Circuit module and soldered circuit module

Abstract

A circuit module 1 comprises: a substrate 11 having a first main surface 11a and a second main surface 11b; a resin layer 31 provided on the first main surface 11a of the substrate 11; and a connection terminal 41 penetrating the resin layer 31a in a thickness direction. The circuit module 1 is characterized in that: the connection terminal 41 has a first bottom surface 41a located on the substrate 11 side, a second bottom surface 41b opposite to the first bottom surface 41a, and a side surface 41c; the second bottom surface 41b is exposed from the resin layer 31; a recessed portion 33 recessed toward the first main surface 11a of the substrate 11 is formed in a region of the surface of the resin layer 31 surrounding the second bottom surface 41b of the connection terminal 41; part of the side surface 41c of the connection terminal 41 is exposed in the recessed portion 33; the connection terminal 41 includes a first portion 41A having a large width and a second portion 41B having a width smaller than that of the first portion 41A; the width of the connection terminal 41 at the second bottom surface 41b corresponds to the width of the second portion 41B; and a solder wettability improving layer 42 is provided on the second bottom surface 41b of the connection terminal 41 and the part of the side surface 41c of the connection terminal 41 exposed from the recessed portion 33.

Description

Circuit module and soldered circuit module

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

[0002] Patent Document 1 describes a high-frequency module comprising: a module substrate having a first main surface and a second main surface facing each other; a resin member covering the second main surface; and a plurality of external connection terminals arranged apart from each other on the second main surface and each penetrating the resin member from the second main surface, wherein the plurality of external connection terminals include a first external connection terminal, and a first recess recessed toward the second main surface is formed in at least a part of an area on the surface of the resin member surrounding a tip portion of the first external connection terminal.

[0003] Japanese Patent Application Laid-Open No. 2021-197611

[0004] The high-frequency module described in Patent Document 1 does not consider the bondability between the external connection terminals and the solder. In the high-frequency module described in Patent Document 1, when solder is applied to the external connection terminals, the solder does not wet and spread easily, and the bond strength between the external connection terminals and the solder may be insufficient.

[0005] The inventors have considered means for solving the above problems and have found that the bonding strength between the external connection terminal and the solder can be improved by exposing the second bottom surface of the connection terminal from the resin layer, forming a recess that is recessed toward the first main surface of the substrate in the area on the surface of the resin layer that surrounds the second bottom surface of the connection terminal, and exposing a portion of the side surface of the connection terminal in the recess.

[0006] However, when the size of the electrode on the board to which the circuit module is connected is small relative to the size of the second bottom surface of the connection terminal, the solder may spread too much onto the surface of the electrode on the board, resulting in a thin solder thickness on the side surface of the connection terminal.When the solder thickness in this area is thin, the bonding strength between the connection terminal and the electrode on the board may be insufficient.

[0007] The present invention has been made to solve the above problems, and aims to provide a circuit module that can increase the bonding strength between the solder and the connection terminal when the connection terminal is joined to the solder, and can also increase the impact resistance at the joint between the connection terminal and the solder.

[0008] The circuit module of the present invention is a circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; and a connection terminal penetrating the resin layer in the thickness direction, wherein the connection terminal has a first bottom surface located on the substrate side, a second bottom surface opposite the first bottom surface, and a side surface, the second bottom surface being exposed from the resin layer; a recess recessed toward the first main surface of the substrate is formed in the surface of the resin layer in an area surrounding the second bottom surface of the connection terminal, and a portion of the side surface of the connection terminal is exposed in the recess; the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, the width of the connection terminal at the second bottom surface is the same as the width at the second portion; and a solder wettability improving layer is provided on the second bottom surface of the connection terminal and the side surface of the connection terminal that are exposed from the recess.

[0009] The soldered circuit module of the present invention is a soldered circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; connection terminals penetrating the resin layer in a thickness direction; and solder bumps joined to the connection terminals via an intermetallic compound layer, wherein the connection terminals have a first bottom surface located on the substrate side, a second bottom surface opposite to the first bottom surface, and side surfaces, the second bottom surface being not covered by the resin layer, and a recess recessed toward the first main surface of the substrate is formed in a region on the surface of the resin layer surrounding the second bottom surface of the connection terminal, and one of the side surfaces of the connection terminal is in the recess. a portion of the connection terminal is exposed, the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, the width of the connection terminal at the second bottom surface is the width at the second portion, the solder bump is provided so as to cover the second bottom surface of the connection terminal and at least a portion of the portion of the side surface of the connection terminal that is exposed from the recess, and the intermetallic compound layer is present between the connection terminal and the solder bump, and the intermetallic compound layer covers the second bottom surface of the connection terminal and at least a portion of the portion of the side surface of the connection terminal that is exposed from the recess.

[0010] According to the present invention, a circuit module can be provided that, when the connection terminal is joined to the solder, can increase the joining strength between the solder and the connection terminal, and can also increase the impact resistance at the joint between the connection terminal and the solder.

[0011] FIG. 1 is a cross-sectional view schematically illustrating an example of a circuit module. FIG. 2 is a plan view of the circuit module, viewed from the surface on which the resin layer and connection terminals are provided. FIG. 3 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module shown in FIG. 1. FIG. 4 is a schematic diagram illustrating the connection terminals shown in FIG. 3 connected to electrodes on a substrate via solder bumps. FIG. 5 is a schematic diagram illustrating connection terminals with a constant width connected to electrodes on a substrate via solder bumps. FIG. 6 is an enlarged view schematically illustrating another example of the structure around the connection terminals in the circuit module. FIG. 7 is an enlarged view schematically illustrating another example of the structure around the connection terminals in the circuit module. FIG. 8 is an enlarged view schematically illustrating another example of the structure around the connection terminals in the circuit module. FIG. 9 is an enlarged view schematically illustrating another example of the structure around the connection terminals in the circuit module. FIG. 10 is a schematic diagram illustrating the connection terminals shown in FIG. 9 connected to electrodes on a substrate via solder bumps. FIG. 11 is an enlarged view schematically showing another example of the structure around a connection terminal in a circuit module. FIG. 12 is an enlarged view schematically showing another example of the structure around a connection terminal in a circuit module. FIG. 13 is an enlarged view schematically showing another example of the structure around a connection terminal in a circuit module. FIG. 14 is an enlarged view schematically showing another example of the structure around a connection terminal in a circuit module. FIG. 15 is an enlarged view schematically showing another example of the structure around a connection terminal in a circuit module. FIG. 16 is a cross-sectional view schematically showing an example of a soldered circuit module. FIG. 17 is an enlarged view schematically showing the structure around a connection terminal in the soldered circuit module shown in FIG. 16. FIG. 18 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. FIG. 19 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. FIG. 20 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. Fig. 21 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. Fig. 22 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. Fig. 23 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention.

