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

Multilayer substrate

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

[0002] Conventionally, module components using multilayer substrates with built-in passive elements have been put to practical use. For example, a well-known DC-DC converter module is formed 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 in 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 thermoplastic resin layer 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 ceramic multilayer substrate, 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 a thermoplastic resin layer are bonded by 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. The intermetallic compound layer is generated when a metal such as Sn or an Sn alloy constituting the interlayer connection conductor melts upon heating and reacts with a metal (e.g., Cu) constituting the conductor wiring layer. That is, the intermetallic compound layer is generated during liquid phase diffusion bonding.

[0007] Patent No. 6819668 International Publication No. 2019 / 003729

[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 also formed between a conductor portion (terminal electrode) provided in a ceramic layer and an interlayer connection conductor (interlayer conductor) provided in a thermoplastic resin layer.

[0009] The conductor portion formed in the ceramic layer, the interlayer connection conductor provided in the thermoplastic resin layer, and the intermetallic compound layer have different linear expansion coefficients, so thermal stress is likely to occur between them. In particular, the intermetallic compound has low ductility, so 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.

[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.

[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.

[0013] FIG. 1A is a cross-sectional view schematically showing 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 in FIG. 1A. 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. 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. FIG. 4A is a process diagram schematically showing an example of a via hole filling step in an LTCC green sheet in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 4B is a process diagram schematically showing an example of a via hole filling step in an LTCC green sheet in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 5 is a process diagram schematically showing an example of an electrode pattern formation step in an LTCC green sheet in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 6 is a process diagram schematically showing an LTCC green sheet lamination step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 7 is a process diagram schematically showing an LTCC green sheet laminate firing step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 8 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 first embodiment of the present invention. FIG. 9A is a process diagram schematically showing an example of a thermoplastic resin layer electrode pattern formation step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 9B is a process diagram schematically showing an example of a thermoplastic resin layer electrode pattern formation step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 10A is a process diagram schematically showing an example of a thermoplastic resin layer via hole filling step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 10B is a process diagram schematically showing an example of a thermoplastic resin layer via hole filling step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 11 is a process diagram schematically showing an example of a thermoplastic resin layer lamination step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 12A is a process diagram schematically showing an example of a multilayer ceramic layer and a multilayer thermoplastic resin layer lamination step in the method for producing a laminated substrate according to the first embodiment of the present invention. FIG. 12B is a process diagram schematically showing an example of a multilayer ceramic layer and a multilayer thermoplastic resin layer lamination step in the method for producing a laminated substrate according to the first embodiment of the present invention.FIG. 13A is an explanatory diagram schematically showing an example of a connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. FIG. 13B is an explanatory diagram schematically showing an example of a connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. FIG. 13C is an explanatory diagram schematically showing an example of a connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. FIG. 13D is an explanatory diagram schematically showing an example of a connection between an interlayer connection conductor and a first electrode by liquid phase diffusion bonding. FIG. 14 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in a laminated substrate according to a second embodiment of the present invention. FIG. 15 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in a laminated substrate according to a third embodiment of the present invention. FIG. 16 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in a laminated substrate according to a fourth embodiment of the present invention. FIG. 17 is a cross-sectional view schematically showing an example of the vicinity of an interlayer connection conductor in a laminated substrate according to a fifth embodiment of the present invention.

[0014] The laminated substrate of the present invention will be described below. However, the present invention is not limited to the following configuration, and can be appropriately modified and applied within the scope that does not change the gist of the present invention. Note that a combination of two or more of the individual desirable configurations of the present invention described below also constitutes the present invention.

