Multilayer substrate

Abstract

Provided is a multilayer substrate which is not susceptible to fracture of a metal compound that is formed between a conductor part which is provided in a ceramic layer and an interlayer connection conductor which is provided in a thermoplastic resin layer even if heated. A multilayer substrate (1) according to the present invention comprises: a first thermoplastic resin layer which has a first main surface (21a) and a second main surface (21b) that is opposite to the first main surface (21a), while having a via hole (21h) that penetrates the first thermoplastic resin layer from the first main surface to the second main surface; and a ceramic layer (11) which is arranged so as to be in contact with the first main surface (21a). An interlayer connection conductor (50) is arranged in the via hole (21h); a conductor part (31), which is connected to the interlayer connection conductor (50), is arranged in the ceramic layer (11); an intermetallic compound (61) is formed between the interlayer connection conductor (50) and the conductor part (31); ceramic particles (70) are present within the intermetallic compound (61); and some of the ceramic particles (70) are first ceramic particles (71) that are in contact with both the intermetallic compound (61) and the conductor part (31).

Description

[Technical Field]

[0001] The present invention relates to a laminated substrate. [Background technology]

[0002] Conventionally, modular components using multilayer substrates with built-in passive elements have been put to practical use. For example, a DC-DC converter module is well known, which is configured by mounting a switching IC (integrated circuit) chip and a chip capacitor on a multilayer substrate with a built-in coil as the passive element.

[0003] A known multilayer substrate used in such module components is one in which ceramic substrates are stacked. In a multilayer substrate in which ceramic substrates are stacked, warping of the ceramic substrates may occur. To solve this problem, Patent Document 1 discloses a laminated substrate (module component) in which a substrate (thermoplastic resin layer) made of a thermoplastic resin is stacked on a multilayer substrate in which ceramic substrates are stacked.

[0004] That is, Patent Document 1 discloses a ceramic multilayer substrate having a passive element built therein and having a first terminal electrode and a second terminal electrode connected to the passive element 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 land 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 land serving as a connection terminal to a motherboard; and a ceramic multilayer substrate mounted on the first thermoplastic resin layer and having a first thermoplastic resin layer. and a surface-mounted component connected to the first land of a layer, wherein the first thermoplastic resin layer and the second thermoplastic resin layer have different thicknesses, the first thermoplastic resin layer being thicker than the second thermoplastic resin layer, the ceramic multilayer substrate being a substrate made of 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 in the first thermoplastic resin layer, and the second terminal electrode of the ceramic multilayer substrate and the interlayer conductor provided in the second thermoplastic resin layer are bonded by liquid phase diffusion bonding.

[0005] In Patent Document 1, terminal electrodes provided on a ceramic multilayer substrate and interlayer conductors provided on thermoplastic resin layers are bonded by transient liquid phase diffusion bonding.

[0006] Patent Document 2 discloses an interlayer connection conductor that connects 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. The intermetallic compound layer is generated when a metal such as Sn or an Sn alloy constituting the interlayer connection conductor melts by heating and reacts with a metal (e.g., Cu) constituting the conductor wiring layer. That is, the intermetallic compound layer is generated when liquid phase diffusion bonding is performed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6819668 [Patent Document 2] International Publication No. 2019 / 003729 Summary of the Invention [Problem to be solved by the invention]

[0008] In the laminated substrate (module component) described in Patent Document 1, an intermetallic compound layer such as that disclosed in Patent Document 2 is formed between the conductor portion (terminal electrode) provided in the ceramic layer and the interlayer connection conductor (interlayer conductor) provided in the thermoplastic resin layer.

[0009] The conductor portions formed on the ceramic layers, the interlayer connection conductors provided on the thermoplastic resin layers, and the intermetallic compound layers all have different linear expansion coefficients, so thermal stress is likely to occur between them. In particular, since the intermetallic compound has low ductility, it is difficult for the intermetallic compound to absorb thermal stress, and the intermetallic compound is prone to fracture.

[0010] The present invention has been made to solve the above problems, and the object of the present invention is to provide a laminated substrate in which the metal compound formed between the conductor portion provided in the ceramic layer and the interlayer connecting conductor provided in the thermoplastic resin layer is less likely to break even when heated. [Means for solving the problem]

[0011] The laminated substrate of the present invention comprises a first main surface and a second main surface opposite to the first main surface, a first thermoplastic resin layer having a via hole penetrating from the first main surface to the second main surface, and a ceramic layer arranged to contact the first main surface, wherein an interlayer connection conductor is arranged in the via hole, and a conductor portion connected to the interlayer connection conductor is formed in the ceramic layer, an intermetallic compound is formed between the interlayer connection conductor and the conductor portion, ceramic particles are present inside the intermetallic compound, and some of the ceramic particles are first ceramic particles that contact both the intermetallic compound and the conductor portion. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a laminated substrate in which the metal compound formed between the conductor portion provided in the ceramic layer and the interlayer connecting conductor provided in the thermoplastic resin layer is less likely to break even when heated. [Brief explanation of the drawings]

[0013] [Figure 1A] FIG. 1A is a cross-sectional view schematically illustrating an example of a laminated substrate according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is an enlarged view of the dashed line portion of FIG. 1A. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in another example of the laminated substrate according to the first embodiment of the present invention. [Figure 3] FIG. 3 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 first embodiment of the present invention. [Figure 4A] FIG. 4A is a process diagram schematically showing an example of a step of filling via holes in an LTCC green sheet in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 4B] FIG. 4B is a process diagram schematically showing an example of a step of filling via holes in an LTCC green sheet in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 5]FIG. 5 is a process diagram schematically showing an example of a step of forming an electrode pattern on an LTCC green sheet in the method for producing a laminated substrate according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a process diagram schematically showing an example of an LTCC green sheet laminating step in the method for manufacturing the laminated substrate according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a process diagram schematically showing an example of an LTCC green sheet laminate firing step in the method for producing a laminated substrate according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a process diagram schematically showing an example of a thermoplastic resin layer preparation step in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 9A] FIG. 9A is a process diagram schematically showing an example of a step of forming an electrode pattern on a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 9B] FIG. 9B is a process diagram schematically showing an example of the step of forming an electrode pattern on a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 10A] FIG. 10A is a process diagram schematically showing an example of a step of filling via holes with a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 10B] FIG. 10B is a process diagram schematically showing an example of the step of filling via holes with a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a process diagram schematically illustrating an example of a step of laminating a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. [Figure 12A] FIG. 12A is a process diagram schematically illustrating an example of a step of laminating multilayer ceramic layers and multilayer thermoplastic resin layers in the method for manufacturing a multilayer substrate according to the first embodiment of the present invention. [Figure 12B] FIG. 12B is a process diagram schematically illustrating an example of a step of laminating multilayer ceramic layers and multilayer thermoplastic resin layers in the method for manufacturing a multilayer substrate according to the first embodiment of the present invention. [Figure 13A]FIG. 13A is an explanatory view schematically showing an example of connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. [Figure 13B] FIG. 13B is an explanatory view that schematically shows an example of connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. [Figure 13C] FIG. 13C is an explanatory view that schematically shows an example of connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. [Figure 13D] FIG. 13D is an explanatory view schematically showing an example of connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. [Figure 14] FIG. 14 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a second embodiment of the present invention. [Figure 15] FIG. 15 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a third embodiment of the present invention. [Figure 16] FIG. 16 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a fourth embodiment of the present invention. [Figure 17] FIG. 17 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The laminated substrate of the present invention will be described below. 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. Note that the present invention also includes a combination of two or more of the individual desirable configurations of the present invention described below.

