Circuit module and soldered circuit module

Abstract

The present invention provides a circuit module 1 comprising: 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 through the resin layer 31 in the thickness direction, wherein the connection terminal 41 has a first base surface 41a located on the substrate 11 side, a second base surface 41b opposite from the first base surface 41a, and a lateral surface 41c, the second base surface 41b is exposed from the resin layer 31, a recess 33 indented toward the first main surface 11a of the substrate 11 is formed in an area of the surface of the resin layer 31 that surrounds the second base surface 41b of the connection terminal 41, a portion of the lateral surface 41c of the connection terminal 41 is exposed in the recess 33, and a solder wetting enhancement layer 42 is provided on the second base surface 41b of the connection terminal 41 and on a portion 41c1 of the lateral surface 41c of the connection terminal 41, said portion being exposed from the recess 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 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 terminals when the connection terminals are bonded to the solder, and can increase the impact resistance at the bonded portions between the connection terminals and the solder. Another aim of the present invention is to provide a soldered circuit module that has high bonding strength between the solder and the connection terminals, and has high impact resistance at the bonded portions between the connection terminals and the solder.

[0006] 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 formed on the surface of the resin layer in an area surrounding the second bottom surface of the connection terminal that is recessed toward the first main surface of the substrate, a portion of the side surface of the connection terminal being exposed in the recess, and a solder wettability improving layer being provided on the second bottom surface of the connection terminal and the side surface of the connection terminal that are exposed from the recess.

[0007] 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 a side surface, the second bottom surface being not covered by the resin layer, and a surface of the resin layer surrounding the second bottom surface of the connection terminals, the first bottom surface of the substrate being not covered by the resin layer, and the second bottom surface of the substrate being not covered by the resin layer. A recess is formed that is recessed toward one main surface, a portion of the side surface of the connection terminal is exposed in the recess, 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, 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.

[0008] According to the present invention, it is possible to provide a circuit module that can increase the bonding strength between the solder and the connection terminal when the connection terminal is bonded to the solder, and can increase the impact resistance at the bonded portion between the connection terminal and the solder. Also, according to the present invention, it is possible to provide a soldered circuit module that has high bonding strength between the solder and the connection terminal, and has high impact resistance at the bonded portion between the connection terminal and the solder.

[0009] FIG. 1 is a cross-sectional view schematically illustrating an example of a circuit module according to a first embodiment. FIG. 2 is a plan view of the circuit module according to the first embodiment, viewed from the surface on which the resin layer and the connection terminals are provided. FIG. 3 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module according to the first embodiment. FIG. 4 is a schematic view illustrating a state in which solder bumps are joined to the connection terminals shown in FIG. 3. FIG. 5 is a schematic view illustrating an example of a laser irradiation mark on a connection terminal. FIG. 6 is a schematic view illustrating another example of a laser irradiation mark on a connection terminal. FIG. 7 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module according to a second embodiment. FIG. 8 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module according to a third embodiment. FIG. 9 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module according to a fourth embodiment. FIG. 10 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module according to a fifth embodiment. FIG. 11 is a cross-sectional view schematically illustrating an example of a soldered circuit module according to the first embodiment. FIG. 12 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the first embodiment. FIG. 13 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the second embodiment. FIG. 14 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the third embodiment. FIG. 15 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the fourth embodiment. FIG. 16 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the fifth embodiment. FIG. 17 is a process diagram schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. 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 chart schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. Fig. 22 is a process chart schematically showing an example of a manufacturing process for a soldered circuit module of the present invention. Fig. 23 is an enlarged view schematically showing the structure around a connection terminal in a circuit module of a sixth embodiment.Fig. 24 is an enlarged view schematically showing the structure around a connection terminal in a soldered circuit module of the sixth embodiment. Fig. 25 is an enlarged view schematically showing the structure around a connection terminal in another example of the circuit module of the sixth embodiment. Fig. 26 is an enlarged view schematically showing the structure around a connection terminal in another example of the circuit module of the sixth embodiment. Fig. 27 is an enlarged view schematically showing the structure around a connection terminal in a circuit module of the seventh embodiment. Fig. 28 is a plan view of a first modified circuit module of the present invention, seen from the side on which the resin layer and connection terminals are provided. Fig. 29 is a plan view of a second modified circuit module of the present invention, seen from the side on which the resin layer and connection terminals are provided.

[0010] 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.

[0011] First, the circuit module of the present invention will be described.

[0012] Fig. 1 is a cross-sectional view schematically illustrating an example of a circuit module according to a first embodiment, and Fig. 2 is a plan view of the circuit module according to the first embodiment, seen from the surface on which a resin layer and connection terminals are provided.

[0013] 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. The circuit module 1 includes a substrate 11, an electronic component 21, resin layers 31 and 32, and connection terminals 41.

[0014] 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.

[0015] 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 ３ Examples 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] In the circuit module 1, the first bottom surface 41 a is in contact with the electrode 12 provided on the first main surface 11 a 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 11 a of the substrate 11 is also included in the case where the connection terminal 41 is provided on the first main surface 11 a of the substrate, and is also included in the case where the connection terminal 41 penetrates in the thickness direction through the resin layer 31 provided on the first main surface 11 a of the substrate 11. The second bottom surface 41 b is exposed from the resin layer 31.

[0023] The shape of the connection terminal 41 is not particularly limited, and may be, for example, a columnar conductor, or may have a cylindrical, approximately cylindrical, or rectangular columnar shape. Although not shown, the connection terminal 41 may have a tapered shape in which the width increases toward the first main surface 11 a of the substrate 11 in the cross section shown in FIG.

[0024] The material constituting the connection terminal 41 is not particularly limited, but is preferably Cu, Ag, Au, Al, Ni, Cr, or Ti, or an alloy containing at least one of these metals.

[0025] 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.

[0026] 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.

[0027] 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. That is, one recess 33 may be provided so as to surround the periphery of a plurality of connection terminals 41. Modified examples of recesses 33 in which one recess 33 surrounds the periphery of a plurality of connection terminals 41 will be described later.

[0028] FIG. 3 is an enlarged view schematically showing the structure around the connection terminals in the circuit module of the first embodiment.