[0015] The laminated substrate of the present invention includes a first thermoplastic resin layer having a first main surface and a second main surface opposite 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 in contact with the first main surface. The via hole is an interlayer connection conductor arranged in the via hole. The ceramic layer has a conductor portion connected to the interlayer connection conductor. An intermetallic compound is formed between the interlayer connection conductor and the conductor portion. Ceramic particles are present within 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, the ceramic particles are present within the intermetallic compound. This reduces the difference between the linear expansion coefficient of the intermetallic compound and the linear expansion coefficient of the conductor portion formed in the ceramic layer. As a result, the thermal stress applied to the intermetallic compound can be reduced. This prevents the intermetallic compound from being fractured due to thermal stress. Furthermore, when manufacturing the laminated substrate of the present invention, the interlayer connection conductor and the conductor portion are connected by liquid phase diffusion bonding. In this case, the intermetallic compound is formed by a 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 intermetallic compound in excess of what is necessary. In particular, if the conductor portion contains enough ceramic particles to sufficiently suppress the reaction, some of the ceramic particles will be in contact with both the intermetallic compound and the conductor portion in the manufactured laminated substrate. Note that 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 a micro 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 showing an example of the laminated substrate according to the first embodiment of the present invention. Fig. 1B is an enlarged view of the dashed line portion in Fig. 1A.

[0018] The laminated substrate 1 shown in Fig. 1A includes a multilayer ceramic layer 2 formed by stacking a plurality of ceramic layers 10, and a multilayer thermoplastic resin layer 3 formed by stacking a plurality of thermoplastic resin layers 20. In the laminated substrate 1 shown in Fig. 1A, the multilayer ceramic layer 2 is stacked on the 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] 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. Also, 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] As shown in Fig. 1A, the multilayer ceramic layer 2 includes a ceramic layer 11 disposed 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 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 multilayer thermoplastic resin layer 3 includes a second thermoplastic resin layer 22 arranged so as to be in contact with the second main surface 21 b. A second electrode 32 is formed on the main surface of the second thermoplastic resin layer 22 in contact with the second main surface 21 b.

[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] 1B , in the laminated substrate 1, ceramic particles 70 are present inside the intermetallic compound 61. This makes it 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. This makes it possible to prevent the intermetallic compound 61 from being broken by the thermal stress.

[0025] In the laminated 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 the ceramic particles 70 inside the intermetallic compound 61 means that the first electrode 31 contained the ceramic particles 70 when manufacturing the laminated substrate 1. If the first electrode 31 contains the ceramic particles 70, the contact area between the 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, when the first electrode 31 contains a sufficient amount of ceramic particles 70 to sufficiently suppress the reaction, some of the ceramic particles 70 in the manufactured laminated substrate 1 will come into contact with both the intermetallic compound 61 and the first electrode 31.

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

[0027] Preferred embodiments of each configuration of the laminated substrate 1 will be described below.

[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. During this process, 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> section below.

[0029] (Multilayer Ceramic Layer) The multilayer ceramic layer 2 is composed of ceramic layers 10 including a ceramic layer 11. Examples of materials that compose the ceramic layer 10 include low-temperature co-fired ceramic (LTCC) materials. Low-temperature co-fired ceramic materials are ceramic materials that can be sintered at temperatures of 1000°C or less and can be co-fired with Au, Ag, Cu, or other materials that have low resistivity. Specific examples of low-temperature co-fired ceramic materials include glass composite low-temperature co-fired ceramic materials that are obtained by mixing ceramic powders such as alumina, zirconia, magnesia, and forsterite with borosilicate glass, and ZnO-MgO-Al ２ O ３ -SiO ２ Glass-ceramic low-temperature sintering ceramic material using BaO-Al ２ O ３ -SiO ２ Ceramic powder and Al ２ O ３ -CaO-SiO ２ -MgO-B ２ O ３ Examples of suitable materials include non-glass-based low-temperature sintered ceramic materials using ceramic powders.

[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 sintered bodies 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 sintered bodies of copper (Cu) and 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), and alloys thereof. 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] The glass components include borosilicate glass and ZnO-MgO-Al ２ O ３ -SiO ２ 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, and forsterite. Among these, alumina is preferred. The ceramic particles 70 may contain 50% by 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 a cross section of the intermetallic compound 61 in a direction perpendicular to the first main surface 21a of the laminated 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 proportion 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 large, making the contact area between the first electrode and the intermetallic compound narrow, and making it easier for the electrical resistance to increase.

