Laminated substrate

Abstract

Provided is a laminated substrate in which cracks and peeling do not readily occur in a connection portion where a conductor is connected between an electrode provided in a ceramic layer and an interlayer provided in a thermoplastic resin layer, even if thermal stress is generated. This laminated substrate (1) is provided with a first thermoplastic resin layer (21), which is provided with a first main surface (21a) and a second main surface (21b) facing the first main surface (21a), and which has a via hole (21h) penetrating the second main surface (21b) from the first main surface (21a), a ceramic layer (11), which is disposed so as to be in contact with the first main surface (21a), and a second thermoplastic resin layer (22), which is disposed so as to be in contact with the second main surface (21b). The second thermoplastic resin layer (22) is disposed so as to be in contact with the second main surface (21b), a first electrode (31) is formed on the main surface of the ceramic layer (11) that is in contact with the first main surface (21a), and a protective layer (40) is formed so as to cover at least a part of the contour of the first electrode (31). A second electrode (32) is formed on the main surface of the second thermoplastic resin layer (22) that is in contact with the second main surface (21b), an interlayer connection conductor (50) that connects the first electrode (31) and the second electrode (32) is disposed in the via hole (21h), and an intermetallic compound (61) is formed between the interlayer connection conductor (50) and the first electrode (31).

Description

Technical Field

[0001] The present invention relates to a laminate substrate. Background Art

[0002] Conventionally, module components using multilayer substrates with built-in passive components have been put into practical use. For example, a DCDC converter module is known in which a switch IC (integrated circuit) chip and a chip capacitor are mounted on a multilayer substrate with built-in coils as the passive components.

[0003] As a multilayer substrate used in such a module component, a multilayer substrate formed by stacking ceramic substrates is known. In the multilayer substrate formed by stacking ceramic substrates, warping of the ceramic substrates sometimes occurs. In order to solve such a problem, Patent Document 1 discloses a stacked substrate (module component) in which a substrate (thermoplastic resin layer) made of a thermoplastic resin is stacked on a multilayer substrate formed by stacking ceramic substrates.

[0004] That is, Patent Document 1 discloses a module component, comprising: a ceramic multilayer substrate having a built-in passive component and having a first terminal electrode and a second terminal electrode connected to the passive component on one main surface and the other main surface, respectively; a first thermoplastic resin layer provided on the one main surface of the ceramic multilayer substrate and having a first wiring connected to the first terminal electrode and a first soldering pad for mounting a surface mounted component; a second thermoplastic resin layer provided on the other main surface of the ceramic multilayer substrate and having a second wiring connected to the second terminal electrode and a second soldering pad serving as a connection terminal to a motherboard; and a second thermoplastic resin layer provided on the first thermoplastic resin layer. The ceramic multilayer substrate is a substrate using a non-glass-based low-temperature co-fired ceramic material, and the first terminal electrode of the ceramic multilayer substrate and the interlayer conductor provided on the first thermoplastic resin layer, and the second terminal electrode of the ceramic multilayer substrate and the interlayer conductor provided on the second thermoplastic resin layer are respectively bonded by liquid phase diffusion bonding.

[0005] In Patent Document 1, terminal electrodes provided on a ceramic multilayer substrate and interlayer conductors provided on a thermoplastic resin layer are bonded by liquid phase diffusion bonding (Transient Liquid Phase Diffusion Bonding).

[0006] Patent Document 2 discloses an interlayer connection conductor connected to a conductor wiring layer, and discloses that an intermetallic compound layer containing an intermetallic compound is formed between the conductor wiring layer and the interlayer connection conductor.

[0007] The intermetallic compound layer is formed by heating and melting the metal such as Sn or Sn alloy constituting the interlayer connection conductor and reacting with the metal (for example, Cu) constituting the conductor wiring layer. That is, the intermetallic compound layer is formed during liquid phase diffusion bonding.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent No. 6819668

[0011] Patent Document 2: International Publication No. 2019 / 003729 Summary of the invention

[0012] In the laminated substrate (module component) described in Patent Document 1, an intermetallic compound layer as disclosed in Patent Document 2 is also formed between electrodes (terminal electrodes) provided on the ceramic layer and interlayer connection conductors (interlayer conductors) provided on the thermoplastic resin layer.

[0013] Since the linear thermal expansion coefficient of the ceramic layer is different from the linear thermal expansion coefficient of the thermoplastic resin layer, when heat is applied to the laminated substrate, thermal stress is generated between the ceramic layer and the thermoplastic resin layer.

[0014] Such thermal stress is easily applied to the interlayer connection conductor located at the boundary between the ceramic layer and the thermoplastic resin layer. In particular, thermal stress is more likely to be applied to the connection portion between the interlayer connection conductor and the electrode provided on the ceramic layer.

[0015] As described above, the intermetallic compound layer is formed between the electrode provided on the ceramic layer and the interlayer connection conductor provided on the thermoplastic resin layer. Since the intermetallic compound has low ductility, the intermetallic compound is unlikely to absorb thermal stress.

[0016] Therefore, there is a problem that, when the interlayer connection conductor is subjected to the above-mentioned thermal stress, cracks or separation are likely to occur starting from the intermetallic compound or the interlayer connection conductor in the vicinity thereof.

[0017] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a laminated substrate in which cracks or peeling are unlikely to occur at the connection portion between an electrode provided on a ceramic layer and an interlayer connection conductor provided on a thermoplastic resin layer even when thermal stress occurs.

[0018] The laminated substrate of the present invention comprises a first thermoplastic resin layer, a ceramic layer and a second thermoplastic resin layer, wherein the first thermoplastic resin layer comprises a first main surface and a second main surface opposite to the first main surface, and has a via hole penetrating from the first main surface to the second main surface, the ceramic layer is arranged in contact with the first main surface, the second thermoplastic resin layer is arranged in contact with the second main surface, a first electrode is formed on the main surface of the ceramic layer in contact with the first main surface, and a protective layer is formed in a manner covering at least a part of the contour of the first electrode, a second electrode is formed on the main surface of the second thermoplastic resin layer in contact with the second main surface, an interlayer connection conductor connecting the first electrode and the second electrode is arranged in the via hole, and an intermetallic compound is formed between the interlayer connection conductor and the first electrode.

[0019] According to the present invention, it is possible to provide a laminated substrate in which cracks or peeling are unlikely to occur at the connection portion between the electrode provided on the ceramic layer and the interlayer connection conductor provided on the thermoplastic resin layer even if thermal stress occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A It is a cross-sectional view schematically showing an example of a multilayer substrate according to the first embodiment of the present invention.

[0021] Figure 1B yes Figure 1A An enlarged view of the dotted line portion.

[0022] Figure 2 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to a second embodiment of the present invention.

[0023] Figure 3 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a multilayer substrate in another form according to the second embodiment of the present invention.

[0024] Figure 4 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a third embodiment of the present invention.

[0025] Figure 5 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to a fourth embodiment of the present invention.

[0026] Figure 6 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to another embodiment of the present invention.

[0027] Figure 7This is a process diagram schematically showing an example of an LTCC green sheet preparation step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0028] Fig. 8A This is a process diagram schematically showing an example of a via hole filling step of an LTCC green sheet in the method for manufacturing a laminated substrate according to the fifth embodiment of the present invention.

[0029] Figure 8B This is a process diagram schematically showing an example of a via hole filling step of an LTCC green sheet in the method for manufacturing a laminated substrate according to the fifth embodiment of the present invention.