[0012] The circuit module and soldered circuit module of the present invention are described below. However, the present invention is not limited to the following configurations, and can be modified as appropriate within the scope of the present invention. Note that a combination of two or more of the preferred configurations of each embodiment of the present invention described below also constitutes the present invention.

[0013] First, the circuit module of the present invention will be described.

[0014] Fig. 1 is a cross-sectional view schematically showing an example of a circuit module, and Fig. 2 is a plan view of the circuit module as seen from the surface on which the resin layer and the connection terminals are provided.

[0015] Fig. 1 is a cross-sectional view taken along line II in the plan view shown in Fig. 2. An example of a circuit module of the present invention will now be described with reference to Fig. 1 and Fig. 2. The circuit module 1 includes a substrate 11, an electronic component 21, resin layers 31 and 32, and a connection terminal 41.

[0016] The substrate 11 has a first main surface 11a and a second main surface 11b facing each other. Electrodes 12 are provided on the first main surface 11a and the second main surface 11b of the substrate 11. The substrate 11 includes an insulator layer 13, and pattern conductors 14 and via conductors 15, which are conductors necessary for configuring an electronic circuit.

[0017] The substrate 11 is a ceramic substrate in which the insulator layer 13 is made of, for example, a low-temperature co-fired ceramic material. The low-temperature co-fired ceramic material is a type of ceramic material that can be co-fired with silver or copper, which are used as metal materials, at a firing temperature of 1000° C. or less. For example, SiO ２ -CaO-Al ２ O ３ -B ２ O ３ based glass ceramic or SiO ２ -MgO-Al ２ O ３ -B ２ O ３Examples of suitable materials include those containing glass ceramics. However, the type of insulator layer 13 is not limited to this. For example, insulator layer 13 may be formed from glass epoxy resin, ceramics other than low-temperature co-fired ceramic materials, glass, etc. The pattern conductors 14 and via conductors 15 are formed using a metal material selected from Cu, Cu alloys, etc. However, the materials of pattern conductors 14 and via conductors 15 are not limited to this. The substrate 11 may be either a multilayer substrate or a single-layer substrate.

[0018] The electrode 12 is formed by plating the surface of a metal material selected from Cu, Cu alloys, etc. with a metal material selected from Ni, Ni alloys, etc. However, the material of the electrode 12 is not limited to this.

[0019] The electronic component 21 is connected to the electrode 12 provided on the first main surface 11a or the second main surface 11b of the substrate 11 by a connecting member 16. The electronic component 21 is preferably, for example, a chip component such as a multilayer capacitor, a multilayer inductor, or various filters, or a semiconductor component such as various ICs or memories. The connecting member 16 is, for example, a Sn-Ag-Cu based Pb-free solder. However, the material of the connecting member 16 is not limited to this.

[0020] 1, the electronic components 21 are provided on both the first main surface 11a and the second main surface 11b of the substrate 11, but the electronic components 21 may be provided on at least one of the first main surface 11a and the second main surface 11b of the substrate 11. Alternatively, the electronic components 21 may not be provided on the substrate 11.

[0021] The resin layer 31 is provided on the first main surface 11a of the substrate 11. The resin layer 32 is provided on the second main surface 11b of the substrate 11. Each of the resin layers 31 and 32 is preferably a resin composition in which a glass material, silica, or the like is dispersed as a filler in a resin material. A high thermal conductivity material may be used as the filler. For example, the filler may be an oxide or nitride such as aluminum oxide, aluminum nitride, or boron nitride, or a metal material such as copper coated with an insulator. The resin layers 31 and 32 may also be layers made solely of a resin material. The resin layers 31 and 32 may be formed using the same or different resin materials. Note that the circuit module 1 does not necessarily require a resin layer to be provided on the second main surface 11b.

[0022] The electronic component 21 may be completely covered by the resin layer 31 or the resin layer 32, or the surface of the electronic component 21 may be exposed from the outer surface of the resin layer 31 or the resin layer 32. In this specification, the outer surface of the resin layer means the main surface that is not in contact with the substrate 11, of the two main surfaces that are opposite to each other in the thickness direction of the resin layer.

[0023] The connection terminal 41 penetrates in the thickness direction through the resin layer 31 provided on the first main surface 11a of the substrate 11. The connection terminal 41 has a first bottom surface 41a located on the substrate 11 side, a second bottom surface 41b opposite the first bottom surface 41a, and a side surface 41c.

[0024] In the circuit module 1, the first bottom surface 41a is in contact with the electrode 12 provided on the first main surface 11a of the substrate 11. Although not shown, the connection terminal 41 may be in direct contact with the substrate 11 without the electrode 12. Note that the case where the connection terminal 41 is in contact with the electrode 12 provided on the first main surface 11a of the substrate 11 is also included in the case where the connection terminal 41 is provided on the first main surface 11a of the substrate, and is also included in the case where the connection terminal 41 penetrates the resin layer 31 provided on the first main surface 11a of the substrate 11 in the thickness direction. The second bottom surface 41b is exposed from the resin layer 31. A solder wettability improving layer 42 is provided in a portion including the second bottom surface 41b.

[0025] The material constituting the connection terminal 41 is not particularly limited, but is preferably Cu, Ag, Au, Al, Ni, Cr, Ti, or an alloy containing at least one of these metals. The shape of the connection terminal 41 will be described in detail later.

[0026] 2, a recess 33 recessed toward the first main surface 11a of the substrate 11 is formed in a region on the surface of the resin layer 31 that surrounds the second bottom surface 41b of the connection terminal 41. The method for forming the recess 33 is not particularly limited, but for example, the recess 33 may be formed by irradiating a laser to remove a portion of the resin 31.

[0027] 2, in the circuit module 1, recesses 33 are provided around all of the connection terminals 41, but recesses 33 may be provided around only some of the connection terminals 41. For example, recesses 33 may be provided around only the connection terminal 41E located at the end of the circuit module 1.

[0028] 2, each recess 33 is provided so as to surround the periphery of each connection terminal 41, but the recesses 33 surrounding the connection terminals 41 may be connected to each other. In other words, one recess 33 may be provided so as to surround the periphery of a plurality of connection terminals 41.

[0029] FIG. 3 is an enlarged view schematically showing the structure around the connection terminals in the circuit module shown in FIG.

[0030] 3, 6 to 9, and 11 to 15 show views in which the structure in Fig. 1 is inverted upside down. The structure around the connection terminal 41 will be described below with reference to Fig. 3. Fig. 3 shows a configuration in which the solder wettability improving layer 42 is an OSP treatment layer 44.