[0039] The above-mentioned 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 the direction perpendicular to the first main surface of the laminated substrate is photographed using a scanning electron microscope (SEM). In the photographed image, an area of ​​length x width = 20 μm x 20 μm is arbitrarily selected. In that area, the area ratio occupied by ceramic particles is calculated. The calculation of the above-mentioned area ratio occupied by ceramic particles is performed at three locations. The average value of the area ratio occupied by ceramic particles at each location is defined as the "area ratio occupied by 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, in a cross section of the intermetallic compound perpendicular to the first main surface, the line forming the interface between the intermetallic compound and the first electrode (conductor portion) 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 line to the total length of the first and second lines is preferably 0.1% to 50.0%, more preferably 1.0% to 20.0%. If this ratio is less than 0.1%, the proportion of ceramic particles is small, making it difficult to reduce the contact area between the first electrode and the liquid-phase component of the interlayer connection conductor when connecting the first electrode and the interlayer connection conductor during manufacturing the laminated substrate, and the intermetallic compound is likely to be formed widely. If this ratio is more than 50.0%, the number of first ceramic particles is large, making the contact area between the first electrode and the intermetallic compound narrow, and the electrical resistance is likely to increase.

[0041] The ratio of the total length of the second lines to the total length of the first and second lines is measured using 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 laminated 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 designated as the first line, and the interface between the intermetallic compound and the first ceramic particle is designated as the second line. The lengths of the first and second lines are then calculated from the number of pixels of the first and second lines. The total length of the second line is then divided by the total length of the first and second lines to calculate the ratio. The same operation is performed three times on another cross section. The average of the calculated values ​​is then used as the "ratio of the total length of the second lines to the total length of the first and second lines."

[0042] (Multilayer 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 compose the thermoplastic resin layer 20 include liquid crystal polymer (LCP), thermoplastic polyimide resin, polyether ether ketone resin (PEEK), and polyphenylene sulfide resin (PPS). Of these, liquid crystal polymer (LCP) is preferred. Liquid crystal polymer has 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. The tapered shape preferably has a stepwise inclination angle. In this 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, and 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 using a technique such as etching. 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 2b 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 laminated substrate 101 shown in FIG. 2 has the same configuration as the laminated substrate 1 described above, 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, and the connection reliability can be improved.

[0051] One method for forming the intermetallic compound 61 so as to penetrate into a portion between the first ceramic particles 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, the structure shown in Fig. 2 can also be formed by adjusting the average particle size of the ceramic particles 70 and the composition of the interlayer connection conductor 50.

[0052] Next, a method for manufacturing a laminated substrate according to a first embodiment of the present invention will be described, in which the ceramic layers are made of an LTCC material.

[0053] <LTCC Green Sheet Preparation Step> Figure 3 is a process diagram schematically showing an example of an LTCC green sheet preparation step in the method for manufacturing the 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, a plurality of LTCC green sheets 10' are prepared, as shown in Figure 3. The LTCC green sheets 10' can be prepared by the following method.

[0054] First, a ceramic powder, a binder, and a plasticizer are mixed in desired amounts to prepare a slurry. The ceramic powder may be any of the materials listed above as preferred materials for the ceramic layer 10. Conventionally known binders and plasticizers may be used.

[0055] Next, the slurry is applied onto a carrier film and formed into a sheet to obtain an LTCC green sheet 10'. A lip coater or a doctor blade can be used to apply the slurry. In this case, it is preferable that the thickness of the LTCC green sheet 10' be 5 μm or more and 100 μm or less.

[0056] 4A and 4B are process diagrams schematically illustrating an example of a process of filling a via hole in an 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. 4A, 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 may be a mechanical punch, a CO ２ The via hole 10h' can be formed using a laser, a UV laser, etc. The opening diameter of the via hole 10h' is not particularly limited, but is preferably 20 μm or more and 200 μm or less.

[0057] Next, as shown in FIG. 4B , the via holes 10h′ are filled with a conductive paste 2b′ composed of a conductive powder, a plasticizer, and a binder. The ceramic powder that constitutes 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′ is reduced. As a result, cracks and other defects can be prevented from occurring during firing of the LTCC green sheet 10′ and the conductive paste 2b′.