[0030] Fig. 9 This is a process diagram schematically showing an example of an electrode pattern forming step of an LTCC green sheet in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0031] Fig.10 This is a process diagram schematically showing an example of a step of applying a protective layer paste containing a ceramic material in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0032] Fig.11 This is a process diagram schematically showing an example of a LTCC green sheet lamination step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0033] Fig.12 This is a process diagram schematically showing an example of a firing step of an LTCC green sheet laminate in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0034] Fig.13 This is a process diagram schematically showing an example of a thermoplastic resin layer preparation step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0035] Fig.14A This is a process diagram schematically showing an example of a step of forming an electrode pattern of a thermoplastic resin layer in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0036] Fig. 14B This is a process diagram schematically showing an example of a step of forming an electrode pattern of a thermoplastic resin layer in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0037] Fig.15A This is a process diagram schematically showing an example of a via hole filling step of a thermoplastic resin layer in a method for manufacturing a laminated substrate according to a fifth embodiment of the present invention.

[0038] Fig. 15B This is a process diagram schematically showing an example of a via hole filling step of a thermoplastic resin layer in a method for manufacturing a laminated substrate according to a fifth embodiment of the present invention.

[0039] Fig.16 This is a process diagram schematically showing an example of a lamination step of a thermoplastic resin layer in a method for producing a laminated substrate according to a fifth embodiment of the present invention.

[0040] Fig.17A This is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a fifth embodiment of the present invention.

[0041] Fig. 17B This is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a fifth embodiment of the present invention.

[0042] Fig.18A This is an explanatory diagram schematically showing an example of connecting an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0043] Fig.18B This is an explanatory diagram schematically showing an example of connecting an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0044] Fig.18C This is an explanatory diagram schematically showing an example of connecting an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0045] Fig.18D This is an explanatory diagram schematically showing an example of connecting an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0046] Fig.19 This is a cross-sectional view schematically showing an example of a multilayer ceramic layer prepared in the method for manufacturing a laminated substrate according to the sixth embodiment of the present invention.

[0047] Fig. 20 This is a cross-sectional view schematically showing an example of a plurality of thermoplastic resin layers prepared in the method for producing a laminated substrate according to the sixth embodiment of the present invention.

[0048] Fig.21 This is a process diagram schematically showing an example of a step of disposing a protective layer made of a thermoplastic resin in the method for producing a laminated substrate according to the sixth embodiment of the present invention.

[0049] Fig.22AThis is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a sixth embodiment of the present invention.

[0050] Fig. 22B This is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a sixth embodiment of the present invention. DETAILED DESCRIPTION

[0051] The laminated substrate of the present invention will be described below.

[0052] However, the present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope of the present invention. It should be noted that a configuration in which two or more of the preferred configurations of the present invention described below are combined also constitutes the present invention.

[0053] The laminated substrate of the present invention comprises: a first thermoplastic resin layer, a ceramic layer and a second thermoplastic resin layer, the first thermoplastic resin layer comprising a first main surface and a second main surface opposite to the first main surface, and having a via hole penetrating from the first main surface to the second main surface, the ceramic layer being arranged in contact with the first main surface, the second thermoplastic resin layer being arranged in contact with the second main surface, a first electrode being formed on the main surface of the ceramic layer in contact with the first main surface, and a protective layer being formed so as to cover at least a part of the contour of the first electrode, a second electrode being formed on the main surface of the second thermoplastic resin layer in contact with the second main surface, an interlayer connection conductor connecting the first electrode and the second electrode being arranged in the via hole, and an intermetallic compound being formed between the interlayer connection conductor and the first electrode.

[0054] That is, in the laminated substrate of the present invention, the protective layer is formed to cover at least a portion of the contour of the first electrode. Forming such a protective layer can prevent the formation of low-ductility intermetallic compounds that spread at the connection portion between the interlayer connection conductor and the first electrode.

[0055] Therefore, even when thermal stress is generated in the laminated substrate, the range where the intermetallic compound is formed is narrow, and the portion where the thermal stress is not easily relaxed becomes small.

[0056] As a result, even when thermal stress is generated in the laminated substrate, cracks or separation are unlikely to occur at the connection portion between the electrode provided on the ceramic layer and the interlayer connection conductor provided on the thermoplastic resin layer.

[0057] The laminated substrate of the present invention can be used as a laminated substrate with a built-in coil, and an ultra-small DCDC converter using the laminated substrate can be widely used in electronic devices such as mobile information terminals and digital cameras.

[0058] Hereinafter, embodiments of the multi-layer substrate of the present invention will be described with reference to the drawings.

[0059] [First embodiment]

[0060] First, a laminated substrate according to a first embodiment of the present invention will be described.

[0061] Figure 1A It is a cross-sectional view schematically showing an example of a multilayer substrate according to the first embodiment of the present invention.

[0062] Figure 1B yes Figure 1A An enlarged view of the dotted line portion.

[0063] Figure 1A The laminated substrate 1 shown includes a multilayer ceramic layer 2 in which a plurality of ceramic layers 10 are laminated, and a multilayer thermoplastic resin layer 3 in which a plurality of thermoplastic resin layers 20 are laminated.

[0064] exist Figure 1A In the laminated substrate 1 shown, a plurality of ceramic layers 2 are laminated on a plurality of thermoplastic resin layers 3 .

[0065] like Figure 1A and Figure 1B As shown, the multi-layer thermoplastic resin layer 3 includes a first thermoplastic resin layer 21 in contact with the multi-layer ceramic layer 2 .

[0066] like Figure 1B As shown, the first thermoplastic resin layer 21 includes a first main surface 21 a and a second main surface 21 b facing the first main surface 21 a , and has a via hole 21 h penetrating from the first main surface 21 a to the second main surface 21 b .

[0067] Furthermore, the first main surface 21 a of the first thermoplastic resin layer 21 is in contact with the multilayer ceramic layer 2 .

[0068] The multilayer ceramic layer 2 includes a ceramic layer 11 arranged in contact with a first main surface 21a of a first thermoplastic resin layer 21. A first electrode 31 is formed on a main surface of the ceramic layer 11 in contact with the first main surface 21a, and a protective layer 40 is formed to cover an outline 31c of the first electrode 31.

[0069] In addition, in the multilayer substrate of the present invention, the protective layer may be formed so as to cover the entire outline of the first electrode, or may be formed so as to cover a part of the outline of the first electrode.

[0070] The multilayer thermoplastic resin layer 3 includes a second thermoplastic resin layer 22 disposed in contact with the second main surface 21 b .

[0071] A second electrode 32 is formed on a principal surface of the second thermoplastic resin layer 22 that is in contact with the second principal surface 21 b .

[0072] The interlayer connection conductor 50 connecting the first electrode 31 and the second electrode 32 is disposed in the via hole 21h. An intermetallic compound 61 is formed between the interlayer connection conductor 50 and the first electrode 31. An intermetallic compound 62 is formed between the interlayer connection conductor 50 and the second electrode 32.

[0073] The via hole 21 h has a tapered shape in which the opening on the first main surface 21 a side is larger than the opening on the second main surface 21 b side.

[0074] With such a shape, the connection strength between the interlayer connection conductor 50 and the first electrode 31 can be improved.

[0075] In the laminated substrate 1, a protective layer 40 is formed so as to cover the contour 31c of the first electrode 31. If such a protective layer 40 is formed, it is possible to prevent the intermetallic compound 61 with low ductility from spreading and forming at the connection portion between the interlayer connection conductor 50 and the first electrode 31. The intermetallic compound 61 has low ductility and becomes a portion where thermal stress is difficult to relax.

[0076] In the laminated substrate 1 , since the range in which the intermetallic compound 61 is formed is narrow, the portion where thermal stress is difficult to relax is reduced.

[0077] Therefore, even when thermal stress is generated in the multilayer substrate 1 , cracks or peeling are unlikely to occur at the connection portion between the first electrode 31 provided on the ceramic layer 11 and the interlayer connection conductor 50 provided on the first thermoplastic resin layer 21 .