[0031] 3, a portion of the side surface 41c of the connection terminal 41 is exposed in the recess 33. That is, the side surface 41c of the connection terminal 41 includes a portion 41c1 that is exposed in the recess 33 and a portion 41c2 that is not exposed in the recess 33. In FIG. 3, the portion 41c1 and the portion 41c2 are each shown surrounded by a dotted line.

[0032] The thickness of the resin layer 31 may be 50 μm or more and 200 μm or less. The thickness of the resin layer 31 means the thickness at the position where the thickness is greatest. The depth of the recess 33 (the length indicated by the double arrow A in FIG. 3) is not particularly limited, but may be, for example, 5 μm or more and 50 μm or less. The depth of the recess 33 means the depth at the position where the depth is greatest.

[0033] The connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion. In the connection terminal 41 shown in Figure 3, a portion 41c2 where the side surface 41c is not exposed from the recess 33 corresponds to the first portion 41A, and the width Wa of the connection terminal 41 is larger in the first portion 41A. A portion 41c1 where the side surface 41c of the connection terminal 41 is exposed from the recess 33 corresponds to the second portion 41B, and the width Wb of the connection terminal 41 in the second portion 41B is smaller than the width Wa. The width of the connection terminal 41 at the second bottom surface 41b is the same as the width Wb at the second portion 41B.

[0034] It is preferable that the connection terminal has a step on the side surface thereof so that the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion.

[0035] When the connection terminal 41 is cylindrical or approximately cylindrical, the width Wb of the connection terminal 41 at the second portion 41B (the width of the connection terminal 41 at the second bottom surface 41b) may be 25 μm or more and 290 μm or less. The width Wa of the connection terminal 41 at the first portion 41A may be 75 μm or more and 300 μm or less. The difference between the width Wa and the width Wb (Wa-Wb) may be 10 μm or more and 50 μm or less. The height of the connection terminal 41 may be 50 μm or more and 200 μm or less.

[0036] 3, the position of the boundary 45 of the step provided on the side surface 41c of the connection terminal 41 coincides with the location 43 where the side surface of the connection terminal 41 is exposed from the recess 33. The width Wc of the connection terminal 41 at the location 43 where the side surface of the connection terminal 41 is exposed from the recess 33 is smaller than the width Wa of the connection terminal 41 at the first portion 41A. The width Wc of the connection terminal 41 at the location 43 where the side surface of the connection terminal 41 is exposed from the recess 33 is the same as the width Wb of the connection terminal 41 at the second portion 41B, and is the same as the width of the connection terminal 41 at the second bottom surface 41b.

[0037] In the circuit module of the present invention, the width of the connection terminal is small in the second portion including the second bottom surface, so when the connection terminal is joined to the solder, the joining strength between the solder and the connection terminal can be increased and the impact resistance at the joint between the connection terminal and the solder can be increased.

[0038] FIG. 4 is a schematic diagram showing a state in which the connection terminals shown in FIG. 3 are connected to electrodes on a substrate via solder bumps.

[0039] 4 schematically shows the structure around the connection terminal 41 when the soldered circuit module 101, which has solder bumps 111 joined to the connection terminals 41 of the circuit module, is connected to the electrodes 210 of the substrate 200. When the connection terminals 41 and the solder bumps 111 are connected, an intermetallic compound layer 121 is formed, and the solder bumps 111 are joined to the connection terminals 41 via the intermetallic compound layer 121.

[0040] The solder bump 111 corresponds to the second portion 41B including the second bottom surface 41b, and has a sufficient thickness to wet and spread in a portion 41c1 where the side surface 41c of the connection terminal 41 is exposed from the recess. In this case, the connection terminal 41 and the solder bump 111 are bonded to each other at the second bottom surface 41b and the side surface 41c of the connection terminal 41. This increases the bonding strength between the connection terminal 41 and the solder bump 111. As a result, the bonding strength between the electrode 210 of the substrate 200 bonded to the solder bump 111 and the connection terminal 41 is also increased.

[0041] In contrast to the configuration shown in Figure 4, we will explain a configuration in which the width of the connection terminal is constant, the shape of the connection terminal is not distinguished between a first part and a second part, and the width of the connection terminal at the second bottom surface is the same as the width of the other parts of the connection terminal (the width of the connection terminal at the second bottom surface is not smaller than the other parts).

[0042] FIG. 5 is a schematic diagram showing a state in which a connection terminal with a constant width is connected to an electrode on a substrate via a solder bump. In the configuration shown in FIG. 5 , for a connection terminal 41′, the width Wb′ of the connection terminal 41′ at the second bottom surface 41b′ ​​is the same as the width Wa (the width of the connection terminal 41′ in the resin layer 31) at other portions of the connection terminal 41′. In FIGS. 4 and 5 , the width of the electrode 210 on the substrate 200 is the same. In the configuration shown in FIG. 5 , the solder bump 111 barely spreads in the portion 41c1′ where the side surface 41c′ of the connection terminal 41′ is exposed from the recess. Therefore, the connection between the connection terminal 41′ and the solder bump 111 is almost entirely formed only at the second bottom surface 41b′ ​​of the connection terminal 41′, and the connection between the side surface 41c′ of the connection terminal 41′ and the solder bump 111 hardly contributes to improving the bonding strength. 4, the bonding strength between the connection terminal 41′ and the solder bump 111 is lower. As a result, the bonding strength between the electrode 210 of the substrate 200, which is bonded to the solder bump 111, and the connection terminal 41′ is also lower.

[0043] 3 and 4, the solder wettability improving layer will be described below. A solder wettability improving layer 42 is provided on the second bottom surface 41b of the connection terminal 41 and on a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The solder wettability improving layer is a layer that has been treated to make the surface of the connection terminal easier for solder to wet and spread.

[0044] When solder bumps 111 are joined to connection terminals 41 whose side surfaces 41c are partially exposed from recesses 33, the solder bumps 111 are unlikely to wet and spread to the side surfaces 41c. For example, if the connection terminals 41 contain Cu as a main component and the solder wettability improving layer 42 is not provided on the surfaces of the connection terminals 41, the wettability between the connection terminals 41 and the solder bumps 111 is low, so the solder bumps 111 are joined only to the second bottom surfaces 41b of the connection terminals 41 and are unlikely to wet and spread to the side surfaces 41c. On the other hand, in the circuit module of the present invention, the solder wettability improving layer 42 is provided on the second bottom surfaces 41b of the connection terminals 41 and on portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from recesses 33.

