Multilayer substrate

Abstract

A laminated substrate 1 comprises: a resin layer 10A that has one pair of main surfaces 10Aa, 10Ab facing each other in the thickness direction; a conductor layer 20A that is adjacent to the resin layer 10A on at least one main surface side; and an interlayer connection conductor 30A that penetrates the resin layer 10A in the thickness direction and is connected to the conductor layer 20A. The resin layer 10A includes a first resin material 11a and a second resin material 11b formed from a thermoplastic resin. The Young's modulus of the second resin material 11b is lower than the Young's modulus of the first resin material 11a. The second resin material 11b is dug into the interlayer connection conductor 30A in a plane direction perpendicular to the thickness direction. In the resin layer 10A, the first resin material 11a is dug into the second resin material 11b that is dug into the interlayer connection conductor 30A.

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, in a multilayer wiring substrate in which via holes are formed in an interlayer insulating layer that separates a lower conductor layer and an upper conductor layer, and via conductors that connect the lower conductor layer and the upper conductor layer are formed in the via holes, the surface of the interlayer insulating layer is a rough surface, the via holes open at the rough surface of the interlayer insulating layer, and an opening edge surrounding the via holes is a stepped portion that is lower than a peripheral region of the opening edge, and a surface roughness of the stepped portion is larger than a surface roughness of the peripheral region. A multilayer wiring substrate is disclosed.

Prior Art Documents

Patent Documents

[0006] However, the present inventors have found that in the multilayer wiring board described in Patent Document 1, the surface roughness of the via holes formed in the interlayer insulating layer is small, resulting in insufficient adhesion between the via conductors formed in the via holes and the interlayer insulating layer. Consequently, the via conductors tend to peel off from the interlayer insulating layer.

[0007] The present invention was made to solve the above problems and aims to provide a laminated substrate in which the interlayer connecting conductor is less likely to peel off from the resin layer. [Means for solving the problem]

[0008] The laminated substrate of the present invention comprises a resin layer having a pair of main surfaces facing each other in the thickness direction, a conductor layer adjacent to at least one of the main surfaces of the resin layer, and an interlayer connecting conductor connected to the conductor layer while penetrating the resin layer in the thickness direction, wherein the resin layer comprises a first resin material and a second resin material made of thermoplastic resin, the Young's modulus of the second resin material is lower than that of the first resin material, the second resin material bites into the interlayer connecting conductor in a planar direction perpendicular to the thickness direction, and the first resin material bites into the second resin material that bites into the interlayer connecting conductor within the resin layer. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminated substrate in which the interlayer connecting conductor is less likely to peel off from the resin layer. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 1 of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing an enlarged version of the laminated substrate shown in Figure 1, and is a cross-sectional view illustrating a method for determining whether or not the second resin material is embedded in the interlayer connecting conductor. [Figure 3] Figure 3 is a schematic cross-sectional view showing an enlarged version of the laminated substrate shown in Figure 1, and is a cross-sectional view intended to explain the method for determining the protrusion angle of the convex portion. [Figure 4] Figure 4 is a schematic cross-sectional view showing the process of manufacturing a resin sheet with a conductive layer in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention. [Figure 5] Figure 5 is a schematic cross-sectional view showing the step of forming through holes in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention. [Figure 6] Figure 6 is a schematic cross-sectional view showing a step of filling a conductive paste in an example of a method for manufacturing a laminated substrate according to Embodiment 1 of the present invention. [Figure 7] Figure 7 is a schematic cross-sectional view showing the process of forming an interlayer connecting conductor in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention. [Figure 8] Figure 8 is an example of a cross-sectional image showing an enlarged view of the laminated substrate of Embodiment 1 of the present invention. [Figure 9] Figure 9 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 2 of the present invention. [Figure 10] Figure 10 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 3 of the present invention. [Figure 11] Figure 11 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 4 of the present invention. [Figure 12] Figure 12 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 5 of the present invention. [Modes for carrying out the invention]

[0011] Hereinafter, the laminated substrate of the present invention will be described. Note that the present invention is not limited to the following configurations and may be appropriately modified without departing from the gist of the present invention. Also, a combination of a plurality of the individual preferred configurations described below is also within the scope of the present invention.

[0012] Each of the embodiments shown below is illustrative, and it is needless to say that partial substitution or combination of the configurations shown in different embodiments is possible. In the embodiments after the second embodiment, descriptions of matters common to the first embodiment will be omitted, and different points will be mainly described. In particular, for the same operational effects due to the same configurations, they will not be sequentially mentioned for each embodiment.

[0013] In the following description, when not particularly distinguishing each embodiment, it is simply referred to as "the laminated substrate of the present invention".

[0014] The drawings shown below are schematic diagrams, and their dimensions, scales of aspect ratios, etc. may differ from those of actual products.

[0015] In this specification, unless otherwise specified, terms indicating the relationship between elements (e.g., "parallel", "perpendicular", etc.) and terms indicating the shape of elements do not only mean a strictly literal aspect but also mean a substantially equivalent range, for example, a range including a difference of about several percent.

[0016] The laminated substrate of the present invention includes a resin layer having a pair of main surfaces facing each other in the thickness direction, a conductor layer adjacent to at least one of the main surface sides of the resin layer, and an interlayer connection conductor penetrating the resin layer in the thickness direction and connected to the conductor layer. The resin layer includes a first resin material and a second resin material made of a thermoplastic resin. The Young's modulus of the second resin material is lower than that of the first resin material. The second resin material bites into the interlayer connection conductor in a plane direction perpendicular to the thickness direction, and the first resin material bites into the second resin material that has bitten into the interlayer connection conductor within the resin layer.

[0017] [Embodiment 1] FIG. 1 is a cross-sectional view schematically showing an example of a laminated substrate according to Embodiment 1 of the present invention.

[0018] The laminated substrate 1 shown in FIG. 1 has a resin layer 10A, a conductor layer 20A, and an interlayer connection conductor 30A. ​​​​​​​​​​​​​​​​​​​​​​​​​​Copolymers of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are generally called type II fully aromatic polyesters (also known as type 1.5 fully aromatic polyesters). Type II fully aromatic polyesters are less susceptible to hydrolysis than type III partially aromatic polyesters, making them preferable as constituent materials for the laminated substrate 1. Furthermore, because type II fully aromatic polyesters have a low dielectric loss tangent due to their naphthalene ring origin, they contribute to reducing electrical energy loss in the resin layer 10A of the laminated substrate 1.

[0026] When the first resin material 11a is made of a liquid crystal polymer, the liquid crystal polymer constituting the first resin material 11a may further contain a type I fully aromatic polyester in addition to a type II fully aromatic polyester, or it may further contain a type III partially aromatic polyester, or it may further contain a type I fully aromatic polyester and a type III partially aromatic polyester.

[0027] The structure (type) of each monomer constituting the liquid crystal polymer can be analyzed by reaction pyrolysis gas chromatography-mass spectrometry (reaction pyrolysis GC-MS).

[0028] The first resin material 11a may be made of a thermosetting resin.

[0029] It is preferable that the thermal expansion coefficient of the first resin material 11a in the planar direction is smaller than the thermal expansion coefficient of the conductive layer 20A in the planar direction. In this case, it is preferable that the difference between the thermal expansion coefficient of the first resin material 11a in the planar direction and the thermal expansion coefficient of the conductive layer 20A in the planar direction is 2 ppm / °C or more and 10 ppm / °C or less.

[0030] The second resin material 11b is made of a thermoplastic resin.

[0031] Examples of thermoplastic resins constituting the second resin material 11b include perfluoroalkoxyalkanes (PFA) (fluorine-containing resins), thermoplastic polyimides (TPI), polyphenylene sulfides (PPS), polyether ether ketones (PEEK), polyphenylene ethers (PPE), polymethylpentene (PMP), crosslinked polyethylene (XLPE), and polynorbornene (PNB).

[0032] The second resin material 11b is preferably made of a perfluoroalkoxyalkane. Since perfluoroalkoxyalkanes have a lower dielectric constant than liquid crystal polymers, the dielectric properties of the laminated substrate 1 in the high-frequency range are more easily improved when the second resin material 11b is made of a perfluoroalkoxyalkane. In addition, since perfluoroalkoxyalkanes have low hygroscopicity, similar to liquid crystal polymers, the dielectric properties of the laminated substrate 1 are less likely to change due to moisture absorption when the second resin material 11b is made of a perfluoroalkoxyalkane. Furthermore, since perfluoroalkoxyalkanes have a high heat resistance temperature of 260°C or higher, the laminated substrate 1 is less likely to be damaged when the second resin material 11b is made of a perfluoroalkoxyalkane, for example, when the laminated substrate 1 is incorporated into electronic equipment by reflow soldering.

