Method for manufacturing glass substrate with conductive vias

Abstract

A method for manufacturing a glass substrate with conductive vias includes the steps of: preparing a glass substrate having holes formed therein; providing a metal paste portion containing metal particles and a volatile solvent so as to fill the insides of the holes and cover at least the surface of the glass substrate around the holes; heating the metal paste portion to remove a portion of the volatile solvent; removing a portion of the heated metal paste portion so as to expose the surface, thereby forming a conductive via precursor containing metal particles and the remainder of the volatile solvent and having a flattened exposed surface inside the holes; and firing the conductive via precursor, wherein the metal particles include first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less, the metal particle concentration of the metal paste portion provided in the step a is 95.0 mass% or more, and the content of the second metal particles in the metal paste portion provided in the step a is 50 mass% or less based on the total amount of metal particles.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a glass substrate with conductive vias, a metal paste, and a glass substrate with conductive vias. [Background technology]

[0002] In recent years, in order to miniaturize, enhance the functionality, and integrate electronic devices and components, attention has been focused on three-dimensional packaging technology in which glass substrates arranged above and below are electrically connected via electrodes called through-glass vias (TGVs) on the glass substrate, and semiconductor chips are densely stacked in the vertical direction (height direction).

[0003] As a method for forming a through electrode, for example, Patent Document 1 below discloses a method for manufacturing a semiconductor device having a glass through electrode, which includes a step of electroplating a non-through via formed in a glass substrate with copper by using a specific copper plating solution. Also, Patent Document 2 below proposes a method for manufacturing a semiconductor device, which includes a step of forming a hollow through electrode in a glass substrate by electrolytic copper plating, and further filling the electrode with a mixture of metal powder and a resin material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-134016 A [Patent Document 2] JP 2016-96262 A Summary of the Invention [Problem to be solved by the invention]

[0005] Recently, as glass substrates are being downsized to accommodate the miniaturization of electronic devices or components, the inner diameter of through holes is also being minimized, making it necessary to form conductive vias with sufficient conductivity even in such through holes. Furthermore, wiring may be further provided by plating or the like on the surface of the substrate on which the conductive vias are formed, and even in this case, a sufficiently low connection resistance value is required.

[0006] Recently, the trend toward higher signal speeds, smaller board sizes, and shorter transmission distances have led to lower power consumption, and so there is a demand for even greater connection reliability than ever before. In light of this, a board with conductive vias (wiring board) on which the above-mentioned wiring is formed is required to have not only excellent conductivity, but also an excellent characteristic (hereinafter also referred to as "connection reliability") in which the connection resistance is unlikely to increase even when subjected to temperature changes.

[0007] However, the inventors' studies have revealed that in glass substrates equipped with glass through electrodes of copper plating film, cracks may occur around the glass through electrodes due to the thermal history of temperature cycles, resulting in an increase in connection resistance. Although methods for preventing cracks in glass substrates include changing the material of the glass substrate and reinforcing it with resin, these methods are not sufficient to achieve both low connection resistance and excellent connection reliability.

[0008] Therefore, the present invention aims to provide a method for producing a glass substrate with conductive vias that has a glass through electrode (TGV) and can exhibit a sufficiently low connection resistance even after wiring is formed, and that enables the resulting wiring substrate to have excellent connection reliability; a metal paste that can be used to form the glass through electrode; and a glass substrate with conductive vias. [Means for solving the problem]

[0009] The present inventors conducted extensive research to achieve the above object, and found that the reason why the connection resistance value becomes high after wiring is that the flatness (or smoothness) of the conductive vias on the surface of the substrate with conductive vias is low (in other words, the step between the conductive via portion and the substrate surface is large). Based on this knowledge, the present inventors conducted research into a method for reducing the step. As a result, they found that by forming conductive vias through a specific process using a metal paste containing specific metal particles and a volatile solvent, a sufficiently low connection resistance value can be obtained even when wiring connected to the conductive vias is further formed, and that the obtained wiring substrate has excellent connection reliability without cracks occurring in the glass substrate even after a temperature cycle reliability test, and thus completed the present invention.