[0045] By combining two configurations, namely, a solder wettability improving layer 42 is provided on the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33, and the width of the second bottom surface 41b of the connection terminal 41 is reduced, when the solder bump 111 is joined to the connection terminal 41, the solder bump 111 wets and spreads to the side surface 41c of the connection terminal 41.

[0046] 3 and 4, the solder wettability improving layer 42 is provided on the entire second bottom surface 41b of the connection terminal 41 and the entire portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. However, as long as the effects of the present invention are achieved, the solder wettability improving layer 42 may be provided only on a part of the second bottom surface 41b of the connection terminal 41 and the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33.

[0047] There are several types of solderability improving layers, and FIGS. 3 and 4 illustrate a structure in which the solderability improving layer 42 is an OSP treated layer 44. The OSP treated layer is a layer that has been subjected to an organic solderability preservative treatment (water-soluble preflux treatment). OSP treatment refers to a treatment in which an organic film is formed on the surface of an object to prevent the surface of the object from oxidizing. The OSP treated layer includes an organic film formed on the surface of the connection terminal 41. The presence of the OSP treated layer can suppress a decrease in wettability with solder due to oxidation of the surface of the connection terminal 41. Therefore, the OSP treated layer improves the wettability between the connection terminal 41 and solder. The method for forming the OSP treated layer is not particularly limited; for example, the OSP treatment may be performed using a commercially available preflux liquid.

[0048] The solder wettability improving layer may also be a roughened surface layer. A roughened surface layer refers to a layer having a larger surface roughness Sa (a surface having a larger surface roughness Sa) compared to a surface that has not been subjected to a surface roughening treatment. The roughened surface layer has high wettability with solder. The method for forming the roughened surface layer is not particularly limited, but examples include chemical methods such as etching using a sulfuric acid-hydrogen peroxide-based etching agent, and physical methods such as sandblasting and roughening with a file.

[0049] The surface roughness Sa refers to the arithmetic mean surface roughness Sa. The arithmetic mean surface roughness Sa can be measured using, for example, a shape analysis laser microscope (VR-3000 manufactured by Keyence Corporation). The surface roughness Sa of the roughened surface layer may be 0.3 μm or more and 1.5 μm or less.

[0050] In addition, when the solder wettability improving layer is a roughened surface layer, the intermetallic compound layer formed when the solder bump is bonded to the connection terminal includes the surface of the connection terminal that was the roughened surface layer, and therefore the presence of the roughened surface layer cannot be observed after the solder bump is bonded.

[0051] The OSP treatment and the surface roughening treatment may be combined, and the solder wettability improving layer may be a layer that has been subjected to both the surface roughening treatment and the OSP treatment. The OSP-treated layer may be, for example, a layer that has been subjected to the surface roughening treatment and then the OSP treatment.

[0052] The solder wettability improving layer may also be a Ni-based plating layer. The Ni-based plating layer is not particularly limited as long as it is a plating layer containing Ni, and may be, for example, a NiAu plating layer or a NiPdAu plating layer. That is, the solder wettability improving layer may be a NiAu plating layer or a NiPdAu plating layer.

[0053] The NiAu plating layer is a plating layer containing nickel (Ni) and gold (Au). The NiAu plating layer may include a Ni plating layer and an Au plating layer. For example, a Ni plating layer may be provided on the surface of the connection terminal, and an Au plating layer may be provided on the surface of the Ni plating layer. Such a NiAu plating layer can be formed by plating the connection terminal with Ni and then plating it with Au.

[0054] The method for forming the NiAu plating layer is not particularly limited, and the layer may be formed by electrolytic plating or electroless plating.

[0055] The NiPdAu plating layer is a plating layer containing nickel (Ni), palladium (Pd), and gold (Au). The NiPdAu plating layer may include a Ni plating layer, a Pd plating layer, and an Au plating layer. For example, a Ni plating layer may be provided on the surface of the connection terminal, a Pd plating layer may be provided on the surface of the Ni plating layer, and an Au plating layer may be provided on the surface of the Pd plating layer. Such a NiPdAu plating layer can be formed by plating the connection terminal with Ni, then with Pd, and then with Au.

[0056] The method for forming the NiPdAu plating layer is not particularly limited, and the layer may be formed by electrolytic plating or electroless plating.

[0057] When a connection terminal provided with a Ni-based plating layer as a solder wettability improving layer is joined to a solder bump, a Ni-plating-derived layer derived from the Ni-based plating layer will be present between the connection terminal and the intermetallic compound layer formed when the solder bump is joined to the connection terminal.

[0058] An OSP treatment layer or a surface roughening layer as a solder wettability improving layer may be combined with a Ni-based plating layer, for example, an OSP treatment layer or a surface roughening layer may be provided on the second bottom surface of the connection terminal, and a Ni-based plating layer may be provided on the entire side surface of the connection terminal.

[0059] Next, another embodiment in which the shape of the connection terminal is different will be described. Fig. 6 is an enlarged view schematically illustrating another example of the structure around the connection terminal in the circuit module. In the connection terminal 41 shown in Fig. 6, the width Wc of the connection terminal 41 at a portion 43 where the side surface 41c of the connection terminal 41 is exposed from the recess 33 is the same as the width Wa of the connection terminal 41 at the first portion 41A.

[0060] 6, a step (step boundary 45) is provided on a side surface 41c of the connection terminal 41 to allow the connection terminal 41 to have a first portion 41A having a larger width and a second portion 41B having a smaller width than the first portion 41A. The position of the step boundary 45 is closer to the second bottom surface 41b than a portion 43 where the side surface 41c of the connection terminal 41 is exposed from the recess 33, i.e., it is within the space of the recess 33.

[0061] 6 , the portion 41c1 of the side surface 41c of the connection terminal 41 exposed from the recess 33 is divided into two. One is a narrow portion 41c11 of the connection terminal 41 located closer to the second bottom surface 41b than the boundary 45 of the step and corresponding to the second portion 41B including the second bottom surface 41b. The other is a wide portion 41c12 of the connection terminal 41 located closer to the resin layer 31 than the boundary 45 of the step and corresponding to the first portion 41A. The width Wd of the connection terminal 41 at the wide portion 41c12 of the connection terminal 41 is the same as the width of the connection terminal 41 in the resin layer 31, and is the width Wa of the connection terminal 41 at the first portion 41A.

[0062] Even in the connection terminal 41 of the form shown in Figure 6, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can wet and spread with sufficient thickness in the narrow portion 41c11 of the connection terminal 41, which is located on the side of the side 41c of the connection terminal 41 closer to the second bottom surface 41b than the boundary 45 of the step and corresponds to the second portion 41B including the second bottom surface 41b, and therefore the bonding strength between the connection terminal and the solder bump can be increased in this portion.