[0029] 3 to 4 and 7 to 10 show diagrams in which the state in Fig. 1 is inverted. 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, which will be described later, is a surface roughening layer 43.

[0030] 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.

[0031] 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. Fig. 3 illustrates a structure in which the solder wettability improving layer 42 is a surface roughening layer 43. The solder wettability improving layer is a layer that has been treated to make it easier for solder to wet and spread on the surface of the connection terminal.

[0032] FIG. 4 is a schematic diagram showing a state in which solder bumps are joined to the connection terminals shown in FIG.

[0033] 4 is an enlarged view schematically showing the structure around the connection terminal 41 in a soldered circuit module 101 formed by joining the solder bump 111 to the connection terminal 41 of the circuit module 1. When the connection terminal 41 is joined to the solder bump 111, an intermetallic compound layer 121 is formed at the joint between the connection terminal 41 and the solder bump 111. Because the intermetallic compound layer 121 includes the surface of the connection terminal 41 that was previously the roughened surface layer 43, the presence of the roughened surface layer 43 cannot be observed after the solder bump 111 is joined.

[0034] Incidentally, when various types of impacts such as temperature changes or being dropped are applied to the connection terminal 41, stress concentrates on the portion of the connection terminal 41 that is flush with the surface of the surrounding resin layer 31. If the second bottom surface 41b is flush with the surrounding resin layer 31, when solder is joined to the second bottom surface 41b, the intermetallic compound layer 121 generated at the joint between the connection terminal 41 and the solder bump 111 will also be flush with the surrounding resin layer 31. The intermetallic compound layer 121 has low mechanical strength and is likely to become a fracture starting point when an impact is applied. Therefore, if the intermetallic compound layer 121 is flush with the surrounding resin layer 31, stress is likely to concentrate on the fragile intermetallic compound, resulting in reduced impact resistance. On the other hand, in the circuit module 1 of the present invention, the second bottom surface 41b of the connection terminal 41 protrudes from the surrounding recess 33, and therefore the intermetallic compound layer 121 formed at the joint between the second bottom surface 41b and the solder bump 111 also protrudes from the surrounding recess 33. Therefore, the position of the stress concentration point (the portion indicated by S in FIG. 4 ) and the position of the intermetallic compound layer 121 formed at the joint between the second bottom surface 41b and the solder bump 111 are spaced apart, and therefore, the impact resistance when the solder bump 111 is joined to the connection terminal 41 can be improved.

[0035] Next, the effect of providing the solder wettability improving layer 42 will be described. When a solder bump 111 is bonded to a connection terminal 41 whose side surface 41c is partially exposed from the recess 33, the solder bump 111 is less likely to wet and spread to the side surface 41c. For example, if the connection terminal 41 contains Cu as a primary component and the solder wettability improving layer 42 is not provided on the surface of the connection terminal 41, the wettability between the connection terminal 41 and the solder bump 111 is low, so the solder bump 111 is bonded only to the second bottom surface 41b of the connection terminal 41 and does not wet and spread to the side surface 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 surface 41b of the connection terminal 41 and on the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. Therefore, when the solder bump 111 is bonded to the connection terminal 41, the solder bump 111 wets and spreads to the side surface 41c of the connection terminal 41.

[0036] 3, the solder wettability improving layer 42 is provided on the entire 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. 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.

[0037] In the circuit module 1 of the first embodiment, the solder wettability improving layer 42 is the roughened surface layer 43. In Fig. 3, the roughened surface layer 43 is provided on the entire second bottom surfaces 41b of the connection terminals 41 and on the entire portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33. However, as long as the effects of the present invention are achieved, the roughened surface layer 43 may be provided only on a portion of the second bottom surfaces 41b of the connection terminals 41 and on the entire portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33.

[0038] The roughened surface layer refers to a layer having a larger surface roughness Sa than a surface that has not been subjected to a surface roughening treatment (a surface having a larger surface roughness Sa). 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.

[0039] 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).

[0040] The surface roughness Sa of the rough surface layer 43 may be 0.3 μm or more and 1.5 μm or less.

[0041] When the recesses 33 in the resin layer 31 are formed by laser irradiation, laser irradiation marks may be present on the second bottom surfaces 41b of the connection terminals 41. In order to prevent resin components from remaining on the side surfaces 41c of the connection terminals 41 due to deviation in the laser irradiation position caused by distortion of the substrate 11 or the like, part or all of the second bottom surfaces 41b of the connection terminals 41 may be irradiated with laser, and at that time, laser irradiation marks may be formed on part or all of the second bottom surfaces 41b of the connection terminals 41. The laser irradiation marks are not included in the surface roughening layer 43 that becomes the solder wettability improving layer 42.

[0042] When laser irradiation marks are present on the second bottom surface 41b of the connection terminal 41, the second bottom surface 41b having the laser irradiation marks may be subjected to a surface roughening treatment to form the roughened surface layer 43. Furthermore, as will be described later, when the solder wettability improving layer is a metal plating such as Ni-based plating, not only the laser unirradiated portions but also the laser irradiation marks may be covered with the metal plating such as Ni-based plating.

[0043] Fig. 5 is a schematic diagram showing an example of a laser irradiation mark on a connection terminal, and Fig. 6 is a schematic diagram showing another example of a laser irradiation mark on a connection terminal.

[0044] 5 and 6 are schematic diagrams of the connection terminal 41 as viewed from the second bottom surface 41b side.

[0045] In Fig. 5, a recess 33 having a circular cross section is provided so as to surround the periphery of the connection terminal 41. In Fig. 5, a laser irradiation mark 51 exists only in a portion of the second bottom surface 41b of the connection terminal 41. When the laser irradiation mark 51 exists only in a portion of the second bottom surface 41b of the connection terminal 41, the position of the laser irradiation mark is not particularly limited. In Fig. 5, the laser irradiation mark 51 exists so as to surround a non-laser-irradiated portion 52.

[0046] The laser irradiation mark 51 refers to an area where unevenness is formed on the surface by laser irradiation. In Fig. 5, the laser irradiation mark 51 has a spiral depression.