[0010] That is, one aspect of the present invention relates to a method for manufacturing a substrate with conductive vias as follows. [1] A method for manufacturing a glass substrate with conductive vias, comprising: step a) of preparing a glass substrate having a hole; and providing a metal paste portion containing metal particles and a volatile solvent so as to fill the inside of the hole and cover at least the surface of the glass substrate around the hole; step b) of heating the metal paste portion to remove a part of the volatile solvent; step c) of removing a part of the metal paste portion after heating to expose the surface, thereby forming a conductive via precursor containing the metal particles and the remainder of the volatile solvent and having a flattened exposed surface inside the hole; and step d) of firing the conductive via precursor, wherein the metal particles include first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less, a metal particle concentration of the metal paste portion provided in step a is 95.0 mass % or more, and a content of the second metal particles in the metal paste portion provided in step a is 50 mass % or less based on the total amount of the metal particles.

[0011] According to the above manufacturing method, in step a, a metal paste portion containing a volatile solvent and having the above-mentioned specific metal particle configuration is provided, and then, through steps b and c, it is possible to simultaneously fill the inside of the hole well and form a conductive via precursor that is less likely to shrink in volume by firing, and in step d, a conductive via with excellent conductivity in which the occurrence of cracks and voids is sufficiently suppressed can be formed while sufficiently reducing the step with the substrate surface. This makes it possible to obtain a substrate with conductive vias that exhibits a sufficiently low connection resistance even after wiring is formed, and furthermore, the substrate with conductive vias (wiring substrate) on which wiring is formed has excellent connection reliability because the occurrence of cracks in the glass substrate is suppressed even after a temperature cycle reliability test.

[0012] The present inventors speculate as follows about the reason why the above-mentioned crack generation in the glass substrate can be suppressed. First, the main cause of the crack generation is thought to be the stress caused by the glass through electrode. For example, as described in the following reference, it is known that the stress of a copper plating film shows a high Young's modulus of about 100 GPa. Reference: Measurement of Young's modulus of thin films for electronic devices using precision three-point bending method, Transactions of the Japan Society of Mechanical Engineers (Series A), Vol. 77, No. 773 (2011-1) P190 According to the manufacturing method [1], by sintering the specific conductive via precursor, a sintered body having a Young's modulus of less than half that of the copper plating film can be formed, and it is believed that the stress caused by the glass through electrode is alleviated. As a result, the inventors presume that it is possible to suppress cracks in the glass substrate around the glass through electrode, and to achieve both low connection resistance and excellent connection reliability.

[0013] [2] The method for manufacturing a substrate with conductive vias according to [1], wherein the first metal particles and the second metal particles are copper particles. [3] The method for manufacturing a substrate with conductive vias according to [1] or [2], wherein the first metal particles include flaky copper particles.

[0014] Another aspect of the present invention relates to the following metal paste. [4] A metal paste used for forming a glass through electrode, the metal paste containing metal particles and a volatile solvent, the content of the metal particles being 95.0 mass% or more based on the total amount of the metal paste, the metal particles including first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less, and the content of the second metal particles being 50 mass% or less based on the total amount of the metal particles. [5] The metal paste for forming a glass through electrode according to [4], wherein the first metal particles and the second metal particles are copper particles. [6] The metal paste for forming a glass through electrode according to [4] or [5], wherein the first metal particles include flaky copper particles.

[0015] The above metal paste has sufficient printability, and the metal paste portion can be efficiently formed in the above method for manufacturing a glass substrate with conductive vias.

[0016] Another aspect of the present invention relates to the following glass substrate with conductive vias. [7] A glass substrate with conductive vias, comprising: a glass substrate having a through hole; and a conductive via provided in the through hole, the conductive via comprising a sintered body of a metal paste according to any one of [4] to [6]. Effect of the Invention

[0017] According to the present invention, it is possible to provide a method for producing a glass substrate with conductive vias, which has a glass through electrode (TGV) and can exhibit a sufficiently low connection resistance even after wiring is formed, and the resulting wiring substrate can have excellent connection reliability, a metal paste that can be used to form the glass through electrode, and a glass substrate with conductive vias. [Brief description of the drawings]