[0015] The laminated substrate of the present invention comprises a first main surface and a second main surface opposite to the first main surface, a first thermoplastic resin layer having a via hole penetrating from the first main surface to the second main surface, and a ceramic layer arranged to contact the first main surface, wherein an interlayer connection conductor is arranged in the via hole, and a conductor portion connected to the interlayer connection conductor is formed in the ceramic layer, an intermetallic compound is formed between the interlayer connection conductor and the conductor portion, ceramic particles are present inside the intermetallic compound, and some of the ceramic particles are first ceramic particles that contact both the intermetallic compound and the conductor portion. In the laminated substrate of the present invention, ceramic particles are present inside the intermetallic compound. Therefore, the difference between the linear expansion coefficient of the intermetallic compound and the linear expansion coefficient of the conductor formed on the ceramic layer can be reduced, which in turn reduces the thermal stress applied to the intermetallic compound, thereby preventing the intermetallic compound from being broken by the thermal stress. Furthermore, when the laminated substrate of the present invention is manufactured, the interlayer connection conductor and the conductor portion are connected by liquid phase diffusion bonding, and the intermetallic compound is formed by reaction between the conductor portion and the liquid phase component of the interlayer connection conductor. The presence of ceramic particles inside the intermetallic compound means that the conductor portion contained ceramic particles when the laminated substrate of the present invention was manufactured. If the conductor portion contains ceramic particles, the contact area between the conductor portion and the liquid phase component of the interlayer connection conductor can be reduced, thereby suppressing the reaction and preventing the formation of an excessive amount of intermetallic compound. In particular, if the conductor portion contains enough ceramic particles to sufficiently suppress the reaction, some of the ceramic particles will come into contact with both the intermetallic compound and the conductor portion in the manufactured laminated substrate. In the laminated substrate of the present invention, the conductor portion may be an electrode or a via.

[0016] The laminated substrate of the present invention can be widely used in electronic devices such as portable information terminals and digital cameras as a laminated substrate with a built-in coil and as an ultra-compact DC-DC converter using the laminated substrate.

[0017] Hereinafter, preferred embodiments of the multilayer substrate of the present invention will be described with reference to the drawings. [First embodiment] First, a laminated substrate according to a first embodiment of the present invention will be described. FIG. 1A is a cross-sectional view schematically illustrating an example of a laminated substrate according to a first embodiment of the present invention. FIG. 1B is an enlarged view of the dashed line portion of FIG. 1A.

[0018] The multilayer substrate 1 shown in FIG. 1A includes a multilayer ceramic layer 2 in which a plurality of ceramic layers 10 are stacked, and a multilayer thermoplastic resin layer 3 in which a plurality of thermoplastic resin layers 20 are stacked. In the multilayer substrate 1 shown in FIG. 1A, a multilayer ceramic layer 2 is laminated on a multilayer thermoplastic resin layer 3.

[0019] As shown in FIGS. 1A and 1B, the multilayer thermoplastic resin layer 3 includes a first thermoplastic resin layer 21 in contact with the multilayer ceramic layer 2.

[0020] As shown in FIG. 1B, the first thermoplastic resin layer 21 has a first main surface 21a and a second main surface 21b opposite to the first main surface 21a, and has via holes 21h penetrating from the first main surface 21a to the second main surface 21b. As shown in FIG. 1A, the first main surface 21a of the first thermoplastic resin layer 21 is in contact with the multilayer ceramic layer 2.

[0021] 1A, the multilayer ceramic layer 2 includes a ceramic layer 11 disposed so as to be in contact with the first main surface 21a of the first thermoplastic resin layer 21. 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. The first electrode 31 is a conductor portion in the laminated substrate of the present invention. As shown in FIG. 1B, the first electrode 31 includes ceramic particles 70 .

[0022] The multilayered thermoplastic resin layer 3 includes a second thermoplastic resin layer 22 disposed so as to be in contact with the second main surface 21b. 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.

[0023] An interlayer connection conductor 50 that connects the first electrode 31 and the second electrode 32 is disposed in the via hole 21h. Furthermore, an intermetallic compound 61 is formed between the interlayer connection conductor 50 and the first electrode 31. Furthermore, an intermetallic compound 62 is formed between the interlayer connection conductor 50 and the second electrode 32. The via hole 21h has a tapered shape in which the opening on the first main surface 21a side is larger than the opening on the second main surface 21b side. With such a shape, the connection strength between the interlayer connection conductor 50 and the first electrode 31 can be improved.

[0024] As shown in FIG. 1B, in the multilayer substrate 1, ceramic particles 70 are present inside the intermetallic compound 61. Therefore, it is possible to reduce the difference between the linear expansion coefficient of the intermetallic compound 61 and the linear expansion coefficient of the first electrode 31 formed on the ceramic layer 11. As a result, it is possible to reduce the thermal stress acting on the intermetallic compound 61. Therefore, it is possible to prevent the intermetallic compound 61 from being broken due to the thermal stress.

[0025] In the multilayer substrate 1, some of the ceramic particles 70 exist as first ceramic particles 71 that are in contact with both the intermetallic compound 61 and the first electrode 31. When manufacturing the laminated substrate 1, the interlayer connection conductor 50 and the first electrode 31 are connected by liquid phase diffusion bonding. At this time, the intermetallic compound 61 is formed by a reaction between the first electrode 31 and the liquid phase component of the interlayer connection conductor 50. The presence of ceramic particles 70 inside intermetallic compound 61 means that first electrode 31 contained ceramic particles 70 when laminated substrate 1 was manufactured. If first electrode 31 contains ceramic particles 70, the contact area between first electrode 31 and the liquid phase component of the interlayer connection conductor can be reduced, thereby suppressing the reaction and preventing the intermetallic compound 61 from being formed more than necessary. In particular, if first electrode 31 contains enough ceramic particles 70 to sufficiently suppress the reaction, some of the ceramic particles 70 will be in contact with both intermetallic compound 61 and first electrode 31 in the manufactured laminated substrate 1.

[0026] As shown in FIG. 1A, the multilayer ceramic layer 2 may have an electrode pattern 2a, vias 2b, etc. formed therein, and the multilayer thermoplastic resin layer 3 may have an electrode pattern 3a, vias 3b, etc. formed therein.

[0027] Hereinafter, preferred embodiments of each configuration of the laminated substrate 1 will be described.