[0033] Alternatively, it is preferable that the second resin material 11b is made of polyphenylene ether. Since polyphenylene ether has a low dielectric constant and dielectric loss tangent, similar to perfluoroalkoxyalkanes, the dielectric properties of the laminated substrate 1 in the high-frequency range are easily improved when the second resin material 11b is made of polyphenylene ether. In addition, since polyphenylene ether has low hygroscopicity, similar to perfluoroalkoxyalkanes, the dielectric properties of the laminated substrate 1 are less likely to change due to moisture absorption when the second resin material 11b is made of polyphenylene ether. Furthermore, since polyphenylene ether has a lower coefficient of thermal expansion than perfluoroalkoxyalkanes, the laminated substrate 1 is less prone to dimensional changes when the second resin material 11b is made of polyphenylene ether. Furthermore, since polyphenylene ether has a higher tensile strength (e.g., tensile elongation at break) than perfluoroalkoxyalkanes, the strength of the laminated substrate 1 is increased when the second resin material 11b is made of polyphenylene ether.

[0034] The type of resin material present in the resin layer is identified as follows: First, the laminated substrate is polished to expose a cross-section along the thickness direction. Then, the type of resin material present in the resin layer is identified by analyzing the cross-section of the laminated substrate using a micro Fourier transform infrared spectrophotometer (micro FT-IR).

[0035] It is preferable that the second resin material 11b is dispersed in the first resin material 11a. In this case, the second resin material 11b functions as a filler for the first resin material 11a and is more easily constrained by the first resin material 11a.

[0036] The Young's modulus of the second resin material 11b is lower than that of the first resin material 11a. In other words, the second resin material 11b is more easily deformed by external forces (has lower rigidity) than the first resin material 11a.

[0037] The relative magnitudes of the Young's moduli of the resin materials present in the resin layer can be determined by one of the following methods. (1) Determine the relative magnitudes of the Young's moduli of the resin materials by looking up the general Young's moduli of the resin materials identified by the method described above in publicly available literature such as dictionaries. (2) An atomic force microscope (AFM), a type of scanning probe microscope (SPM), is used to measure the Young's modulus of the resin material present in the resin layer, thereby determining the relative magnitudes of the Young's moduli of the resin materials. (3) When polishing the laminated substrate (resin layer), the relative magnitudes of the Young's modulus of the resin materials are determined by checking how easy or difficult the resin material is to polish. Specifically, resin materials that are easy to polish are judged to have a lower Young's modulus than resin materials that are difficult to polish. In other words, resin materials that are difficult to polish are judged to have a higher Young's modulus than resin materials that are easy to polish.

[0038] Methods (1) and (2) above allow for the determination of the relative magnitudes of the Young's moduli of the resin materials by using the absolute value of the Young's modulus of the resin materials. On the other hand, method (3) above allows for the determination of the relative magnitudes of the Young's moduli of the resin materials without using the absolute value of the Young's modulus of the resin materials.

[0039] The second resin material 11b is preferably flattened in shape.

[0040] A resin material being flattened means that, when viewed in cross-section along the thickness direction of the resin layer, the aspect ratio of the resin material is 3 or greater, and preferably, the aspect ratio of the resin material is 3 or greater and 30 or less.

[0041] The aspect ratio of a resin material is determined as follows: First, the laminated substrate is polished to expose the cross-section along the thickness direction. Next, a scanning electron microscope (SEM) is used to image the cross-section along the thickness direction of the resin layer. Subsequently, image analysis software is used to draw an ellipse with the smallest area circumscribing the resin material in the cross-sectional image of the resin layer. Then, the dimension of the major axis / the dimension of the minor axis of the drawn ellipse is calculated and defined as the aspect ratio of the resin material.

[0042] The melting point of the second resin material 11b is preferably lower than the melting point of the first resin material 11a. In this case, the difference between the melting points of the first resin material 11a and the second resin material 11b is preferably 10°C or more and 200°C or less.

[0043] The melting point of a resin material is determined as follows: First, the resin layer is removed from the laminated substrate by methods such as peeling or etching. Then, the target resin material is extracted from the resin layer by methods such as scraping. After that, the melting point of the target resin material is measured using a differential scanning calorimeter (DSC). In cases where the melting point of the target resin material cannot be clearly measured using the above method, or when the target resin material is an amorphous resin material, the glass transition temperature (Tg) may be used as a substitute.

[0044] It is preferable that the thermal expansion coefficient of the second resin material 11b in the planar direction is greater than the thermal expansion coefficient of the first resin material 11a in the planar direction. In this case, it is preferable that the difference between the thermal expansion coefficient of the first resin material 11a in the planar direction and the thermal expansion coefficient of the second resin material 11b in the planar direction is 30 ppm / °C or more and 120 ppm / °C or less.

[0045] It is preferable that the thermal expansion coefficient of the first resin material 11a in the planar direction is smaller than the thermal expansion coefficient of the conductive layer 20A in the planar direction. In this case, it is preferable that the difference between the thermal expansion coefficient of the first resin material 11a in the planar direction and the thermal expansion coefficient of the conductive layer 20A in the planar direction is 2 ppm / °C or more and 10 ppm / °C or less.

[0046] It is preferable that the thermal expansion coefficient of the second resin material 11b in the planar direction is greater than the thermal expansion coefficient of the conductive layer 20A in the planar direction. In this case, it is preferable that the difference between the thermal expansion coefficient of the second resin material 11b in the planar direction and the thermal expansion coefficient of the conductive layer 20A in the planar direction is 30 ppm / °C or more and 110 ppm / °C or less.

[0047] Furthermore, if the conductive layer 20A is made of copper foil, the coefficient of thermal expansion of the conductive layer 20A in the planar direction is approximately 16 ppm / °C.

[0048] The thermal expansion coefficient in the planar direction of the resin material present in the resin layer is determined as follows. First, the target resin layer is extracted from the laminated substrate by removing the conductive layer, etc., by methods such as peeling or etching. Then, the thermal expansion coefficient in the planar direction of the target resin layer is measured by thermomechanical analysis (TMA). In this case, for example, a sample of the resin layer with a length of 20 mm and a width of 4 mm is cut out, and under measurement conditions of tensile mode, a chuck distance of 10 mm, a load of 5 g, a heating rate of 40 °C / min, and a cooling rate of 10 °C / min, the resin layer sample is heated and then cooled, and the change in the chuck distance in the temperature range from 100 °C to 50 °C during the cooling process is measured to determine the thermal expansion coefficient in the planar direction of the target resin layer sample. Next, the elastic modulus of the target resin layer sample is measured by dynamic viscoelasticity measurement (DMA) in tensile mode. Meanwhile, the type of resin material present in the target resin layer sample is identified for the cross section along the thickness direction of the target resin layer sample using the method described above. Then, for example, using image analysis software, the area ratio of the target resin material (e.g., the first resin material or the second resin material) in the cross-section of the target resin layer sample is measured. In addition, the elastic modulus of the target resin material in the cross-section of the target resin layer sample is measured using the elastic modulus measurement mode of a scanning probe microscope (SPM). Based on the measurement data obtained in this way, the thermal expansion coefficient in the planar direction of the target resin material is calculated from the thermal expansion coefficient in the planar direction of the target resin layer sample, according to the area ratio and elastic modulus of the target resin material. For example, when using a sample of a resin layer 10A containing a first resin material 11a and a second resin material 11b, if the coefficient of thermal expansion in the planar direction of the first resin material 11a is CTE1 (unit: ppm / °C), the coefficient of thermal expansion in the planar direction of the second resin material 11b is CTE2 (unit: ppm / °C), the coefficient of thermal expansion in the planar direction of the resin layer 10A sample is CTEt (unit: ppm / °C), the elastic modulus of the first resin material 11a is E1 (unit: GPa), the elastic modulus of the second resin material 11b is E2 (unit: GPa), the elastic modulus of the resin layer 10A sample is Et (unit: GPa), the area ratio of the first resin material 11a is V1 (unit: %), and the area ratio of the second resin material 11b is V2 (unit: %), then the following equation (A) holds true as a relationship where the stress is neutral. CTE1×E1×V1+CTE2×E2×V2=CTEt×Et×(V1+V2)...(A) Here, CTEt, E1, E2, Et, V1, and V2 are measured by the method described above. Furthermore, CTE2 is measured by the following method. First, the first resin material 11a is removed from the resin layer 10A sample by strong alkali treatment. Then, the second resin material 11b (a lump of multiple irregular shapes) taken from the resin layer 10A sample is subjected to a heat press process (pressure set to, for example, 2 MPa or more and 3 MPa or less) at a temperature 20°C lower than the melting point of the second resin material 11b and below the melting point of the second resin material 11b (i.e., (Tm2-20) or more and Tm2 or less) to produce a resin sheet made of the second resin material 11b with a thickness of 50 μm or more and 500 μm or less. After that, the coefficient of thermal expansion CTE2 in the planar direction of the resin sheet made of the second resin material 11b is measured by thermomechanical analysis. Using CTE2, CTEt, E1, E2, Et, V1, and V2 obtained as described above, CTE1 can be calculated from the following equation (B), which is obtained by rearranging equation (A) above. CTE1=[CTEt×Et×(V1+V2)-CTE2×E2×V2] / [E1×V1]...(B)

[0049] The coefficient of thermal expansion in the planar direction of a conductive layer is determined as follows: First, the conductive layer in question is removed from the laminated substrate by a method such as delamination. Then, the coefficient of thermal expansion in the planar direction of the conductive layer is measured by thermomechanical analysis. When measuring the coefficient of thermal expansion in the planar direction of the conductive layer, the same measurement conditions as when measuring the coefficient of thermal expansion in the planar direction of a resin layer are used.