[0047] In Fig. 6, a groove-shaped recess 33 is provided so as to surround the periphery of the connection terminal 41. Although not shown, the groove-shaped recess 33 may cover the periphery of a plurality of connection terminals 41. In Fig. 6, laser irradiation marks 51 exist on the entire second bottom surface 41b of the connection terminal 41. The laser irradiation marks 51 shown in Fig. 6 have lattice-shaped depressions.

[0048] An example of the dimensions of the connection terminal 41, resin layer 31, recess 33, etc. will be described below with reference to FIG. 3 . When the connection terminal 41 is cylindrical or approximately cylindrical, its radius may be 50 μm or more and 150 μm or less. The height of the connection terminal 41 may be 50 μm or more and 200 μm or less. 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 refers to the thickness at the position where it is thickest. 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 refers to the depth at the position where it is thickest.

[0049] Hereinafter, examples of specific configurations of the recess 33 and the connection terminal 41 will be described.

[0050] Although not shown, the recess 33 may be deeper in the vicinity of the connection terminal 41. For example, from the viewpoint of suppressing a decrease in the strength of the substrate, improving the productivity of the laser processing, and improving the reliability of the circuit module, the recess 33 may have a vicinity portion on the connection terminal 41 side and an outer portion away from the connection terminal 41, and the depth of the vicinity portion may be greater than the depth of the outer portion.

[0051] Furthermore, the recesses 33 may contain a larger amount of filler components than the portions of the surface of the resin layer 31 that are not irradiated with the laser (portions of the surface of the resin layer 31 other than the recesses 33). It is preferable that no electrode components adhere to the recesses 33 in the vicinity of the connection terminals 41. Examples of electrode components include Cu, Ni, and Au. Cu, Ni, Au, and the like that are scattered from the electrode and adhere to the resin surface during laser processing may cause plating to deposit outside the electrode during plating processing, or solder may adhere to these electrode components during solder bump formation, resulting in unintended solder coating outside the electrode. Therefore, it is preferable that no electrode components adhere to the vicinity of the connection terminals 41.

[0052] A resin component may be present in a portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. This resin component may be derived from the resin layer 31 or may be a filler component. From the viewpoint of suppressing the inhibition of plating deposition and the inhibition of solder bump formation, the resin component may not be present in the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. Whether a resin component is present in the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33 can be confirmed by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX).

[0053] 7 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module of the second embodiment. In the circuit module 2 of the second embodiment, the solder wettability improving layer 42 is an OSP treatment layer 44. In FIG. 7, the OSP treatment layer 44 is provided on the entire second bottom surfaces 41b of the connection terminals 41 and on the entire portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33. However, as long as the effects of the present invention are achieved, the OSP treatment layer 44 may be provided only on a portion of the second bottom surfaces 41b of the connection terminals 41 and on the entire portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33.

[0054] The OSP treatment 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 oxidation of the surface of the object. The OSP treatment layer includes an organic film formed on the surface of the connection terminal 41. The presence of the OSP treatment layer can suppress a decrease in wettability with solder due to oxidation of the surface of the connection terminal 41. Therefore, the OSP treatment layer improves the wettability between the connection terminal 41 and solder. The method for forming the OSP treatment layer is not particularly limited, and for example, the OSP treatment may be performed using a commercially available preflux liquid.

[0055] The OSP-treated layer 44 may be a layer that has been subjected to both a surface roughening treatment and an OSP treatment, or may be a layer that has been subjected to a surface roughening treatment and then an OSP treatment.

[0056] 7 shows an example in which the side surface 33a of the recess 33 opposite the connection terminal 41 has a tapered shape such that the depth of the recess 33 decreases with increasing distance from the connection terminal 41. Such a shape may be obtained by forming the recess 33 by laser processing. Although not shown, in circuit modules of other embodiments, the side surface 33a of the recess 33 opposite the connection terminal 41 may also have a tapered shape such that the depth of the recess 33 decreases with increasing distance from the connection terminal 41.

[0057] FIG. 8 is an enlarged view schematically showing the structure around the connection terminals in the circuit module of the third embodiment.

[0058] In the circuit module of the third embodiment, the solder wettability improving layer is a plating layer. The plating layer is preferably a NiAu plating layer or a NiPdAu plating layer. In the circuit module 3 of the third embodiment shown in FIG. 8 , the solder wettability improving layer 42 is a Ni-based plating layer 45. In FIG. 8 , the Ni-based plating layer 45 is provided on the entire second bottom surface 41 b of the connection terminal 41 and the entire portion 41 c 1 of the side surface 41 c 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 Ni-based plating layer 45 may be provided only on a portion of the second bottom surface 41 b of the connection terminal 41 and the entire portion 41 c 1 of the side surface 41 c of the connection terminal 41 that is exposed from the recess 33.

[0059] The Ni-based plating layer 45 in the circuit module 3 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 42 may be a NiAu plating layer or a NiPdAu plating layer.

[0060] 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 41, 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 41 with Ni and then plating it with Au.

[0061] The method for forming the NiAu plating layer is not particularly limited, and the layer may be formed by electrolytic plating or electroless plating.

[0062] 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 41, 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 41 with Ni, then with Pd, and then with Au.

[0063] The method for forming the NiPdAu plating layer is not particularly limited, and the layer may be formed by electrolytic plating or electroless plating.

[0064] When the connection terminal 41 provided with the Ni-based plating layer 45 is joined to a solder bump, a Ni-plating-derived layer derived from the Ni-based plating layer 45 is present between the connection terminal 41 and the intermetallic compound layer.

[0065] The ratio of the thickness C (length indicated by the double-headed arrow C in FIG. 8 ) of the Ni-based plating layer 45 provided on the side surface 41 c of the connection terminal 41 to the thickness B (length indicated by the double-headed arrow B in FIG. 8 ) of the Ni-based plating layer 45 provided on the second bottom surface 41 b of the connection terminal 41 is preferably, for example, C / B = 0.8 or more and 1.2 or less. In this case, the influence of the thickness of the Ni-based plating layer 45 on the diameter and height of the connection terminal 41 can be suppressed.

