of the first electrode that is joined to the connection terminal is defined as a first portion, a portion surrounding the outer periphery of the first portion is defined as a second portion, and a portion surrounding the outer periphery of the second portion is defined as a third portion, and a plating film is provided on a surface of the second portion, and a ceramic protective film made of a ceramic material is provided on a surface of the third portion.

[0020] Fig. 1 is a top view schematically showing an example of a circuit module of the present invention. Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1. As shown in Figs. 1 and 2, the circuit module 1 includes a substrate 10, a first resin layer 20, and connection terminals 30, with electronic components 40 and connection terminals 30 exposed on the main surface of the first resin layer 20 opposite the substrate 10.

[0021] As shown in Figure 2, the substrate 10 has one main surface 10a and the other main surface 10b, and has a first electrode 11 and a second electrode 13 provided on the one main surface 10a, via conductors 15 and wiring 17 provided inside, and a third electrode 19 provided on the other main surface 10b.

[0022] The first resin layer 20 is disposed on one main surface 10a of the substrate 10, and the one main surface 10a of the substrate 10 is covered with a sealing resin 26. The first resin layer 20 has a first main surface 20a on the substrate 10 side and a second main surface 20b on the opposite side to the substrate 10.

[0023] An electronic component 40 is mounted on one main surface 10a of the substrate 10. The electronic component 40 is connected to the second electrode 13 via solder 50. It can be said that the electronic component 40 is disposed in the first resin layer 20. A plating film 23 may be formed on the surface of the second electrode 13, as shown in Fig. 2. Furthermore, a plating film 23 may also be formed on the surface of the third electrode 19, as shown in Fig. 2.

[0024] The connection terminal 30 is disposed on one main surface 10a of the substrate 10. One end of the connection terminal 30 is joined to the first electrode 11, and the other end is exposed on the second main surface 20b of the first resin layer 20. The connection terminal 30 extends in the thickness direction of the substrate 10 (the vertical direction on the paper), and its height (indicated by the double-headed arrow h in FIG. 3 ) is 1 / 2. ３０ The height indicated by ( ) is equal to the thickness of the first resin layer 20 .

[0025] The surface of the connection terminal 30 exposed on the second main surface 20b side of the first resin layer 20 is not covered with a plating film, but may be covered with a plating film. This plating film may be a plating film provided integrally with the side surface of the connection terminal 30, or may be a different plating film.

[0026] Fig. 3 is a diagram showing the correspondence between the partially enlarged view of Fig. 2 and a schematic diagram of the bonding surface between the connection terminal and the first electrode in the enlarged view, as viewed from the connection terminal side. The lower view of Fig. 3 is the partially enlarged view of Fig. 2, and the upper view of Fig. 3 is a schematic diagram of the bonding surface between the connection terminal and the first electrode in the partially enlarged view, as viewed from the connection terminal side.

[0027] As shown in the lower drawing of FIG. 3, the direction in which the first electrodes 11 extend (left-right direction on the paper) is perpendicular to the direction in which the connection terminals 30 extend (up-down direction on the paper).

[0028] As shown in Fig. 3, the first electrode 11 is defined as having three portions: a first portion, a second portion, and a third portion. The first portion is the portion of the first electrode 11 that is joined to the connection terminal 30 (the portion indicated by reference symbol 11a and a double-headed arrow 11a in Fig. 3). The second portion is the portion that surrounds the outer periphery of the first portion 11a (the portion indicated by reference symbol 11b and a double-headed arrow 11b in Fig. 3). The third portion is the portion that surrounds the outer periphery of the second portion 11b (the portion indicated by reference symbol 11c and a double-headed arrow 11c in Fig. 3).

[0029] In the first portion 11a, the surface of the first electrode 11 is joined to the connection terminal 30. The first portion 11a of the first electrode 11 is flush with one main surface 10a of the substrate 10. In the second portion 11b, a plating film 23 is provided on the surface of the first electrode 11. The second portion 11b of the first electrode 11 is flush with one main surface 10a of the substrate 10. In the third portion 11c, a ceramic protective film 70 made of a ceramic material is provided on the surface of the first electrode 11. It can be said that the third portion 11c of the first electrode 11 is buried under the ceramic protective film 70.

[0030] 3, when the plating film 23 is provided on the surface of the second portion 11b of the first electrode 11 and the ceramic protective film 70 is provided on the surface of the third portion 11c, the thermal expansion of the first portion 11a is less likely to be transmitted directly to the substrate, improving the thermal temperature cycle characteristics. In addition, the provision of the ceramic protective film 70 on the third portion 11c, which is outside the plating film 23, improves the mechanical strength of the first electrode 11, contributing to improved thermal temperature cycle characteristics.

[0031] Unless otherwise specified, the surface of the first electrode in this specification refers to the surface of the first electrode on the connection terminal side. In other words, the surface of the first electrode on the connection terminal side is the surface that can be seen when viewing the first electrode from the connection terminal side in the thickness direction.