[0050] The relative permittivity of the second resin material 11b is preferably lower than that of the first resin material 11a.

[0051] The relative permittivity of the resin material present in the resin layer is determined as follows. For example, when a resin layer 10A containing a first resin material 11a and a second resin material 11b is used as a sample, first, the second resin material 11b is extracted by strongly alkali treatment of the resin layer 10A. Then, the relative permittivity of the second resin material 11b is measured using a resin sheet sample obtained by molding the extracted second resin material 11b into a sheet with a thickness of 50 μm or more and 500 μm or less, using the dielectric resonator method (mode: TE011 mode, frequency range: 12 GHz or more, 60 GHz or less). Next, the relative permittivity of the resin layer 10A is measured using the dielectric resonator method under the same conditions as above. Furthermore, the three-dimensional structure of the first resin material 11a and the second resin material 11b in the resin layer 10A is identified using an X-ray CT device, and then the volume ratio of the first resin material 11a and the second resin material 11b in the resin layer 10A is measured using analysis software. Then, the relative permittivity of the first resin material 11a is calculated from the relative permittivity of the resin layer 10A and the relative permittivity of the second resin material 11b, as measured by the method described above, according to the volume ratio of the first resin material 11a and the second resin material 11b in the resin layer 10A.

[0052] It is preferable that the dielectric loss tangent of the second resin material 11b is lower than that of the first resin material 11a.

[0053] The dielectric loss tangent of the resin material present in the resin layer is determined as follows. For example, when a resin layer 10A containing a first resin material 11a and a second resin material 11b is used as a sample, first, the second resin material 11b is extracted by strongly alkali treatment of the resin layer 10A. Then, the dielectric loss tangent of the second resin material 11b is measured using a resin sheet sample obtained by molding the extracted second resin material 11b into a sheet with a thickness of 50 μm or more and 500 μm or less, using the dielectric resonator method (mode: TE011 mode, frequency range: 12 GHz or more, 60 GHz or less). Next, the dielectric loss tangent of the resin layer 10A is measured using the dielectric resonator method under the same conditions as above. Furthermore, the three-dimensional structure of the first resin material 11a and the second resin material 11b in the resin layer 10A is identified using an X-ray CT device, and then the volume ratio of the first resin material 11a and the second resin material 11b in the resin layer 10A is measured using analysis software. Then, from the dielectric loss tangent of the resin layer 10A and the dielectric loss tangent of the second resin material 11b, measured by the method described above, the dielectric loss tangent of the first resin material 11a is calculated according to the volume ratio of the first resin material 11a and the second resin material 11b in the resin layer 10A.

[0054] It is preferable that the adhesion between the second resin materials 11b (e.g., tensile elongation at break) is higher than the adhesion between the first resin materials 11a (e.g., tensile elongation at break). The first resin material 11a mainly plays a role in providing rigidity to the resin layer 10A and suppressing dimensional changes in the resin layer 10A. On the other hand, the second resin material 11b mainly plays a role in improving the dielectric properties of the resin layer 10A and providing flexibility to the resin layer 10A. Therefore, if the adhesion between the second resin materials 11b is higher than the adhesion between the first resin materials 11a, the bendability of the laminated substrate 1 is more likely to improve.

[0055] The relative strength of the adhesion (e.g., tensile elongation at break) between identical resin materials present in a resin layer is determined as follows. First, tensile stress is applied to the resin layer in the laminated substrate by pulling it. In this case, for example, after removing the resin layer from the laminated substrate, a tensile test of the resin layer is performed in accordance with "JIS K 7127-1999". Then, it is confirmed which resin material breaks first when tensile stress is applied to the resin layer. In this case, if the first resin material 11a breaks before the second resin material 11b breaks, it is determined that the adhesion (e.g., tensile elongation at break) between the second resin materials 11b is higher than the adhesion (e.g., tensile elongation at break) between the first resin materials 11a.

[0056] The resin layer 10A may further contain other materials (e.g., resin materials) in addition to the first resin material 11a and the second resin material 11b. In this case, for example, the first resin material 11a has the largest content in the resin layer 10A, followed by the second resin material 11b. The content ratio of the resin materials is determined, for example, by measuring the area ratio of the resin material in a cross-sectional image along the thickness direction of the resin layer using image analysis software.

[0057] The conductor layer 20A is adjacent to one of the main surfaces of the resin layer 10A. In the example shown in Figure 1, the conductor layer 20A is adjacent to the first main surface 10Aa of the resin layer 10A.

[0058] The conductor layer 20A may be a planar shape spread over the entire first main surface 10Aa of the resin layer 10A, or it may be a patterned shape that is patterned for wiring, etc., on a part of the first main surface 10Aa of the resin layer 10A.

[0059] Examples of materials that make up the conductive layer 20A include copper, silver, aluminum, stainless steel, nickel, gold, and alloys containing at least one of these metals.

[0060] The conductive layer 20A is made of, for example, a metal foil, and preferably a copper foil. In this case, metals other than copper may be present on the surface of the copper foil.

[0061] The thickness of the conductor layer 20A is preferably 1 μm or more and 35 μm or less, and more preferably 6 μm or more and 18 μm or less.

[0062] The interlayer connecting conductor 30A penetrates the resin layer 10A in the thickness direction and is connected to the conductor layer 20A. In the example shown in Figure 1, the interlayer connecting conductor 30A penetrates the resin layer 10A in the thickness direction but does not penetrate the conductor layer 20A in the thickness direction and is connected to the conductor layer 20A.

[0063] When viewing a cross-section along the thickness direction, the width of the interlayer connecting conductor 30A may decrease, increase, or remain constant from the conductor layer 20A side toward the opposite side, as shown in Figure 1. In other words, when viewing a cross-section perpendicular to the thickness direction, the cross-sectional area of ​​the interlayer connecting conductor 30A may decrease, increase, or remain constant from the conductor layer 20A side toward the opposite side.

[0064] The interlayer connecting conductor 30A is formed, for example, by filling a through-hole that penetrates the resin layer 10A in the thickness direction with conductive paste and then performing heat treatment, plating treatment on the inner wall, or sputtering treatment on the inner wall.

[0065] When the interlayer connecting conductor 30A is formed by heat treatment of a conductive paste, examples of metals that can be included in the interlayer connecting conductor 30A include copper, tin, and silver. In particular, it is preferable that the interlayer connecting conductor 30A contains copper, and more preferably that it contains both copper and tin. For example, if the interlayer connecting conductor 30A contains copper and tin and the conductor layer 20A is made of copper foil, the interlayer connecting conductor 30A undergoes an alloying reaction with the conductor layer 20A at low temperatures, making it easier for the two to conduct electricity.

[0066] When the interlayer connecting conductor 30A is formed by heat treatment of a conductive paste, the resin contained in the interlayer connecting conductor 30A preferably includes at least one thermosetting resin selected from the group consisting of epoxy resin, phenolic resin, polyimide resin, silicone resin or a 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.

[0067] When the interlayer connecting conductor 30A is formed by a plating process, examples of metals constituting the interlayer connecting conductor 30A include copper, tin, and silver. Among these, it is preferable that the interlayer connecting conductor 30A contains copper.

[0068] When the interlayer connecting conductor 30A is formed by sputtering, examples of metals constituting the interlayer connecting conductor 30A include copper, tin, and silver. Among these, it is preferable that the interlayer connecting conductor 30A contains copper.

[0069] The laminated substrate 1 may further have a conductive layer 20B.

[0070] In the example shown in Figure 1, the conductive layer 20B is adjacent to the second main surface 10Ab side of the resin layer 10A.

[0071] In the example shown in Figure 1, the conductor layer 20B is connected to the interlayer connecting conductor 30A. In other words, the conductor layer 20B is electrically connected to the conductor layer 20A via the interlayer connecting conductor 30A.

[0072] The conductor layer 20B may be a planar shape that extends over the entire second main surface 10Ab of the resin layer 10A, or it may be a patterned shape that is patterned for wiring, etc., on a part of the second main surface 10Ab of the resin layer 10A.

[0073] The constituent material of the conductor layer 20B may be the same as or different from the constituent material of the conductor layer 20A.

[0074] The thickness of the conductor layer 20B may be the same as or different from the thickness of the conductor layer 20A.

[0075] In the laminated substrate 1, the second resin material 11b is embedded in the interlayer connecting conductor 30A in a planar direction perpendicular to the thickness direction (left-right direction in Figure 1). In the example shown in Figure 1, the second resin material 11b protrudes further toward the interlayer connecting conductor 30A than the first resin material 11a in the planar direction. As a result, the surface of the resin layer 10A on the side facing the interlayer connecting conductor 30A is uneven. The interlayer connecting conductor 30A is provided to follow the unevenness of the surface of the resin layer 10A on the side facing the interlayer connecting conductor 30A. Specifically, the interlayer connecting conductor 30A is provided to be in contact with the first resin material 11a and the second resin material 11b.

[0076] In the laminated substrate 1, the second resin material 11b is embedded in the interlayer connecting conductor 30A, thereby exhibiting an anchoring effect. As a result, in the laminated substrate 1, the interlayer connecting conductor 30A is less likely to peel off from the resin layer 10A (especially the second resin material 11b).