[0063] 7 is an enlarged view schematically illustrating another example of the structure around a connection terminal in a circuit module. The connection terminal 41 shown in FIG. 7 has two steps (step boundaries 45a and 45b) on the side surface 41c of the connection terminal 41 to accommodate a first portion 41A having a larger width and a second portion 41B having a smaller width than the first portion 41A. The boundary 45a of one step is located closer to the second bottom surface 41b than the portion 43 where the side surface 41c of the connection terminal 41 is exposed from the recess 33, i.e., within the space of the recess 33. The boundary 45b of the other step is located within the resin layer 31.

[0064] 7, the shape of the portion 41c1 of the side surface 41c of the connection terminal 41 exposed from the recess 33 is similar to that of the embodiment shown in Fig. 6, and the portion 41c1 of the side surface 41c of the connection terminal 41 exposed from the recess is divided into two parts. One is a narrow portion 41c11 of the connection terminal 41 located closer to the second bottom surface 41b than the boundary 45a of the step and corresponding to the second portion 41B including the second bottom surface 41b. The other is a wide portion 41c12 of the connection terminal 41 located closer to the resin layer 31 than the boundary 45a of the step and corresponding to the first portion 41A.

[0065] 7, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can spread with sufficient thickness at the narrow portion 41c11 of the side surface 41c of the connection terminal 41, which is located closer to the second bottom surface 41b than the boundary 45a of the step and corresponds to the second portion 41B including the second bottom surface 41b, thereby increasing the bonding strength between the connection terminal and the solder bump in this portion. Note that the presence of a step on the side surface 41c of the connection terminal 41 in the resin layer 31 does not affect the bonding strength between the connection terminal and the solder bump.

[0066] 8 is an enlarged view schematically illustrating another example of the structure around a connection terminal in a circuit module. The connection terminal 41 shown in FIG. 8 has two steps (step boundaries 45a and 45b) on the side surface 41c of the connection terminal 41 to allow the connection terminal 41 to have a first portion 41A with a larger width and a second portion 41B with a smaller width than the first portion 41A. The boundary 45a of one step is located closer to the second bottom surface 41b than the portion 43 where the side surface 41c of the connection terminal 41 is exposed from the recess 33, i.e., within the space of the recess 33. The boundary 45b of the other step is also located within the space of the recess 33, but closer to the resin layer 31 than the boundary 45a.

[0067] 8 , the portion 41c1 of the side surface 41c of the connection terminal 41 exposed from the recess 33 is divided into three parts. One is a narrow portion 41c11 of the connection terminal 41 located closer to the second bottom surface 41b than the boundary 45a of the step and corresponding to the second portion 41B including the second bottom surface 41b. One is a wide portion 41c12 of the connection terminal 41 located between the boundary 45a of the step and the boundary 45b of the step and corresponding to the first portion 41A. The other is a narrow portion 41c13 of the connection terminal 41 located closer to the resin layer 31 than the boundary 45b of the step.

[0068] 8, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can spread with sufficient thickness at the narrow portion 41c11 of the side surface 41c of the connection terminal 41, which is located closer to the second bottom surface 41b than the boundary 45a of the step and corresponds to the second portion 41B including the second bottom surface 41b, thereby increasing the bonding strength between the connection terminal and the solder bump in this portion. The provision of a step on the side surface 41c of the connection terminal 41 at a position closer to the resin layer 31 than the wide portion 41c12 of the connection terminal 41 does not affect the bonding strength between the connection terminal and the solder bump.

[0069] Next, another embodiment in which the shape of the connection terminal is different will be described. Fig. 9 is an enlarged view schematically illustrating another example of the structure around the connection terminal in the circuit module. The connection terminal 41 shown in Fig. 9 has a first portion 41A having a larger width and a second portion 41B having a smaller width than the first portion 41A. To achieve this, the side surface 41c of the connection terminal 41 is provided with a taper 46 that widens outward from the second bottom surface 41b toward the first main surface of the substrate. In the embodiment shown in Fig. 9, the position of the end point 46a of the taper 46 on the first main surface side of the substrate coincides with the portion 43 where the side surface 41c of the connection terminal 41 is exposed from the recess 33.

[0070] 9, a portion 41c2 of the side surface 41c of the connection terminal 41 that is not exposed from the recess 33 corresponds to the first portion 41A, and the width Wa of the connection terminal 41 is large. A portion 41c1 of the side surface 41c of the connection terminal 41 that is provided with a taper 46 and that is exposed from the recess 33 corresponds to the second portion 41B, and the width of the connection terminal 41 is smaller than the width Wa wherever the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33 is taken.

[0071] FIG. 10 is a schematic diagram showing a state in which the connection terminals shown in FIG. 9 are connected to electrodes on a substrate via solder bumps.

[0072] FIG. 10 shows a schematic diagram of the structure around the connection terminal 41 when a soldered circuit module 101, in which solder bumps 111 are joined to the connection terminal 41 of the circuit module, is connected to an electrode 210 of a substrate 200.

[0073] The solder bump 111 corresponds to the second portion 41B including the second bottom surface 41b, and has a sufficient thickness at a portion 41c1 where the side surface 41c of the connection terminal 41 is exposed from the recess and has a taper 46. In this case, the connection terminal 41 and the solder bump 111 are bonded to each other at the second bottom surface 41b and the side surface 41c of the connection terminal 41. This increases the bonding strength between the connection terminal 41 and the solder bump 111. As a result, the bonding strength between the electrode 210 of the substrate 200 bonded to the solder bump 111 and the connection terminal 41 is also increased.

[0074] 11 is an enlarged view schematically illustrating another example of the structure around a connection terminal in a circuit module. In connection terminal 41 shown in FIG. 11, end point 46a of taper 46 on the first main surface side of the substrate is located closer to second bottom surface 41b than point 43 where side surface 41c of connection terminal 41 is exposed from recess 33, i.e., within the space of recess 33.

[0075] 11 , the portion 41c1 of the side surface 41c of the connection terminal 41 exposed from the recess is divided into two. One is a narrow portion 41c11 of the connection terminal 41 located closer to the second bottom surface 41b than the end point 46a of the taper 46 on the first main surface side of the substrate, and corresponds to the second portion 41B including the second bottom surface 41b. The other is a wide portion 41c12 of the connection terminal 41 located closer to the resin layer 31 than the end point 46a, is not tapered, and corresponds to the first portion 41A.

[0076] Even in the connection terminal of the form shown in Figure 11, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can wet and spread with sufficient thickness at the tapered portion 41c11 of the side surface 41c of the connection terminal 41, which is located closer to the second bottom surface 41b than the end point 46a and corresponds to the second portion 41B including the second bottom surface 41b, so that the bonding strength between the connection terminal and the solder bump can be increased at this portion.