[0032] As shown in the upper diagram of FIG. 3, when the first electrode 11 is viewed from the thickness direction, the shape of the first portion 11a is a diameter R １１ａ The shape of the second portion 11b is a circle having a width W １１ｂ The third portion 11c has a ring shape with a width W １１ｃ It has a ring shape.

[0033] Diameter R of the first portion 11a of the connection terminal 30 １１ａ is the diameter R of the connection terminal 30 ３０ is equal to.

[0034] The ceramic protective film 70 is also provided on the outer periphery of the third portion 11c of the first electrode 11. For example, in the upper drawing of Figure 3, the ceramic protective film 70 is provided so as to cover the outer periphery of the third portion 11c of the first electrode 11.

[0035] (Substrate) The substrate has one main surface and the other main surface.

[0036] The substrate is formed by laminating multiple insulating layers on which conductor patterns that form circuits are arranged, such as electrodes exposed on one or the other main surface of the substrate, and wiring and via conductors arranged inside the substrate.

[0037] A first electrode is provided on one main surface of the substrate, and the first electrode is an electrode to be bonded to a connection terminal.

[0038] A second electrode may be provided on one main surface of the substrate. The second electrode is, for example, an electrode to be connected to an electronic component.

[0039] A third electrode may be provided on the other main surface of the substrate. The third electrode is an electrode to be connected to, for example, an electronic component.

[0040] Examples of electronic components include multilayer capacitors, multilayer inductors, filters, and ICs.

[0041] The ceramic material that constitutes the insulating layer includes a low temperature co-fired ceramic (LTCC) material.

[0042] Low-temperature co-fired ceramic materials are ceramic materials that can be fired at temperatures of 1000°C or less and can be co-fired with Au, Ag, Cu, etc., which have low resistivity. Specific examples of low-temperature co-fired ceramic materials include glass composite low-temperature co-fired ceramic materials obtained by mixing ceramic powders such as alumina, zirconia, magnesia, and forsterite with borosilicate glass; ZnO-MgO-Al ２ O ３ -SiO ２ Glass-ceramic low-temperature fired ceramic material using BaO-Al ２ O ３ -SiO ２ Ceramic powder and Al ２ O ３ -CaO-SiO ２ -MgO-B ２ O ３ Examples of suitable ceramic materials include non-glass-based low-temperature fired ceramic materials using ceramic powders.

[0043] The conductive material constituting the conductor pattern may be any material that can be co-fired with the low-temperature co-fired ceramic material, such as Cu, Ag, Au, and alloys thereof.

[0044] (First Electrode) The first electrode is provided on one main surface of the substrate.

[0045] In this specification, the first electrode is defined as having three portions, a first portion, a second portion, and a third portion, when viewed from the thickness direction. The first portion is a portion that is joined to the connection terminal. The second portion is a portion that surrounds the outer periphery of the first portion. The third portion is a portion that surrounds the outer periphery of the second portion.

[0046] In the first portion, the surface of the first electrode is joined to the connection terminal, in the second portion, a plating film is provided on the surface of the first electrode, and in the third portion, a ceramic protective film made of a ceramic material is provided on the surface of the first electrode.

[0047] The first, second, and third portions of the first electrode can be defined by the following procedure: First, identify the portion of the first electrode that is bonded to the connection terminal. When viewed from the thickness direction, define the portion of the first electrode that is bonded to the connection terminal as the first portion. Next, identify the portion of the surface of the first electrode where a plating film is provided around the first portion. Define the portion of the first electrode where a plating film is provided so as to surround the periphery of the first portion as the second portion. Finally, identify the portion of the surface of the first electrode where a ceramic protective film is provided around the periphery of the second portion. Define the portion of the first electrode where a ceramic protective film is provided so as to surround the periphery of the second portion as the third portion.

[0048] The surface of the first electrode means the surface of the first electrode on the connection terminal side. The surface of the first electrode opposite the connection terminal is the surface that is connected to the via conductor in the substrate.

[0049] The shape of the first portion as viewed in the thickness direction is not particularly limited, but examples thereof include a circle and a polygon.

[0050] The area of ​​the first portion as viewed in the thickness direction is not particularly limited, but is preferably 25,000 μm ２ More than 50000 μm ２ It is preferable that:

[0051] The thickness of the first electrode in the first portion is preferably 5 μm or more and 20 μm or less.

[0052] The shape of the second portion as viewed in the thickness direction is preferably a ring shape surrounding the outer periphery of the first portion.

[0053] The width of the second portion as viewed in the thickness direction is preferably 10 μm or more and 30 μm or less. For example, if the shape of the second portion as viewed in the thickness direction is annular, the width of the second portion can be calculated by {[(outer diameter of the second portion) - (inner diameter of the second portion)] / 2}.