[0028] (Interlayer connection conductor) The interlayer connection conductor 50 is formed by filling the via hole 21h with a conductive paste containing a first metal powder and a second metal powder having a melting point higher than that of the first metal powder, and then melting and solidifying the conductive paste. At this time, the first metal powder contained in the conductive paste reacts with the first electrode 31 to form an intermetallic compound 61. Preferably, the first metal powder is made of Sn or an Sn alloy, and the second metal powder is made of a Cu-Ni alloy or a Cu-Mn alloy. The conductive paste will be described in detail in the <Method for manufacturing a laminated substrate> below.

[0029] (multi-layer ceramic layer) The multilayer ceramic layer 2 is composed of ceramic layers 10 including a ceramic layer 11 . An example of a material constituting the ceramic layer 10 is a low-temperature co-fired ceramic (LTCC) material. The low-temperature co-fired ceramic material is a ceramic material that can be sintered at a temperature of 1000°C or less and can be co-fired with Au, Ag, Cu, or other materials with low resistivity. Specific examples of the low-temperature co-fired ceramic material include a glass composite low-temperature co-fired ceramic material obtained by mixing borosilicate glass with ceramic powder such as alumina, zirconia, magnesia, or forsterite; a crystallized glass low-temperature co-fired ceramic material using ZnO-MgO-Al2O3-SiO2 crystallized glass; and a non-glass low-temperature co-fired ceramic material using BaO-Al2O3-SiO2 ceramic powder or Al2O3-CaO-SiO2-MgO-B2O3 ceramic powder.

[0030] The thickness of the ceramic layer 10 is preferably determined appropriately depending on the design, and is preferably, for example, 5 μm or more and 100 μm or less.

[0031] The first electrode 31, the electrode pattern 2a and the via 2b are preferably a sintered body of a conductive paste made of a conductive powder, a plasticizer and a binder. The first electrode 31, the electrode pattern 2a and the via 2b are preferably made of a sintered body of copper (Cu) or its alloy. The first electrode 31, the electrode pattern 2a, and the via 2b may contain silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), gold (Au), alloys thereof, or the like. Furthermore, the first electrode 31, the electrode pattern 2a, and the via 2b may be made of the same material or different materials.

[0032] The thickness of the first electrode 31 is preferably determined appropriately depending on the design, and is preferably, for example, 5 μm or more and 20 μm or less. In this specification, the "thickness of the first electrode" means the maximum thickness of the first electrode.

[0033] (ceramic particles) The ceramic particles 70 may be formed by firing a ceramic component obtained by pre-firing a glass component and a ceramic material, or both of them.

[0034] As the glass component, borosilicate glass, ZnO-MgO-Al2O3-SiO2 crystallized glass, or the like can be used. Furthermore, the ceramic particles 70 may contain 50 mass % or more of a glass component.

[0035] Examples of ceramic materials include alumina, zirconia, titania, quartz, barium titanate, silicon carbide, zinc oxide, forsterite, etc. Among these, alumina is preferred. Furthermore, the ceramic particles 70 may contain 50 mass % or more of alumina.

[0036] The material of the ceramic particles 70 may be the same as the material that constitutes the ceramic layer 11 .

[0037] The average particle size of the ceramic particles 70 is preferably 0.5 μm or more and 3 μm or less.

[0038] In the cross section of the intermetallic compound 61 in the direction perpendicular to the first main surface 21a of the multilayer substrate 1, the area occupied by the ceramic particles 70 is preferably 0.1% or more and 20.0% or less, and more preferably 1.0% or more and 10.0% or less. If the area ratio is less than 0.1%, the ratio of ceramic particles is small, making it difficult to reduce the difference between the linear expansion coefficient of the intermetallic compound and the linear expansion coefficient of the first electrode. If the area ratio exceeds 20.0%, the proportion of ceramic particles is high, the area of ​​contact between the first electrode and the intermetallic compound is narrowed, and the electrical resistance value is likely to increase.

[0039] The above area ratio in the cross section of the intermetallic compound in the direction perpendicular to the first main surface is measured by the following method. First, a cross section of the intermetallic compound in a direction perpendicular to the first main surface of the multilayer substrate is photographed using a scanning electron microscope (SEM). In the captured image, a region measuring 20 μm x 20 μm is arbitrarily selected. The percentage of the area occupied by ceramic particles in that region is calculated. The ratio of ceramic particles is calculated at three locations. The average value of the proportion of the ceramic particles in each location is defined as the "proportion of the area occupied by the ceramic particles in the cross section of the intermetallic compound in the direction perpendicular to the first main surface."

[0040] In the laminated substrate 1, when the line forming the interface between the intermetallic compound and the first electrode (conductor portion) in a cross section of the intermetallic compound in a direction perpendicular to the first main surface is defined as the first line, and the line forming the interface between the intermetallic compound and the first ceramic particle is defined as the second line, the ratio of the total length of the second lines to the total length of the first lines and the second lines is preferably 0.1% or more and 50.0% or less, and more preferably 1.0% or more and 20.0% or less. If the above ratio is less than 0.1%, the proportion of ceramic particles is low, and when connecting the first electrode and the interlayer connection conductor in manufacturing the laminated substrate, it is difficult to reduce the contact area between the first electrode and the liquid phase component of the interlayer connection conductor, making it easier for intermetallic compounds to be formed widely. If the ratio exceeds 50.0%, the number of first ceramic particles becomes large, the contact area between the first electrode and the intermetallic compound becomes small, and the electrical resistance value tends to increase.

[0041] The ratio of the total length of the second line to the total length of the first line and the second line is measured by the following method. First, a cross section of the first electrode and the intermetallic compound in a direction perpendicular to the first main surface of the multilayer substrate is photographed using a scanning electron microscope (SEM). Then, in the image of the cross section, the interface between the intermetallic compound and the first electrode is defined as a first line, and the interface between the intermetallic compound and the first ceramic particle is defined as a second line, and the lengths of the first line and the second line are calculated from the number of pixels of the first line and the number of pixels of the second line. Then, the total length of the second lines is divided by the total length of the first lines and the second lines to calculate the value. The same procedure is carried out three times on different cross sections. The average value of the calculated values ​​is then set as the "ratio of the total length of the second line to the total length of the first line and the second line."

[0042] (Multi-layer thermoplastic resin layer) 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 . Examples of materials that can be used to form the thermoplastic resin layer 20 include liquid crystal polymer (LCP), thermoplastic polyimide resin, polyether ether ketone resin (PEEK), and polyphenylene sulfide resin (PPS). Among these, liquid crystal polymers (LCPs) are preferred. Liquid crystal polymers have a lower water absorption rate than other thermoplastic resins, and can prevent variations in electrical properties and a decrease in electrical connection reliability.

[0043] The thickness of the thermoplastic resin layer 20 is preferably determined appropriately depending on the design, and is preferably, for example, 10 μm or more and 100 μm or less.