[0077] Next, a description will be given of yet another embodiment of the circuit module of the present invention, in which a NiAu plating layer is provided on at least a portion of the side surface of the connection terminal.

[0078] Fig. 12 is an enlarged view showing another example of the structure around the connection terminal of the circuit module, which corresponds to the embodiment shown in Fig. 3 in which a NiAu plating layer 47 is provided on a portion 41c2 of the side surface 41c of the connection terminal 41 that is not exposed from the recess 33.

[0079] A solder wettability improving layer 42 is provided on a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The solder wettability improving layer is not particularly limited, and a surface roughening layer, an OSP treatment layer, a NiAu plating layer, a NiPdAu plating layer, or the like can be used. Fig. 12 illustrates an OSP treatment layer 44 as a solder wettability improving layer. In addition, in the embodiment shown in Fig. 12, a NiAu plating layer 47 is not provided on the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33, and therefore Fig. 12 can be said to illustrate an embodiment in which a NiAu plating layer is provided on a portion of the side surface of the connection terminal.

[0080] Even in the connection terminal of the form shown in Figure 12, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can wet and spread with sufficient thickness in the narrow portion 41c1 of the side surface 41c of the connection terminal 41, which corresponds to the second portion 41B including the second bottom surface 41b, so that the bonding strength between the connection terminal and the solder bump can be increased in this portion.

[0081] Next, we will explain yet another embodiment of the circuit module of the present invention, in which a first NiAu plating layer is provided on at least a portion of the side surface of the connection terminal, a portion of the first NiAu plating layer is exposed from a recess, and the first NiAu plating layer exposed from the recess is covered with a second NiAu plating layer or a NiPdAu plating layer as a solder wettability improving layer.

[0082] Fig. 13 is an enlarged view showing a schematic diagram of another example of the structure around the connection terminal in the circuit module. The configuration shown in Fig. 13 corresponds to the configuration shown in Fig. 6 in which a first NiAu plating layer 47 is provided on a portion 41c12 that is a part of the portion 41c1 exposed from the recess 33 and a portion 41c2 that is not exposed from the recess 33 of the side surface 41c of the connection terminal 41, and a second NiAu plating layer 48 is provided as the solder wettability improving layer 42.

[0083] The portion 41c12 and the portion 41c2 of the side surface 41c of the connection terminal 41 are continuous surfaces, and are continuously provided with the first NiAu plating layer 47. This portion of the connection terminal 41 has a large width, and corresponds to the first portion 41A.

[0084] A portion 41c11 of the side surface 41c of the connection terminal 41 has a smaller width than the second portion 41B of the connection terminal 41. A second NiAu plating layer 48 serving as a solder wettability improving layer is continuously provided on the portions 41c11 and 41c12. A first NiAu plating layer 47 is provided on the portion 41c12 of the side surface 41c of the connection terminal 41 exposed from the recess 33, and the first NiAu plating layer 47 is covered with the second NiAu plating layer 48 serving as the solder wettability improving layer 42.

[0085] Even in the connection terminal of the form shown in Figure 13, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can wet and spread with sufficient thickness in the narrow portion 41c11 of the side surface 41c of the connection terminal 41, which corresponds to the second portion 41B including the second bottom surface 41b, so that the bonding strength between the connection terminal and the solder bump can be increased in this portion.

[0086] Next, we will explain yet another embodiment of the circuit module of the present invention, in which a NiAu plating layer is provided on at least a portion of the side surface of the connection terminal, and the side surface of the connection terminal is tapered, widening outward from the second bottom surface toward the first main surface of the substrate.

[0087] Fig. 14 is an enlarged view showing another example of the structure around the connection terminal in the circuit module, which corresponds to the embodiment shown in Fig. 9 in which a NiAu plating layer 47 is provided on a portion 41c2 of the side surface 41c of the connection terminal 41 that is not exposed from the recess 33 and on a part of the taper 46.

[0088] A solder wettability improving layer 42 is provided on a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The solder wettability improving layer is not particularly limited, and may be a roughened surface layer, an OSP treated layer, a NiAu plated layer, a NiPdAu plated layer, or the like. Fig. 14 illustrates an OSP treated layer 44 as a solder wettability improving layer.

[0089] Fig. 15 is an enlarged view schematically illustrating another example of the structure around the connection terminal in the circuit module. The configuration shown in Fig. 15 corresponds to the configuration shown in Fig. 11 in which, of the side surface 41c of the connection terminal 41, a portion 41c2 that is not exposed from the recess 33, a portion 41c12 that is part of the portion 41c1 that is exposed from the recess 33, and a portion of the taper 46 are provided with a NiAu plating layer 47.

[0090] A solder wettability improving layer 42 is provided on a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The solder wettability improving layer is not particularly limited, and may be a roughened surface layer, an OSP treated layer, a NiAu plated layer, a NiPdAu plated layer, or the like. Fig. 15 illustrates an OSP treated layer 44 as a solder wettability improving layer.

[0091] Even in the connection terminal of the form shown in Figures 14 and 15, the width of the connection terminal 41 at the second bottom surface 41b is small, and the solder bump can wet and spread with sufficient thickness at the tapered portion 41c11 of the side surface 41c of the connection terminal 41, which corresponds to the second portion 41B including the second bottom surface 41b, so that the bonding strength between the connection terminal and the solder bump can be increased at this portion.

[0092] Next, the soldered circuit module of the present invention will be described.

[0093] The soldered circuit module of the present invention is a circuit module of the present invention with solder joined to the connection terminals thereof.

[0094] FIG. 16 is a cross-sectional view showing a schematic example of a soldered circuit module.

[0095] FIG. 17 is an enlarged view showing a schematic structure of the periphery of the connection terminals in the soldered circuit module shown in FIG.

[0096] FIG. 17 shows a diagram in which the state of FIG. 16 is inverted.

[0097] The soldered circuit module 101 can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 1 shown in Fig. 1. The intermetallic compound layer 121 shown in Fig. 17, which is generated by joining the solder bumps 111 to the connection terminals 41, is the same as that shown in Fig. 4.

[0098] The configurations of the substrate 11, electronic components 21, and resin layer 31 in the soldered circuit module 101 are the same as those in the circuit module 1, and therefore detailed description thereof will be omitted.

[0099] A solder bump 111 is provided so as to cover the second bottom surface 41b of the connection terminal 41 and at least a part of a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The solder bump 111 is bonded to the connection terminal 41 via an intermetallic compound layer 121.