[0054] The area of ​​the second portion as viewed in the thickness direction is not particularly limited, but is preferably 2900 μm ２ Above, 21600μm ２ It is preferable that:

[0055] The thickness of the second portion is preferably 5 μm or more and 20 μm or less, and is preferably the same as the thickness of the first portion.

[0056] The third portion preferably has a ring shape when viewed in the thickness direction, surrounding the outer periphery of the second portion.

[0057] The width of the third portion as viewed in the thickness direction is preferably 20 μm or more and 50 μm or less. For example, if the shape of the third portion as viewed in the thickness direction is annular, the width of the third portion can be calculated by {[(outer diameter of the third portion) - (inner diameter of the third portion)] / 2}.

[0058] The thickness of the first electrode in the third portion may be gradually reduced from the center (the second portion side) toward the outside, i.e., the surface of the first electrode in the third portion may be inclined toward the outside.

[0059] When viewed in the thickness direction, the width of the third portion is preferably larger than the width of the second portion. When the width of the third portion is larger than the width of the second portion, the contribution of thermal expansion of the ceramic protective film disposed on the surface of the third portion becomes larger than the contribution of thermal expansion of the plating film disposed on the surface of the second portion, making it easier for the ceramic protective film to suppress thermal expansion of the second portion.

[0060] When viewed in the thickness direction, the total area of ​​the third portion is preferably larger than the total area of ​​the first portion and the second portion. Note that the area of ​​the third portion means the area when the third portion is projected in the thickness direction, i.e., the maximum projected area. If the area of ​​the third portion is larger than the total area of ​​the first portion and the second portion, the ceramic protective film can easily suppress thermal expansion of the first portion and the second portion.

[0061] (Connection Terminal) The connection terminal is disposed on one main surface side of the substrate.

[0062] On one main surface of the substrate, one end of the connection terminal is joined to a part of the first electrode.

[0063] The connection terminal extends along the thickness direction of the substrate, and the other end is exposed on the second main surface of the first resin layer.

[0064] The height of the connection terminals can be adjusted appropriately to match the height of the electronic components mounted on one main surface of the substrate, and can be, for example, 30 μm or more and 150 μm or less.

[0065] The connecting terminal may have any shape as long as it is columnar, for example, may be a circular cylinder or a polygonal cylinder. A columnar connecting terminal is also called a metal pillar.

[0066] The connection terminal may have a tapered shape.

[0067] Examples of materials that can form the connection terminals include Cu, Ag, Au, and alloys thereof.

[0068] When the connection terminal has a cylindrical shape, the diameter of the connection terminal is preferably 150 μm or more and 250 μm or less, and more preferably 180 μm or more and 250 μm or less.

[0069] (Plating Film) Materials constituting the plating film include Cu, Ag, Au, Ni, Sn, and Pd.

[0070] The thickness of the plating film provided on the surface of the second portion of the first electrode is not particularly limited, but is preferably 5 μm or more and 10 μm or less.

[0071] (Ceramic Protective Film) Materials constituting the ceramic protective film include low-temperature co-fired ceramic (LTCC) materials.

[0072] The ceramic protective film may be disposed so as to cover the outer periphery of the third portion.

[0073] The low-temperature co-fired ceramic that constitutes the ceramic protective film may be the same as or different from the low-temperature co-fired ceramic that constitutes the substrate.

[0074] The thermal expansion coefficient of the connection terminal is μ １ , the thermal expansion coefficient of the plating film is μ ２ , the thermal expansion coefficient of the ceramic protective film is μ ３ When μ １ >μ ２ >μ ３ If the connection terminal, plating film, and ceramic protective film provided on the surface of the first electrode are made of materials with increasing thermal expansion coefficients from the inside out, the thermal expansion of the connection terminal is less likely to be transmitted to the outer substrate.

[0075] Thermal expansion coefficient μ of connection terminal １ , the thermal expansion coefficient μ of the plating film ２ and the thermal expansion coefficient μ of the ceramic protective film ３ can be measured by thermomechanical analysis.

[0076] Thermal expansion coefficient μ of connection terminal １ is 15 x 10 －６ [K －１ ] or more, 17 x 10 －６ [K －１ The thermal expansion coefficient μ of the plating film is preferably 0.01 to 0.01. ２ is 13 x 10 －６ [K －１ ] or more, 15 x 10 －６ [K －１ The thermal expansion coefficient μ of the ceramic protective film is preferably equal to or less than 10 ... ３ is 3 x 10 －６ [K －１ ] or more, 12 x 10 －６ [K －１ ] or less.

[0077] When the low-temperature co-fired ceramic forming the ceramic protective film and the low-temperature co-fired ceramic forming the substrate have the same material composition, it may be impossible to confirm the presence of the ceramic protective film on the surface of the first electrode in the third portion. An example of this case will be described with reference to FIG.