[0044] As shown in FIG. 1B, the via hole 21h formed in the first thermoplastic resin layer 21 has a tapered shape. Furthermore, it is preferable that the tapered shape has a stepwise change in inclination angle, in which case the inclination angle may change in two steps, or in three or more steps. In the laminated substrate of the present invention, the via hole may have 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 may have 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.

[0045] The diameter of the opening of the via hole 21h on the first main surface 21a side is preferably 20 μm or more and 200 μm or less. The diameter of the opening of the via hole 21h on the second main surface 21b side is preferably 20 μm or more and 200 μm or less.

[0046] 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 a method such as etching. Furthermore, the second electrode 32 and the electrode pattern 3a may be made of the same material or different materials. The preferred material for the via 2 b is the same as the preferred material for the interlayer connection conductor 50 .

[0047] The thickness of the second electrode 32 is preferably determined appropriately depending on the design, and is preferably, for example, 3 μm or more and 40 μm or less.

[0048] Next, another example of the laminated substrate according to the first embodiment of the present invention will be described. FIG. 2 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in another example of the laminated substrate according to the first embodiment of the present invention.

[0049] The multilayer substrate 101 shown in FIG. 2 has the same configuration as the multilayer substrate 1, except that the intermetallic compound 61 is formed so as to penetrate into a portion between the first ceramic particles 71 and the first electrode 31.

[0050] When the intermetallic compound 61 is formed so as to penetrate into a portion between the first ceramic particle 71 and the first electrode 31, the anchor effect can improve the connection strength between the intermetallic compound 61 and the first electrode 31, thereby improving the connection reliability.

[0051] One method for forming the intermetallic compound 61 so that it penetrates into a portion between the first ceramic particle 71 and the first electrode 31 in this manner is to adjust the temperature and pressure when connecting the interlayer connection conductor 50 and the first electrode 31 in the manufacture of the laminated substrate 101. In addition, by adjusting the average particle diameter of the ceramic particles 70 and the composition of the interlayer connection conductor 50, a structure as shown in FIG. 2 can be formed.

[0052] Next, a method for manufacturing a laminated substrate according to the first embodiment of the present invention will be described. In the following description, a case where the ceramic layer is made of an LTCC material will be described.

[0053] <LTCC Green Sheet Preparation Step> FIG. 3 is a process diagram schematically showing an example of the LTCC green sheet preparation step of the method for manufacturing a laminated substrate according to the first embodiment of the present invention. When manufacturing the laminated substrate according to the first embodiment of the present invention, first, as shown in FIG. 3, a plurality of LTCC green sheets 10´ are prepared. The LTCC green sheet 10´ can be prepared by the following method.

[0054] First, a slurry is prepared by mixing ceramic powder, a binder, and a plasticizer in an arbitrary amount. As the ceramic powder, the materials mentioned above as the preferable materials for the ceramic layer 10 can be used. Conventional known binders and plasticizers can be used.

[0055] Next, the slurry is applied onto a carrier film and sheet-shaped to obtain an LTCC green sheet 10´. For slurry application, a lip coater or a doctor blade can be used. At this time, the thickness of the LTCC green sheet 10´ is preferably 5 μm or more and 100 μm or less.

[0056] <Via Hole Filling Step of LTCC Green Sheet> FIGS. 4A and 4B are process diagrams schematically showing an example of the via hole filling step of the LTCC green sheet of the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 4A, via holes 10h' are formed in the LTCC green sheet 10'. The method for forming the via holes 10h' is not particularly limited, and they can be formed using a mechanical punch, a CO2 laser, a UV laser, or the like. The opening diameter of the via holes 10h' is not particularly limited, but is preferably 20 μm or more and 200 μm or less.

[0057] Next, as shown in FIG. 4B, a conductive paste 2b' composed of a conductive powder, a plasticizer, and a binder is filled into the via holes 10h'. Note that ceramic powder constituting the LTCC green sheet 10' may be added to the conductive paste 2b'. When the conductive paste 2b' contains such ceramic powder, the difference in shrinkage rate between the LTCC green sheet 10' and the conductive paste 2b' becomes small. As a result, it is possible to prevent cracks or the like from occurring during firing of the LTCC green sheet 10' and the conductive paste 2b'.

[0058] <Electrode pattern formation step of LTCC green sheet> FIG. 5 is a process diagram schematically showing an example of the electrode pattern formation step of the LTCC green sheet in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 5, an electrode pattern 2a' is printed on the surface of the LTCC green sheet 10' using a conductive paste composed of a conductive powder, a plasticizer, and a binder. As the printing method, screen printing, inkjet, gravure printing, or the like can be employed.

[0059] In a subsequent step, a plurality of LTCC green sheets 10' are laminated to form a laminate. In the laminate, among the electrode patterns 2a' of the LTCC green sheet 10' located in the outermost layer, some electrode patterns (indicated by reference numeral "31'" in FIG. 5) become the first electrodes that connect to the interlayer connection conductors in the manufactured laminated substrate. In addition, the LTCC green sheet 10' on which the electrode pattern 31' is formed becomes a ceramic substrate that contacts the first main surface of the first thermoplastic resin layer in the laminated substrate to be manufactured.

[0060] In this step, unfired ceramic particles 70' are mixed into the conductive paste for forming the electrode pattern 31'. The unfired ceramic particles 70' preferably consist of a glass composition and a ceramic material, or a ceramic component obtained by calcining both. Among the inorganic solids contained in the conductive paste for forming the electrode pattern 31', the content of the unfired ceramic particles 70' is preferably 0.1% by weight or more and 20% by weight or less. When the above content is less than 0.1% by weight, the content of the ceramic particles formed through subsequent steps decreases, making it difficult to obtain the effect of reducing the linear expansion coefficient of the intermetallic compound, and also difficult to obtain the effect of making the formation of the intermetallic compound difficult.

[0061] <LTCC Green Sheet Lamination Step> FIG. 6 is a process diagram schematically showing an example of the LTCC green sheet lamination step of the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 6, a plurality of LTCC green sheets 10' are laminated to form an LTCC green sheet laminate 2'. The number of laminated sheets is preferably determined appropriately according to the design. Thereafter, the LTCC green sheet laminate 2' is placed in a mold and pressure-bonded. The pressure and temperature are preferably set arbitrarily according to the design.

[0062] <LTCC Green Sheet Laminate Firing Step> FIG. 7 is a process diagram schematically showing an example of the LTCC green sheet laminate firing step of the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 7, the LTCC green sheet laminate 2' is heated and fired to form a multilayer ceramic layer 2. By carrying out this step, the conductive paste 2b' is fired into the vias 2b, and the electrode pattern 2a' and the electrode pattern 31' are fired into the electrode pattern 2a and the first electrode 31. Also, the unfired ceramic particles 70' become the ceramic particles 70. The firing can be performed using a firing furnace such as a batch furnace, a belt furnace, etc. The firing conditions are not particularly limited, but a temperature of 800°C or higher and 1000°C or lower is preferred. When the conductive paste 2b', the electrode pattern 2a', and the electrode pattern 31' contain copper (Cu), it is preferable to perform firing in a reducing atmosphere.