[0066] FIG. 9 is an enlarged view schematically showing the structure around the connection terminals in the circuit module of the fourth embodiment.

[0067] In the circuit module 4 of the fourth embodiment, a surface roughening layer 43 is provided on the second bottom surface 41b of the connection terminal 41 as the solder wettability improving layer 42. In the circuit module 4 of the fourth embodiment, a Ni-based plating layer 45 is provided on the entire side surface 41c of the connection terminal 41, and a portion 45a of the Ni-based plating layer 45 exposed from the recess 33 serves as the solder wettability improving layer 42.

[0068] The Ni-based plating layer 45 is provided on the entire side surface 41 c of the connection terminal 41. That is, the Ni-based plating layer 45 is also provided on the portion of the side surface 41 c of the connection terminal 41 that is surrounded by the resin layer 31. In other words, a portion of the Ni-based plating layer 45 is covered with the resin layer 31.

[0069] The Ni-based plating layer 45 in the circuit module 4 may be, for example, a NiAu plating layer. That is, the NiAu plating layer may be provided on the entire side surface 41c of the connection terminal 41, and the portion of the NiAu plating layer exposed from the recess 33 may serve as the solder wettability improving layer 42. The Ni-based plating layer 45 in the circuit module 4 may be, for example, a NiPdAu plating layer.

[0070] The roughened surface layer 43 in the circuit module 4 of the fourth embodiment may be replaced with the OSP treated layer 44 shown in Fig. 7. That is, the second bottom surface 41b of the connection terminal 41 may be provided with the roughened surface layer 43 or the OSP treated layer 44 as the solder wettability improving layer 42, or the OSP treated layer 44 alone.

[0071] In Figure 9, the surface roughening layer 43 is provided only on the second bottom surface 41b of the connection terminal 41, but the surface of the portion 45a of the Ni-based plating layer 45 exposed from the recess 33 may also be subjected to surface roughening treatment or OSP treatment.

[0072] FIG. 10 is an enlarged view schematically showing the structure around the connection terminals in the circuit module of the fifth embodiment.

[0073] In the circuit module 5 of the fifth embodiment, a first Ni-based plating layer 46 is provided on the entire side surface 41c of the connection terminal 41. A portion of the first Ni-based plating layer 46 is exposed from the recess 33. Furthermore, a second Ni-based plating layer 47 is provided as a solder wettability improving layer 42 on the second bottom surface 41b of the connection terminal 41 and on a portion 46a of the first Ni-based plating layer 46 that is exposed from the recess 33.

[0074] The first Ni-based plating layer 46 is provided on the entire side surface 41c of the connection terminal 41. A portion of the first Ni-based plating layer 46 is covered with the resin layer 31. A portion 46a of the first Ni-based plating layer 46 that is exposed from the recess 33 is covered with a second Ni-based plating layer 47.

[0075] The second Ni-based plating layer 47 is provided on the second bottom surface 41 b of the connection terminal 41 and on a portion 41 c 1 of the side surface 41 c of the connection terminal 41 that is exposed from the recess 33 .

[0076] The first Ni-based plating layer 46 is, for example, a NiAu plating layer. The second Ni-based plating layer 47 is, for example, a NiAu plating layer or a NiPdAu plating layer. That is, the first NiAu plating layer is provided on the entire side surface 41 c of the connection terminal 41, and the second NiAu plating layer or NiPdAu plating layer is provided as the solder wettability improving layer 42 on the second bottom surface 41 b of the connection terminal 41 and on the portion 41 c 1 of the side surface 41 c of the connection terminal 41 that is exposed from the recess 33. The first NiAu plating layer may be covered with the second NiAu plating layer or NiPdAu plating layer on the portion 41 c 1 of the side surface 41 c of the connection terminal 41 that is exposed from the recess 33.

[0077] The first Ni-based plating layer 46 and the second Ni-based plating layer 47 may be integral with each other, with no interface therebetween.

[0078] The ratio of the total thickness E (length indicated by double-headed arrow E in FIG. 10 ) of the first and second Ni-based plating layers 46 and 47 formed on the side surface 41 c of the connection terminal 41 to the thickness D (length indicated by double-headed arrow D in FIG. 10 ) of the second Ni-based plating layer 47 formed on the second bottom surface 41 b of the connection terminal 41 is preferably, for example, E / D = 1.2 or more and 3.3 or less. In this case, the influence of the thicknesses of the first and second Ni-based plating layers 46 and 47 on the diameter and height of the connection terminal 41 can be suppressed.

[0079] The Ni-based plating layer 45 in the third and fourth embodiments, and the first Ni-based plating layer 46 and the second Ni-based plating layer 47 in the fifth embodiment, may be replaced with other Ni-based plating layers that improve solder wettability. Examples of other Ni-based plating layers include NiAg plating layers. When the Ni-based plating layer 45, the first Ni-based plating layer 46, or the second Ni-based plating layer 47 is formed by electroless plating, the Ni-based plating layer 45, the first Ni-based plating layer 46, or the second Ni-based plating layer 47 may be a plating in which a reducing agent-derived component is co-deposited, such as Ni—P plating or Ni—B plating. The Ni-based plating layer 45 in the third and fourth embodiments, and the first Ni-based plating layer 46 and the second Ni-based plating layer 47 in the fifth embodiment, may be replaced with a non-Ni-based plating layer that improves solder wettability. That is, in the present invention, the solder wettability improving layer 42 may be a non-Ni-based plating layer. Examples of the non-Ni-based plating layer that serves as the solder wettability improving layer 42 include a PdAu plating layer, an AuPdAu plating layer, an Ag plating layer, and an Au plating layer.

[0080] Next, the soldered circuit module of the present invention will be described.

[0081] The soldered circuit module of the present invention is a circuit module of the present invention with solder joined to the connection terminals thereof.

[0082] FIG. 11 is a cross-sectional view schematically showing an example of the soldered circuit module of the first embodiment.

[0083] FIG. 12 is an enlarged view showing a schematic structure of the periphery of a connection terminal in the soldered circuit module of the first embodiment.

[0084] 12 to 16 show the state in which FIG. 11 is turned upside down.