[0078] 4 is a diagram showing a correspondence between an enlarged view of a bonding portion between a connection terminal and a first electrode in another example of a circuit module of the present invention and a schematic view of the bonding surface between the connection terminal and the first electrode in the enlarged view, as viewed from the connection terminal side, in which the lower view of FIG. 4 is a partial enlarged view of the bonding portion between the connection terminal and the first electrode, and the upper view of FIG. 4 is a schematic view of the bonding surface between the connection terminal and the first electrode in the partial enlarged view, as viewed from the connection terminal side.

[0079] 4, similarly to the circuit module shown in FIG. 3, the first electrode can be divided into three parts: a first part, a second part, and a third part. The first part 11a is a part that is joined to the connection terminal 30. The second part 11b is a part that surrounds the outer periphery of the first part 11a. The third part 11c is a part that surrounds the outer periphery of the second part 11b.

[0080] In the first portion 11 a , the first electrode 11 is joined to the connection terminal 30 .

[0081] In the second portion 11b, a plating film 23 is provided on the surface of the first electrode 11. In the second portion 11b of the first electrode 11, the surface of the first electrode 11 is not in contact with the connection terminal 30 and the sealing resin 26 that constitutes the first resin layer 20.

[0082] In the third portion 11c, a ceramic protective film 70 made of a ceramic material is provided on the surface of the first electrode 11. However, if the ceramic material constituting the ceramic protective film 70 provided on the surface of the third portion 11c of the first electrode 11 and the ceramic material constituting the substrate 10 have the same composition, the ceramic protective film cannot be distinguished from the substrate 10 in a cross section such as that shown in the lower part of Figure 4. However, in Figure 4, the region where the ceramic protective film is presumed to be formed is indicated by a dashed line and is designated by the reference numeral 70.

[0083] However, the third portion 11c is a portion that surrounds the outer periphery of the second portion 11b, and since the third portion 11c constitutes the outermost portion of the first electrode 11, once the second portion 11b is identified, all of the portions outside it are determined to be the third portion 11c.

[0084] Therefore, when the first electrode 11 is viewed from the thickness direction, the shape of the first portion 11a is a diameter R １１ａ The shape of the second portion 11b is a circle having a width W １１ｂ The third portion 11c has a ring shape with a width W １１ｃ It has a ring shape.

[0085] In the third portion 11c, the thickness of the first electrode 11 gradually decreases outward (toward the opposite side from the first portion). １ The thickness of the ceramic material disposed between the first resin layer 20 and the second portion 11b is thinner as it approaches the second portion 11b and is thicker as it moves away from the second portion 11b.

[0086] In the first portion 11a and the second portion 11b, the surface of the first electrode 11 on the connection terminal 30 side is parallel to the surface opposite to the connection terminal 30, whereas in the third portion 11c, the surface 11c of the first electrode 11 on the connection terminal 30 side is parallel to the surface １ and the surface 11c opposite to the connection terminal 30. ２ and are not parallel.

[0087] The cross-sectional shape of the third portion 11c of the first electrode 11 in FIG. 4 is a widthwise end portion 11c of the first electrode 11 extending from the outer edge of the second portion 11b of the first electrode 11 on the surface on the connection terminal 30 side to the end portion 11c of the first electrode 11 in the width direction. ３ The edge extending toward the surface 11c １ ) and a widthwise end 11c of the first electrode 11 from the outer edge of the second portion 11b of the first electrode 11 on the surface opposite to the connection terminal 30. ３ The edge extending toward the surface 11c ２ It can be said that the shape is surrounded by (the side corresponding to

[0088] The outer edge of the third portion 11c of the first electrode 11, i.e., the end 11c in the width direction of the first electrode 11 in the cross-sectional view ３ The position of the first electrode 11 may be on an extension plane L extending from the surface of the first part 11a and the second part 11b of the first electrode 11 opposite the connection terminal 30, or may be on the opposite side of the connection terminal 30 (below the paper) based on the extension plane L.

[0089] The end 11c in the width direction of the first electrode 11 shown in FIG. ３ is disposed on the opposite side of the connection terminal 30 (lower side of the drawing) with respect to the extension plane L. In this case, it can be said that the third portion 11c of the first electrode 11 is slightly bent toward the opposite side of the connection terminal 30. The bending point is the boundary between the second portion 11b and the third portion 11c.

[0090] (First Resin Layer) A first resin layer may be disposed on one main surface of the substrate.

[0091] The first resin layer has a first main surface facing the substrate and a second main surface facing away from the substrate.

[0092] When the first resin layer is disposed, the connection terminals are disposed in the first resin layer.

[0093] The sealing resin constituting the first resin layer may be either a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include phenolic resin, epoxy resin, polyester resin, silicone resin, and polyimide resin. Examples of thermoplastic resins include thermoplastic liquid crystal polymer (LCP), thermoplastic polyimide resin, polyether ether ketone resin (PEEK), and polyphenylene sulfide resin (PPS).

[0094] The sealing resin constituting the first resin layer may contain additives such as fillers, etc. Examples of fillers include glass, silica, aluminum oxide, aluminum nitride, and boron nitride.