[0058] <Step of Forming Electrode Patterns on LTCC Green Sheets> Figure 5 is a process diagram schematically illustrating an example of the step of forming electrode patterns on LTCC green sheets in the method for producing a laminated substrate according to the first embodiment of the present invention. Next, as shown in Figure 5, an electrode pattern 2a' is printed on the surface of an LTCC green sheet 10' using a conductive paste containing conductive powder, a plasticizer, and a binder. Examples of printing methods that can be used include screen printing, inkjet printing, and gravure printing.

[0059] In a later step, multiple LTCC green sheets 10' are stacked to form a laminate. In this laminate, a portion of the electrode patterns 2a' of the LTCC green sheets 10' located on the outermost layers (indicated by the reference symbol "31'" in FIG. 5) will become first electrodes that connect to interlayer connection conductors in the laminated substrate to be manufactured. Furthermore, the LTCC green sheets 10' on which the electrode patterns 31' are formed will become ceramic substrates that contact the first main surface of the first thermoplastic resin layer in the laminated substrate to be manufactured.

[0060] In this process, unsintered ceramic particles 70' are mixed into the conductive paste for forming the electrode pattern 31'. The unsintered ceramic particles 70' are preferably composed of a ceramic component obtained by pre-sintering a glass composition and a ceramic material, or both. The content of the unsintered ceramic particles 70' among the inorganic solids contained in the conductive paste for forming the electrode pattern 31' is preferably 0.1 wt % or more and 20 wt % or less. If the content is less than 0.1 wt %, the content of the ceramic particles formed in the subsequent process will be small, making it difficult to obtain the effect of reducing the linear expansion coefficient of the intermetallic compound, and making it difficult to obtain the effect of making the intermetallic compound less likely to be formed.

[0061] <LTCC Green Sheet Lamination Step> Figure 6 is a process diagram schematically illustrating an example of the LTCC green sheet lamination step in the manufacturing method for the laminated substrate according to the first embodiment of the present invention. Next, as shown in Figure 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 depending on the design. Thereafter, the LTCC green sheet laminate 2' is placed in a mold and pressure-bonded. The pressure and temperature are preferably set as desired depending on the design.

[0062] <LTCC Green Sheet Laminate Firing Step> FIG. 7 is a process diagram schematically illustrating an example of an LTCC green sheet laminate firing step in 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. Through this step, the conductive paste 2b′ is fired into vias 2b, and the electrode patterns 2a′ and 31′ are fired into electrode patterns 2a and first electrodes 31. Furthermore, the unfired ceramic particles 70′ become ceramic particles 70. Firing can be performed using a firing furnace such as a batch furnace or a belt furnace. The firing conditions are not particularly limited, but are preferably 800°C or higher and 1000°C or lower. When the conductive paste 2b′, electrode patterns 2a′, and electrode patterns 31′ contain copper (Cu), firing in a reducing atmosphere is preferred.

[0063] <Thermoplastic Resin Layer Preparation Step> Figure 8 is a process diagram schematically illustrating an example of the thermoplastic resin layer preparation step in the method for manufacturing a laminated substrate according to the first embodiment of the present invention. Next, as shown in Figure 8, a plurality of sheet-shaped thermoplastic resin layers 20 are prepared. Since the preferred material for the thermoplastic resin layer 20 has already been described, its description 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 an Electrode Pattern on a Thermoplastic Resin Layer> FIGS. 9A and 9B are process diagrams schematically illustrating an example of the step of forming an electrode pattern on a thermoplastic resin layer in the manufacturing method of a laminated substrate according to the first embodiment of the present invention. Next, as shown in FIG. 9A , a metal foil 3 a' is laminated on the main surface of the thermoplastic resin layer 20. Next, as shown in FIG. 9B , the metal foil 3 a' is patterned by etching or the like to form an electrode pattern 3 a. Examples of the metal foil 3 a' include copper (Cu), silver (Ag), aluminum (Al), nickel (Ni), stainless steel (SUS), and alloys thereof. It is preferable that one main surface of the metal foil 3 a' be a shiny surface and the other be a matte surface. It is preferable that the metal foil 3 a' be 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 3 a' 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, some of the electrode patterns 2a formed on the main surface of the second thermoplastic resin layer 22 on the second main surface 21b side become second electrodes 32 that connect to interlayer connection conductors in the laminated substrate to be manufactured.