[0018] [Figure 1]1A to 1C are schematic diagrams illustrating an example of a method for manufacturing a glass substrate with conductive vias according to an embodiment of the present invention. [Diagram 2] 1A to 1C are schematic diagrams illustrating an example of a method for manufacturing a glass substrate with conductive vias according to an embodiment of the present invention. [Diagram 3] 1A to 1C are schematic diagrams illustrating an example of a method for manufacturing a glass substrate with conductive vias according to an embodiment of the present invention. [Figure 4] 1A to 1C are schematic diagrams showing an example of a method for forming wiring. [Diagram 5] FIG. 2 is a schematic diagram showing a test piece. [Figure 6] 3 is a diagram showing a cross-sectional image of a conductive via in a glass substrate with a conductive via produced in Example 1. FIG. [Figure 7] 1A and 1B are diagrams showing the appearance and cross section of a wiring board produced in Example 1. [Figure 8] FIG. 13 is a diagram showing the surface of the wiring board produced in Example 12 after a temperature cycle reliability test. [Figure 9] FIG. 13 is a diagram showing the surface of the wiring board produced in Comparative Example 7 after a temperature cycle reliability test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0020] <Metal paste> The metal paste of this embodiment contains metal particles and a volatile solvent, and the content of the metal particles is 95.0 mass% or more based on the total amount of the metal paste. The metal paste of this embodiment can be used to form a metal paste portion in a manufacturing method for a glass substrate with conductive vias, which will be described later, and can form a glass through electrode.

[0021] The content of metal particles in the metal paste of this embodiment, based on the total amount of the metal paste, may be 95.2 mass% or more, 95.5 mass% or more, 95.7 mass% or more, or 96 mass% or more, and may be 98 mass% or less, 97 mass% or less, or 96.5 mass% or less, or may be 95.0 to 98 mass%, 95.2 to 97 mass%, or 95.7 to 96.5 mass%.

[0022] [Metal particles] Examples of the metal particles include particles of nickel, silver, copper, gold, palladium, platinum, solder, etc. When the metal paste contains copper particles, it is easy to obtain a conductor having sufficient conductivity and a resistance value that is unlikely to increase even when subjected to temperature changes, and a base having a through electrode having sufficient conductivity and excellent connection reliability. In this embodiment, the metal particles include first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less.

[0023] In this specification, the volume average particle size of particles (hereinafter sometimes referred to as "average particle size") means the 50% volume average particle size (D50). The volume average particle size of metal particles can be determined by, for example, dispersing raw metal particles in a dispersion medium such as water or alcohol and measuring the dispersion using a laser diffraction / scattering particle size distribution analyzer.

[0024] The first metal particles and the second metal particles may be copper particles from the viewpoints of reducing resistance, ensuring ion migration resistance, and facilitating wiring formation. This embodiment will be described in detail below using as an example a case in which the first metal particles are copper particles (hereinafter referred to as "first copper particles") and the second metal particles are copper particles (hereinafter referred to as "second copper particles").

[0025] (First copper particles) The average particle size of the first copper particles may be 0.8 μm or more, 1.0 μm or more, 2.0 μm or more, or 3.0 μm or more, from the viewpoint of improving the sintering density in holes (e.g., through holes or non-through holes) of the substrate and suppressing the generation of voids and cracks in the holes; for example, from the viewpoint of suppressing particle clogging in microvias with an inner diameter of 100 μm or less and improving filling ability, the average particle size may be 10 μm or less, 8.0 μm or less, 5.0 μm or less, or 4.0 μm or less; and from the viewpoint of suppressing voids and cracks and suppressing particle clogging in the microvias, the average particle size may be 0.8 μm to 4.0 μm, 1.0 μm to 3.5 μm, or 1.2 μm to 3.0 μm. The ratio (DC1 / DH) of the average particle diameter DC1 of the first copper particles to the inner diameter DH of the hole may be 0.01 or more, 0.03 or more, or 0.04 or more from the viewpoint of suppressing clogging of the particles in the micro vias and improving the filling property, and may be 0.15 or less, 0.1 or less, or 0.05 or less from the viewpoint of suppressing voids and cracks by reducing shrinkage due to firing. From the above viewpoint, the ratio (DC1 / DH) may be 0.01 to 0.15, or 0.03 to 0.1.