[0095] A second resin layer may further be disposed on the other main surface of the substrate.

[0096] An electronic component may be disposed in the second resin layer. When an electronic component is disposed in the second resin layer, the electronic component is preferably connected to a third electrode disposed on the other main surface of the substrate via solder. In this case, the electronic component can be said to be mounted on the other main surface of the substrate.

[0097] The types of sealing resin and filler constituting the second resin layer may be the same as or different from those of the first resin layer.

[0098] (Shielding Film) A shielding film may be provided on the surface (top surface) and side surfaces of the second resin layer opposite the substrate, and on the side surfaces of the substrate. The shielding film can be formed by, for example, sputtering. In addition to sputtering, the shielding film can also be formed by existing methods such as coating of a conductive resin, plating, and vapor deposition.

[0099] In this case, it is preferable that a ground electrode is provided so as to be exposed on the side surface of the substrate, and that the ground electrode is connected to the shielding film.

[0100] The shielding film may extend to the side surface of the first resin layer.

[0101] The circuit module may have a plurality of connection terminals.

[0102] [Method for Manufacturing Circuit Module] Next, an example of a method for manufacturing the circuit module of the present invention will be described with reference to the drawings. However, the order of each step described below, the number of layers, and the configuration of each sheet are not limited to the contents of the drawings. Furthermore, each step described below is a method for manufacturing a circuit module in a pre-divided state, but multiple circuit modules may be manufactured in an assembled state and then divided into individual pieces.

[0103] 5 is a cross-sectional view showing a schematic example of a constraining layer sheet used in manufacturing a circuit module. First, as shown in FIG. 5, a constraining layer sheet 130 and a carrier film 90 are laminated together to prepare a laminate. The constraining layer sheet 130 with the carrier film 90 peeled off is also referred to as a laminated sheet 100A.

[0104] The raw material for the constraining layer sheet, a hard-to-sinter ceramic material, is mixed with an organic binder and a plasticizer in any desired amounts to prepare a slurry, which is then applied to the surface of a carrier film and formed into a sheet, thereby obtaining a laminate of a constraining layer sheet and a carrier film, as shown in Figure 5.

[0105] Examples of the sintering-resistant ceramic material include Al ２ O ３ Examples include powders.

[0106] Fig. 6 is a cross-sectional view schematically showing a step of printing a conductive paste on the surface of the constraining layer sheet shown in Fig. 5. As shown in Fig. 6, a conductive paste 142 is printed on the surface of the constraining layer sheet 130 shown in Fig. 5. This allows a laminate sheet 100B to be obtained in which the conductive paste 142 is printed on the surface of the constraining layer sheet 130.

[0107] The conductive paste can be obtained by dispersing a conductive material, such as copper powder, in an organic binder.

[0108] The conductive paste is printed on the surface of the constraining layer sheet by a known method such as screen printing.

[0109] Fig. 7 is a cross-sectional view schematically showing a process of forming a through hole in the surface of the constraining layer sheet shown in Fig. 5. As shown in Fig. 7, a through hole 180 is formed in the constraining layer sheet 130 shown in Fig. 5. The method for forming the through hole is not particularly limited, and examples include laser irradiation and drilling.

[0110] Fig. 8 is a cross-sectional view schematically showing a step of filling the through holes of the constraining layer sheet shown in Fig. 7 with a conductive paste. Next, as shown in Fig. 8, the through holes 180 of the constraining layer sheet 130 shown in Fig. 7 are filled with a conductive paste. This results in a laminated sheet 100C in which the conductive paste 131 is filled so as to penetrate the constraining layer sheet 130 in the thickness direction. The conductive paste 131 filled in the through holes 180 becomes a connection terminal by sintering.

[0111] The conductive paste is filled into the through holes by a known method such as screen printing.

[0112] 9 is a cross-sectional view showing a schematic example of a ceramic green sheet used in manufacturing a circuit module. As shown in FIG. 9, a laminate of a carrier film 90 and a ceramic green sheet 110 is prepared.

[0113] A low-temperature co-fired ceramic material, an organic binder, and a plasticizer are mixed in any desired amounts to prepare a slurry, which is then applied to the surface of a carrier film and formed into a sheet, thereby obtaining a laminate of a ceramic green sheet and a carrier film, as shown in FIG.

[0114] Fig. 10 is a cross-sectional view schematically showing a step of printing a conductive paste on the surface of the ceramic green sheet shown in Fig. 9. Subsequently, as shown in Fig. 10, a conductive paste 142 is printed by printing on the surface of the ceramic green sheet 110 shown in Fig. 9. This results in a laminate sheet 100D in which the conductive paste 142 is printed on the surface of the ceramic green sheet 110. Note that in Fig. 15 described later, two types of laminate sheets 100D are used, in which the printed conductive paste 142 is printed at different positions.