[0066] 10A and 10B are process diagrams schematically illustrating an example of the step of filling via holes in 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, 22h, and 20h are formed in the first thermoplastic resin layer 21, the second thermoplastic resin layer 22, and the other thermoplastic resin layer 20, respectively. The method for forming these via holes is not particularly limited, and may be a mechanical punch, a CO ２ The via holes can be formed using a laser, a UV laser, or the like. After forming these via holes, it is preferable to perform a desmear treatment such as oxygen plasma treatment, corona discharge treatment, or potassium permanganate treatment. The opening diameters of the via holes 21h, 22h, and 20h are not particularly limited, but are preferably 20 μm or more and 200 μm or less. In FIG. 10A , for the convenience of showing the internal structure in a plan view, the via holes are formed directly below the electrode pattern 3a, and there are some locations where the via holes do not appear to be formed as through-holes. However, in reality, the positions where the electrode pattern 3a and the via holes are formed are offset in the depth direction, and the via holes are formed as through-holes.

[0067] 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. The first metal powder contained in the conductive paste 50' is preferably made of Sn or an Sn alloy, and the second metal powder is preferably 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 will be referred to as the first metal, and the metal component contained in the second metal powder will be 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 wt % or more of Sn, more preferably 85 wt % 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 compound. 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, all of the Sn tends to remain without forming an intermetallic compound. Furthermore, when the proportion of Ni in the Cu—Ni alloy and the proportion of Mn in the Cu—Mn alloy exceed 15% by weight, all of the Sn tends to remain without forming an intermetallic compound.

[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 of the conductive paste 50' is preferably 30% by weight or more. That is, the proportion of the first metal in the metal components of 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 typically 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, these can also be used as thixotropic agents to which 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 have been added.

[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] 11 is a process diagram schematically illustrating an example of the step of laminating thermoplastic resin layers 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 other thermoplastic resin layers 20 are laminated to form a multilayer thermoplastic resin layer 3.

[0087] 12A and 12B are process diagrams schematically illustrating an example of the process of laminating the multilayer ceramic layer and the multilayer 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. 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] 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 multilayer thermoplastic resin layer 3 and the multilayer ceramic layer 2 are closely attached to each other by an anchor effect.

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

[0090] In this process, 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 described with reference to the drawings. Figures 13A to 13D are explanatory diagrams 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 the conductive paste 50' is heated in this state and reaches the melting point of the first metal powder 51, the first metal powder 51 melts and becomes the first metal 51a in a liquid phase.

[0094] 13C , when heat is further applied, the liquid phase first metal 51a reacts with the second metal powder 52 to form an intermetallic compound 60. Furthermore, the liquid phase first metal 51a spreads in a diffusive manner to the first electrode 31, and the liquid phase first metal 51a reacts with the metal constituting the first electrode 31 to form 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 intermetallic compound 61 from being formed over a wide area.

[0096] Thereafter, when the heating is completed and the temperature drops, as shown in Fig. 13D, the liquid-phase 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. Note that for convenience, the outline of the intermetallic compound 60 derived from the second metal powder 52 is shown by a dashed line in Fig. 13D, 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 an intermetallic compound 61 is also formed between the interlayer connection conductor 50 and the second electrode 32 .

[0098] Through the above steps, the laminated 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 schematically illustrating an example of the vicinity of an interlayer connection conductor in a laminated substrate according to the second embodiment of the present invention. The laminated substrate 201 shown in FIG. 14 has the same configuration as the laminated 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 need to contain 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 is [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 laminated substrate 201, the thickness of the first conductor layer 231a is preferably 5 μm or more and 10 μm or less, and the thickness of the second conductor layer 231b is preferably 5 μm or more and 10 μm or less.