[0077] Furthermore, in the laminated substrate 1, the second resin material 11b, which is embedded in the interlayer connecting conductor 30A, has a lower Young's modulus than the first resin material 11a, meaning it is more easily deformed by external forces than the first resin material 11a. Therefore, even if stress (thermal stress, bending stress, etc.) is generated at the interface between the resin layer 10A and the interlayer connecting conductor 30A by heating or bending the laminated substrate 1, the second resin material 11b acts as a buffer, making it easier to relieve the stress. In particular, in the laminated substrate 1, since the second resin material 11b is made of thermoplastic resin, even if stress is generated at the interface between the resin layer 10A and the interlayer connecting conductor 30A by heating the laminated substrate 1, the second resin material 11b acts as a buffer, making it easier to relieve the stress. As a result, in the laminated substrate 1, even if stress is generated at the interface between the resin layer 10A and the interlayer connecting conductor 30A, the occurrence of cracks in the interlayer connecting conductor 30A is suppressed, thus reducing the reliability of the connection of the interlayer connecting conductor 30A.

[0078] Whether or not the second resin material 11b is embedded in the interlayer connecting conductor 30A is determined as follows.

[0079] Figure 2 is a schematic cross-sectional view showing an enlarged version of the laminated substrate shown in Figure 1, and is a cross-sectional view illustrating a method for determining whether or not the second resin material is embedded in the interlayer connecting conductor.

[0080] First, the laminated substrate 1 is polished to expose a cross-section along the thickness direction, as shown in Figure 2. Next, a scanning electron microscope is used to image the cross-section of the laminated substrate 1 along the thickness direction. Then, in the obtained cross-sectional image of the laminated substrate 1, endpoints E1 and E2 are determined at the interface between the resin layer 10A and the conductor layer 20B, located on the interlayer connecting conductor 30A side in the plane direction, and a straight line L1 is drawn connecting endpoints E1 and E2. Subsequently, the midpoint F1 of line L1 is determined, and a straight line L2 perpendicular to line L1 is drawn from midpoint F1. After that, the distance G1 in the plane direction from line L2 to the resin layer 10A is measured while changing the position in the thickness direction. At this time, if the distance G1 changes from decreasing to increasing, it is determined that the resin layer 10A is indented into the interlayer connecting conductor 30A. Furthermore, by confirming the presence of the second resin material 11b in the portion where the resin layer 10A has penetrated the interlayer connecting conductor 30A using the method described above, it is determined that the second resin material 11b has penetrated the interlayer connecting conductor 30A.

[0081] Furthermore, in determining whether the second resin material 11b is embedded in the interlayer connecting conductor 30A, instead of drawing a straight line L1 connecting endpoints E1 and E2 as described above, two endpoints located on the interlayer connecting conductor 30A side in the planar direction at the interface between the resin layer 10A and the conductor layer 20A may be determined, and a straight line connecting these two endpoints may be drawn. After that, the determination of whether the second resin material 11b is embedded in the interlayer connecting conductor 30A can be made in the same manner as described above.

[0082] Furthermore, in the laminated substrate 1, the first resin material 11a is embedded within the resin layer 10A into the second resin material 11b, which is embedded in the interlayer connecting conductor 30A. More precisely, the second resin material 11b embedded in the interlayer connecting conductor 30A has an embedded portion 11ba that is substantially embedded in the interlayer connecting conductor 30A and a non-embedded portion 11bb that is not substantially embedded in the interlayer connecting conductor 30A. The first resin material 11a is embedded in the non-embedded portion 11bb within the resin layer 10A.

[0083] The embodiments in which the first resin material 11a is embedded in the second resin material 11b include an embodiment in which the first resin material 11a is embedded in one second resin material 11b, and an embodiment in which the first resin material 11a is embedded in the gaps between multiple second resin materials 11b that are partially in contact with each other.

[0084] In the laminated substrate 1, the first resin material 11a is embedded within the resin layer 10A of the second resin material 11b, which is embedded in the interlayer connecting conductor 30A, making it easier for the first resin material 11a to support the second resin material 11b. Here, if the first resin material 11a is made of a thermosetting resin, it will be easier for the first resin material 11a to support the second resin material 11b even when heated. In this way, in the laminated substrate 1, when the first resin material 11a supports the second resin material 11b, the second resin material 11b becomes less likely to move when it is embedded in the interlayer connecting conductor 30A. Therefore, in the laminated substrate 1, the anchoring effect of the second resin material 11b is further enhanced, and as a result, the interlayer connecting conductor 30A becomes even less likely to peel off from the resin layer 10A.

[0085] Whether the first resin material 11a is embedded in the second resin material 11b, which is embedded in the interlayer connecting conductor 30A, within the resin layer 10A can be determined by examining a cross-section along the thickness direction of the laminated substrate 1 using a scanning electron microscope.

[0086] In the laminated substrate 1, when viewing a cross-section along the thickness direction, if the portion where the second resin material 11b bites into the interlayer connecting conductor 30A is defined as a protrusion 12 (the same portion as the biting portion 11ba), it is preferable that the total number of protrusions 12 at the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A (the left and right interfaces in Figure 1) is between 3 and 20. In this case, when viewing the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A as a whole, the anchoring effect by the protrusions 12 (second resin material 11b) is further enhanced, making it even more difficult for the interlayer connecting conductor 30A to peel off from the resin layer 10A.

[0087] If the total number of protrusions 12 at a pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is less than three, the number of protrusions 12 that function as anchors will be reduced, and therefore the anchoring effect of the protrusions 12 may not be fully realized.

[0088] If the total number of protrusions 12 at a pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is greater than 20, the spacing between the protrusions 12 becomes narrower, making it difficult for the conductor layer 20A to penetrate between the protrusions 12. As a result, the anchoring effect of the protrusions 12 may not be fully realized.

[0089] In the laminated substrate 1, it is preferable that the number of protrusions 12 at one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is between 2 and 10. In this case, when looking at one interface between the resin layer 10A and the interlayer connecting conductor 30A in the laminated substrate 1, the anchoring effect by the protrusions 12 is further enhanced, making it even more difficult for the interlayer connecting conductor 30A to peel off from the resin layer 10A.

[0090] If the number of protrusions 12 at one interface between the resin layer 10A and the interlayer connecting conductor 30A is less than two, the number of protrusions 12 that function as anchors will be reduced, and therefore the anchoring effect of the protrusions 12 may not be fully realized.

[0091] If the number of protrusions 12 at one interface between the resin layer 10A and the interlayer connecting conductor 30A is greater than 10, the spacing between the protrusions 12 becomes narrower, making it difficult for the conductor layer 20A to penetrate between the protrusions 12. As a result, the anchoring effect of the protrusions 12 may not be fully realized.

[0092] Similarly, it is preferable that the number of protrusions 12 at the other interface of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is between 2 and 10.

[0093] Based on the above, it is preferable that the number of protrusions 12 at each interface between the resin layer 10A and the interlayer connecting conductor 30A is between 2 and 10.

[0094] In the laminated substrate 1, when viewing a cross-section along the thickness direction, if the portion where the second resin material 11b bites into the interlayer connecting conductor 30A is defined as the protrusion portion 12 (the same portion as the biting portion 11ba), then the protrusion angle at which the protrusion portion 12 protrudes toward the interlayer connecting conductor 30A is preferably 20° or more and 80° or less.

[0095] The projection angle of the protrusion portion 12 is determined as follows.

[0096] Figure 3 is a schematic cross-sectional view showing an enlarged version of the laminated substrate shown in Figure 1, and is a cross-sectional view intended to explain the method for determining the protrusion angle of the convex portion.

[0097] First, in the laminated substrate 1, as shown in Figure 3, when viewing a cross-section along the thickness direction, the portion where the second resin material 11b bites into the interlayer connecting conductor 30A is defined as the protrusion 12 (the same portion as the biting portion 11ba). Next, one endpoint of the protrusion 12 in the thickness direction is defined as the first point P1, the other endpoint of the protrusion 12 in the thickness direction is defined as the second point P2, and the vertex of the protrusion 12 in the plane direction is defined as the third point P3. Then, the angle θ between the straight line M1 connecting the first point P1 and the third point P3 and the straight line M2 connecting the second point P2 and the third point P3 is defined as the projection angle of the protrusion 12.

[0098] In the laminated substrate 1, when the protrusion angle θ of the protrusion portion 12 is 20° or more and 80° or less, the anchoring effect of the protrusion portion 12 is further enhanced, making it even more difficult for the interlayer connecting conductor 30A to peel off from the resin layer 10A.

[0099] If the protrusion angle θ of the protrusion 12 is less than 20°, the tip of the protrusion 12 may become too sharp, which can easily reduce the strength of the protrusion 12, and thus the anchoring effect of the protrusion 12 may not be fully realized.

[0100] If the protrusion angle θ of the protrusion 12 is greater than 80°, the tip of the protrusion 12 becomes too gradual, which tends to reduce the depth to which the protrusion 12 bites into the interlayer connecting conductor 30A, and thus the anchoring effect of the protrusion 12 may not be fully realized.