[0085] The soldered circuit module 101 of the first embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 1 of the first embodiment shown in Figures 1 to 3. Figure 12 is the same as Figure 4, which shows the solder bumps 111 joined to the connection terminals 41 of the circuit module 1. In this case, the intermetallic compound layer 121 includes the surface of the connection terminals 41 that was previously the roughened surface layer 43, so the presence of the roughened surface layer 43 cannot be observed after the solder bumps 111 are joined.

[0086] The soldered circuit module 101 includes a substrate 11 , an electronic component 21 , a resin layer 31 , a resin layer 32 , connection terminals 41 and solder bumps 111 .

[0087] 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.

[0088] The electronic component 21 is connected to the electrode 12 provided on the first main surface 11 a of the substrate 11 or the second main surface 11 b of the substrate 11 by a connecting member 16 .

[0089] The resin layer 31 is provided on the first major surface 11a of the substrate 11. The resin layer 32 is provided on the second major surface 11b of the substrate 11.

[0090] 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.

[0091] 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.

[0092] The second bottom surface 41b is exposed from the resin layer 31. A recess 33 recessed toward the first main surface 11a of the substrate 11 is formed in an area of ​​the surface of the resin layer 31 surrounding the second bottom surface 41b of the connection terminal 41. A part 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 exposed from the recess 33 and a portion 41c2 not exposed from the recess 33.

[0093] As described above, a recess 33 recessed toward the first main surface 11a of the substrate 11 is formed in the area surrounding the second bottom surface 41b of the connection terminal 41, so that the second bottom surface 41b protrudes from the surrounding resin layer 31.

[0094] 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.

[0095] 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.

[0096] In the soldered circuit module 101, the solder bumps 111 cover not only the second bottom surfaces 41b of the connection terminals 41 but also part of the side surfaces 41c of the connection terminals 41. This increases the bonding strength between the connection terminals 41 and the solder bumps 111.

[0097] Furthermore, in the soldered circuit module 101, since the recess 33 is provided, the intermetallic compound layer 121 is generated at a position (second bottom surface 41b of the connection terminal 41) above the recess 33 in Fig. 12. Therefore, the position of the stress concentration point (the portion indicated by S in Fig. 12) and the position of the intermetallic compound layer 121 generated on the second bottom surface 41b are separated from each other, and therefore, the impact resistance at the joint between the connection terminal 41 and the solder bump 111 can be improved.

[0098] 12 , 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 are entirely covered with the solder bump 111 and the intermetallic compound layer 121. That is, the solder bump 111 and the intermetallic compound layer 121 reach the surface of the resin layer 31 that is recessed in the recess 33. In this case, the bonding strength between the connection terminal 41 and the solder bump 111 can be further increased.

[0099] Although not shown, the solder bump 111 and the intermetallic compound layer 121 may cover only a portion of the portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. In other words, the solder bump 111 and the intermetallic compound layer 121 may not reach the surface of the resin layer 31 recessed in the recess 33.

[0100] 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.

[0101] FIG. 13 is an enlarged view showing a schematic structure of the periphery of a connection terminal in a soldered circuit module according to the second embodiment.

[0102] The soldered circuit module 102 of the second embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 2 of the second embodiment shown in Fig. 7. In this case, the OSP processing layer 44 of the circuit module 2 cannot be seen in the soldered circuit module 102.

[0103] For the above reasons, the second embodiment of the soldered circuit module 102 shown in Figure 13 has the same configuration as the first embodiment of the soldered circuit module 101 shown in Figures 11 and 12, except that the side surface 33a of the recess 33 opposite the connection terminal 41 has a tapered shape such that the depth of the recess 33 decreases as it moves away from the connection terminal 41.

[0104] Although not shown, in other embodiments of the soldered circuit module, the side surface 33a of the recess 33 opposite the connection terminal 41 may have a tapered shape such that the depth of the recess 33 decreases as it moves away from the connection terminal 41.

[0105] FIG. 14 is an enlarged view showing a schematic structure of the periphery of a connection terminal in a soldered circuit module according to the third embodiment.

[0106] The soldered circuit module 103 of the third embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 3 of the third embodiment shown in FIG.

[0107] In the soldered circuit module 103 , a Ni plating-derived layer 131 exists between the connection terminal 41 and the intermetallic compound layer 121 .

[0108] The Ni-plating-derived layer 131 contains Ni. The Ni-plating-derived layer 131 may be a layer derived from the Ni-based plating layer 45 in FIG.

[0109] In FIG. 14 , the Ni-plating-derived layer 131 is present over the entire area between the connection terminal 41 and the intermetallic compound layer 121, but the Ni-plating-derived layer 131 may be present only in a portion of the area between the connection terminal 41 and the intermetallic compound layer 121.

[0110] A method for confirming the presence of the Ni plating-derived layer 131 includes, for example, observing the joint between the connection terminal 41 and the solder bump 111 in a cross section of the soldered circuit module 103 using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX).

[0111] FIG. 15 is an enlarged view showing a schematic structure around a connection terminal in a soldered circuit module according to the fourth embodiment.

[0112] The soldered circuit module 104 of the fourth embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 4 of the fourth embodiment shown in FIG.

[0113] In the soldered circuit module 104 of the fourth embodiment, a Ni-based plating layer 45 is provided on the entire side surface 41c of the connection terminal 41. In FIG. 15 , the solder bump 111 and the intermetallic compound layer 121 cover the entire portion 45a of the Ni-based plating layer 45 that is exposed from the recess 33. Although not shown, the solder bump 111 and the intermetallic compound layer 121 may cover only a portion of the portion 45a of the Ni-based plating layer 45 that is exposed from the recess 33. In the soldered circuit module 104, the Ni-based plating layer 45 is, for example, a NiAu plating layer. In the soldered circuit module 104, the Ni-based plating layer 45 may be a NiPdAu plating layer, a NiAg plating layer, or the like. In the Ni-based plating layer 45, the portion 45a that is exposed from the recess 33 may be a Ni-plating-derived layer. In this case, the Ni-plating-derived layer is present so as to cover the side surface 41 c of the connection terminal 41 , and the Ni-plating-derived layer is not present on the second bottom surface 41 b of the connection terminal 41 .