[0101] The laminated substrate 201 having such a configuration can be manufactured by the same method as the method for manufacturing the laminated substrate according to the first embodiment of the present invention, except for the above-mentioned <LTCC green sheet laminate firing step> being modified as follows: That is, in the above-mentioned <LTCC green sheet laminate firing step>, when forming the first electrode 231, a conductive paste containing a large amount of unsintered ceramic particles is printed, and then a conductive paste containing a small amount of unsintered ceramic particles or no unsintered ceramic particles is printed thereon.

[0102] The conductive paste containing a large amount of unsintered ceramic particles preferably contains the same ceramic calcined powder as the LTCC green sheet in an amount of 5% to 70% by volume of the inorganic solids. The conductive paste containing a small amount of unsintered ceramic particles preferably contains the same ceramic calcined powder as the LTCC green sheet and / or alumina in an amount of 2% by volume or more of the inorganic solids.

[0103] When the laminated substrate 201 is manufactured using this method, 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. When the interlayer connection conductor 50 and the first electrode 231 are connected by liquid phase diffusion bonding, the first conductor layer 231a quickly becomes the intermetallic compound 261 because the weight percentage of the ceramic particles 70 contained in the first conductor layer 231a is low. When the intermetallic compound 261 reaches the second conductor layer 231b, the second conductor layer 231b is less likely to become the intermetallic compound 261 because the weight percentage of the ceramic particles 70 contained in the second conductor layer 231b is high. In other words, the intermetallic compound 261 is less likely to form 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 these reasons, it is possible to prevent the intermetallic compound 261 from diffusing excessively in the thickness direction. In addition, since the first conductor layer 231a easily becomes the intermetallic compound 261, it is possible to reliably connect the interlayer connection conductor 50 and the first electrode 231.

[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 schematically showing an example of the vicinity of an interlayer connection conductor of the laminated substrate according to the third embodiment of the present invention.

[0107] The laminated substrate 301 shown in FIG. 15 has the same configuration as the laminated substrate 1 according to the first embodiment, except for the following differences. The laminated substrate 301 does not include a first electrode 31. The ceramic layer 11 includes vias 302b that connect to the interlayer connection conductors 50. An intermetallic compound 361 is formed between the interlayer connection conductors 50 and the vias 302b. Ceramic particles 70 exist within 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 vias 302b. In the laminated substrate 301, the vias 302b function as conductors. In the laminated substrate 301 configured as described above, the intermetallic compound 361 contains ceramic particles, which reduces the difference between the linear expansion coefficients of the intermetallic compound 361 and the vias 302b. As a result, thermal stress on the intermetallic compound 361 can be reduced. This prevents the intermetallic compound 361 from being broken due to thermal stress.

[0108] The preferred material of the via 302b is the same as the preferred material of the first electrode 31. In particular, the via 302b is preferably 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 schematically showing an example of the vicinity of an interlayer connection conductor of a laminated substrate according to the fourth embodiment of the present invention. The laminated substrate 401 shown in Fig. 16 has the same configuration as the laminated substrate 301 according to the third embodiment, except for the following differences.

[0110] In the laminated substrate 401, the via 402b is connected to the first conductor layer 402b on the first thermoplastic resin layer 21 side. １ and the first conductor layer 402b １ a second conductor layer 402b laminated on the ２ Furthermore, the first conductor layer 402b １ The weight ratio of the ceramic particles 70 contained in the second conductor layer 402b is ２ The weight ratio of the ceramic particles 70 contained in the first conductor layer 402b is lower than that of the ceramic particles 70 contained in the first conductor layer 402b. １The first conductor layer 402b may not contain the ceramic particles 70. １ contains ceramic particles 70, the second conductor layer 402b ２ The weight of the ceramic particles 70 contained in the first conductor layer 402b １ It is preferable that the weight ratio of the ceramic particles 70 contained in the first conductor layer is [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 402b １ Since the weight ratio of the ceramic particles 70 contained in the first conductor layer 402b is low, １ The intermetallic compound 461 quickly becomes an intermetallic compound 461. The intermetallic compound 461 is formed on the second conductor layer 402b. ２ When the second conductor layer 402b ２ Since the weight ratio of the ceramic particles 70 contained in the second conductor layer 402b is high, ２ The first conductor layer 402b is unlikely to become an intermetallic compound 461. １ and the second conductor layer 402b ２ In FIG. 16, the first conductor layer 402b １ However, in the laminated substrate of the present invention, the first conductor layer may be entirely made of an intermetallic compound.