[0026] The shape of the first copper particles may be, for example, spherical, blocky, needle-like, flat (flake-like), approximately spherical, etc. The first metal particles may be an aggregate of copper particles having these shapes. The metal paste of this embodiment may contain spherical copper particles as the first copper particles from the viewpoint of reducing the step between the conductive via portion to be formed and the substrate surface and suppressing the fluctuation of the connection resistance even after a reliability test (for example, a temperature cycle test).

[0027] From the viewpoint of improving the printability of the metal paste, the first copper particles may contain particles such as spherical particles having an aspect ratio of 2 or less in an amount of 60% by mass or more, 80% by mass or more, or 100% by mass. The aspect ratio (major axis / minor axis) of the particles can be determined, for example, by observing an SEM image of the particles and measuring the major axis and minor axis (e.g., thickness).

[0028] The metal paste of the present embodiment may contain flaky copper particles as the first copper particles from the viewpoint of suppressing voids and cracks by reducing shrinkage due to firing, and may contain spherical copper particles and flaky copper particles from the viewpoint of reducing the viscosity of the metal paste to improve filling into microvias and suppressing voids and cracks by reducing shrinkage due to firing. When spherical copper particles and flaky copper particles are used in combination, the mass ratio thereof (spherical copper particles) / (flaky copper particles) may be 1 to 9, 1.2 to 2.5, or 1.4 to 4.

[0029] The flaky copper particles may have an aspect ratio of 1.5 or more, 2 or more, or 3 or more.

[0030] The first copper particles may be produced by a chemical reduction method, an atomization method, an electrolysis method, a pulverization method, a plasma rotating electrode method, a uniform liquid spray method, a heat treatment method, or the like, and may be wet copper powder or atomized copper powder from the viewpoint of easily obtaining a uniform diameter and improving the dispersibility of the metal paste.

[0031] The first copper particles may contain wet copper powder. In this case, a conductive via with excellent conductivity is easily obtained. It is considered that such an effect is obtained due to the property of the wet copper powder that it easily bonds with the copper particles mixed as the second metal. The wet copper powder may have a D90 / D50 of 1.5 or less.

[0032] The copper particles may contain wet copper powder and atomized copper powder. In this case, it is easy to improve the printability of the metal paste, reduce the step between the conductive via portion to be formed and the substrate surface, and suppress the fluctuation of the connection resistance even after a reliability test (for example, a temperature cycle test). The reason for obtaining such an effect is presumed to be as follows. That is, the coexistence of wet copper powder, which is easily bonded to the second copper particles and has a uniform particle size, and atomized copper powder, which has a wide particle size distribution, allows the wet copper powder to bond between the atomized copper powder particles while also bonding with the second copper particles, thereby forming a strong sintered body with a close-packed structure, and suppressing the occurrence of voids and cracks and dents due to the suppression of shrinkage during sintering. The atomized copper powder may have a D90 / D50 of 1.6 or more, 1.7 or more, or 1.8 or more.

[0033] When the first copper particles contain wet copper powder and atomized copper powder, the content of the wet copper powder may be more than 0 parts by mass and less than 100 parts by mass, or may be 20 to 80 parts by mass, relative to 100 parts by mass of the total amount of the wet copper powder and the atomized copper powder.

[0034] As the first copper particles, commercially available ones can be used. Examples of commercially available first copper particles include 1050Y (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 0.81 μm, D90: 1.1 μm, spherical, wet copper powder), 1100Y (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 1.1 μm, D90: 1.6 μm, spherical, wet copper powder), 1200Y (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 2.1 μm, D90: 3.1 μm, spherical, wet copper powder), 1300Y (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 3.5 μm, D90: 5 μm, spherical, wet copper powder), 1100YP (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 1.4 μm, D90: 2.3 μm, flat, wet copper powder), 1200YP (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 3.1 μm, D90: 5.3 μm, flat, wet copper powder), MA-C02K (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 1.8 μm, D90: 3.6 μm, spherical, atomized copper powder), MA-C025K (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 2.4 μm, D90: 5.2 μm, spherical, atomized copper powder), MA-C03K (manufactured by Mitsui Kinzoku Co., Ltd., trade name, average particle size (D50): 3.4 μm, D90: 6.3 μm, spherical, atomized copper powder).