[0063] <Thermoplastic resin layer preparation process> FIG. 8 is a process diagram schematically showing an example of a thermoplastic resin layer preparation step in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, a plurality of sheet-shaped thermoplastic resin layers 20 are prepared as shown in Fig. 8. The preferred materials for the thermoplastic resin layers 20 have already been explained, so explanations thereof will be omitted here. The thickness of the thermoplastic resin layer 20 is preferably 10 μm or more and 100 μm or less.

[0064] <Step of forming electrode pattern on thermoplastic resin layer> 9A and 9B are process diagrams schematically illustrating an example of a step of forming an electrode pattern on a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in Fig. 9A, a metal foil 3a' is laminated onto the main surface of the thermoplastic resin layer 20. Next, as shown in Fig. 9B, the metal foil 3a' is patterned by etching or the like to form an electrode pattern 3a. Examples of the metal foil 3a' include copper (Cu), silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), and alloys thereof. Preferably, one main surface of the metal foil 3a' is shiny and the other is matte. The metal foil 3a' is preferably laminated so that the matte surface is in contact with the main surface of the thermoplastic resin layer 20. The matte surface of the metal foil 3a' is subjected to a roughening treatment, and the surface roughness Rz (JIS B 0601-2001) is preferably 1 μm or more and 15 μm or less.

[0065] In a later step, the plurality of thermoplastic resin layers 20 are stacked to form a laminate. In the laminate, the thermoplastic resin layer 20 located at the outermost layer becomes the first thermoplastic resin layer 21. 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. Furthermore, among the electrode patterns 2a formed on the main surface of the second thermoplastic resin layer 22 on the second main surface 21b side, some of the electrode patterns become second electrodes 32 that connect to interlayer connection conductors in the laminated substrate to be manufactured.

[0066] <Process for filling via holes in thermoplastic resin layer> 10A and 10B are process diagrams schematically illustrating an example of a step of filling via holes with a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 10A, via holes 21h, via holes 22h, and via holes 20h are formed in the first thermoplastic resin layer 21, the second thermoplastic resin layer 22, and the other thermoplastic resin layers 20, respectively. The method for forming these via holes is not particularly limited, and they can be formed using a mechanical punch, a CO2 laser, a UV laser, or the like. After forming these via holes, it is preferable to carry out a desmear treatment such as an oxygen plasma treatment, a corona discharge treatment, or a potassium permanganate treatment. The opening diameter of the via holes 21h, 22h, and 20h is not particularly limited, but is preferably 20 μm or more and 200 μm or less. In Figure 10A, for the convenience of showing the internal structure in a plan view, there are places where via holes are formed directly below the electrode pattern 3a, and the via holes do not appear to be formed as through holes; however, in reality, the positions where the electrode pattern 3a is formed and the positions where the via holes are formed are shifted in the depth direction, and the via holes are formed as through holes.

[0067] Next, as shown in FIG. 10B, the via holes 21h, 22h, and 20h are filled with a conductive paste 50' which is a precursor of the interlayer connection conductor. The filling method is not particularly limited, but screen printing, vacuum printing, etc. can be used.

[0068] The conductive paste 50' contains a first metal powder and a second metal powder having a melting point higher than that of the first metal powder. Preferably, the first metal powder contained in the conductive paste 50' is made of Sn or a Sn alloy, and the second metal powder is made of a Cu-Ni alloy or a Cu-Mn alloy. Examples of such conductive paste 50' include the conductive paste described in Japanese Patent No. 5146627. 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.

[0069] Examples of Sn or Sn alloys include simple Sn, or alloys containing Sn and at least one element selected from the group consisting of 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, and more preferably 85% by weight or more.

[0070] The proportion of Ni in the Cu-Ni alloy is preferably 10% by weight or more and 15% by weight or less. Furthermore, the proportion of Mn in the Cu-Mn alloy is preferably 10% by weight or more and 15% by weight or less. This allows for the supply of sufficient Ni or Mn to form the desired intermetallic compounds. When the proportion of Ni in the Cu-Ni alloy and the proportion of Mn in the Cu-Mn alloy are less than 10% by weight, Sn tends to remain without forming intermetallic compounds. Furthermore, when the proportion of Ni in the Cu-Ni alloy and the proportion of Mn in the Cu-Mn alloy are more than 15% by weight, Sn also tends to remain without forming intermetallic compounds.

[0071] The Cu-Ni alloy or Cu-Mn alloy may contain Mn and Ni simultaneously, or may contain a third component such as P.

[0072] The arithmetic mean particle diameters of the first metal powder and the second metal powder are preferably 3 μm or more and 10 μm or less, respectively. If the mean particle diameters of these metal powders are too small, the manufacturing cost increases. Also, oxidation of the metal powder progresses, which tends to inhibit the reaction. On the other hand, if the mean particle diameters of these metal powders are too large, it becomes difficult to fill each via hole with the conductive paste 50′.

[0073] The proportion of the second metal in the metal components in the conductive paste 50' is preferably 30% by weight or more. That is, the proportion of the first metal in the metal components in the conductive paste 50' is preferably 70% by weight or less. In this case, the residual proportion of the first metal, such as Sn, is further reduced, and the proportion of intermetallic compounds can be increased.

[0074] The proportion of the metal component in the conductive paste 50' is preferably 70% by weight or more and 95% by weight or less. If the metal component exceeds 95% by weight, it becomes difficult to obtain a conductive paste 50' with excellent filling properties and low viscosity. On the other hand, if the metal component is less than 70% by weight, flux components are likely to remain.

[0075] The conductive paste 50' preferably contains a flux component. The flux component may be any of various known flux components commonly used in conductive paste materials, including a resin. Examples of components other than the resin include a vehicle, a solvent, a thixotropic agent, and an activator.

[0076] The resin preferably contains at least one thermosetting resin selected from the group consisting of epoxy resin, phenol resin, polyimide resin, silicone resin or modified resin thereof, and acrylic resin, or at least one thermoplastic resin selected from the group consisting of polyamide resin, polystyrene resin, polymethacrylic resin, polycarbonate resin, and cellulose-based resin.

[0077] Examples of the vehicle include rosin-based resins made from rosin and derivatives thereof such as modified rosin, synthetic resins, and mixtures thereof. Examples of the rosin-based resins made from rosin and derivatives thereof such as modified rosin include 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 various other rosin derivatives. Examples of the synthetic resins made from rosin and derivatives thereof such as modified rosin include polyester resin, polyamide resin, phenoxy resin, and terpene resin.