[0078] like Figure 1A and Figure 1B As shown, in the multilayer substrate 1 , a portion of the protective layer 40 is located inside the opening of the via hole 21 h on the first main surface 21 a , and a portion of the protective layer 40 located inside the via hole 21 h is in contact with the interlayer connection conductor 50 .

[0079] When manufacturing the multilayer substrate 1 , the conductive paste is filled in the via hole 21 h , and then the conductive paste is brought into contact with the first electrode 31 , and the conductive paste is melted and then solidified, thereby forming the interlayer connection conductor 50 .

[0080] When the laminated substrate 1 has the above structure, the opening of the via hole 21h on the first main surface 21a is large, so that the conductive paste can be in sufficient contact with the exposed surface of the first electrode 31. Therefore, the reliability of electrical connection can be improved.

[0081] It should be explained, such as Figure 1AAs shown, electrode patterns 2 a , through holes 2 b , etc. may be formed on the multilayer ceramic layer 2 , and electrode patterns 3 a , through holes 3 b , etc. may be formed on the multilayer thermoplastic resin layer 3 .

[0082] Hereinafter, preferred embodiments of the respective configurations of the multilayer substrate 1 will be described.

[0083] (Interlayer connection conductor)

[0084] The interlayer connection conductor 50 is formed by filling the conductive paste containing the first metal powder and the second metal powder having a higher melting point than the first metal powder into the via hole 21h, and then melting the conductive paste and solidifying it. At this time, the first metal powder contained in the conductive paste reacts with the first electrode 31 to form an intermetallic compound 61.

[0085] Preferably, the first metal powder is composed of Sn or a Sn alloy, and the second metal powder is composed of a Cu—Ni alloy or a Cu—Mn alloy.

[0086] In addition, the conductive paste is described in detail in the <Method for Producing a Laminated Substrate> described later.

[0087] (Multilayer ceramic layer)

[0088] The multilayer ceramic layer 2 is composed of ceramic layers 10 including ceramic layers 11 .

[0089] As a material constituting the ceramic layer 10, for example, a low temperature co-fired ceramic (LTCC) material can be cited. A low temperature co-fired ceramic material refers to a ceramic material that can be sintered at a temperature below 1000°C and can be co-fired with Au, Ag, Cu, etc., which have a low resistivity. As a low temperature co-fired ceramic material, specifically, a glass composite low temperature co-fired ceramic material formed by mixing borosilicate glass with ceramic powders such as alumina, zirconia, magnesia, and forsterite, a microcrystalline glass-based low temperature co-fired ceramic material using microcrystalline glass of ZnO-MgO-Al2O3-SiO2, and a non-glass-based low temperature co-fired ceramic material using BaO-Al2O3-SiO2 ceramic powder, Al2O3-CaO-SiO2-MgO-B2O3 ceramic powder, etc. can be cited.

[0090] The thickness of the ceramic layer 10 is preferably appropriately determined according to the design, and is preferably 5 μm to 100 μm, for example.

[0091] The first electrode 31 , the electrode pattern 2 a , and the through hole 2 b are preferably a sintered body of a conductive paste composed of a conductive powder, a plasticizer, and a binder.

[0092] Furthermore, the first electrode 31 , the electrode pattern 2 a , and the through hole 2 b are more preferably a sintered body of copper (Cu) or an alloy thereof.

[0093] It should be noted that the first electrode 31 , the electrode pattern 2 a , and the through hole 2 b may contain silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), gold (Au), and alloys thereof.

[0094] In addition, the first electrode 31 , the electrode pattern 2 a , and the through hole 2 b may be made of the same material or different materials.

[0095] The thickness of the first electrode 31 is preferably appropriately determined according to the design, and is preferably 3 μm to 40 μm, for example. In this specification, “the thickness of the first electrode” refers to the maximum thickness of the first electrode.

[0096] (Protective layer)

[0097] The protective layer 40 may be made of the same material as that constituting the first thermoplastic resin layer 21 , or may be made of the same material as that constituting the ceramic layer 11 .

[0098] The thickness of the protective layer 40 is preferably 2 μm to 10 μm.

[0099] If the thickness of the protective layer is less than 2 μm, the first electrode is likely to float.

[0100] If the thickness of the protective layer exceeds 10 μm, the protective layer becomes an obstacle when laminating the first thermoplastic resin layer and the ceramic layer, resulting in a gap between the interlayer connection conductor and the first electrode, making the connection impossible, or the first electrode, electrode pattern, internal conductors such as through holes, etc. are easily deformed.

[0101] The protective layer 40 preferably covers a range of 30 μm to 100 μm inward from the contour of the first electrode 31 .

[0102] By forming the protective layer 40 in such a range, it is possible to prevent the first electrode 31 from floating.

[0103] (Multi-layer thermoplastic resin layer)

[0104] The multilayer thermoplastic resin layer 3 is composed of a thermoplastic resin layer 20 including a first thermoplastic resin layer 21 and a second thermoplastic resin layer 22 .

[0105] Examples of the material constituting the thermoplastic resin layer 20 include liquid crystal polymer (LCP), thermoplastic polyimide resin, polyetheretherketone resin (PEEK), polyphenylene sulfide resin (PPS), and the like.

[0106] Among them, liquid crystal polymer (LCP) is preferred. Liquid crystal polymer has a lower water absorption rate than other thermoplastic resins, and can prevent changes in electrical characteristics and reduction in electrical connection reliability.

[0107] The thickness of the thermoplastic resin layer 20 is preferably appropriately determined according to the design, and is preferably 10 μm to 100 μm, for example.

[0108] like Figure 1B As shown, the via hole 21h formed in the first thermoplastic resin layer 21 has a tapered shape.

[0109] In addition, the tapered shape preferably has a different inclination angle in stages. In this case, the inclination angle may be changed in two stages, or may be changed in three or more stages.

[0110] It should be noted that in the laminated substrate of the present invention, the conductive hole can be a tapered shape in which the opening on the first main surface side is smaller than the opening on the second main surface side, or can be a cylindrical shape in which the opening on the first main surface side and the opening on the second main surface side are the same size.

[0111] The diameter of the opening of the via hole 21 h on the first main surface 21 a side is preferably 20 μm to 200 μm.

[0112] The diameter of the opening of the via hole 21h on the second main surface 21b side is preferably 20 μm to 200 μm.

[0113] exist Figure 1B In the stacked substrate 1 shown, the area of ​​the first electrode 31 (the area of ​​the portion in contact with the intermetallic compound 61 and the protective layer 40) is larger than the opening area of ​​the via hole 21h on the first main surface 21a side, but in the stacked substrate 1 of the present invention, the area of ​​the first electrode can be the same as the opening area of ​​the via hole on the first main surface side, and the area of ​​the first electrode can be smaller than the opening area of ​​the via hole on the first main surface side.

[0114] Examples of materials for the second electrode 32 and the electrode pattern 3a include copper (Cu), silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), and alloys thereof. The second electrode 32 and the electrode pattern 3a can be formed by laminating a metal foil on the thermoplastic resin layer 20 and patterning it by etching or the like.

[0115] In addition, the second electrode 32 and the electrode pattern 3 a may be made of the same material or different materials.

[0116] In addition, a preferred material for the via 2 b is the same as a preferred material for the interlayer connection conductor 50 .

[0117] The thickness of the second electrode 32 is preferably appropriately determined according to the design, and is preferably 3 μm to 40 μm, for example.

[0118] [Second embodiment]

[0119] Next, a multilayer substrate according to a second embodiment of the present invention will be described.