[0035] The first copper particles may be treated with a surface treatment agent from the viewpoint of dispersion stability and oxidation resistance. The surface treatment agent may be one that is removed during wiring formation (when sintering the copper particles). Examples of such surface treatment agents include aliphatic carboxylic acids such as palmitic acid, stearic acid, arachidic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; aliphatic alcohols such as cetyl alcohol, stearyl alcohol, isobornylcyclohexanol, and tetraethylene glycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, and stearylamine; aliphatic nitriles such as stearonitrile and decanenitrile; silane coupling agents such as alkylalkoxysilanes; and polymer treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomers. The surface treatment agents may be used alone or in combination of two or more.

[0036] The amount of the surface treatment agent may be an amount of one molecular layer or more on the particle surface. The amount of the surface treatment agent varies depending on the specific surface area of ​​the first copper particles, the molecular weight of the surface treatment agent, and the minimum coverage area of ​​the surface treatment agent. The amount of the surface treatment agent is usually 0.001 mass% or more.

[0037] The amount of the surface treatment agent is determined by the number of molecular layers (n) attached to the surface of the first copper particles and the specific surface area (A p ) (unit: m 2 / g) and the molecular weight of the surface treatment agent (M s ) (unit: g / mol) and the minimum coverage area of ​​the surface treatment agent (S S ) (unit: m 2 / piece) and Avogadro's number (N A )(6.02×10 23 Specifically, the amount of surface treatment agent can be calculated by the following formula: Surface treatment agent amount (mass%) = {(n × A p ×M s ) / (S S ×N A +n×A p ×M s)}×100%.

[0038] The specific surface area of ​​the first copper particles can be calculated by measuring the dried copper particles using a BET specific surface area measurement method. The minimum coverage area of ​​the surface treatment agent is 2.05 × 10 -19 m 2 The carbon content of the surface treatment agent is 1 / molecule. In the case of other surface treatment agents, it can be measured, for example, by calculation from a molecular model or by the method described in "Chemistry and Education" (Katsuhiro Ueda, Sumio Inafuku, Iwao Mori, 40(2), 1992, p114-117). An example of a method for quantifying the surface treatment agent is shown below. The surface treatment agent can be identified by a thermal desorption gas-gas chromatograph mass spectrometer of the dried powder obtained by removing the dispersing medium from the metal paste, and the carbon number and molecular weight of the surface treatment agent can be determined. The carbon content of the surface treatment agent can be analyzed by carbon content analysis. Examples of carbon content analysis methods include high-frequency induction heating furnace combustion / infrared absorption method. The amount of the surface treatment agent can be calculated from the carbon number, molecular weight and carbon content of the identified surface treatment agent using the above formula.

[0039] (Second copper particles) The average particle size of the second copper particles may be 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, or 0.2 μm or less from the viewpoint of sinterability, and may be 0.01 μm or more, 0.03 μm or more, 0.05 μm or more, 0.08 μm or more, or 0.1 μm or more from the viewpoints of reducing synthesis costs, achieving good dispersibility, and reducing the amount of surface treatment agent used, and may be 0.1 μm to 0.3 μm, 0.12 μm to 0.28 μm, or 0.15 μm to 0.25 μm from the viewpoints of obtaining sinterability at low temperatures and good dispersibility in the paste.

[0040] The second copper particles can act as copper particles that suitably bond the first copper particles together. In addition, the second copper particles have better sinterability than the first copper particles, and can have the function of promoting the sintering of the copper particles. For example, compared to the case where the first copper particles are used alone as the copper particles, the copper particles can be sintered at a lower temperature.

[0041] The second copper particles may be wet copper powder made by a chemical reduction method.

[0042] The shape of the second copper particles may be, for example, spherical, blocky, needle-like, flat (flake-like), approximately spherical, etc. The second copper particles may be an aggregate of copper particles having these shapes. From the viewpoint of dispersibility and packing property, the shape of the second copper particles may be spherical, approximately spherical, or flat (flake-like), and from the viewpoint of combustibility and mixability with the first copper particles, etc., the shape of the second copper particles may be spherical or approximately spherical.