[0078] Known examples of the solvent include alcohols, ketones, esters, ethers, aromatic solvents, and hydrocarbons. Specific examples include benzyl alcohol, ethanol, isopropyl alcohol, butanol, diethylene glycol, ethylene glycol, glycerin, 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, hexylene glycol, cyclohexanedimethanol, 2-terpinyloxyethanol, 2-dihydroterpinyloxyethanol, and mixtures thereof. Preferred are terpineol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0079] Specific examples of the thixotropic agent include hydrogenated castor oil, carnauba wax, amides, hydroxy fatty acids, dibenzylidene sorbitol, bis(p-methylbenzylidene)sorbitols, beeswax, stearic acid amide, hydroxystearic acid ethylene bisamide, etc. Furthermore, if necessary, the above may be supplemented with fatty acids such as caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, hydroxy fatty acids such as 1,2-hydroxystearic acid, antioxidants, surfactants, and amines, and these may also be used as thixotropic agents.

[0080] Examples of the activator include amine hydrohalides, organic halogen compounds, organic acids, organic amines, and polyhydric alcohols.

[0081] Examples of the amine hydrohalides include diphenylguanidine hydrobromide, diphenylguanidine hydrochloride, cyclohexylamine hydrobromide, ethylamine hydrochloride, ethylamine hydrobromide, diethylaniline hydrobromide, diethylaniline hydrochloride, triethanolamine hydrobromide, and monoethanolamine hydrobromide.

[0082] Examples of the organic halogen compounds 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.

[0083] Examples of the organic acids 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.

[0084] Examples of the organic amine include monoethanolamine, diethanolamine, triethanolamine, tributylamine, aniline, and diethylaniline.

[0085] Examples of the polyhydric alcohol include erythritol, pyrogallol, and ribitol.

[0086] <Thermoplastic resin layer lamination process> FIG. 11 is a process diagram schematically illustrating an example of a step of laminating a thermoplastic resin layer in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 11, a first thermoplastic resin layer 21, a second thermoplastic resin layer 22 and another thermoplastic resin layer 20 are laminated to form a multi-layered thermoplastic resin layer 3.

[0087] <Laminating process of multilayer ceramic layer and multilayer thermoplastic resin layer> 12A and 12B are process diagrams schematically illustrating an example of a lamination step of multilayer ceramic layers and multilayer thermoplastic resin layers in the method for manufacturing a multilayer substrate according to the first embodiment of the present invention. 12A, the multilayer ceramic layer 2 is laminated on the multilayer thermoplastic resin layer 3. At this time, the multilayer ceramic layer 2 is aligned so that the conductive paste 50' filled in the first thermoplastic resin layer 21 of the multilayer thermoplastic resin layer 3 contacts the exposed surface of the first electrode 31 of the ceramic layer 11 arranged on the outermost layer of the multilayer ceramic layer 2.

[0088] Thereafter, as shown in FIG. 12B, the multilayer thermoplastic resin layer 3 and the multilayer ceramic layer 2 are integrated by applying pressure and heat. At this time, the first thermoplastic resin layer 21 conforms to the irregularities on the surface of the ceramic layer 11, and the multilayered thermoplastic resin layer 3 and the multilayered ceramic layer 2 are closely attached to each other due to the anchor effect.

[0089] In this step, for example, the treatment may be carried out at 230° C. or higher and 350° C. or lower under normal pressure.

[0090] In this step, the conductive paste 50' melts and then solidifies to become the interlayer connection conductor 50. 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.

[0091] This liquid phase diffusion bonding will be explained with reference to the drawings. 13A to 13D are explanatory views that schematically show an example of connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding.

[0092] 13A, the conductive paste 50′ contains a first metal powder 51 and a second metal powder 52 having a melting point higher than that of the first metal powder 51. The conductive paste 50′ is in contact with the first electrode 31.

[0093] As shown in FIG. 13B, when conductive paste 50' is heated in this state and reaches the melting point of first metal powder 51, first metal powder 51 melts and becomes first metal 51a in liquid phase.

[0094] Thereafter, as heat is continued to be applied, the liquid phase first metal 51a reacts with the second metal powder 52, forming an intermetallic compound 60, as shown in FIG. 13C. Furthermore, the liquid-phase first metal 51a spreads over the first electrode 31 in a diffusive manner, and the liquid-phase first metal 51a reacts with the metal constituting the first electrode 31, forming an intermetallic compound 61.

[0095] The first electrode 31 contains ceramic particles 70. The ceramic particles 70 suppress the diffusion of the liquid-phase first metal 51a, thereby preventing the formation of intermetallic compounds 61 over a wide area.

[0096] 13D, when the heating is finished and the temperature drops, the liquid first metal 51a solidifies to become the interlayer connection conductor 50. At this time, some of the ceramic particles 70 become the first ceramic particles 71 that are in contact with both the first electrode 31 and the intermetallic compound 61. In FIG. 13D, for the sake of convenience, the outline of the intermetallic compound 60 derived from the second metal powder 52 is shown by a dashed line, but in reality, the boundary is not clear and the intermetallic compound 60 does not appear to be particulate.

[0097] In this step, the interlayer connection conductor 50 and the second electrode 32 are also connected by liquid phase diffusion bonding, so that the intermetallic compound 61 is also formed between the interlayer connection conductor 50 and the second electrode 32 .

[0098] Through the above steps, the multilayer substrate 1 can be manufactured.

[0099] [Second embodiment] Next, a laminated substrate according to a second embodiment of the present invention will be described. FIG. 14 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a second embodiment of the present invention. The multilayer substrate 201 shown in FIG. 14 has the same configuration as the multilayer substrate 1 according to the first embodiment, except for the following differences. In the laminated substrate 201, the first electrode 231 includes a first conductor layer 231a on the side of the first thermoplastic resin layer 21, and a second conductor layer 231b laminated on the first conductor layer 231a. Furthermore, the weight percentage of the ceramic particles 70 contained in the first conductor layer 231a is lower than the weight percentage of the ceramic particles 70 contained in the second conductor layer 231b. Note that the first conductor layer 231a does not necessarily have to contain the ceramic particles 70. In addition, when the first conductor layer 231a contains ceramic particles 70, it is preferable that the ratio of the weight of the ceramic particles 70 contained in the first conductor layer 231a to the weight of the ceramic particles 70 contained in the second conductor layer 231b, [weight of ceramic particles contained in the first conductor layer] / [weight of ceramic particles contained in the second conductor layer], is greater than 0 and not more than 0.7.

[0100] In the multilayer substrate 201, the thickness of the first conductor layer 231a is preferably 5 μm or more and 10 μm or less. Also, the thickness of the second conductor layer 231b is preferably 5 μm or more and 10 μm or less.

[0101] The multilayer substrate 201 having such a configuration can be manufactured by the same method as the method for manufacturing a multilayer substrate according to the first embodiment of the present invention, except that the <LTCC green sheet laminate firing step> is changed as follows. That is, in the <LTCC green sheet laminate firing step>, when forming the first electrode 231, a conductive paste containing a large amount of unfired ceramic particles is printed, and a conductive paste containing a small amount of unfired ceramic particles or not containing unfired ceramic particles is printed thereon.