[0101] From the viewpoint of enhancing the anchoring effect of the protrusion 12, it is more preferable that the protrusion angle θ of the protrusion 12 is 30° or more and 60° or less.

[0102] It is preferable that the proportion of protrusions 12 at one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is 30% or more and 70% or less. Similarly, it is preferable that the proportion of protrusions 12 at the other of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is also 30% or more and 70% or less. Therefore, it is preferable that the proportion of protrusions 12 at each interface between the resin layer 10A and the interlayer connecting conductor 30A is 30% or more and 70% or less.

[0103] The proportion of protrusions 12 at the interface between the resin layer 10A and the interlayer connecting conductor 30A is determined as follows. First, using the method described above (see Figure 3), the first point P1 and second point P2 of all protrusions 12, which are portions in which the second resin material 11b penetrates the interlayer connecting conductor 30A, are determined at the interface between the resin layer 10A and the interlayer connecting conductor 30A (either one interface or the other interface). Then, 100 × "the sum of the distances between the first point P1 and the second point P2 at all protrusions 12" / "the thickness of the resin layer 10A" is calculated, and this is determined as the proportion of protrusions 12 at the interface between the resin layer 10A and the interlayer connecting conductor 30A.

[0104] The laminated substrate 1 is manufactured, for example, as follows:

[0105] <Process for manufacturing a resin sheet with a conductive layer> Figure 4 is a schematic cross-sectional view showing the process of manufacturing a resin sheet with a conductive layer in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention.

[0106] First, a resin composition containing a first resin material 11a and a second resin material 11b is prepared. In this process, for example, the first resin material 11a and the second resin material 11b are finely ground and then dispersed in a dispersion medium to prepare a paste-like or slurry-like resin composition. As the dispersion medium, for example, butanediol, water, ethanol, or a mixture containing at least two of these can be used.

[0107] Next, a resin sheet 110A containing a first resin material 11a and a second resin material 11b is prepared using the resin composition. In this case, the resin sheet 110A is prepared by, for example, a method in which the resin composition is coated and then dried (the dispersion medium is evaporated), or a method in which the resin composition is made into paper and then dried (the dispersion medium is evaporated).

[0108] In this specification, "sheet" is synonymous with "film," and the two are not distinguished by their thickness.

[0109] Next, a resin sheet 210A with a conductive layer is manufactured, as shown in Figure 4, in which a conductive layer 20A is adjacent to the first main surface 110Aa side of a resin sheet 110A having a first main surface 110Aa and a second main surface 110Ab facing each other in the thickness direction. In this case, for example, the resin sheet 210A with a conductive layer is manufactured by pressing the conductive layer 20A onto the first main surface 110Aa of the resin sheet 110A.

[0110] When pressing the conductive layer 20A onto the resin sheet 110A, for example, a heat press is performed by applying pressure in the thickness direction while heating the laminate of the resin sheet 110A and the conductive layer 20A. The temperature during the heat press is preferably above the melting point of the second resin material 11b and below the melting point of the first resin material 11a. When the heat press is performed, for example, under the above temperature conditions, the second resin material 11b tends to melt and connect in the planar direction, resulting in a flattened shape (layered) along the planar direction.

[0111] Alternatively, the conductive layer 20A may be patterned by etching it after it has been pressed onto the resin sheet 110A.

[0112] <Process for forming through holes> Figure 5 is a schematic cross-sectional view showing the step of forming through holes in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention.

[0113] As shown in Figure 5, a through-hole 131A is formed in the resin sheet 210A with a conductive layer, penetrating the resin sheet 110A in the thickness direction. In the example shown in Figure 5, the through-hole 131A is formed in the resin sheet 210A with a conductive layer, penetrating the resin sheet 110A in the thickness direction but reaching the conductor layer 20A without penetrating the conductor layer 20A in the thickness direction. As a result, a portion of the conductor layer 20A is exposed through the through-hole 131A.

[0114] When forming the through-hole 131A, for example, laser processing is performed by irradiating the conductive layer-attached resin sheet 210A with laser light from the resin sheet 110A side. In this case, by taking advantage of the difference in processability between the first resin material 11a and the second resin material 11b, for example, if the second resin material 11b is made of a material with lower laser processability than the first resin material 11a, then by deliberately performing laser processing with lower energy, the second resin material 11b will protrude in the planar direction relative to the formed through-hole 131A. Furthermore, by adjusting the energy during laser processing, the number of protruding portions (later protrusions 12) of the second resin material 11b relative to the through-hole 131A, the protrusion angle, etc. can be controlled.

[0115] <Process of filling with conductive paste> Figure 6 is a schematic cross-sectional view showing a step of filling a conductive paste in an example of a method for manufacturing a laminated substrate according to Embodiment 1 of the present invention.

[0116] As shown in Figure 6, conductive paste 132A is filled into the through-hole 131A of the conductive layered resin sheet 210A.

[0117] Methods for filling with conductive paste 132A include, for example, screen printing and vacuum filling.

[0118] The conductive paste 132A contains, for example, a metal and a resin.

[0119] Examples of metals that can be included in the conductive paste 132A include copper, tin, and silver. In particular, the conductive paste 132A preferably contains copper, and more preferably contains both copper and tin.

[0120] The resin contained in the conductive paste 132A preferably includes at least one thermosetting resin selected from the group consisting of epoxy resin, phenolic resin, polyimide resin, silicone resin or a modified 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.

[0121] The conductive paste 132A may further contain a vehicle, a solvent, a thixotropic agent, an activator, and the like.

[0122] Examples of vehicles include rosin-based resins consisting of rosin and derivatives thereof such as modified rosin, synthetic resins consisting of rosin and derivatives thereof such as modified rosin, or mixtures of these resins.

[0123] Rosin-based resins consisting of rosin and derivatives thereof such as modified rosin include, for example, gum rosin, tall rosin, wood rosin, polymerized rosin, hydrogenated rosin, formylated rosin, rosin esters, rosin-modified maleic acid resins, rosin-modified phenolic resins, rosin-modified alkyd resins, and various other rosin derivatives.

[0124] Examples of synthetic resins comprising rosin and derivatives thereof such as modified rosin include polyester resins, polyamide resins, phenoxy resins, and terpene resins.

[0125] Examples of solvents include alcohols, ketones, esters, ethers, aromatics, 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, diethylene glycol monoethyl ether, diisobutyl adipate, hexylene glycol, cyclohexanedimethanol, 2-terpinyloxyethanol, 2-dihydroterpinyloxyethanol, and mixtures thereof. Among these, terpineol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, or diethylene glycol monoethyl ether are preferred.

[0126] Examples of thixotropes include hydrogenated castor oil, carnauba wax, amides, hydroxy fatty acids, dibenzylidene sorbitol, bis(p-methylbenzylidene) sorbitols, beeswax, stearic acid amide, and hydroxystearate ethylenebisamide. These thixotropes may also contain, as needed, 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.

[0127] Examples of activators include amine hydrohalides, organic halogen compounds, organic acids, organic amines, and polyhydric alcohols.

[0128] Examples of amine hydrohalides include diphenylguanidine hydrobromide, diphenylguanidine hydrochloride, cyclohexylamine hydrobromide, ethylamine hydrochloride, ethylamine hydrobromide, diethylaniline hydrobromide, diethylaniline hydrochloride, triethanolamine hydrobromide, and monoethanolamine hydrobromide.

[0129] Examples of organic halogen compounds include paraffin chloride, tetrabromoethane, dibromopropanol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, and tris(2,3-dibromopropyl) isocyanurate.

[0130] Examples of 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.

[0131] Examples of organic amines include monoethanolamine, diethanolamine, triethanolamine, tributylamine, aniline, and diethylaniline.

[0132] Examples of polyhydric alcohols include erythritol, pyrogallol, and ribitol.

[0133] <Process for forming interlayer connecting conductors> Figure 7 is a schematic cross-sectional view showing the process of forming an interlayer connecting conductor in an example of a manufacturing method for a laminated substrate according to Embodiment 1 of the present invention.

[0134] As shown in Figure 7, the conductive layer 20B is positioned adjacent to the second main surface 110Ab side of the resin sheet 110A and connected to the conductive paste 132A, thereby forming the structure 101 shown in Figure 7. Then, the structure 101 is subjected to heat and pressure in the thickness direction, thereby performing a heat press process. As a result, the resin sheet 110A, the conductive layer 20A, and the conductive layer 20B are pressed together, and the resin sheet 110A becomes the resin layer 10A. In addition, the conductive paste 132A solidifies during the heat press process, becoming the interlayer connecting conductor 30A. In this way, the interlayer connecting conductor 30A is formed in the through hole 131A.

[0135] When forming the interlayer connecting conductor 30A, instead of filling the through-hole 131A with conductive paste 132A, a plating treatment may be performed on the inner wall of the through-hole 131A using a metal such as copper, tin, or silver.

[0136] Based on the above steps, the laminated substrate 1 shown in Figure 1 is manufactured.