[0043] The aspect ratio of the second copper particles may be 5 or less, 4 or less, or 3 or less, from the viewpoints of dispersibility, packing property, and mixability with the first copper particles.

[0044] The second copper particles may be synthesized or commercially available. Examples of commercially available second copper particles include CH0200L1 (manufactured by Mitsui Kinzoku Co., Ltd., average particle size (D50): 200 nm, spherical) and Tn-Cu100 (manufactured by Taiyo Nippon Sanso Co., Ltd., average particle size (D50): 120 nm, spherical).

[0045] The second copper particles may be treated with a specific surface treatment agent. Examples of the specific surface treatment agent include organic acids having 8 to 16 carbon atoms. Examples of the organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanoic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, capric acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethylnonanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, Saturated fatty acids such as pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyloctanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pentyldecanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyldecanoic acid, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, and nonylcyclohexanecarboxylic acid; octene Examples of the organic acid include unsaturated fatty acids such as benzoic acid, nonenoic acid, methylnonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, and sapienic acid; and aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, and nonylbenzoic acid. The organic acid may be used alone or in combination of two or more.By combining such an organic acid with the second copper particles, it tends to be possible to achieve both the dispersibility of the second copper particles and the desorption property of the organic acid during sintering.

[0046] The amount of the surface treatment agent may be an amount that adheres to the surface of the second copper particles in a monolayer to trilayer form. The amount of the surface treatment agent may be 0.07% by mass or more, 0.10% by mass or more, or 0.2% by mass or more, and may be 2.1% by mass or less, 1.6% by mass or less, or 1.1% by mass or less. The amount of the surface treatment agent of the second copper particles can be calculated by the method described above for the first copper particles. The same applies to the specific surface area, the molecular weight of the surface treatment agent, and the minimum coverage area of ​​the surface treatment agent.

[0047] The content of the second metal particles in the metal paste is 50 mass % or less based on the total amount of metal particles from the viewpoint of connection reliability, and may be 10 to 50 mass % or 20 to 40 mass % from the viewpoints of lowering the sintering temperature to improve adhesion to the base metal layer, reducing the porosity of the sintered body while suppressing shrinkage during sintering, and suppressing the occurrence of cracks.

[0048] The total content of the first copper particles and the second copper particles in the metal paste may be 100 parts by mass, 85 to 99.5 parts by mass, 90 to 99 parts by mass, or 95 to 98 parts by mass, when the total mass of the metal particles is 100 parts by mass.

[0049] The contents of the first copper particles and the second copper particles may be 50 to 90 parts by mass and 50 to 10 parts by mass, 55 to 85 parts by mass and 45 to 15 parts by mass, or 60 to 80 parts by mass and 40 to 20 parts by mass, respectively, relative to 100 parts by mass of the total of the first copper particles and the second copper particles.

[0050] The metal paste of the present embodiment may contain copper particles and metal particles other than copper particles (hereinafter, also referred to as "other metal particles"). In this case, the other metal particles may be nickel particles, silver particles, gold particles, palladium particles, platinum particles, or solder particles. These may be contained in one or more kinds. The average particle size of the other metal particles may be 0.01 μm or more, 0.03 μm or more, or 0.05 μm or more, and may be 5 μm or less, 3.0 μm or less, or 2.0 μm or less. The average particle size of the solder particles may be 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more, and may be 15 μm or less, 10 μm or less, 8.0 μm or less, or 5.0 μm or less.

[0051] The content of the other metal particles may be 5 parts by mass or less, 3 parts by mass or less, 1 part by mass or less, or 0.8 parts by mass or less, when the total mass of the copper particles is 100 parts by mass. The metal paste of the present embodiment may not include solder particles as the other metal particles.