[0115] Fig. 11 is a cross-sectional view schematically showing a step of forming a through hole in the surface of the ceramic green sheet shown in Fig. 9. As shown in Fig. 11, a through hole 181 is formed in the ceramic green sheet 110 shown in Fig. 9. The method of forming the through hole is the same as the step shown in Fig. 7.

[0116] Fig. 12 is a cross-sectional view schematically showing a step of filling the through holes of the ceramic green sheet shown in Fig. 11 with a conductive paste. Subsequently, as shown in Fig. 12, the conductive paste is filled into the through holes 181. This results in a laminated sheet 100E in which the conductive paste 140 is filled so as to penetrate the ceramic green sheet 110 in the thickness direction.

[0117] Fig. 13 is a cross-sectional view schematically showing a step of printing a conductive paste on the surface of the ceramic green sheet shown in Fig. 12. Subsequently, as shown in Fig. 13, a conductive paste 142 is printed by printing on the surface of the ceramic green sheet 110 shown in Fig. 12. As a result, the conductive paste 140 is filled so as to penetrate the ceramic green sheet 110 in the thickness direction, and a laminate sheet 100F having the conductive paste 142 printed on the surface is obtained.

[0118] 14 is a cross-sectional view schematically illustrating a process of printing a conductive paste and a ceramic protective film paste on the surface of the ceramic green sheet shown in FIG. 12. Next, as shown in FIG. 14, a conductive paste 142 is printed on the surface of the ceramic green sheet 110 shown in FIG. 12. Furthermore, a ceramic protective film paste 170 is printed so as to extend over a portion of the surface of the printed conductive paste 142 and the surface of the ceramic green sheet 110. At this time, the ceramic protective film paste 170 is formed so as to surround the outer edge of the conductive paste 142 that will become the first electrode. As a result, the conductive paste 142 that will become the first electrode and the conductive paste 142 that will become the second electrode are printed on the surface of the ceramic green sheet 110, resulting in a laminate sheet 100G in which the ceramic protective film paste 170 is printed so as to surround the outer edge of the conductive paste 142 that will become the first electrode. 14. Note that a portion of the conductive paste 142 printed on the surface of the ceramic green sheet 110 in FIG. 14 overlaps with the conductive paste 142 printed on the surface of the ceramic green sheet 110 in FIG.

[0119] FIG. 15 is a diagram schematically illustrating an example of a process for stacking prepared laminate sheets. As shown in FIG. 15, laminate sheets 100A to 100G prepared in the above process are stacked in a predetermined order. In FIG. 15, from the top, laminate sheet 100C, laminate sheet 100C, laminate sheet 100G, laminate sheet 100D, laminate sheet 100D, laminate sheet 100F, laminate sheet 100B, and laminate sheet 100A are stacked in this order to form laminate body 200.

[0120] FIG. 16 is a diagram schematically illustrating an example of a process for compressing a laminate. As shown in FIG. 16 , a laminate 200 is compressed to obtain a compressed body 210. Because the ceramic protective film paste 170 is printed to cover the outer edge of the conductive paste 142 that will become the first electrode, during compression bonding, the portion of the conductive paste 142 that will become the first electrode and that overlaps with the ceramic protective film paste 170 bends toward the inside of the substrate (toward the bottom of the page) and deforms so that its thickness decreases toward the outside. This changes the shape of the conductive paste 142 to a shape similar to the first electrode 11 shown in FIG. 3 .

[0121] The pressure and temperature when the laminate is pressed together can be set arbitrarily according to the design.

[0122] 17 is a diagram schematically illustrating an example of a process for firing the pressure-bonded body 210. As shown in FIG. 17, firing the pressure-bonded body 210 sinters the conductive paste filled in the through holes and the printed conductive paste, and also progresses the sintering of the ceramic green sheets, resulting in a fired body 220.

[0123] At this time, the ceramic green sheets are sintered to form the substrate 10, and the conductive paste filled in the constraining layer sheets is sintered to form the connection terminals 30. The conductive paste filled or printed on the ceramic green sheets is sintered to form the first electrode 11, the second electrode 13, the via conductors 15, the wiring 17, and the third electrode 19. Furthermore, the ceramic green sheets 110 and the ceramic protective film paste 170 are sintered to form the substrate 10 and the ceramic protective film 70.

[0124] Only a portion of the surface of the first electrode 11 is joined to the connection terminal 30. Of the surface of the first electrode 11, the portion joined to the connection terminal 30 is the first portion.

[0125] A ceramic protective film 70 is provided on a portion of the surface of the first electrode 11. The portion of the surface of the first electrode 11 on which the ceramic protective film 70 is provided is a third portion.

[0126] Furthermore, if the ceramic material constituting the ceramic green sheet 110 and the ceramic material constituting the ceramic protective film paste 170 have the same material composition, it may become impossible to distinguish between the ceramic protective film in the fired body 220 and the ceramic material constituting the substrate.