[0114] FIG. 16 is an enlarged view showing a schematic structure around a connection terminal in a soldered circuit module according to the fifth embodiment.

[0115] The soldered circuit module 105 of the fifth embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 5 of the fifth embodiment shown in FIG.

[0116] In the soldered circuit module 105 of the fifth embodiment, a first Ni-based plating layer 46 is provided over the entire side surface 41c of the connection terminal 41. A Ni-plating-derived layer 131 is present between the connection terminal 41 and the intermetallic compound layer 121. The Ni-plating-derived layer 131 is mainly derived from the second Ni-based plating layer 47 (see FIG. 10 ). The Ni-plating-derived layer 131 is also present between the intermetallic compound layer 121 and a portion 46a of the first Ni-based plating layer 46 exposed from the recess 33. The interface between the Ni-plating-derived layer 131 and the first Ni-based plating layer 46 does not have to be visible.

[0117] 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 5 shown in Fig. 10 and joining solder bumps 111 to the circuit module 5 to manufacture the soldered circuit module 105 shown in Fig. 16 will be described with reference to Figs. 17 to 22.

[0118] 17, 18, 19, 20, 21, and 22 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 steps from the step of forming the resin layer onward in the manufacturing process for a soldered circuit module of the present invention.

[0119] 17 shows a state in which the connection terminal 41 is formed on the first main surface 11a of the substrate 11. A first Ni-based plating layer 46 is formed to cover the connection terminal 41 except for the portion that contacts the first main surface 11a. The first Ni-based plating layer 46 is, for example, a NiAu plating layer. Note that in FIGS. 17 to 22, the configuration of the electronic components, resin layer, etc. on the second main surface 11b side of the substrate 11 is omitted.

[0120] 18 , 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, the connection terminals 41, and the first Ni-based plating layer 46. 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.

[0121] 19 , the electronic component 21, the connection terminal 41, the first Ni-based plating layer 46, and the resin layer 31 are polished from the surface of the resin layer 31 opposite to the surface that is in contact with the substrate 11. By polishing to a position where the polished surface of the connection terminal 41 is exposed, the second bottom surface 41b of the connection terminal 41 is exposed from the resin layer 31. In addition, the second bottom surface 41b of the connection terminal 41 is not covered with the first Ni-based plating layer 46.

[0122] 20 , 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. The conditions for the laser irradiation are not particularly limited as long as they allow the resin layer 31 to be removed. 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.

[0123] If resin residue remains on the side surface 41c of the connection terminal 41, it will hinder plating deposition on the electrode side surface and solder wetting, 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.

[0124] 21 , a second Ni-based plating layer 47 is formed to cover the second bottom surfaces 41b of the connection terminals 41 and the portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33. The second Ni-based plating layer 47 becomes the solder wettability improving layer 42. The second Ni-based plating layer 47 is, for example, a NiAu plating layer or a NiPdAu plating layer. In this manner, the circuit module 5 is obtained.

[0125] 22 , solder is joined to the connection terminals 41 to form solder bumps 111. At this time, an intermetallic compound layer 121 is formed between the connection terminals 41 and the solder bumps 111. Furthermore, a Ni plating-derived layer 131 is formed between the connection terminals 41 and the intermetallic compound layer 121. In this way, a soldered circuit module 105 is obtained.

[0126] When manufacturing the circuit module 1 shown in Fig. 3 and then manufacturing the soldered circuit module 101 shown in Fig. 12, a substrate including connection terminals 41 on which the first Ni-based plating layer 46 is not formed is used in the above process shown in Fig. 17. Also, in Fig. 21, instead of forming the second Ni-based plating layer 47, a roughened surface layer 43 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 the recesses 33.

[0127] When manufacturing the circuit module 2 shown in Fig. 7 and then manufacturing the soldered circuit module 102 shown in Fig. 13, a substrate is used that includes connection terminals 41 that are not formed with the first Ni-based plating layer 46 in the above process shown in Fig. 17. Also, in Fig. 21, instead of forming the second Ni-based plating layer 47, an OSP treatment layer 44 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 the recesses 33.

[0128] When manufacturing the circuit module 3 shown in Fig. 8 and then manufacturing the soldered circuit module 103 shown in Fig. 14, a substrate is used that includes connection terminals 41 that are not formed with the first Ni-based plating layer 46 in the above process shown in Fig. 17. Also, in Fig. 21, the Ni-based plating layer 45 shown in Fig. 8 is formed on the second bottom surfaces 41b of the connection terminals 41 and on the portions 41c1 of the side surfaces 41c of the connection terminals 41 that are exposed from the recesses 33.

[0129] 9 is manufactured, and then the soldered circuit module 104 shown in Fig. 15 is manufactured. In the above process shown in Fig. 21, instead of forming the second Ni-based plating layer 47, a roughened surface layer 43 is provided on the second bottom surface 41b of the connection terminal 41. In this case, the first Ni-based plating layer 46 shown in Fig. 17 is a layer that is considered to be the Ni-plated layer 45.

[0130] A sixth embodiment, which is yet another embodiment of the circuit module and soldered circuit module of the present invention, will be described below. In the circuit module of the sixth embodiment described below, a solder wettability improving layer is further provided on the surface of the recess.

[0131] Fig. 23 is an enlarged view schematically illustrating the structure around a connection terminal in a circuit module according to the sixth embodiment. In the circuit module 6 according to the sixth embodiment, the solderability improving layer 42 is a Ni-based plating layer 45. In Fig. 23, the Ni-based plating layer 45 is provided on the entire second bottom surface 41b of the connection terminal 41 and on the entire portion 41c1 of the side surface 41c of the connection terminal 41 that is exposed from the recess 33. Furthermore, the Ni-based plating layer 45, which serves as the solderability improving layer 42, is also provided on a portion of the bottom surface 33c of the recess 33, which is the surface of the recess 33. Except for the Ni-based plating layer, which serves as the solderability improving layer, being further provided on the bottom surface of the recess, the circuit module according to the third embodiment can have the same configuration.