[0137] In the laminated substrate 1 manufactured in this manner, the second resin material 11b protrudes toward the through hole 131A in the planar direction, as described above, and thus becomes embedded in the interlayer connecting conductor 30A formed in the through hole 131A. Furthermore, in the laminated substrate 1, the first resin material 11a becomes embedded within the resin layer 10A in relation to the second resin material 11b, which is embedded in the interlayer connecting conductor 30A.

[0138] Figure 8 is an example of a cross-sectional image showing an enlarged view of the laminated substrate of Embodiment 1 of the present invention.

[0139] In the cross-sectional image of the laminated substrate 1 shown in Figure 8, it was confirmed that the second resin material 11b was embedded in the interlayer connecting conductor 30A in the planar direction. Furthermore, in the cross-sectional image of the laminated substrate 1 shown in Figure 8, it was confirmed that the first resin material 11a was embedded in the second resin material 11b, which was embedded in the interlayer connecting conductor 30A, within the resin layer 10A.

[0140] [Embodiment 2] In the laminated substrate of Embodiment 2 of the present invention, unlike the laminated substrate of Embodiment 1 of the present invention, when viewed in cross-section along the thickness direction, the second resin material is present over the entirety of at least one of the pair of interfaces between the resin layer and the interlayer connecting conductor.

[0141] Figure 9 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 2 of the present invention.

[0142] In the laminated substrate 2 shown in Figure 9, when viewed in cross-section along the thickness direction, the second resin material 11b is present over the entirety of at least one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A.

[0143] In the example shown in Figure 9, the second resin material 11b is present (aggregated) throughout each interface between the resin layer 10A and the interlayer connecting conductor 30A.

[0144] The second resin material 11b may be present over the entirety of one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A.

[0145] In the laminated substrate 2, the second resin material 11b is present over the entirety of at least one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A. Combined with the fact that the second resin material 11b is made of a thermoplastic resin and has a lower Young's modulus than the first resin material 11a, even if stress occurs at the interface between the resin layer 10A and the interlayer connecting conductor 30A, the second resin material 11b acts as a buffer, making it easier to sufficiently relieve the stress. As a result, in the laminated substrate 2, even if stress occurs at the interface between the resin layer 10A and the interlayer connecting conductor 30A, the occurrence of cracks in the interlayer connecting conductor 30A is sufficiently suppressed, and the connection reliability of the interlayer connecting conductor 30A is less likely to deteriorate.

[0146] From the viewpoint of providing a configuration that prevents a decrease in connection reliability of the interlayer connecting conductor 30A even when stress occurs at the interface between the resin layer 10A and the interlayer connecting conductor 30A, as in laminated substrate 1 (Embodiment 1) and laminated substrate 2 (Embodiment 2), it is preferable that the proportion of the second resin material 11b at one of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is 30% or more and 100% or less. Similarly, it is preferable that the proportion of the second resin material 11b at the other of the pair of interfaces between the resin layer 10A and the interlayer connecting conductor 30A is also 30% or more and 100% or less. For these reasons, it is preferable that the proportion of the second resin material 11b at each interface between the resin layer 10A and the interlayer connecting conductor 30A is 30% or more and 100% or less.

[0147] The proportion of the second resin material 11b at the interface between the resin layer 10A and the interlayer connecting conductor 30A is determined as follows. First, when viewing a cross-section along the thickness direction of the laminated substrate (see, for example, Figure 2), all of the second resin material 11b in contact with the interlayer connecting conductor 30A at the interface between the resin layer 10A and the interlayer connecting conductor 30A (either one interface or the other interface) is identified. Then, the formula 100 × "the sum of the maximum dimensions in the thickness direction of the portions of all identified second resin material 11b in contact with the interlayer connecting conductor 30A" / "the thickness of the resin layer 10A" is calculated, and this is defined as the proportion of the second resin material 11b at the interface between the resin layer 10A and the interlayer connecting conductor 30A.

[0148] [Embodiment 3] In the laminated substrate of Embodiment 3 of the present invention, unlike the laminated substrates of Embodiments 1 and 2 of the present invention, when viewing a cross-section along the thickness direction, the second resin material is longer than the interlayer connecting conductor along the same straight line extending in the plane direction.

[0149] Figure 10 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 3 of the present invention.

[0150] In the laminated substrate 3 shown in Figure 10, when viewing a cross-section along the thickness direction, the second resin material 11b is longer than the interlayer connecting conductor 30A along the same straight line extending in the plane direction. In the example shown in Figure 10, the second resin material 11b is longer than the interlayer connecting conductor 30A along the straight line N1 extending in the plane direction.

[0151] In the laminated substrate 3, the second resin material 11b is longer than the interlayer connecting conductor 30A along the same straight line extending in the planar direction. Combined with the fact that the second resin material 11b is made of thermoplastic resin and has a lower Young's modulus than the first resin material 11a, even if stress occurs at the interface between the resin layer 10A and the interlayer connecting conductor 30A, the second resin material 11b acts as a buffer, making it easier for the stress to be sufficiently relieved. As a result, in the laminated substrate 3, even if stress occurs at the interface between the resin layer 10A and the interlayer connecting conductor 30A, the occurrence of cracks in the interlayer connecting conductor 30A is sufficiently suppressed, and the connection reliability of the interlayer connecting conductor 30A is not easily reduced.

[0152] [Embodiment 4] Embodiments 1 to 3 show an embodiment in which the laminated substrate of the present invention has one resin layer, but the laminated substrate of the present invention may have multiple resin layers.

[0153] Figure 11 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 4 of the present invention.

[0154] The laminated substrate 4 shown in Figure 11 has a resin layer 10A, a resin layer 10B, a resin layer 10C, a conductor layer 20A, a conductor layer 20B, a conductor layer 20C, a conductor layer 20D, and an interlayer connecting conductor 30A.

[0155] As described above, the resin layer 10A has a first main surface 10Aa and a second main surface 10Ab that are opposite to each other in the thickness direction.

[0156] As described above, the resin layer 10A includes the first resin material 11a and the second resin material 11b.

[0157] The resin layer 10B has a first main surface 10Ba and a second main surface 10Bb that are opposite to each other in the thickness direction.

[0158] The first main surface 10Ba of the resin layer 10B faces the second main surface 10Ab of the resin layer 10A. In the example shown in Figure 11, the first main surface 10Ba of the resin layer 10B is in contact with the second main surface 10Ab of the resin layer 10A, except where it is in contact with the conductor layer 20B.

[0159] The resin layer 10B preferably contains a first resin material 11a and a second resin material 11b.

[0160] The resin layer 10C has a first main surface 10Ca and a second main surface 10Cb that are opposite to each other in the thickness direction.

[0161] The second main surface 10Cb of the resin layer 10C faces the first main surface 10Aa of the resin layer 10A. In the example shown in Figure 11, the second main surface 10Cb of the resin layer 10C is in contact with the first main surface 10Aa of the resin layer 10A, except where it is in contact with the conductor layer 20A.

[0162] The resin layer 10C preferably contains a first resin material 11a and a second resin material 11b.

[0163] The thicknesses of resin layer 10A, resin layer 10B, and resin layer 10C may be the same, different from each other, or partially different.

[0164] As described above, the conductor layer 20A is adjacent to the first main surface 10Aa side of the resin layer 10A. Furthermore, the conductor layer 20A is also adjacent to the second main surface 10Cb side of the resin layer 10C. In other words, the conductor layer 20A is located between the resin layer 10A and the resin layer 10C, and is provided in contact with the first main surface 10Aa of the resin layer 10A and the second main surface 10Cb of the resin layer 10C. Thus, no other layers, such as adhesive layers, are provided between the resin layer 10A and the conductor layer 20A, or between the resin layer 10C and the conductor layer 20A.

[0165] It is preferable that the conductive layer 20A is provided across the interface between the resin layer 10A and the resin layer 10C. As a result, the interface between the resin layer 10A and the conductive layer 20A, and the interface between the resin layer 10C and the conductive layer 20A are shifted in the thickness direction from the interface between the resin layer 10A and the resin layer 10C, thereby suppressing delamination at the interface between the resin layer 10A and the conductive layer 20A, and at the interface between the resin layer 10C and the conductive layer 20A.

[0166] Although Figure 11 shows the interface between resin layer 10A and resin layer 10C, this interface does not necessarily have to be clearly visible in reality. If the interface between resin layer 10A and resin layer 10C is not clearly visible, the interface between resin layer 10A and resin layer 10C is considered to be the plane that passes through the center of the thickness direction of the cross-section of the conductive layer 20A and lies along the plane direction, as shown in Figure 11.

[0167] As described above, the conductor layer 20B is adjacent to the second main surface 10Ab side of the resin layer 10A. Furthermore, the conductor layer 20B is also adjacent to the first main surface 10Ba side of the resin layer 10B. In other words, the conductor layer 20B is located between the resin layer 10A and the resin layer 10B, and is provided in contact with the second main surface 10Ab of the resin layer 10A and the first main surface 10Ba of the resin layer 10B. Thus, no other layers, such as adhesive layers, are provided between the resin layer 10A and the conductor layer 20B, or between the resin layer 10B and the conductor layer 20B.