[0120] Figure 2 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to a second embodiment of the present invention.

[0121] Figure 2 The laminated substrate 101 according to the second embodiment of the present invention shown has the same configuration as the laminated substrate 1 according to the first embodiment except that the shape of the intermetallic compound is different.

[0122] The structure of the laminate substrate 101 will be described in detail below with reference to the drawings.

[0123] like Figure 2 As shown, first, the end of the protective layer 40 located inside the outline of the first electrode 31 is defined as the inner end 41, and the main surface of the protective layer 40 in contact with the outline of the first electrode 31 so as to cover the outer surface is defined as the covering surface 40a.

[0124] In the multilayer substrate 101 , a portion 161 a of the intermetallic compound 161 is formed in contact with the coating surface 40 a on the inner end portion 41 side of the protective layer 40 and is continuous with the intermetallic compound 161 formed between the interlayer connection conductor 50 and the first electrode 31 .

[0125] That is, a portion 161 a of the intermetallic compound 161 is formed so as to intrude between the protective layer 40 and the first electrode 31 .

[0126] in addition, Figure 2 The shape of the intermetallic compound 161 in FIG. 1 is such that a portion in contact with the coating surface 40 a of the protective layer 40 (ie, a portion indicated by the symbol “ 161 a ”) is raised compared to other portions.

[0127] When manufacturing the multilayer substrate of the present invention, the first electrode is brought into contact with a conductive paste as a precursor of an interlayer connection conductor, and the conductive paste is melted and then solidified, thereby producing an interlayer connection conductor.

[0128] At this time, if the protective layer is formed on the contour of the first electrode, the exposed surface of the first electrode (the contact surface with the conductive paste) becomes narrower.

[0129] In the manufactured laminated substrate, the physical connection stability and conductivity between the first electrode and the interlayer connection conductor depend on the contact area between them via the intermetallic compound. Therefore, if a protective layer is formed on the contour of the first electrode, these effects become disadvantageous.

[0130] However, if a portion 161a of the intermetallic compound 161 is formed in a manner that contacts the coating surface 40a on the inner end portion 41 side of the protective layer 40 and is continuous with the intermetallic compound 161 formed between the interlayer connection conductor 50 and the first electrode 31 as in the laminated substrate 101, the contact area between the first electrode 31 and the intermetallic compound 161 can be increased. Therefore, the physical connection stability and conductivity between the first electrode 31 and the interlayer connection conductor 50 can be improved.

[0131] In the laminated substrate 101 , the thickness of the first electrode 31 is preferably appropriately determined according to the design, and is preferably 3 μm to 40 μm, for example. In the laminated substrate 101 , the first electrode 31 is thinned at a portion in contact with the portion 161 a of the intermetallic compound 161 .

[0132] However, as described above, the “thickness of the first electrode” in this specification refers to the maximum thickness of the first electrode, and thus such a thinned portion is not considered when measuring the “thickness of the first electrode”.

[0133] In the laminated substrate 101 , the thickness of the protective layer 40 is preferably 2 μm to 10 μm.

[0134] If the thickness of the protective layer is less than 2 μm, the first electrode is likely to float.

[0135] If the thickness of the protective layer exceeds 10 μm, the liquid phase in liquid phase diffusion bonding is unlikely to exceed the protective layer when forming the intermetallic compound, and the intermetallic compound is unlikely to be formed in contact with the coating surface on the inner end side of the protective layer.

[0136] Next, another aspect of the multilayer substrate according to the second embodiment of the present invention will be described.

[0137] Figure 3 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a multilayer substrate in another form according to the second embodiment of the present invention.

[0138] Figure 3 The illustrated multilayer substrate 201 has the same configuration as the multilayer substrate 101 according to the second embodiment except that the shape of the intermetallic compound is different.

[0139] exist Figure 3 In the illustrated multilayer substrate 201 , the intermetallic compound 261 has a shape in which the surface in contact with the first electrode 31 is flat.

[0140] If the intermetallic compound 261 has such a shape, the contact area between the first electrode 31 and the intermetallic compound 261 can be increased similarly to the above-mentioned laminated substrate 101. Therefore, the physical connection stability and conductivity between the first electrode 31 and the interlayer connection conductor 50 can be improved.

[0141] [Third Embodiment]

[0142] Next, a multilayer substrate according to a third embodiment of the present invention will be described.

[0143] Figure 4 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a third embodiment of the present invention.

[0144] Figure 4 The laminated substrate 301 according to the third embodiment of the present invention shown has the same configuration as the laminated substrate 101 according to the second embodiment except that the opening size of the via hole 21 h of the first thermoplastic resin layer 21 is different.

[0145] exist Figure 4 In the illustrated laminated substrate 301 , the opening area of ​​the via hole 321 h on the first main surface 321 a of the first thermoplastic resin layer 321 is smaller than the contact area between the intermetallic compound 161 and the first electrode 31 .

[0146] When manufacturing the laminated substrate of the present invention, the first electrode is brought into contact with a conductive paste as a precursor of the interlayer connection conductor, and the conductive paste is melted and then solidified to produce the interlayer connection conductor. At this time, the first electrode and the interlayer connection conductor are bonded by liquid phase diffusion bonding. When the liquid phase diffusion bonding is performed, the liquid phase flows and covers the entire exposed surface of the first electrode 31.

[0147] Therefore, the intermetallic compound 161 is formed on the entire exposed surface of the first electrode 31 .

[0148] Therefore, in the multilayer substrate 301 , no gap is generated between the first electrode 31 and the first thermoplastic resin layer 321 , and the physical connection stability and electrical conductivity between the first electrode 31 and the interlayer connection conductor 50 can be sufficiently improved.

[0149] [Fourth embodiment]

[0150] Next, a multilayer substrate according to a fourth embodiment of the present invention will be described.

[0151] Figure 5 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to a fourth embodiment of the present invention.

[0152] Figure 5 The laminated substrate 401 according to the fourth embodiment of the present invention shown has the same configuration as the laminated substrate 101 according to the second embodiment except that the opening size of the via hole 21 h of the first thermoplastic resin layer 21 is different.

[0153] exist Figure 5 In the illustrated laminated substrate 401 , the opening area of ​​the via hole 421 h on the first main surface 421 a of the first thermoplastic resin layer 421 is the same as the opening area of ​​the protective layer 40 .

[0154] Even in such a form, the physical connection stability and electrical conductivity between the first electrode 31 and the interlayer connection conductor 50 can be sufficiently improved.

[0155] [Another way]

[0156] In the multilayer substrate of the present invention, when the protective layer is made of a ceramic material, pores are formed in the protective layer.

[0157] Therefore, when the first electrode and the interlayer connection conductor are connected by liquid phase diffusion bonding, the liquid phase may enter the pores of the protective layer. Such a form will be described with reference to the drawings.

[0158] Figure 6 This is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor of a laminate substrate according to another embodiment of the present invention.

[0159] Figure 6 The illustrated multilayer substrate 501 has the same structure as the above-described multilayer substrate 101 , except that the protective layer 540 is made of a ceramic material and a portion of the intermetallic compound 161 enters the pores 545 of the protective layer 540 .

[0160] Such a laminated substrate is also included in the laminated substrate of the present invention.

[0161] <Method for manufacturing laminated substrate>

[0162] Next, the method for producing the laminated substrate of the present invention will be described. It should be noted that the following description will be based on the case where the ceramic layer is composed of an LTCC material.

[0163] [Fifth embodiment]

[0164] <LTCC green sheet preparation process>

[0165] Figure 7 This is a process diagram schematically showing an example of an LTCC green sheet preparation step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0166] When manufacturing the laminated substrate according to the first embodiment of the present invention, first, Figure 7 As shown, a plurality of LTCC green sheets 10 ′ are prepared.