[0132] FIG. 24 is an enlarged view showing a schematic structure of the periphery of a connection terminal in a soldered circuit module according to the sixth embodiment.

[0133] The soldered circuit module 106 of the sixth embodiment can be obtained by joining solder bumps 111 to the connection terminals 41 of the circuit module 6 of the sixth embodiment shown in Fig. 23. In the circuit module 6 of the sixth embodiment, the Ni-based plating layer 45, which is the solder wettability improving layer 42, is also provided on a part of the bottom surface 33c of the recess 33, which is the surface of the recess 33, so that the solder bumps wet and spread over the surface of the recess 33 as well.

[0134] In the soldered circuit module 106, the Ni-plating-derived layer 131 exists between the connection terminal 41 and the intermetallic compound layer 121. The Ni-plating-derived layer 131 also exists on a part of the bottom surface 33c of the recess 33, which is the surface of the recess 33. The intermetallic compound layer 121 also exists on the surface of the Ni-plating-derived layer 131 on a part of the bottom surface 33c of the recess 33, which is the surface of the recess 33.

[0135] The Ni-plating-derived layer 131 contains Ni. The Ni-plating-derived layer 131 may be a layer derived from the Ni-based plating layer 45 in FIG.

[0136] The recess may have a tapered shape on the side opposite the connection terminal, such that the depth of the recess decreases with increasing distance from the connection terminal. Fig. 25 is an enlarged view schematically illustrating the structure around the connection terminal in another example of the circuit module of the sixth embodiment. In the circuit module 6a shown in Fig. 25 , the side 33a of the recess 33 opposite the connection terminal 41 has a tapered shape, such that the depth of the recess 33 decreases with increasing distance from the connection terminal 41. The surfaces of the recess 33 include a bottom surface 33c and a side surface 33a of the recess 33. The Ni-based plating layer 45, which serves as the solder wettability improving layer 42, is provided on the entire bottom surface 33c of the recess 33 and is further provided on a portion of the side surface 33a of the recess 33, continuing from the bottom surface 33c of the recess 33.

[0137] Fig. 26 is an enlarged view schematically illustrating the structure around the connection terminal in another example of the circuit module according to the sixth embodiment. In the circuit module 6b shown in Fig. 26, the side surface 33a of the recess 33 opposite the connection terminal 41 has a tapered shape, starting from the contact point 33b between the recess 33 in the resin layer and the connection terminal 41, such that the depth of the recess 33 decreases with increasing distance from the connection terminal 41. In other words, the recess 33 has no bottom surface 33c but only the side surface 33a. The Ni-based plating layer 45, which is the solder wettability improving layer 42, is provided on a portion of the side surface 33a of the recess 33, extending from the contact point 33b between the recess 33 in the resin layer and the connection terminal 41.

[0138] Regarding the circuit module 6a shown in FIG. 25 and the circuit module 6b shown in FIG. 26, the soldered circuit module obtained by joining solder bumps to the connection terminals is not shown, but a Ni-plating-derived layer and an intermetallic compound layer are present on the surface of the recess corresponding to the position of the Ni-based plating layer.

[0139] A seventh embodiment, which is yet another embodiment of the circuit module and soldered circuit module of the present invention, will be described below. The circuit module of the seventh embodiment described below corresponds to the circuit module of the fifth embodiment in which a solder wettability improving layer is further provided on the surface of the recess.

[0140] 27 is an enlarged view schematically illustrating the structure around the connection terminals in the circuit module of the seventh embodiment. In the circuit module 7 of the seventh embodiment, a first Ni-based plating layer 46 is provided over the entire side surface 41c of the connection terminal 41. A portion of the first Ni-based plating layer 46 is exposed from the recess 33. Furthermore, a second Ni-based plating layer 47 is provided as the solderability improving layer 42 on the second bottom surface 41b of the connection terminal 41 and on the portion 46a of the first Ni-based plating layer 46 that is exposed from the recess 33. Furthermore, the second Ni-based plating layer 47, which is the solderability improving layer 42, is also provided on a portion of the bottom surface 33c of the recess 33, which is the surface of the recess 33. Aside from the second Ni-based plating layer, which is the solderability improving layer, being provided on the bottom surface of the recess, the circuit module 7 of the seventh embodiment can have the same configuration as the circuit module of the fifth embodiment.

[0141] Regarding the circuit module 7 shown in FIG. 27 , the soldered circuit module obtained by joining solder bumps to the connection terminals is not shown, but a Ni-plating-derived layer and an intermetallic compound layer are present on the surface of the recesses in correspondence with the position of the second Ni-based plating layer.

[0142] A modified example of the circuit module of the present invention, in which one recess surrounds a plurality of connection terminals, will be described below.

[0143] FIG. 28 is a plan view of a first modified example of the circuit module of the present invention, seen from the surface on which the resin layer and the connection terminals are provided.

[0144] In the circuit module 8, the recesses 33 are frame-shaped. One frame-shaped recess 33 is provided so as to surround a plurality of connection terminals 41. In the circuit module 8, one frame-shaped recess 33 is provided so as to surround the peripheries of all of the connection terminals 41.

[0145] FIG. 29 is a plan view of a second modified example of the circuit module of the present invention, seen from the surface on which the resin layer and the connection terminals are provided.

[0146] In the circuit module 9, the recesses 33 are linear. One linear recess 33 is provided so as to surround a plurality of connection terminals 41. In the circuit module 9, one linear recess 33 is provided so as to surround the peripheries of all of the connection terminals 41.

[0147] Examples in which the bonding strength between the solder and the connection terminals in the soldered circuit module of the present invention was evaluated are shown below, but the present invention is not limited to these examples.

[0148] (Example) A circuit module of the example was prepared in which a NiAu plating layer was provided as a solder wettability improving layer on the second bottom surface of the connection terminal and on the side surface of the connection terminal that was exposed from the recess. That is, a circuit module was prepared in which the Ni-based plating layer 45 in Fig. 8 was a NiAu plating layer. Solder was joined to the connection terminal of the circuit module of the example, and a soldered circuit module of the example was obtained.