[0102] The conductive paste containing a large amount of unfired ceramic particles preferably contains the same ceramic pre-fired powder as the LTCC green sheet in an amount of 5% by volume or more and 70% by volume or less of the inorganic solid content. The conductive paste containing a small amount of unfired ceramic particles preferably contains the same ceramic pre-fired powder as the LTCC green sheet and / or alumina in an amount of 2% by volume or more of the inorganic solid content.

[0103] When the multilayer substrate 201 is manufactured by such a method, when connecting the interlayer connection conductor 50 and the first electrode 231 by liquid-phase diffusion bonding, an intermetallic compound 261 is formed as follows. When the interlayer connection conductor 50 and the first electrode 231 are connected by liquid-phase diffusion bonding, since the weight ratio of the ceramic particles 70 contained in the first conductor layer 231a is low, the first conductor layer 231a quickly becomes the intermetallic compound 261. When the intermetallic compound 261 reaches the second conductor layer 231b, since the weight ratio of the ceramic particles 70 contained in the second conductor layer 231b is high, the second conductor layer 231b is less likely to become the intermetallic compound 261. That is, the intermetallic compound 261 is less likely to be formed at the boundary between the first conductor layer 231a and the second conductor layer 231b.

[0104] Therefore, by adjusting the weight ratio of the ceramic particles 70 contained in the first conductor layer 231a and the second conductor layer 231b, the thickness of the first conductor layer 231a and the second conductor layer 231b, etc., the range in which the intermetallic compound 261 is formed can be controlled.

[0105] For this reason, the intermetallic compound 261 can be prevented from diffusing excessively in the thickness direction. Furthermore, since the first conductor layer 231a easily becomes the intermetallic compound 261, the interlayer connection conductor 50 and the first electrode 231 can be reliably connected.

[0106] [Third embodiment] Next, a laminated substrate according to a third embodiment of the present invention will be described. FIG. 15 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a third embodiment of the present invention.

[0107] The multilayer substrate 301 shown in FIG. 15 has the same configuration as the multilayer substrate 1 according to the first embodiment, except for the following differences. In the laminated substrate 301, the first electrode 31 is not formed, and the ceramic layer 11 has a via 302b formed therein that connects to the interlayer connection conductor 50, and an intermetallic compound 361 is formed between the interlayer connection conductor 50 and the via 302b. Ceramic particles 70 exist inside the intermetallic compound 361, and some of the ceramic particles 70 are first ceramic particles 71 that contact both the intermetallic compound 361 and the via 302b. In the laminated substrate 301, the vias 302b function as conductors. In the laminated substrate 301 having such a configuration, the intermetallic compound 361 contains ceramic particles, so that the difference between the linear expansion coefficient of the intermetallic compound 361 and the linear expansion coefficient of the via 302b can be reduced. As a result, the thermal stress applied to the intermetallic compound 361 can be reduced. Therefore, the intermetallic compound 361 can be prevented from being broken by the thermal stress.

[0108] The preferred material for the via 302b is the same as the preferred material for the first electrode 31 described above. In particular, the via 302b is preferably made of a sintered body of copper (Cu) or its alloy.

[0109] [Fourth embodiment] Next, a laminated substrate according to a fourth embodiment of the present invention will be described. FIG. 16 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a fourth embodiment of the present invention. The multilayer substrate 401 shown in FIG. 16 has the same configuration as the multilayer substrate 301 according to the third embodiment, except for the following differences.

[0110] In the laminated substrate 401, the via 402b includes a first conductor layer 402b1 on the first thermoplastic resin layer 21 side, and a second conductor layer 402b2 laminated on the first conductor layer 402b1. Furthermore, the weight percentage of the ceramic particles 70 contained in the first conductor layer 402b1 is lower than the weight percentage of the ceramic particles 70 contained in the second conductor layer 402b2. Note that the first conductor layer 402b1 does not necessarily have to contain the ceramic particles 70. In addition, when the first conductor layer 402b1 contains ceramic particles 70, it is preferable that the ratio of the weight of the ceramic particles 70 contained in the first conductor layer 402b1 to the weight of the ceramic particles 70 contained in the second conductor layer 402b2, [weight of ceramic particles contained in the first conductor layer] / [weight of ceramic particles contained in the second conductor layer], is greater than 0 and not more than 0.7.

[0111] When the interlayer connection conductor 50 and the via 402b are connected by liquid phase diffusion bonding, the first conductor layer 402b1 quickly becomes an intermetallic compound 461 because the weight ratio of the ceramic particles 70 contained in the first conductor layer 402b1 is low. When the intermetallic compound 461 reaches the second conductor layer 402b2, the weight ratio of the ceramic particles 70 contained in the second conductor layer 402b2 is high, so the second conductor layer 402b2 is unlikely to become the intermetallic compound 461. In other words, the intermetallic compound 461 is less likely to be formed at the boundary between the first conductor layer 402b1 and the second conductor layer 402b2. Although the first conductor layer 402b1 remains in FIG. 16, in the laminated substrate of the present invention, the first conductor layer may be entirely made of an intermetallic compound.

[0112] For this reason, the intermetallic compound 461 can be prevented from diffusing excessively in the thickness direction. Furthermore, since the first conductor layer 402b1 easily becomes the intermetallic compound 461, the interlayer connection conductor 50 and the via 402b can be reliably connected.

[0113] The preferred materials for the first conductor layer 402b1 are the same as the preferred materials for the first conductor layer 231a. The preferred materials for the second conductor layer 402b2 are the same as the preferred materials for the second conductor layer 231b.

[0114] [Fifth embodiment] Next, a laminated substrate according to a fifth embodiment of the present invention will be described. FIG. 17 is a cross-sectional view that schematically shows an example of the vicinity of an interlayer connection conductor of a multilayer substrate according to a fifth embodiment of the present invention. The multilayer substrate 501 shown in FIG. 17 has the same configuration as the multilayer substrate 1 according to the first embodiment, except for the following differences.

[0115] In the multilayer substrate 501, a via 502b is formed in the ceramic layer 11 so as to connect to the first electrode 531. The first electrode 531 and the via 502b contain ceramic particles . Furthermore, in laminated substrate 501, the weight percentage of ceramic particles 70 contained in first electrode 531 is lower than the weight percentage of ceramic particles 70 contained in vias 502b. Note that first electrode 531 does not necessarily have to contain ceramic particles 70. In addition, when the first electrode 531 contains ceramic particles 70, it is preferable that the ratio of the weight of the ceramic particles 70 contained in the first electrode 531 to the weight of the ceramic particles 70 contained in the via 502b is [weight of the ceramic particles contained in the first electrode] / [weight of the ceramic particles contained in the via] is greater than 0 and not more than 0.7.

[0116] The preferred materials for the first electrode 531 are the same as the preferred materials for the first conductor layer 231a. The preferred material for the via 502b is the same as the preferred material for the second conductor layer 231b.

[0117] In the laminated substrate 501, both the first electrode 531 and the via 502b function as a conductive portion. Furthermore, the first electrode 531 functions as a first conductor layer, and the via 502b functions as a second conductor layer.