[0100] An intermetallic compound layer 121 exists between the connection terminal 41 and the solder bump 111. The intermetallic compound layer 121 covers the second bottom surface 41b of the connection terminal 41 and at least a part of a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33.

[0101] The solder bump 111 corresponds to the second portion 41B including the second bottom surface 41b, and has a sufficient thickness to wet and spread in a portion 41c1 where the side surface 41c of the connection terminal 41 is exposed from the recess 33. In this case, the connection terminal 41 and the solder bump 111 are bonded to each other at the second bottom surface 41b and the side surface 41c of the connection terminal 41. This increases the bonding strength between the connection terminal 41 and the solder bump 111.

[0102] The soldered circuit module 101 may be mounted on another substrate (such as a printed circuit board) via solder bumps 111. Alternatively, the solder bumps 111 may be pre-coated solder before mounting on the other substrate. In this case, when the soldered circuit module 101 is mounted on the other substrate, additional solder is supplied to the solder bumps 111 as necessary to perform soldering.

[0103] Furthermore, a layer derived from Ni plating may be present between the connection terminal and the intermetallic compound layer. The Ni plating-derived layer may be, for example, a layer derived from the second NiAu plating layer 48 shown in FIG.

[0104] By joining solder bumps to the connection terminals shown in FIGS. 3, 6 to 9, and 11 to 15, it is possible to obtain a soldered circuit module having connection terminals of each type.

[0105] Next, a method for manufacturing the circuit module and soldered circuit module of the present invention will be described. As an example, a method for manufacturing the circuit module 1 shown in Fig. 1 and joining solder bumps 111 to the circuit module 1 to manufacture the soldered circuit module 101 shown in Fig. 16 will be described with reference to Figs. 18 to 23. Note that Figs. 18 to 23 omit the configuration of the electronic components, resin layer, etc. on the second main surface 11b of the substrate 11.

[0106] 18, 19, 20, 21, 22, and 23 are process diagrams that schematically show an example of a manufacturing process for a soldered circuit module of the present invention. The following describes the manufacturing process for a soldered circuit module from the step of forming the resin layer onward.

[0107] FIG. 18 shows a state in which connection terminals 41 are formed on the first main surface 11 a of the substrate 11 .

[0108] 19 , a resin layer 31 is formed on the first main surface 11 a of the substrate 11 so as to entirely cover the electronic components 21 and the connection terminals 41. The step of forming the resin layer 31 on the first main surface 11 a of the substrate 11 can be performed by a known method, such as applying a resin material for forming the resin layer 31 to the first main surface 11 a of the substrate 11.

[0109] 20 , the electronic components 21, the connection terminals 41, and the resin layer 31 are polished from the surface side opposite to the surface of the resin layer 31 that is in contact with the substrate 11. At this time, by polishing to a position where the polished surface of the connection terminals 41 is exposed, the second bottom surfaces 41 b of the connection terminals 41 are exposed from the resin layer 31.

[0110] As shown in FIG. 21 , a recess 33 is formed on the surface of the resin layer 31 in a region surrounding the second bottom surface 41b of the connection terminal 41. The recess 33 is obtained by irradiating the surface of the resin layer 31 with a laser and removing a portion of the resin layer 31. Furthermore, a portion of the periphery of the second bottom surface 41b of the connection terminal 41 is removed by laser irradiation to form a second portion 41B having a narrower width in the connection terminal 41. The conditions for the laser irradiation are not particularly limited as long as they are conditions that allow removal of the resin layer 31 and a portion of the connection terminal 41. The type of laser is also not particularly limited, and may be, for example, a UV laser, an IR laser, or a visible light laser. Note that if a connection terminal having a second portion with a narrower width is used as the connection terminal, removal of the connection terminal by laser irradiation may not be performed. Furthermore, the method for removing the resin layer and a portion of the connection terminal is not limited to laser irradiation, and machining such as cutting may also be used.

[0111] If resin residue remains on the side surface 41c of the connection terminal 41, it will hinder plating deposition and solder wetting on the electrode side surface, so after laser irradiation, a desmear treatment may be performed on the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. The desmear treatment refers to a process of removing resin residue generated during laser processing. The desmear treatment may be performed on the second bottom surface 41b of the connection terminal 41, or on both the second bottom surface 41b of the connection terminal 41 and the portion 41c1 of the side surface 41c that is exposed from the recess 33. The desmear treatment method may include a treatment using a chemical solution (desmear solution) made of a permanganate such as sodium permanganate or potassium permanganate, or a treatment using O ２ +CF ４ The plasma treatment may be carried out by a plasma cleaning device using a gas containing the compound.

[0112] 22, the solder wettability improving layer 42 is formed so as to cover the second bottom surface 41b of the connection terminal 41 and the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. In this way, the circuit module 1 is obtained.

[0113] 23, solder bumps 111 are formed by joining solder to connection terminals 41. At this time, an intermetallic compound layer 121 is generated between the connection terminals 41 and the solder bumps 111. This results in a soldered circuit module 101. The present specification discloses the following matters.

[0114] <1> A circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; and a connection terminal penetrating the resin layer in a thickness direction, wherein the connection terminal has a first bottom surface located on the substrate side, a second bottom surface opposite the first bottom surface, and a side surface, the second bottom surface being exposed from the resin layer, a recess recessed toward the first main surface of the substrate is formed in an area of ​​the surface of the resin layer surrounding the second bottom surface of the connection terminal, and a part of the side surface of the connection terminal is exposed in the recess, the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, and the width of the connection terminal at the second bottom surface is the same as the width at the second portion, and the circuit module is characterized in that a solder wettability improving layer is provided on the second bottom surface of the connection terminal and the part of the side surface of the connection terminal that is exposed from the recess.

[0115] <2> The circuit module according to <1>, wherein a step is provided on the side surface of the connection terminal.

[0116] <3> The circuit module according to <2>, wherein the width of the connection terminal at the portion where the side surface of the connection terminal is exposed from the recess is smaller than the width of the connection terminal at the first portion.

[0117] <4> The circuit module according to <2>, wherein the width of the connection terminal at the portion where the side surface of the connection terminal is exposed from the recess is the same as the width of the connection terminal at the first portion.

[0118] <5> The circuit module according to <1>, wherein the side surface of the connection terminal is provided with a taper that widens outward from the second bottom surface toward the first main surface of the substrate.

[0119] <6> The circuit module according to <5>, wherein an end point of the taper on the first main surface side of the substrate coincides with a position where the side surface of the connection terminal is exposed from the recess.

[0120] <7> The circuit module according to <5>, wherein an end point of the taper on the first main surface side of the substrate is located closer to the second bottom surface than a point where the side surface of the connection terminal is exposed from the recess.