[0149] (Comparative Example 1) A circuit module of Comparative Example 1 was prepared in the same manner as the circuit module of Example, except that no recesses were formed on the surface of the resin layer in the region surrounding the second bottom surfaces of the connection terminals, and a NiAu plating layer was provided as a solder wettability improving layer only on the second bottom surfaces of the connection terminals. As in Example, solder was joined to the connection terminals of the circuit module of Comparative Example 1, and a soldered circuit module of Comparative Example 1 was obtained.

[0150] (Comparative Example 2) A circuit module of Comparative Example 2 was prepared in the same manner as the circuit module of Example, except that the solder wettability improving layer was not provided on the second bottom surface of the connection terminal and on the portion of the side surface of the connection terminal that was exposed from the recess. As in Example, solder was joined to the connection terminal of the circuit module of Comparative Example, and a soldered circuit module of Comparative Example 2 was obtained.

[0151] (Evaluation of Bonding Strength) A high-speed ball shear test was performed on the soldered circuit module of the example and the soldered circuit modules of Comparative Examples 1 and 2. The high-speed ball shear test is a test that examines the bonding strength between the solder and the electrode by applying shear stress between the solder and the electrode using a shear tool. Here, the bonding strength between the solder and the connection terminal was examined by applying shear stress between the solder and the connection terminal. As a result, the soldered circuit module of the example had approximately twice the bonding strength between the solder and the connection terminal compared to the soldered circuit modules of Comparative Examples 1 and 2.

[0152] The present specification discloses the following:

[0153] <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; and 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.

[0154] <2> The circuit module according to <1>, wherein the solder wettability improving layer is a surface roughening layer or an OSP treated layer.

[0155] <3> The circuit module according to <1>, wherein the solder wettability improving layer is a plating layer.

[0156] <4> The circuit module according to <3>, wherein the solder wettability improving layer is a NiAu plated layer or a NiPdAu plated layer.

[0157] <5> The circuit module according to <1>, wherein a surface roughening layer or an OSP treated layer is provided on the second bottom surface of the connection terminal as the solder wettability improving layer, a NiAu plating layer is provided on the entire side surface of the connection terminal, and a portion of the NiAu plating layer exposed from the recess serves as the solder wettability improving layer.

[0158] <6> The circuit module according to <1>, wherein a first NiAu plating layer is provided on the entire side surface of the connection terminal, a second NiAu plating layer or a NiPdAu plating layer is provided as the solder wettability improving layer on the second bottom surface of the connection terminal and on a portion of the side surface of the connection terminal that is exposed from the recess, and the first NiAu plating layer is covered with the second NiAu plating layer or the NiPdAu plating layer on the portion of the side surface of the connection terminal that is exposed from the recess.

[0159] <7> The circuit module according to any one of <1> to <6>, wherein the solder wettability improving layer is further provided on the surface of the recess.

[0160] <8> 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 a side surface, 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, 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.

[0161] <9> The soldered circuit module according to <8>, wherein the solder bumps and the intermetallic compound layer reach the surface of the resin layer recessed in the recess.

[0162] <10> The soldered circuit module according to <8> or <9>, wherein a layer derived from Ni plating is present between the connection terminal and the intermetallic compound layer.

[0163] DESCRIPTION OF SYMBOLS 1, 2, 3, 4, 5, 6, 6a, 6b, 7, 8, 9 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 33a Side surface of recess 33b Contact point between recess in resin layer and connection terminal 33c Bottom surface of recess 41, 41E Connection terminal 41a First bottom surface 41b Second bottom surface 41c Side surface 41c1 Portion of side surface exposed from recess 41c2 Portion of side surface not exposed from recess 42 Solder wettability improving layer 43 Surface roughening layer 44 OSP treatment layer 45 Ni-based plating layer 45a Portion of Ni-based plating layer exposed from recess 46 First Ni-based plating layer 46a: Portion of first Ni-based plating layer exposed from recess 47: Second Ni-based plating layer 51: Laser irradiation mark 52: Non-laser irradiated portion 101, 102, 103, 104, 105, 106: Soldered circuit module 111: Solder bump 121: Intermetallic compound layer 131: Ni-plating derived layer

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 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 in an area on the surface of the resin layer surrounding the second bottom surface of the connection terminal, a portion of the side surface of the connection terminal being exposed in the recess, and a solder wettability improving layer being 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 the solder wettability improving layer is a surface roughening layer or an OSP treatment layer.

3. The circuit module according to claim 1, wherein the solder wettability improving layer is a plating layer.

4. The circuit module according to claim 3, wherein the solder wettability improving layer is a NiAu plated layer or a NiPdAu plated layer.

5. The circuit module described in claim 1, wherein the second bottom surface of the connection terminal is provided with a surface roughening layer or an OSP treatment layer as the solder wettability improving layer, the entire side surface of the connection terminal is provided with a NiAu plating layer, and the portion of the NiAu plating layer exposed from the recess becomes the solder wettability improving layer.

6. The circuit module described in claim 1, wherein a first NiAu plating layer is provided on the entire side surface of said connection terminal, a second NiAu plating layer or a NiPdAu plating layer is provided as said solder wettability improving layer on said second bottom surface of said connection terminal and on said portion of said side surface of said connection terminal exposed from said recess, and said first NiAu plating layer is covered with said second NiAu plating layer or NiPdAu plating layer on said portion of said side surface of said connection terminal exposed from said recess.

7. The circuit module according to any one of claims 1 to 6, wherein the solder wettability improving layer is further provided on the surface of the recess.

8. 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; a connection terminal penetrating the resin layer in a thickness direction; and a solder bump bonded to the connection terminal via an intermetallic compound layer, 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 not covered by 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 portion of the side surface of the connection terminal is exposed in the recess, and 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 exposed from the recess, a soldered circuit module, characterized in that 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 side surface of the connection terminal that is exposed from the recess.

9. The solder circuit module according to claim 8, wherein the solder bumps and the intermetallic compound layer reach the surface of the resin layer recessed in the recess.

10. The soldered circuit module according to claim 8 or 9, wherein a layer derived from Ni plating is present between the connection terminal and the intermetallic compound layer.

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