[0118] When the interlayer connection conductor 50 and the first electrode 531 are connected by liquid phase diffusion bonding, the first electrode 531 quickly becomes an intermetallic compound 561 because the weight ratio of the ceramic particles 70 contained in the first electrode 531 is low. When the intermetallic compound 61 reaches the via 502b, the weight ratio of the ceramic particles 70 contained in the second conductor layer 502b2 is high, so that the via 502b is unlikely to become an intermetallic compound 561. In other words, the intermetallic compound 561 is less likely to be formed at the boundary between the first electrode 531 and the via 502b.

[0119] For this reason, the intermetallic compound 561 can be prevented from diffusing excessively in the thickness direction. Furthermore, since the first electrode 531 easily becomes the intermetallic compound 561, the interlayer connection conductor 50 and the first electrode 531 can be reliably connected.

[0120] This specification describes the following:

[0121] The present disclosure (1) is a laminated substrate comprising: a first thermoplastic resin layer having a first main surface and a second main surface opposite to the first main surface, the first thermoplastic resin layer having a via hole penetrating from the first main surface to the second main surface; and a ceramic layer arranged to contact the first main surface, wherein an interlayer connection conductor is arranged in the via hole, a conductor portion connected to the interlayer connection conductor is formed in the ceramic layer, an intermetallic compound is formed between the interlayer connection conductor and the conductor portion, ceramic particles are present inside the intermetallic compound, and some of the ceramic particles are first ceramic particles that contact both the intermetallic compound and the conductor portion.

[0122] The present disclosure (2) is the laminated substrate according to the present disclosure (1), wherein the intermetallic compound is formed so as to penetrate into a part between the first ceramic particles and the conductor portion.

[0123] The present disclosure (3) is the laminated substrate according to the present disclosure (1) or (2), wherein the ceramic particles account for 0.1% or more and 20.0% or less of an area of ​​a cross section of the intermetallic compound in a direction perpendicular to the first main surface.

[0124] The present disclosure (4) is the laminated substrate according to any one of the present disclosures (1) to (3), wherein, in a cross section of the intermetallic compound in a direction perpendicular to the first main surface, when a line forming an interface between the intermetallic compound and the conductor portion is defined as a first line and a line forming an interface between the intermetallic compound and the first ceramic particle is defined as a second line, a ratio of the total length of the second lines to the total length of the first lines and the second lines is 0.1% or more and 50.0% or less.

[0125] The present disclosure (5) is a laminated substrate according to any one of the present disclosures (1) to (4), wherein the conductor portion includes the ceramic particles, the conductor portion includes a first conductor layer on the first thermoplastic resin layer side, and a second conductor layer laminated on the first conductor layer, and the weight proportion of the ceramic particles included in the first conductor layer is lower than the weight proportion of the ceramic particles included in the second conductor layer.

[0126] The present disclosure (6) is the laminated substrate according to any one of the present disclosures (1) to (5), in which the conductor portion is an electrode.

[0127] The present disclosure (7) is the laminated substrate according to any one of the present disclosures (1) to (5), wherein the conductor portion is a via.

[0128] The present disclosure (8) is the laminated substrate according to any one of the present disclosures (1) to (7), wherein the ceramic particles contain 50% by weight or more of a glass component.

[0129] The present disclosure (9) is the laminated substrate according to any one of the present disclosures (1) to (7), wherein the ceramic particles contain 50 mass % or more of alumina.

[0130] The present disclosure (10) is the laminated substrate according to any one of the present disclosures (1) to (9), wherein the ceramic particles are made of the same material as the ceramic layer. [Explanation of symbols]

[0131] 1, 101, 201, 301, 401, 501 laminated board 2 multi-layer ceramic layers 2´ LTCC green sheet laminate 2a, 2a´, 3a electrode patterns 2b, 3b, 302b, 402b, 502b vias 3 Multi-layer thermoplastic resin layer 3a´ Metal foil 10, 11 Ceramic layer 10´ LTCC green sheet 10am, 8pm, 9pm, 10pm, Beer Hall 20 Thermoplastic resin layer 21 First thermoplastic resin layer 21a: First main surface of first thermoplastic resin layer 21b: second main surface of the first thermoplastic resin layer 22 Second thermoplastic resin layer 31, 231, 531 1st electrode 31´ electrode pattern 31c Outline of first electrode 32 2nd electrode 50 Interlayer connecting conductor 50´ Conductive Paste 51 First metal powder 51a Liquid phase first metal 52 Secondary metal powder 60, 61, 62, 261, 361, 461, 561 Intermetallic compounds 70 ceramic particles 70´ Unfired Ceramic Grains 71 First ceramic particle 231a, 402b1 first conductor layer 231b, 402b2 second conductor layer

Claims

1. a first thermoplastic resin layer having a first main surface and a second main surface opposite to the first main surface, the first thermoplastic resin layer having a via hole penetrating from the first main surface to the second main surface; a ceramic layer disposed in contact with the first main surface; an interlayer connection conductor is disposed in the via hole; a conductor portion connected to the interlayer connection conductor is formed in the ceramic layer; the conductor portion includes ceramic particles, an intermetallic compound is formed between the interlayer connection conductor and the conductor portion, The ceramic particles are present inside the intermetallic compound, some of the ceramic particles are first ceramic particles that are in contact with both the intermetallic compound and the conductor portion; the conductor portion includes a first conductor layer on the first thermoplastic resin layer side and a second conductor layer laminated on the first conductor layer, A laminated substrate, wherein the weight percentage of the ceramic particles contained in the first conductor layer is lower than the weight percentage of the ceramic particles contained in the second conductor layer.

2. The multilayer substrate according to claim 1 , wherein the intermetallic compound is formed so as to penetrate into a portion between the first ceramic particles and the conductor portion.

3. 3. The multilayer substrate according to claim 1, wherein the ceramic particles occupy an area of ​​0.1% or more and 20.0% or less in a cross section of the intermetallic compound taken along a direction perpendicular to the first main surface.

4. 3. The laminated substrate according to claim 1, wherein, in a cross section of the intermetallic compound in a direction perpendicular to the first main surface, a line forming an interface between the intermetallic compound and the conductor portion is defined as a first line, and a line forming an interface between the intermetallic compound and the first ceramic particle is defined as a second line, and a ratio of a total length of the second lines to a total length of the first lines and the second lines is 0.1% or more and 50.0% or less.

5. The laminated substrate according to claim 1 or 2, wherein the conductor portion is an electrode.

6. The laminated substrate according to claim 1 or 2, wherein the conductor portion is a via.

7. 3. The laminated substrate according to claim 1, wherein the ceramic particles contain 50% by weight or more of a glass component.

8. 3. The laminated substrate according to claim 1, wherein the ceramic particles contain 50% by mass or more of alumina.

9. 3. The laminated substrate according to claim 1, wherein the ceramic particles are made of the same material as the ceramic layer.

Images