[0127] 15 and 16 , in the pressure-bonded body 210, the constraining layer sheet 130 is laminated on the surface of the ceramic protective film paste 170, and therefore, during firing, some of the components of the hard-to-sinter ceramic that constitutes the constraining layer sheet 130 may diffuse toward the ceramic protective film paste 170. In such a case, by checking the area outside the second portion of the first electrode by elemental mapping or the like where the content of the elements that constitute the hard-to-sinter ceramic is high, it may be possible to indirectly identify the portion where the ceramic protective film is formed (the region where the ceramic protective film 70 is formed, shown in FIG. 4 ).

[0128] The firing can be performed using a firing furnace such as a batch furnace, a belt furnace, etc. The firing temperature is not particularly limited, but is preferably 800°C or higher and 1000°C or lower.

[0129] 18 is a diagram schematically illustrating an example of a step of removing the constraining layer. Next, as shown in FIG. 18, the constraining layer 190 (residue of the constraining layer sheet) is removed by cleaning. By removing the constraining layer, the substrate 10 (object to be cleaned 230) is obtained, with the connection terminals 30 exposed on one main surface 10a.

[0130] The method for removing the constraining layer is not particularly limited, but a known method such as sandblasting can be used.

[0131] By removing the constraining layer 190, a second portion, which is a portion of the surface of the first electrode 11 other than the first portion and the third portion, is exposed.

[0132] 19 is a diagram schematically illustrating an example of a process for forming a plating film. Next, as shown in FIG. 19, a plating film is formed on the surface of the substrate 10. As a result, a plating film 23 is formed on the side and upper surfaces of the connection terminals 30, part of the first electrodes 11, the surfaces of the second electrodes 13, and the surfaces of the third electrodes 19.

[0133] The plating film 23 is formed on a second portion other than the first and third portions of the surface of the first electrode 11. The surface of the first portion of the first electrode 11 is joined to the connection terminal 30, and the ceramic protective film 70 is provided on the surface of the third portion of the first electrode 11, so that the plating film 23 is not formed on either portion.

[0134] 20 is a diagram schematically illustrating an example of a process for mounting an electronic component on one main surface of a substrate. Next, as shown in FIG. 20, the electronic component is mounted on one main surface 10a of the substrate 10 using second electrodes 13. Solder 50 is provided between the second electrodes 13 and the electronic component 40.

[0135] 21 is a cross-sectional view schematically showing an example of a process for encapsulating an electronic component. Subsequently, as shown in FIG. 21, encapsulation resin 26 is applied onto one main surface 10a of the substrate. As a result, electronic component 40 is encapsulated by encapsulation resin 26.

[0136] Fig. 22 is a cross-sectional view schematically showing an example of a step of grinding the surface of the sealing resin. Next, as shown in Fig. 22, the surface of the sealing resin 26 is ground to expose the connection terminals 30. In Fig. 22, the top surface of the electronic component 40 is also exposed, but the top surface of the electronic component 40 does not have to be exposed. Through the above steps, the circuit module 1 described in Fig. 2 is obtained.

[0137] In the above, the ceramic green sheets and the constraining layer sheets are each formed on a carrier film, and then peeled from the carrier film and laminated together. However, instead of the above method, for example, a method may be adopted in which a ceramic green sheet is formed on the surface of a carrier film, and then a constraining layer sheet is formed on the surface of the ceramic green sheet. The method for forming the constraining layer sheet on the surface of the carrier film can be the same as the method for forming the constraining layer sheet on the surface of the carrier film.

[0138] In addition to the above steps, a step of forming a plating film on the surface of the connection terminal exposed on the second main surface of the first resin layer may be performed. FIG. 23 is a cross-sectional view schematically showing the step of forming a plating film on the surface of the connection terminal. As shown in FIG. 23 , a plating film 24 may be formed on the surface of the connection terminal 30. The plating film 24 can be formed, for example, by performing a plating process on the circuit module 1 shown in FIG. 23 . The plating film 24 may be formed of, for example, Ni and / or Sn. By adding the above steps, a plating film can be formed on the surface of the connection terminal exposed on the second main surface of the first resin layer.

[0139] In addition to the above steps, a step of mounting electronic components on the other main surface of the substrate and sealing it with a sealing resin to form a second resin layer may be performed.

[0140] 24 is a cross-sectional view schematically showing a process of mounting an electronic board on the other main surface of the substrate. Next, as shown in FIG. 24, electronic components 41 and 42 are mounted on the other main surface 10b of the substrate 10. The electronic components 41 and 42 are each connected to a third electrode 19 provided on the other main surface 10b of the substrate 10 via solder 50.

[0141] 25 is a cross-sectional view schematically illustrating an example of a process for encapsulating electronic components. Subsequently, as shown in FIG. 25 , encapsulating resin 63 is applied onto the other main surface 10b of substrate 10. As a result, electronic components 41 and 42 are encapsulated by encapsulating resin 63.