[0167] The LTCC green sheet 10 ′ can be prepared by the following method.

[0168] First, ceramic powder, a binder, and a plasticizer are mixed in arbitrary amounts to prepare slurry. As the ceramic powder, the materials mentioned above as the preferred materials for the ceramic layer 10 can be used. As the binder and the plasticizer, conventionally known materials can be used.

[0169] Next, the slurry is applied onto a carrier film to form a sheet, thereby producing an LTCC green sheet 10 ′.

[0170] The slurry can be applied using a lip coater or a doctor blade. At this time, the thickness of the LTCC green sheet 10 ′ is preferably 5 μm to 100 μm.

[0171] <LTCC green sheet via hole filling process>

[0172] Fig. 8A and Figure 8B This is a process diagram schematically showing an example of a via hole filling step of an LTCC green sheet in the method for manufacturing a laminated substrate according to the fifth embodiment of the present invention.

[0173] Next, if Fig. 8A As shown, a via hole 10h' is formed in the LTCC green sheet 10'. The method for forming the via hole 10h' is not particularly limited, and the via hole 10h' can be formed using a mechanical punch, a CO2 laser, a UV laser, or the like.

[0174] The opening diameter of the via hole 10h' is not particularly limited, but is preferably 20 μm to 200 μm.

[0175] Next, if Figure 8B As shown, conductive paste 2b' consisting of conductive powder, plasticizer, and binder is filled into via hole 10h'.

[0176] It should be noted that ceramic powder constituting the LTCC green sheet 10' may be added to the conductive paste 2b'. If the conductive paste 2b' contains such ceramic powder, the difference in shrinkage between the LTCC green sheet 10' and the conductive paste 2b' becomes small. As a result, it is possible to prevent cracks from being generated during the firing of the LTCC green sheet 10' and the conductive paste 2b'.

[0177] <LTCC green sheet electrode pattern formation process>

[0178] Fig. 9This is a process diagram schematically showing an example of an electrode pattern forming step of an LTCC green sheet in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0179] Next, if Fig. 9 As shown, the electrode pattern 2a' is printed on the surface of the LTCC green sheet 10' using a conductive paste composed of conductive powder, a plasticizer, and a binder. As a printing method, screen printing, inkjet printing, gravure printing, etc. can be used.

[0180] It should be noted that ceramic powder constituting the LTCC green sheet 10' may be added to the conductive paste for forming the electrode pattern 2a'. If the conductive paste for forming the electrode pattern 2a' contains such ceramic powder, the difference in shrinkage between the LTCC green sheet 10' and the electrode pattern 2a' becomes small. As a result, it is possible to prevent cracks from being generated during the firing of the LTCC green sheet 10' and the electrode pattern 2a'.

[0181] It should be noted that in the subsequent process, a plurality of LTCC green sheets 10' are stacked to form a stacked body. In the stacked body, a portion of the electrode pattern 2a' of the LTCC green sheet 10' located on the outermost layer ( Fig. 9 In the manufacturing process, the first electrode (indicated by reference numeral “ 31 ′”) becomes the first electrode connected to the interlayer connection conductor in the manufactured multilayer substrate.

[0182] The LTCC green sheet 10 ′ on which the electrode pattern 31 ′ is formed becomes a ceramic substrate in contact with the first main surface of the first thermoplastic resin layer in the manufactured laminated substrate.

[0183] <Step of applying protective layer paste containing ceramic material>

[0184] Fig.10 This is a process diagram schematically showing an example of a step of applying a protective layer paste containing a ceramic material in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0185] Next, if Fig.10 As shown, a protective layer paste 40 ′ is applied to the contour of the electrode pattern 31 ′.

[0186] The protective layer paste 40 ′ is preferably made of the same material as that of the LTCC green sheet 10 ′.

[0187] If the protective layer paste 40 ′ and the LTCC green sheet 10 ′ are made of the same material, the shrinkage ratios during firing are the same, so that cracks can be prevented from being generated during firing of the protective layer paste 40 ′ and the LTCC green sheet 10 ′.

[0188] The thickness of the protective layer paste 40 ′ is preferably 2 μm to 10 μm.

[0189] If the thickness of the protective layer paste is less than 2 μm, the first electrode formed in the subsequent step is likely to float.

[0190] If the thickness of the protective layer paste exceeds 10 μm, the protective layer formed in the subsequent process becomes thicker. Therefore, in the subsequent process, the protective layer becomes an obstacle when laminating the first thermoplastic resin layer and the ceramic layer, and a gap is likely to be generated between the interlayer connection conductor and the first electrode.

[0191] In addition, if the thickness of the protective layer paste exceeds 10 μm, the protective layer formed in the subsequent process becomes thicker. Therefore, when the intermetallic compound is formed in the subsequent process, the liquid phase reaction is difficult to exceed the protective layer, and the intermetallic compound is difficult to form in a manner that contacts the coating surface on the inner end side of the protective layer.

[0192] The protective layer paste 40 ′ preferably covers a range of 30 μm to 100 μm inward from the contour of the electrode pattern 31 ′.

[0193] When the protective layer paste 40 ′ is formed in such a range, it is possible to prevent the first electrode 31 formed in a subsequent step from floating.

[0194] <LTCC green sheet lamination process>

[0195] Fig.11 This is a process diagram schematically showing an example of a LTCC green sheet lamination step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0196] Next, if Fig.11 As shown, a plurality of LTCC green sheets 10' are stacked to produce an LTCC green sheet stack 2'. The number of stacked sheets is preferably appropriately determined according to the design.

[0197] Thereafter, the LTCC green sheet stack 2' is placed in a mold and pressure-bonded. The pressure and temperature are preferably set arbitrarily according to the design.

[0198] <LTCC green sheet stacking process>

[0199] Fig.12 This is a process diagram schematically showing an example of a firing step of an LTCC green sheet laminate in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0200] Next, if Fig.12 As shown, the multilayer ceramic layer 2 is formed by heating and firing the LTCC green sheet stack 2 ′.

[0201] By performing this process, the conductive paste 2 b ′ is fired to form the through-hole 2 b , and the electrode pattern 2 a ′ is fired to form the electrode pattern 2 a and the first electrode 31 .

[0202] The calcination can be performed using a calcination furnace such as a batch furnace or a belt furnace. The calcination conditions are not particularly limited, but the calcination is preferably performed at 850° C. to 1050° C. for 60 minutes to 180 minutes.

[0203] In addition, when the conductive paste 2b' and the electrode pattern 2a' contain copper (Cu), it is preferable to bake them in a reducing atmosphere.

[0204] <Thermoplastic resin layer preparation process>

[0205] Fig.13 This is a process diagram schematically showing an example of a thermoplastic resin layer preparation step in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0206] Next, if Fig.13 As shown, a plurality of sheet-shaped thermoplastic resin layers 20 are prepared. Preferred materials for the thermoplastic resin layer 20 have been described above, and the description here is omitted.

[0207] The thickness of the thermoplastic resin layer 20 is preferably 10 μm to 100 μm.

[0208] <Step of forming an electrode pattern on the thermoplastic resin layer>

[0209] Fig.14A and Fig. 14B This is a process diagram schematically showing an example of a step of forming an electrode pattern of a thermoplastic resin layer in the method for producing a laminated substrate according to the fifth embodiment of the present invention.

[0210] Next, if Fig.14A As shown in FIG. 1 , a metal foil 3a' is laminated on the main surface of the thermoplastic resin layer 20. Next, as shown in FIG. Fig. 14B As shown, the electrode pattern 3a is formed by patterning the metal foil 3a' by etching or the like.