[0052] [Volatile solvent] Examples of volatile solvents include monohydric and polyhydric alcohols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol (e.g., 1,3-butanediol), α-terpineol, and isobornylcyclohexanol (MTPH); ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether (ethyl carbitol), diethylene glycol butyl ether (e.g., diethylene glycol mono-n-butyl ether), diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, and propylene glycol propyl ether. ethers such as dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, and tripropylene glycol dimethyl ether; esters such as dimethyl phthalate, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, propylene glycol diacetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, and propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexane, octane, nonane, decane, and undecane; aromatic hydrocarbons such as benzene, toluene, and xylene; mercaptans having an alkyl group having 1 to 18 carbon atoms; and mercaptans having a cycloalkyl group having 5 to 7 carbon atoms.Examples of mercaptans having an alkyl group having 1 to 18 carbon atoms include ethyl mercaptan, n-propyl mercaptan, i-propyl mercaptan, n-butyl mercaptan, i-butyl mercaptan, t-butyl mercaptan, pentyl mercaptan, hexyl mercaptan, and dodecyl mercaptan. Examples of mercaptans having a cycloalkyl group having 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan, and cycloheptyl mercaptan. The volatile solvent may be used alone or in combination of two or more.

[0053] From the viewpoints of printability and suppressing volumetric shrinkage before and after firing the conductive via precursor (for example, between step c of forming the conductive via precursor and step d of firing the conductive via precursor) and suppressing voids and cracks, the metal paste of this embodiment may contain a solvent having a vapor pressure of 4 Pa ​​or more and 30 Pa or less at 20° C. (hereinafter, also referred to as a “high vapor pressure solvent”) as a volatile solvent. One type of high vapor pressure solvent may be used alone, or two or more types may be used in combination.

[0054] Examples of high vapor pressure solvents include α-terpineol, 1,3-butanediol, ethyl carbitol, and propylene glycol diacetate.

[0055] The metal paste of the present embodiment may contain, as a volatile solvent, a solvent having a vapor pressure of less than 4 Pa ​​at 20° C. (hereinafter, also referred to as a “low vapor pressure solvent”) from the viewpoint of suppressing powderization due to drying accompanying solvent volatilization during printing or paste preparation. The low vapor pressure solvent may be used alone or in combination of two or more kinds.

[0056] Low vapor pressure solvents include isobornylcyclohexanol (MTPH), dimethyl phthalate, and diethylene glycol mono-n-butyl ether.

[0057] From the viewpoint of achieving both printability and suppressing volumetric shrinkage before and after firing the conductive via precursor (for example, between step c of forming the conductive via precursor and step d of firing the conductive via precursor) to suppress voids and cracks, the metal paste of this embodiment may contain a high vapor pressure solvent and a low vapor pressure solvent. In this case, the high vapor pressure solvent and the low vapor pressure solvent may each be used alone or in combination of two or more. The content ratio of the high vapor pressure solvent and the low vapor pressure solvent may be 20 / 80 to 80 / 20 or 30 / 70 to 70 / 30 in mass ratio [high vapor pressure solvent / low vapor pressure solvent].

[0058] The content of the volatile solvent in the metal paste of this embodiment may be 2 mass% or more, 3 mass% or more, or 3.5 mass% or more, based on the total mass of the metal paste, and may be 5 mass% or less, 4.8 mass% or less, 4.5 mass% or less, 4.3 mass% or less, or 4 mass% or less, or may be 2 to 5 mass%, 3 to 4.8 mass%, or 3.5 to 4.5 mass%.

[0059] The metal paste of the present embodiment may contain a resin component such as an epoxy resin. The metal paste of the present embodiment may have a resin component content of 10 mass % or less, or 5 mass % or less, or may not contain a resin component.

[0060] The metal paste can be prepared by mixing the above-mentioned metal particles such as copper particles and any optional components (additives, etc.) with the above-mentioned volatile solvent. After mixing the components, a stirring process may be performed. The maximum diameter of the dispersion may be adjusted by a classification operation. In addition, a three-roll mill, a kneader, a planetary mixer, or other means may be used to mix the components.

[0061] When the metal paste contains the above-mentioned first copper particles and second particles, the second copper particles, the surface treatment agent, and the dispersion medium may be mixed in advance, and a dispersion liquid of the second copper particles may be prepared by performing a dispersion treatment, and the first copper particles, and if necessary, other metal particles and any additives may be mixed to prepare the metal paste. By adopting such a procedure, the dispersibility of the second copper particles is improved, and the mixability with the first copper particles is improved, and the performance of the metal paste is further improved. The dispersion liquid of the second copper particles may be subjected to a classification operation to remove aggregates.