[0168] It is preferable that the conductive layer 20B is provided across the interface between the resin layer 10A and the resin layer 10B. As a result, the interface between the resin layer 10A and the conductive layer 20B, and the interface between the resin layer 10B and the conductive layer 20B are shifted in the thickness direction from the interface between the resin layer 10A and the resin layer 10B, thereby suppressing delamination at the interface between the resin layer 10A and the conductive layer 20B, and delamination at the interface between the resin layer 10B and the conductive layer 20B.

[0169] Although Figure 11 shows the interface between resin layer 10A and resin layer 10B, this interface does not necessarily have to be clearly visible in reality. If the interface between resin layer 10A and resin layer 10B is not clearly visible, the interface between resin layer 10A and resin layer 10B is considered to be the plane that passes through the center of the cross-section of the conductive layer 20B in the thickness direction and is aligned with the plane direction, as shown in the cross-section along the thickness direction in Figure 11.

[0170] The conductive layer 20C is adjacent to the second main surface 10Bb side of the resin layer 10B. In this manner, no other layers, such as an adhesive layer, are provided between the resin layer 10B and the conductive layer 20C.

[0171] The conductor layer 20C may be a planar shape that extends over the entire second main surface 10Bb of the resin layer 10B, or it may be a patterned shape that is patterned for wiring, etc., on a part of the second main surface 10Bb of the resin layer 10B.

[0172] The conductive layer 20D is adjacent to the first main surface 10Ca side of the resin layer 10C. In this manner, no other layers, such as an adhesive layer, are provided between the resin layer 10C and the conductive layer 20D.

[0173] The conductor layer 20D may be a planar shape that extends over the entire first main surface 10Ca of the resin layer 10C, or it may be a patterned shape that is patterned for wiring, etc., on a part of the first main surface 10Ca of the resin layer 10C.

[0174] The constituent materials of conductor layer 20A, conductor layer 20B, conductor layer 20C, and conductor layer 20D may be the same as each other, may be different from each other, or may be different in part.

[0175] The thicknesses of the conductor layers 20A, 20B, 20C, and 20D may be the same, different from each other, or partially different.

[0176] As described above, the interlayer connecting conductor 30A penetrates the resin layer 10A in the thickness direction but does not penetrate the conductor layers 20A and 20B in the thickness direction, and is connected to the conductor layers 20A and 20B. In other words, the conductor layers 20A and 20B are electrically connected via the interlayer connecting conductor 30A.

[0177] The laminated substrate 4 can be used, for example, as a circuit board.

[0178] When the laminated substrate 4 is used as a circuit board, the laminated substrate 4 may have a conductor layer 20A as a signal line for transmitting signals, thereby forming a transmission line. Alternatively, the laminated substrate 4 may have a conductor layer 20B instead of conductor layer 20A as a signal line.

[0179] When the laminated substrate 4 has a conductive layer 20A or a conductive layer 20B as a signal line for transmitting signals and constitutes a transmission line, as described above, if the relative permittivity of the second resin material 11b is lower than that of the first resin material 11a, and furthermore, if there is a large amount of the second resin material 11b near the signal line, the high-frequency characteristics of the laminated substrate 4 will be excellent.

[0180] When the laminated substrate 4 has a conductor layer 20A or a conductor layer 20B as a signal line for transmitting signals and constitutes a transmission line, as described above, if the dielectric loss tangent of the second resin material 11b is lower than that of the first resin material 11a, and furthermore, if there is a large amount of the second resin material 11b near the signal line, the transmission loss characteristics of the laminated substrate 4 will be excellent.

[0181] When the laminated substrate 4 is used as a circuit board, the laminated substrate 4 may have a conductor layer 20A or conductor layer 20B as a signal line for transmitting signals, and a conductor layer 20C and a conductor layer 20D as ground electrodes. In this case, the laminated substrate 4 constitutes a stripline type transmission line. In such a configuration, the conductor layer 20C and the conductor layer 20D may be electrically connected via an interlayer connecting conductor (not shown) that penetrates the resin layer 10A, the resin layer 10B, and the resin layer 10C in the thickness direction. Note that the conductor layer 20C and the conductor layer 20D do not necessarily have to be electrically connected.

[0182] When the laminated substrate of the present invention constitutes a transmission line, the laminated substrate of the present invention may constitute, for example, a microstrip type transmission line, a coplanar type transmission line, or the like, in addition to the stripline type transmission line described above.

[0183] [Embodiment 5] Embodiments 1 to 4 show a configuration in which the interlayer connecting conductor penetrates the resin layer in the thickness direction but does not penetrate the conductor layer in the thickness direction in the laminated substrate of the present invention. However, the interlayer connecting conductor may penetrate both the resin layer and the conductor layer in the thickness direction.

[0184] Figure 12 is a schematic cross-sectional view showing an example of a laminated substrate according to Embodiment 5 of the present invention.

[0185] In the laminated substrate 5 shown in Figure 12, the interlayer connecting conductor 30B penetrates the resin layer 10A and the conductor layer 20B in the thickness direction and is connected to the conductor layer 20B.

[0186] The interlayer connecting conductor 30B is formed, for example, by applying a conductive paste to through holes that penetrate the resin layer 10A and the conductor layer 20B in the thickness direction, followed by heat treatment, plating, or sputtering the inner walls.

[0187] The laminated substrate of the present invention is not limited to the above embodiments, and various applications and modifications can be made within the scope of the present invention regarding the configuration, manufacturing conditions, etc., of the laminated substrate.

[0188] In the laminated substrate of the present invention, if there are multiple second resin materials within the resin layer, if there are second resin materials that are embedded in the interlayer connecting conductor, there may also be second resin materials that are not embedded in the interlayer connecting conductor.

[0189] In the laminated substrate of the present invention, if a second resin material is embedded in the interlayer connecting conductor, a first resin material embedded in the interlayer connecting conductor may also be present.

[0190] In the laminated substrate of the present invention, the number of resin layers is not particularly limited, as long as there is one or more layers.

[0191] In the laminated substrate of the present invention, the number of conductive layers is not particularly limited, as long as it is one or more layers.

[0192] In the laminated substrate of the present invention, the number of interlayer connecting conductors is not particularly limited, as long as it is one or more. [Examples]

[0193] The following are examples that more specifically disclose the laminated substrate of the present invention. However, the present invention is not limited to the following examples.

[0194] [Examples 1-7] The laminated substrates of Examples 1 to 7 were manufactured using the manufacturing method of the laminated substrate of Embodiment 1. In this process, the materials shown in Table 1 were used as the first resin material and the second resin material. Furthermore, in the <process of forming through holes>, the number of protrusions, which are portions in which the second resin material bites into the interlayer connecting conductor, was changed by adjusting the energy during laser processing.

[0195] [Comparative Example 1] A laminated substrate of Comparative Example 1 was manufactured in the same manner as in Examples 1 to 7, except that the energy used during laser processing in the <process of forming through holes> was increased to prevent the formation of protrusions in the subsequently obtained laminated substrate, which are portions where the second resin material bites into the interlayer connecting conductor.

[0196] [evaluation] The following evaluations were performed on the laminated substrates of Examples 1-7 and Comparative Example 1. The evaluation results are shown in Table 1.

[0197] <Number of protrusions> The number of protrusions, which are portions in which the second resin material has embedded itself in the interlayer connecting conductor, was counted as the number of portions determined to be protrusions (embedded portions) using the method described above (see Figure 2). In this process, for each pair of interfaces between the resin layer and the interlayer connecting conductor, the number of protrusions at one interface, the number of protrusions at the other interface, and the total number of protrusions at both interfaces were counted.

[0198] Furthermore, the protrusion angle of the convex portion was the same in each example of the laminated substrate.

[0199] <Connection reliability> The connection reliability of the interlayer connecting conductors was evaluated as follows. First, the resistivity R1 of the interlayer connecting conductors was measured in the laminated substrate. Next, a hot oil test (thermal shock test) was performed in which the laminated substrate was immersed in oil at 260°C for 10 seconds, followed by immersion in oil at 20°C for 20 seconds, with each cycle lasting 200 cycles. After the hot oil test, the resistivity R2 of the interlayer connecting conductors was measured in the laminated substrate. The change in resistivity of the interlayer connecting conductors before and after the hot oil test (in %) was calculated as 100 × (R2 - R1) / R1. The criteria for determining the connection reliability of the interlayer connecting conductors were as follows. ◎(Excellent): The change in resistivity was 5% or less. ○ (Good): The change in resistivity was greater than 5% but less than or equal to 10%. △ (Acceptable): The change in resistivity was greater than 10% but less than or equal to 20%. × (Incorrect): The change in resistivity was greater than 20%.

[0200] [Table 1]

[0201] As shown in Table 1, the laminated substrates of Examples 1 to 7, which have one or more protrusions, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrate of Comparative Example 1, which does not have any protrusions. In other words, it is considered that the interlayer connecting conductors are less likely to peel off from the resin layer in the laminated substrates of Examples 1 to 7.

[0202] Comparing the laminated substrates of Examples 1 to 4, in which the first and second resin materials are the same, the laminated substrates of Examples 2 and 3, in which the total number of protrusions at both interfaces is between 3 and 20, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 1 and 4, in which the total number of protrusions at both interfaces is either less than 3 or more than 20.