[0211] Examples of the metal foil 3 a ′ include copper (Cu), silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), and alloys thereof.

[0212] In addition, it is preferred that one main surface of the metal foil 3 a ′ is a glossy surface and the other main surface is a matte surface. It is preferred that the metal foil 3 a ′ is laminated so that the matte surface is in contact with the main surface of the thermoplastic resin layer 20 .

[0213] The matte surface of the metal foil 3a' is subjected to a roughening treatment, and the surface roughness Rz (JIS B0601-2001) is preferably 1 μm to 15 μm.

[0214] It should be noted that in the subsequent process, a plurality of thermoplastic resin layers 20 are stacked to form a laminate. In the laminate, the outermost thermoplastic resin layer 20 becomes the first thermoplastic resin layer 21. In addition, the thermoplastic resin layer 20 in contact with the second main surface 21b of the first thermoplastic resin layer 21 becomes the second thermoplastic resin layer 22.

[0215] Furthermore, among the electrode patterns 3 a formed on the principal surface of the second thermoplastic resin layer 22 on the second principal surface 21 b side, a portion of the electrode patterns becomes the second electrodes 32 connected to the interlayer connection conductors in the manufactured laminated substrate.

[0216] <Step of filling via holes in thermoplastic resin layer>

[0217] Fig.15A and Fig. 15B This is a process diagram schematically showing an example of a via hole filling step of a thermoplastic resin layer in a method for manufacturing a laminated substrate according to a fifth embodiment of the present invention.

[0218] Next, if Fig.15A As shown, a via hole 21h, a via hole 22h, and a via hole 20h are formed in the first thermoplastic resin layer 21, the second thermoplastic resin layer 22, and the other thermoplastic resin layer 20, respectively.

[0219] The method for forming these via holes is not particularly limited, and they can be formed using a mechanical punch, a CO 2 laser, a UV laser, or the like.

[0220] After forming these via holes, desmear treatment such as oxygen plasma treatment, corona discharge treatment, potassium permanganate treatment, etc. is preferably performed.

[0221] The opening diameters of the via hole 21h, the via hole 22h, and the via hole 20h are not particularly limited, but are preferably 20 μm to 200 μm.

[0222] It should be noted that Fig.15A In order to facilitate the display of the internal structure in a plane, a via hole is formed directly below the electrode pattern 3a. There are places where the via hole does not appear to be formed as a through hole, but in fact, the formation position of the electrode pattern 3a and the formation position of the via hole are offset in the depth direction, and the via hole is formed as a through hole.

[0223] Next, if Fig. 15B As shown, conductive paste 50 ′, which is a precursor of an interlayer connection conductor, is filled in via hole 21 h , via hole 22 h , and via hole 20 h .

[0224] The filling method is not particularly limited, and screen printing, vacuum printing, etc. can be used.

[0225] Conductive paste 50 ′ contains a first metal powder and a second metal powder having a higher melting point than the first metal powder.

[0226] It is preferred that the first metal powder contained in the conductive paste 50' is composed of Sn or a Sn alloy, and the second metal powder is composed of a Cu-Ni alloy or a Cu-Mn alloy. As such a conductive paste 50', for example, a conductive paste described in Japanese Patent No. 5146627 can be used. Hereinafter, the metal component contained in the first metal powder is also referred to as the first metal, and the metal component contained in the second metal powder is also referred to as the second metal.

[0227] Examples of Sn or Sn alloys include Sn alone or an alloy containing Sn and at least one selected from Cu, Ni, Ag, Au, Sb, Zn, Bi, In, Ge, Al, Co, Mn, Fe, Cr, Mg, Mn, Pd, Si, Sr, Te, and P. The Sn alloy preferably contains 70% by weight or more of Sn, more preferably 85% by weight or more of Sn.

[0228] The ratio of Ni in the Cu-Ni alloy is preferably 10 wt% to 15 wt%. In addition, the ratio of Mn in the Cu-Mn alloy is preferably 10 wt% to 15 wt%. Thus, sufficient Ni or Mn can be supplied to produce the desired intermetallic compound. When the ratio of Ni in the Cu-Ni alloy and the ratio of Mn in the Cu-Mn alloy are less than 10 wt%, Sn will not all become intermetallic compounds and will easily remain. In addition, when the ratio of Ni in the Cu-Ni alloy and the ratio of Mn in the Cu-Mn alloy exceed 15 wt%, Sn will not all become intermetallic compounds and will easily remain.

[0229] In addition, the Cu-Ni alloy or the Cu-Mn alloy may contain both Mn and Ni, and may also contain a third component such as P.

[0230] The arithmetic mean particle size of the first metal powder and the second metal powder is preferably 3 μm to 10 μm, respectively. If the average particle size of these metal powders is too small, the manufacturing cost becomes high. In addition, the oxidation of the metal powder proceeds, which easily hinders the reaction. On the other hand, if the average particle size of these metal powders is too large, it is difficult to fill the conductive paste 50' into each via.

[0231] The ratio of the second metal in the conductive paste 50' to the metal component is preferably 30% by weight or more. That is, the ratio of the first metal in the conductive paste 50' to the metal component is preferably 70% by weight or less. In this case, the residual ratio of the first metal such as Sn can be further reduced, and the ratio of the intermetallic compound can be increased.

[0232] The ratio of the metal component in conductive paste 50' is preferably 70 wt% to 95 wt%. If the metal component exceeds 95 wt%, it is difficult to obtain conductive paste 50' with low viscosity and excellent filling properties. On the other hand, if the metal component is less than 70 wt%, the flux component is likely to remain.

[0233] Conductive paste 50' preferably contains a flux component. As the flux component, various known flux components used in materials of common conductive pastes can be used, including resins. As components other than the resin, for example, carriers, solvents, thixotropic agents, activators, etc. can be cited.

[0234] The above-mentioned resin preferably includes at least one thermosetting resin selected from epoxy resin, phenolic resin, polyimide resin, silicone resin or its modified resin and acrylic resin, or at least one thermoplastic resin selected from polyamide resin, polystyrene resin, polymethacrylic resin, polycarbonate resin and cellulose resin.

[0235] As the above-mentioned carrier, for example, rosin-based resins composed of rosin and modified rosin derivatives thereof, synthetic resins, or mixtures thereof can be cited. As rosin-based resins composed of the above-mentioned rosin and modified rosin derivatives thereof, for example, gum rosin, tall rosin, wood rosin, polymerized rosin, hydrogenated rosin, formylated rosin, rosin ester, rosin-modified maleic acid resin, rosin-modified phenolic resin, rosin-modified alkyd resin and other various rosin derivatives can be cited. As synthetic resins composed of the above-mentioned rosin and modified rosin derivatives thereof, for example, polyester resins, polyamide resins, phenoxy resins, terpene resins, etc. can be cited.

[0236] As the above-mentioned solvent, alcohols, ketones, esters, ethers, aromatics, hydrocarbons, etc. are known, and specific examples thereof include benzyl alcohol, ethanol, isopropanol, butanol, diethylene glycol, ethylene glycol, glycerol, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, butyl benzoate, diethyl adipate, dodecane, tetradecene, α-terpineol, terpineol, 2-methyl-2,4-pentanediol, 2-ethylhexanediol, toluene, xylene, propylene glycol monophenyl ether, diethylene glycol monohexyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diisobutyl adipate, hexanediol, cyclohexanedimethanol, 2-pinyloxyethanol, 2-dihydropinyloxyethanol, and mixtures thereof. Preferred are terpineol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0237] Specific examples of the thixotropic agent include hydrogenated castor oil, carnauba wax, amides, hydroxy fatty acids, dibenzylidene sorbitol, bis(p-methylbenzylidene) sorbitol, beeswax, stearamide, ethylenebishydroxystearic acid amide, etc. In addition, as necessary, a substance to which fatty acids such as caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, hydroxystearic acid such as 1,2-hydroxystearic acid, an antioxidant, a surfactant, an amine, etc. are added can also be used as a thixotropic agent.