[0121] <8> The circuit module according to any one of <1> to <7>, wherein the solder wettability improving layer is a surface roughening layer or an OSP treated layer.

[0122] <9> The circuit module according to any one of <1> to <7>, wherein the solder wettability improving layer is a NiAu plated layer or a NiPdAu plated layer.

[0123] <10> The circuit module according to any one of <1> to <9>, wherein a NiAu plating layer is provided on at least a part of the side surface of the connection terminal.

[0124] <11> The circuit module according to <10>, wherein a first NiAu plating layer is provided on at least a portion of the side surface of the connection terminal, a portion of the first NiAu plating layer is exposed from the recess, and the first NiAu plating layer exposed from the recess is covered with a second NiAu plating layer or a NiPdAu plating layer serving as the solder wettability improving layer.

[0125] <12> A soldered circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; connection terminals penetrating the resin layer in a thickness direction; and solder bumps joined to the connection terminals via an intermetallic compound layer, wherein the connection terminals have a first bottom surface located on the substrate side, a second bottom surface opposite the first bottom surface, and side surfaces, the second bottom surface being not covered by the resin layer, a recess recessed toward the first main surface of the substrate is formed in an area on the surface of the resin layer surrounding the second bottom surface of the connection terminal, and a part of the side surface of the connection terminal is exposed in the recess, the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, and the width of the connection terminal at the second bottom surface is the same as the width at the second portion, and the solder bumps are provided to cover the second bottom surface of the connection terminal and at least a part of the part of the side surface of the connection terminal that is exposed from the recess, a soldered circuit module, characterized in that the intermetallic compound layer exists between the connection terminal and the solder bump, and the intermetallic compound layer covers the second bottom surface of the connection terminal and at least a portion of the side surface of the connection terminal that is exposed from the recess.

[0126] <13> The soldered circuit module according to <12>, wherein a layer derived from Ni plating is present between the connection terminal and the intermetallic compound layer.

[0127] REFERENCE SIGNS LIST 1 Circuit module 11 Substrate 11a First main surface of substrate 11b Second main surface of substrate 12 Electrode 13 Insulator layer 14 Pattern conductor 15 Via conductor 16 Connection member 21 Electronic component 31, 32 Resin layer 33 Recess 41, 41' Connection terminal 41a First bottom surface 41b, 41b' Second bottom surface 41c, 41c' Side surface 41c1, 41c1', 41c11, 41c12, 41c13 Portion of side surface exposed from recess 41c2 Portion of side surface not exposed from recess 41A First portion of connection terminal 41B Second portion of connection terminal 41E Connection terminal present at end of circuit module 42 Solder wettability improving layer 43 Portion of side surface of connection terminal exposed from recess 44 OSP treatment layer 45, 45a, 45b Boundary of step 46 Taper 46a End point of taper 47 NiAu plating layer, first NiAu plating layer 48 Second NiAu plating layer 101 Soldered circuit module 111 Solder bump 121 Intermetallic compound layer 200 Substrate 210 Electrode of substrate

Claims

1. A circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; and a connection terminal penetrating the resin layer in the thickness direction, wherein the connection terminal has a first bottom surface located on the substrate side, a second bottom surface opposite the first bottom surface, and a side surface, the second bottom surface being exposed from the resin layer, a recess recessed toward the first main surface of the substrate is formed in an area on the surface of the resin layer surrounding the second bottom surface of the connection terminal, and a part of the side surface of the connection terminal is exposed in the recess, the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, the width of the connection terminal at the second bottom surface is the same as the width at the second portion, and a solder wettability improving layer is provided on the second bottom surface of the connection terminal and the side surface of the connection terminal that are exposed from the recess.

2. The circuit module according to claim 1, wherein a step is provided on the side surface of the connection terminal.

3. The circuit module according to claim 2, wherein the width of the connection terminal at the location where the side surface of the connection terminal is exposed from the recess is smaller than the width of the connection terminal at the first portion.

4. The circuit module according to claim 2, wherein the width of the connection terminal at the location where the side surface of the connection terminal is exposed from the recess is the same as the width of the connection terminal at the first portion.

5. The circuit module according to claim 1, wherein the side surfaces of the connection terminals are tapered to widen outward from the second bottom surface toward the first main surface of the substrate.

6. The circuit module according to claim 5, wherein an end point of the taper on the first main surface side of the substrate coincides with a location where the side surface of the connection terminal is exposed from the recess.

7. The circuit module according to claim 5, wherein an end point of the taper on the first main surface side of the substrate is located closer to the second bottom surface than the point where the side surface of the connection terminal is exposed from the recess.

8. The circuit module according to any one of claims 1 to 7, wherein the solder wettability improving layer is a surface roughening layer or an OSP treated layer.

9. The circuit module according to any one of claims 1 to 7, wherein the solder wettability improving layer is a NiAu plated layer or a NiPdAu plated layer.

10. The circuit module according to any one of claims 1 to 9, wherein a NiAu plating layer is provided on at least a portion of the side surface of the connection terminal.

11. The circuit module according to claim 10, wherein a first NiAu plating layer is provided on at least a portion of the side surface of the connection terminal, a portion of the first NiAu plating layer is exposed from the recess, and the first NiAu plating layer exposed from the recess is covered with a second NiAu plating layer or a NiPdAu plating layer serving as the solder wettability improving layer.

12. A soldered circuit module comprising: a substrate having a first main surface and a second main surface; a resin layer provided on the first main surface of the substrate; connection terminals penetrating the resin layer in the thickness direction; and solder bumps joined to the connection terminals via an intermetallic compound layer, wherein the connection terminals have a first bottom surface located on the substrate side, a second bottom surface opposite the first bottom surface, and side surfaces, the second bottom surface being not covered by the resin layer, a recess recessed toward the first main surface of the substrate is formed in an area on the surface of the resin layer surrounding the second bottom surface of the connection terminal, and a part of the side surface of the connection terminal is exposed in the recess, the connection terminal has a first portion having a larger width and a second portion having a smaller width than the first portion, and the width of the connection terminal at the second bottom surface is the same as that at the second portion, and the solder bumps are provided so as to cover the second bottom surface of the connection terminal and at least a part of the part of the side surface of the connection terminal that is exposed from the recess, a soldered circuit module, characterized in that the intermetallic compound layer exists between the connection terminal and the solder bump, and the intermetallic compound layer covers the second bottom surface of the connection terminal and at least a portion of the side surface of the connection terminal that is exposed from the recess.

13. The soldered circuit module according to claim 12, wherein a layer derived from Ni plating is present between the connection terminal and the intermetallic compound layer.

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