[0142] 26 is a cross-sectional view schematically showing an example of a step of grinding the surface of the sealing resin. Next, as shown in FIG. 26 , the surface of the sealing resin 63 is ground to adjust the shape of the second resin layer 60. Through the above steps, the electronic components 41 and 42 are mounted on the other main surface 10b of the substrate 10 and sealed with the sealing resin 63, thereby obtaining the circuit module 2 on which the second resin layer 60 is formed.

[0143] This specification describes the following:

[0144] The present disclosure (1) is a circuit module comprising a substrate having one main surface and another main surface, and a connection terminal arranged on the one main surface side of the substrate, wherein a first electrode is provided on the one main surface of the substrate, and one end of the connection terminal is joined to the first electrode on the one main surface side of the substrate, and when the first electrode is viewed in the thickness direction, a portion of the first electrode joined to the connection terminal is defined as a first portion, a portion surrounding the outer periphery of the first portion is defined as a second portion, and a portion surrounding the outer periphery of the second portion is defined as a third portion, and a plating film is provided on the surface of the second portion, and a ceramic protective film made of a ceramic material is provided on the surface of the third portion.

[0145] The present disclosure (2) is to set the thermal expansion coefficient of the connection terminal to μ １ , the thermal expansion coefficient of the plating film is μ ２ , the thermal expansion coefficient of the ceramic protective film is μ ３ When μ １ >μ ２ >μ ３ The circuit module according to the present disclosure (1) satisfies the following.

[0146] The present disclosure (3) is a circuit module according to the present disclosure (1) or (2), in which the width of the third portion is larger than the width of the second portion when viewed in the thickness direction.

[0147] The present disclosure (4) is a circuit module that is any combination of the present disclosures (1) to (3), in which the area of ​​the third portion is larger than the sum of the area of ​​the first portion and the area of ​​the second portion when viewed in the thickness direction.

[0148] The present disclosure (5) is a circuit module of any combination with any of the present disclosures (1) to (4), in which the second portion of the first electrode is flush with the one main surface of the substrate, and the third portion of the first electrode is buried under the ceramic protective film.

[0149] 1, 2 Circuit module 10 Substrate 10a One main surface of the substrate 10b Other main surface of the substrate 11 First electrode 11a First portion of the first electrode 11b Second portion of the first electrode 11c Third portion of the first electrode 11c １ Surface 11c of the third portion on the connection terminal side ２ Surface 11c of the third portion opposite to the connection terminal ３ End of first electrode in width direction 13 Second electrode 15 Via conductor 17 Wiring 19 Third electrode 20 First resin layer 20a First main surface of first resin layer 20b Second main surface of first resin layer 23, 24 Plating film 26 Sealing resin 30 Connection terminal 40, 41, 42 Electronic component 50 Solder 60 Second resin layer 63 Sealing resin 70 Ceramic protective film 90 Carrier film 100A, 100B, 100C, 100D, 100E, 100F, 100G Laminated sheet 110 Ceramic green sheet 130 Constraining layer sheet 131, 140 Filled conductive paste 142 Printed conductive paste 150 Ceramic paste 170 Ceramic protective film paste 180, 181 Through hole 190 Constraining layer 200 laminated body 210 pressed body 220 fired body 230 body to be cleaned G center of gravity of first electrode h ３０ Height of the connection terminal: L Extension surface of the surface of the first and second parts of the first electrode opposite to the connection terminal: R ３０ Diameter of connecting terminal R １１ａ Diameter of first part W １１ｂ Width of second part W １１ｃ Third part width

Claims

1. A circuit module comprising: a substrate having one main surface and another main surface; and a connection terminal arranged on the one main surface side of the substrate, wherein a first electrode is provided on the one main surface of the substrate, and one end of the connection terminal is joined to the first electrode on the one main surface side of the substrate, wherein, when the first electrode is viewed in the thickness direction, a portion of the first electrode joined to the connection terminal is defined as a first portion, a portion surrounding the outer periphery of the first portion is defined as a second portion, and a portion surrounding the outer periphery of the second portion is defined as a third portion, a plating film is provided on a surface of the second portion, and a ceramic protective film made of a ceramic material is provided on a surface of the third portion.

2. The thermal expansion coefficient of the connection terminal is μ １ , the thermal expansion coefficient of the plating film is μ ２ , the thermal expansion coefficient of the ceramic protective film is μ ３ Then, μ １ >μ ２ >μ ３ The circuit module according to claim 1 , which satisfies the following:

3. The circuit module according to claim 1 or 2, wherein the width of the third portion is greater than the width of the second portion when viewed in the thickness direction.

4. A circuit module according to any one of claims 1 to 3, wherein, when viewed in the thickness direction, the area of ​​the third portion is larger than the sum of the area of ​​the first portion and the area of ​​the second portion.

5. A circuit module as described in any one of claims 1 to 4, wherein the second portion of the first electrode is flush with the one main surface of the substrate, and the third portion of the first electrode is buried under the ceramic protective film.

Images