[0238] Examples of the activator include amine hydrohalides, organic halides, organic acids, organic amines, and polyols.

[0239] Examples of the hydrohalide salts of the amines include diphenylguanidine hydrobromide, diphenylguanidine hydrochloride, cyclohexylamine hydrobromide, ethylamine hydrochloride, ethylamine hydrobromide, diethylaniline hydrobromide, diethylaniline hydrobromide, triethanolamine hydrobromide, and monoethanolamine hydrobromide.

[0240] Examples of the organic halide include chlorinated paraffin, tetrabromoethane, dibromopropanol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, and tris(2,3-dibromopropyl)isocyanurate.

[0241] Examples of the organic acid include malonic acid, fumaric acid, glycolic acid, citric acid, malic acid, succinic acid, phenylsuccinic acid, maleic acid, salicylic acid, anthranilic acid, glutaric acid, suberic acid, adipic acid, sebacic acid, stearic acid, abietic acid, benzoic acid, trimellitic acid, pyromellitic acid, and dodecanoic acid.

[0242] Examples of the organic amine include monoethanolamine, diethanolamine, triethanolamine, tributylamine, aniline, and diethylaniline.

[0243] Examples of the polyol include erythritol, pyrogallol, and ribitol.

[0244] <Step of laminating the thermoplastic resin layer>

[0245] Fig.16 This is a process diagram schematically showing an example of a lamination step of a thermoplastic resin layer in a method for producing a laminated substrate according to a fifth embodiment of the present invention.

[0246] Next, if Fig.16 As shown, the first thermoplastic resin layer 21 , the second thermoplastic resin layer 22 , and the other thermoplastic resin layer 20 are stacked to form a multilayer thermoplastic resin layer 3 .

[0247] <Step of laminating multiple ceramic layers and multiple thermoplastic resin layers>

[0248] Fig.17A and Fig. 17B This is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a fifth embodiment of the present invention.

[0249] Next, if Fig.17A As shown, multilayer ceramic layers 2 are stacked on multilayer thermoplastic resin layers 3. At this time, conductive paste 50' filled in first thermoplastic resin layer 21 of multilayer thermoplastic resin layer 3 is aligned so as to contact the exposed surface of first electrode 31 of ceramic layer 11 disposed on the outermost layer of multilayer ceramic layer 2.

[0250] Afterwards, if Fig. 17B As shown, the multi-layer thermoplastic resin layer 3 and the multi-layer ceramic layer 2 are integrated by applying pressure and heat.

[0251] At this time, the first thermoplastic resin layer 21 follows the surface irregularities of the ceramic layer 11 , and the multi-layered thermoplastic resin layer 3 and the multi-layered ceramic layer 2 are closely attached to each other by the anchor effect.

[0252] In this step, for example, there can be mentioned a method of treating at 230° C. to 350° C. under a normal pressure.

[0253] In this step, the conductive paste 50 ′ is melted and then solidified to form the interlayer connection conductor 50 .

[0254] The interlayer connection conductor 50 and the first electrode 31 are connected by liquid phase diffusion bonding. At this time, an intermetallic compound 61 is formed between the interlayer connection conductor 50 and the first electrode 31 .

[0255] This liquid phase diffusion bonding will be described using the drawings.

[0256] FIG. 18A to FIG. 18D This is an explanatory diagram schematically showing an example of connecting an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0257] like Fig.18A As shown, conductive paste 50 ′ includes first metal powder 51 and second metal powder 52 having a higher melting point than first metal powder 51 . Conductive paste 50 ′ is in contact with first electrode 31 .

[0258] like Fig.18B As shown, when the conductive paste 50 ′ is heated in this state and the melting point of the first metal powder 51 is reached, the first metal powder 51 is melted to become the first metal 51 a in the liquid phase.

[0259] Then, if the heating is continued further, Fig.18CAs shown, the first metal 51 a in the liquid phase reacts with the second metal powder 52 to form an intermetallic compound 60 .

[0260] Furthermore, the first metal 51 a in the liquid phase spreads so as to diffuse toward the first electrode 31 , and the first metal 51 a in the liquid phase reacts with the metal constituting the first electrode 31 to form an intermetallic compound 61 .

[0261] Afterwards, if the heating is terminated and the temperature drops, Fig.18D As shown in FIG. 1 , the first metal 51a in the liquid phase solidifies to form the interlayer connection conductor 50. Fig.18D In FIG. 1 , for convenience, the outline of the intermetallic compound 60 derived from the second metal powder 52 is indicated by a dotted line. However, in reality, the boundary is not clear and the intermetallic compound 60 does not appear to be in a particle shape.

[0262] In this step, the interlayer connection conductor and the second electrode are also connected by liquid phase diffusion bonding, so an intermetallic compound is also formed between the interlayer connection conductor and the second electrode.

[0263] The multilayer substrate 1 can be manufactured through the above steps.

[0264] It should be noted that when manufacturing the laminated substrate of the present invention, by adjusting the composition of the conductive paste 50', the composition and thickness of the first electrode 31, the thickness of the protective layer 40, and the pressure and heating temperature in the lamination process of the multi-layer ceramic layer and the multi-layer thermoplastic resin layer, it is possible to form a laminated substrate as shown in FIG. Figure 2 to Figure 6 The shape of the intermetallic compound is shown.

[0265] That is, by performing the above-mentioned adjustment, a part of the intermetallic compound can be formed so as to be in contact with the coating surface on the inner end side of the protective layer and to be continuous with the intermetallic compound formed between the interlayer connection conductor and the first electrode.

[0266] In the manufactured laminated substrate 1, electronic components such as IC chips and SMD components can be mounted by reflow treatment or the like. After the reflow treatment, the laminated substrate 1 with the electronic components mounted thereon can be cleaned and molded with resin. The molded laminated substrate 1 can be further cut into individual pieces by cutting with a cutting machine, laser cutting, etc. Thereafter, a shielding film can be formed on the surface of the molded resin.

[0267] [Sixth embodiment]

[0268] Next, another method for producing the laminated substrate of the present invention will be described. In the following description, the case where the ceramic layer is composed of an LTCC material will be described.

[0269] The method for manufacturing a laminated substrate involved in the sixth embodiment of the present invention does not perform the above-mentioned <step of applying a protective layer paste containing a ceramic material>, and performs the following <step of configuring a protective layer composed of a thermoplastic resin> after the above-mentioned <step of filling the via hole with a thermoplastic resin layer>. Except for this, the method is the same as the method for manufacturing a laminated substrate involved in the fifth embodiment of the present invention.

[0270] Hereinafter, a method for manufacturing a laminated substrate according to a sixth embodiment of the present invention will be described in detail with reference to the drawings.

[0271] <Preparation of multilayer ceramic layers>

[0272] Fig.19 This is a cross-sectional view schematically showing an example of a multilayer ceramic layer prepared in the method for manufacturing a laminated substrate according to the sixth embodiment of the present invention.

[0273] The method for manufacturing a laminated substrate according to the fifth embodiment of the present invention is performed in sequence to manufacture a laminated substrate of the present invention, wherein the <LTCC green sheet preparation step>, <LTCC green sheet via hole filling step>, <LTCC green sheet electrode pattern forming step>, <LTCC green sheet lamination step> and <LTCC green sheet laminate body calcining step> are performed in sequence to manufacture the laminated substrate. Fig.19 A multi-layer ceramic layer 602 is shown.