[0112] For this reason, it is possible to prevent the intermetallic compound 461 from excessively diffusing in the thickness direction. １ Since the metal conductor 50 easily becomes an intermetallic compound 461, the interlayer connection conductor 50 and the via 402b can be reliably connected.

[0113] First conductor layer 402b １ The preferred materials for the second conductor layer 402b are the same as those for the first conductor layer 231a. ２ The preferred materials for the second conductor layer 231b are the same as those 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 schematically showing an example of the vicinity of an interlayer connection conductor of a laminated substrate according to the fifth embodiment of the present invention. The laminated substrate 501 shown in Fig. 17 has the same configuration as the laminated substrate 1 according to the first embodiment, except for the following differences.

[0115] In the laminated 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 70. Furthermore, in the laminated substrate 501, the weight percentage of the ceramic particles 70 contained in the first electrode 531 is lower than the weight percentage of the ceramic particles 70 contained in the via 502b. Note that the first electrode 531 does not necessarily contain ceramic particles 70. Note that, when the first electrode 531 contains ceramic particles 70, 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, [weight of ceramic particles contained in the first electrode] / [weight of ceramic particles contained in the via], is preferably 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, and the preferred materials for the via 502b are the same as the preferred materials 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 weight ratio of the ceramic particles 70 contained in the first electrode 531 is low, so the first electrode 531 quickly becomes an intermetallic compound 561. When the intermetallic compound 61 reaches the via 502b, the second conductor layer 502b ２ Since the weight ratio of the ceramic particles 70 contained in the via 502b is high, the via 502b is less likely 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 these reasons, it is possible to prevent the intermetallic compound 561 from diffusing excessively in the thickness direction. In addition, since the first electrode 531 easily becomes the intermetallic compound 561, it is possible to reliably connect the interlayer connection conductor 50 and the first electrode 531.

[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), in which the intermetallic compound is formed so as to penetrate into a portion 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, 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 the ratio of the total length of the second line to the total length of the first line and the second line 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 percentage of the ceramic particles included in the first conductor layer is lower than the weight percentage 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), in which 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.

[0131] 1, 101, 201, 301, 401, 501 Laminated substrate 2 Multilayer ceramic layer 2' LTCC green sheet laminate 2a, 2a', 3a Electrode pattern 2b, 3b, 302b, 402b, 502b Via 3 Multilayer thermoplastic resin layer 3a' Metal foil 10, 11 Ceramic layer 10' LTCC green sheet 10h', 20h, 21h, 22h, Via hole 20 Thermoplastic resin layer 21 First thermoplastic resin layer 21a First main surface of first thermoplastic resin layer 21b Second main surface of first thermoplastic resin layer 22 Second thermoplastic resin layer 31, 231, 531 First electrode 31' Electrode pattern 31c Outline of first electrode 32 Second electrode 50 Interlayer connecting conductor 50' Conductive paste 51 First metal powder 51a Liquid phase first metal 52 Second metal powder 60, 61, 62, 261, 361, 461, 561 Intermetallic compound 70 Ceramic particle 70' Unsintered ceramic particle 71 First ceramic particle 231a, 402b １ First conductor layer 231b, 402b ２ 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 major surface; an interlayer connection conductor is disposed in the via hole; The ceramic layer has a conductor portion formed thereon, the conductor portion being connected to the interlayer connection conductor, 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 laminated 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 a ratio of an area of ​​the intermetallic compound taken up by the ceramic particles in a cross section perpendicular to the first main surface is 0.1% or more and 20.0% or less.

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, 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 , wherein the conductor portion is an electrode.

6. The laminated substrate according to claim 1 , 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 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.