[0203] Similarly, when comparing the laminated substrates of Examples 1 to 4, in which the first and second resin materials are of the same type, the laminated substrates of Examples 2 and 3, in which the number of protrusions at one interface (the other interface) is between 2 and 10, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 1 and 4, in which the number of protrusions at one interface (the other interface) is either less than 2 or more than 10.

[0204] Comparing the laminated substrates of Examples 1 to 7, which have the same number of protrusions, the laminated substrate of Example 2, in which the second resin material is polyphenylene ether, and the laminated substrate of Example 5, in which the second resin material is perfluoroalkoxyalkane, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 6 and 7, in which the second resin material is other than polyphenylene ether and perfluoroalkoxyalkane.

[0205] [Examples 8-15] The laminated substrates of Examples 8 to 15 were manufactured using the manufacturing method of the laminated substrate of Embodiment 1. In this process, the materials shown in Table 2 were used as the first resin material and the second resin material. Furthermore, in the <process of forming through holes>, the protrusion angle of the convex portion, which is the part in which the second resin material bites into the interlayer connecting conductor, was changed by adjusting the energy during laser processing.

[0206] [evaluation] The following evaluations were performed on the laminated substrates of Examples 8 to 15. The evaluation results are shown in Table 2.

[0207] <Protrusion angle of the convex part> The protrusion angle of the convex portion, which is the part in which the second resin material bites into the interlayer connecting conductor, was measured using the method described above (see Figure 3).

[0208] Furthermore, the number of protrusions was the same in each example of the laminated substrate.

[0209] <Connection reliability> The connection reliability of the interlayer connecting conductors was evaluated using the method described above.

[0210] [Table 2]

[0211] As shown in Table 2, the laminated substrates of Examples 8 to 15 exhibited excellent connection reliability of the interlayer connecting conductors. In other words, it is considered that the interlayer connecting conductors in the laminated substrates of Examples 8 to 15 are less likely to peel off from the resin layer.

[0212] Comparing the laminated substrates of Examples 8 to 12, in which the first and second resin materials are the same, the laminated substrates of Examples 9 to 11, where the protrusion angle of the protrusions is 20° or more and 80° or less, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 8 and 12, where the protrusion angle of the protrusions is less than 20° or greater than 80°. Furthermore, comparing the laminated substrates of Examples 8 to 12, the laminated substrate of Example 10, where the protrusion angle of the protrusions is 30° or more and 60° or less, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 8, 9, 11, and 12, where the protrusion angle of the protrusions is less than 30° or greater than 60°.

[0213] Comparing the laminated substrates of Examples 8-15, specifically Examples 10 and 13-15 which have the same protrusion angle of the convex portion, the laminated substrate of Example 10, in which the second resin material is polyphenylene ether, and the laminated substrate of Example 13, in which the second resin material is perfluoroalkoxyalkane, showed superior connection reliability of the interlayer connecting conductors compared to the laminated substrates of Examples 14 and 15, in which the second resin material is other than polyphenylene ether and perfluoroalkoxyalkane.

[0214] This specification discloses the following:

[0215] <1> A resin layer having a pair of main surfaces facing each other in the thickness direction, A conductive layer adjacent to at least one of the main surfaces of the resin layer, The above resin layer penetrates in the thickness direction and comprises an interlayer connecting conductor connected to the above conductor layer, The above resin layer comprises a first resin material and a second resin material made of a thermoplastic resin. The Young's modulus of the second resin material is lower than that of the first resin material. The above-mentioned second resin material is embedded in the above-mentioned interlayer connecting conductor in a planar direction perpendicular to the thickness direction. A laminated substrate characterized in that the first resin material is embedded within the resin layer of the second resin material which is embedded in the interlayer connecting conductor.

[0216] <2> When viewing a cross-section along the thickness direction, if the portion of the second resin material that bites into the interlayer connecting conductor is defined as a protrusion, then the total number of such protrusions at the pair of interfaces between the resin layer and the interlayer connecting conductor is between 3 and 20. <1> The laminated substrate described above.

[0217] <3> On one side, the number of protrusions on the interface is 2 or more and 10 or less. <2> The laminated substrate described above.

[0218] <4> When viewing a cross-section along the thickness direction, the portion where the second resin material bites into the interlayer connecting conductor is defined as a convex portion, and one endpoint of the convex portion in the thickness direction is defined as the first point, the other endpoint of the convex portion in the thickness direction is defined as the second point, and the vertex of the convex portion in the surface direction is defined as the third point. The angle between the line connecting the first point and the third point and the line connecting the second point and the third point is 20° or more and 80° or less. <1> ~ <3> A laminated substrate as described in any one of the following.

[0219] <5> When a cross-section along the thickness direction is viewed, the second resin material is present over the entirety of at least one of the pair of interfaces between the resin layer and the interlayer connecting conductor. <1> ~ <4> A laminated substrate as described in any one of the following.

[0220] <6> When viewing a cross-section along the thickness direction, along the same straight line extending in the plane direction, the second resin material is longer than the interlayer connecting conductor. <1> ~ <5> A laminated substrate as described in any one of the following.

[0221] <7> The above-mentioned first resin material is made of a thermoplastic resin. <1> ~ <6> A laminated substrate as described in any one of the following.

[0222] <8> The above first resin material is made of a liquid crystal polymer. <7> The laminated substrate described above.

[0223] <9> The above second resin material consists of a perfluoroalkoxyalkane. <1> ~ <8> A laminated substrate as described in any one of the following.

[0224] <10> The above second resin material consists of polyphenylene ether. <1> ~ <8> A laminated substrate as described in any one of the following.

[0225] <11> The above-mentioned second resin material has a flattened shape. <1> ~ <10> A laminated substrate as described in any one of the following.

[0226] <12> The above-mentioned conductor layer is used as a signal line for transmitting signals, and it constitutes a transmission line. <1> ~ <11> A laminated substrate as described in any one of the following. [Explanation of Symbols]

[0227] 1, 2, 3, 4, 5 Multilayer substrate 10A, 10B, 10C resin layer 10Aa, 10Ba, 10Ca, 110Aa First main surface 10Ab, 10Bb, 10Cb, 110Ab Second principal plane 11a First resin material 11b Second resin material 11ba Indentation 11bb Non-insertion area 12 Convex part 20A, 20B, 20C, 20D Conductor layers 30A, 30B Interlayer connecting conductors 101 Structure 110A Resin Sheet 131A Through hole 132A Conductive Paste 210A Resin sheet with conductive layer E1, E2 end points F1 midpoint G1 distance L1, L2, M1, M2, N1 straight line P1 1st point P2 2nd point P3 3rd point θ - Angle of protrusion of the convex part

Claims

1. A resin layer having a pair of main surfaces facing each other in the thickness direction, A conductive layer adjacent to at least one of the main surfaces of the resin layer, The resin layer is penetrated in the thickness direction and comprises an interlayer connecting conductor connected to the conductor layer, The resin layer comprises a first resin material and a second resin material made of a thermoplastic resin. The Young's modulus of the second resin material is lower than that of the first resin material. The second resin material is embedded in the interlayer connecting conductor in a planar direction perpendicular to the thickness direction, A laminated substrate characterized in that the first resin material is embedded in the second resin material, which is embedded in the interlayer connecting conductor, within the resin layer.

2. The laminated substrate according to claim 1, wherein, when viewed in cross-section along the thickness direction, the portion of the second resin material that bites into the interlayer connecting conductor is defined as a protrusion, and the total number of protrusions at the pair of interfaces between the resin layer and the interlayer connecting conductor is 3 or more and 20 or less.

3. The laminated substrate according to claim 2, wherein the number of protrusions at one of the interfaces is two or more and ten or less.

4. A laminated substrate according to any one of claims 1 to 3, wherein, when viewed in cross-section along the thickness direction, the portion of the second resin material that bites into the interlayer connecting conductor is defined as a convex portion, and one endpoint of the convex portion in the thickness direction is defined as the first point, the other endpoint of the convex portion in the thickness direction is defined as the second point, and the vertex of the convex portion in the surface direction is defined as the third point, the angle between the line connecting the first point and the third point and the line connecting the second point and the third point is 20° or more and 80° or less.

5. The laminated substrate according to any one of claims 1 to 3, wherein, when viewed in cross-section along the thickness direction, the second resin material is present over the entirety of at least one of the pair of interfaces between the resin layer and the interlayer connecting conductor.

6. The laminated substrate according to any one of claims 1 to 3, wherein, when viewed in cross-section along the thickness direction, the second resin material is longer than the interlayer connecting conductor along the same straight line extending in the plane direction.

7. The laminated substrate according to any one of claims 1 to 3, wherein the first resin material is made of a thermoplastic resin.

8. The laminated substrate according to claim 7, wherein the first resin material is made of a liquid crystal polymer.

9. The laminated substrate according to any one of claims 1 to 3, wherein the second resin material is made of a perfluoroalkoxyalkane.

10. The laminated substrate according to any one of claims 1 to 3, wherein the second resin material is made of polyphenylene ether.

11. The laminated substrate according to any one of claims 1 to 3, wherein the second resin material has a flattened shape.

12. A laminated substrate according to any one of claims 1 to 3, having the conductor layer as a signal line for transmitting signals, thereby forming a transmission line.

Images