[0274] The multilayer ceramic layer 602 has the same structure as the multilayer ceramic layer 2 except that the protective layer 40 is not formed.

[0275] <Preparation of multiple thermoplastic resin layers>

[0276] Fig. 20 This is a cross-sectional view schematically showing an example of a plurality of thermoplastic resin layers prepared in the method for producing a laminated substrate according to the sixth embodiment of the present invention.

[0277] The <thermoplastic resin layer preparation step>, <thermoplastic resin layer electrode pattern forming step>, <thermoplastic resin layer via hole filling step>, and <thermoplastic resin layer laminating step> in the method for manufacturing a laminated substrate involved in the fifth embodiment of the present invention are performed to prepare a multilayer thermoplastic resin layer 3.

[0278] <Step of arranging a protective layer made of thermoplastic resin>

[0279] Fig.21 This is a process diagram schematically showing an example of a step of disposing a protective layer made of a thermoplastic resin in a method for producing a laminated substrate according to a sixth embodiment of the present invention.

[0280] Next, a protective layer 640 made of a thermoplastic resin is formed on the first thermoplastic resin layer 21 , so that the multi-layered thermoplastic resin layer 3 becomes a multi-layered thermoplastic resin layer 603 .

[0281] The protective layer 640 is preferably made of the same material as the thermoplastic resin layer 20 .

[0282] In the subsequent <Laminating step of multilayer ceramic layers and multilayer thermoplastic resin layers>, the protective layer 640 is formed at a position covering the contour of the first electrode 31 formed on the multilayer ceramic layer 602. Such a position can be determined by design in advance.

[0283] <Step of laminating multiple ceramic layers and multiple thermoplastic resin layers>

[0284] Fig.22A and Fig. 22B This is a process diagram schematically showing an example of a lamination step of a plurality of ceramic layers and a plurality of thermoplastic resin layers in a method for producing a laminated substrate according to a sixth embodiment of the present invention.

[0285] Next, if Fig.22A As shown, multilayer ceramic layers 2 are stacked on multilayer thermoplastic resin layers 603. At this time, conductive paste 50' filled in first thermoplastic resin layer 21 of multilayer thermoplastic resin layer 603 is aligned so as to contact the exposed surface of first electrode 31 of ceramic layer 11 disposed on the outermost layer of multilayer ceramic layer 602.

[0286] Afterwards, if Fig. 22B As shown, the multi-layer thermoplastic resin layer 603 and the multi-layer ceramic layer 602 are integrated by applying pressure and heat.

[0287] Through the above steps, the laminated substrate 601 in which the protective layer 640 is made of a thermoplastic resin can be manufactured.

[0288] The following matters are described in this manual.

[0289] The present disclosure (1) relates to a laminated substrate comprising: a first thermoplastic resin layer, a ceramic layer and a second thermoplastic resin layer, the first thermoplastic resin layer comprising a first main surface and a second main surface opposite to the first main surface, and having a via hole penetrating from the first main surface to the second main surface, the ceramic layer being arranged in contact with the first main surface, the second thermoplastic resin layer being arranged in contact with the second main surface, a first electrode being formed on the main surface of the ceramic layer in contact with the first main surface, and a protective layer being formed in a manner covering at least a portion of the contour of the first electrode, a second electrode being formed on the main surface of the second thermoplastic resin layer in contact with the second main surface, an interlayer connecting conductor connecting the first electrode and the second electrode being arranged in the via hole, and an intermetallic compound being formed between the interlayer connecting conductor and the first electrode.

[0290] The present disclosure (2) is based on the laminated substrate described in the present disclosure (1), wherein the protective layer has an inner end portion located on the inner side of the contour of the first electrode, and a coating surface in contact with the first electrode in a manner covering at least a portion of the contour of the first electrode, and a portion of the intermetallic compound is formed in a manner that is in contact with the coating surface on the inner end side of the protective layer and is continuous with the intermetallic compound formed between the interlayer connecting conductor and the first electrode.

[0291] The present disclosure (3) is the laminated substrate according to the present disclosure (1) or (2), wherein the protective layer is made of the same material as that constituting the ceramic layer.

[0292] The present disclosure (4) is a laminated substrate according to any one of the present disclosures (1) to (3), wherein the protective layer is made of the same material as that constituting the first thermoplastic resin layer.

[0293] The present disclosure (5) is a laminated substrate based on any one of the present disclosures (1) to (4), wherein, on the first main surface, a portion of the protective layer is located inside the opening of the via hole, and a portion of the protective layer located inside the via hole is in contact with the interlayer connecting conductor.

[0294] Explanation of symbols

[0295] 1, 101, 201, 301, 401, 501, 601 laminated substrate

[0296] 2. 602 multi-layer ceramic layer

[0297] 2'LTCC green sheet stack

[0298] 2a, 2a', 3a electrode patterns

[0299] 2b, 3b through holes

[0300] 2b', 50' conductive paste

[0301] 3. 603 multi-layer thermoplastic resin layer

[0302] 3a' Metal foil

[0303] 10.11 Ceramic layer

[0304] 10'LTCC Green Sheet

[0305] 10h', 21h, 22h, 321h, 421h vias

[0306] 20 Thermoplastic resin layer

[0307] 21, 321, 421 first thermoplastic resin layer

[0308] 21a, 321a, 421a: first main surface of the first thermoplastic resin layer

[0309] 21b Second main surface of the first thermoplastic resin layer

[0310] 22 second thermoplastic resin layer

[0311] 31 1st electrode

[0312] 31' electrode pattern

[0313] 31c Outline of the first electrode

[0314] 32 2nd electrode

[0315] 40, 540, 640 protection layers

[0316] 40' protective layer paste

[0317] 40a protective layer coating

[0318] 41 Inner end of protective layer

[0319] 50 interlayer connection conductors

[0320] 51 No.1 Metal Powder

[0321] 51a The first metal in the liquid phase

[0322] 52 2nd Metal Powder

[0323] 60, 61, 62, 161, 261 intermetallic compounds

[0324] 161a Part of intermetallic compound

[0325] 545 air hole

Claims

1. A laminate substrate comprising a first thermoplastic resin layer, a ceramic layer and a second thermoplastic resin layer, in, The first thermoplastic resin layer includes a first main surface and a second main surface opposite to the first main surface, and has a through hole penetrating from the first main surface to the second main surface. The ceramic layer is arranged in contact with the first main surface. The second thermoplastic resin layer is arranged in contact with the second main surface. A first electrode is formed on a main surface of the ceramic layer in contact with the first main surface, and a protective layer is formed so as to cover at least a portion of the contour of the first electrode. A second electrode is formed on a main surface of the second thermoplastic resin layer in contact with the second main surface. An interlayer connection conductor connecting the first electrode and the second electrode is arranged in the via hole. An intermetallic compound is formed between the interlayer connection conductor and the first electrode.

2. The laminate substrate according to claim 1, in, The protective layer has an inner end portion located inside the outline of the first electrode and a covering surface in contact with the first electrode so as to cover at least a portion of the outline of the first electrode. A portion of the intermetallic compound is formed so as to be in contact with the coating surface on the inner end side of the protective layer and to be continuous with the intermetallic compound formed between the interlayer connection conductor and the first electrode.

3. The laminate substrate according to claim 1 or 2, in, The protective layer is composed of the same material as that constituting the ceramic layer.

4. The laminated substrate according to any one of claims 1 to 3, in, The protective layer is made of the same material as that of the first thermoplastic resin layer.

5. The laminated substrate according to any one of claims 1 to 4, in, On the first main surface, a portion of the protective layer is located inside the opening of the via hole, and a portion of the protective layer located inside the via hole is in contact with the interlayer connection conductor.

Images