[0062] From the viewpoint of printability, the metal paste of this embodiment may have a viscosity of 100 to 600 Pa s, or 150 to 400 Pa s at 25° C. The viscosity of the metal paste is measured using a micro spiral viscometer PCU-02V (product name, manufactured by Malcom Corporation) at a rotation speed of 10 rpm and a temperature of 25° C.

[0063] The metal paste of the present embodiment may have a Young's modulus of 15 to 75 GPa, 20 to 60 GPa, or 25 to 50 GPa for the sintered body, as measured by the following method, in which case cracks are less likely to occur around the glass through electrode formed on the glass substrate. [Young's modulus measurement] The metal paste was applied onto a glass substrate so that the dimensions after drying were 40 mm × 10 mm × 0.22 mm. Next, the metal paste coating was fired according to the following procedure. (a) The glass substrate having the metal paste coating was placed in a tube furnace (manufactured by AVC Corporation), and argon gas was flowed at 1 L / min to replace the air in the tube furnace with argon gas. (b) Next, while hydrogen gas was flowing at 300 mL / min, the temperature was raised to 300°C in 10 minutes, and sintering treatment was carried out at 300°C for 60 minutes. (c) Thereafter, argon gas was flowed at a flow rate of 0.3 L / min to cool the glass substrate, and the glass substrate on which the sintered body had been formed was taken out into the air at 50° C. or less. (d) The Young's modulus of the obtained sintered body is measured by a resonance method using a JE2-RT model manufactured by Nippon Technoplus Co., Ltd. under the conditions of a temperature of 23° C. and a resonance frequency of 278.4 Hz.

[0064] In the metal paste of this embodiment, for example, when the firing temperature is lowered to decrease the degree of sintering of the metal particles, or when the porosity is increased by blending or combining the metal particles, the Young's modulus of the sintered body tends to decrease, and when the firing temperature is increased to increase the degree of sintering of the metal particles, or when the porosity is decreased by blending or combining the metal particles, the Young's modulus of the sintered body tends to increase. Therefore, by appropriately setting the firing temperature and the blending composition of the metal particles, the Young's modulus of the sintered body can be set within the above-mentioned range.

[0065] <Method of manufacturing glass substrate with conductive vias> The method for manufacturing a glass substrate with conductive vias of this embodiment includes the steps of: preparing a glass substrate having holes formed therein; providing a metal paste portion containing metal particles and a volatile solvent so as to fill the insides of the holes while covering at least the surface of the glass substrate around the holes; heating the metal paste portion to remove a portion of the volatile solvent; removing a portion of the metal paste portion after heating so as to expose the surface, thereby forming a conductive via precursor containing metal particles and the remainder of the volatile solvent and having a flattened exposed surface inside the holes; and firing the conductive via precursor to form conductive vias, wherein the metal particles include first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less, the metal particle concentration of the metal paste portion provided in the step a is 95.0 mass % or more, and the content of the second metal particles in the metal paste portion provided in the step a is 50 mass % or less based on the total amount of metal particles.

[0066] 1 to 3 are schematic diagrams showing an example of a method for manufacturing a glass substrate with conductive vias according to the present embodiment. FIG. 1 shows an example of a glass substrate used in the method for manufacturing a glass substrate with conductive vias. Hereinafter, the method for manufacturing a glass substrate with conductive vias according to the present embodiment will be described with reference to these drawings. In this embodiment, the metal paste contains the above-mentioned copper particles as metal particles, so that the copper particles, copper layer, and copper sintered body can be read as metal particles, metal layer, and metal sintered body, respectively.

[0067] [Step a] Examples of the material of the glass substrate having holes prepared in this step include alkali-free glass, borosilicate glass, quartz glass, etc. The material of the glass substrate may be borosilicate glass or alkali-free glass from the viewpoint of suppressing the occurrence of cracks around the conductive vias and further improving the connection reliability of the wiring substrate.

[0068] The hole may be a through hole or a non-through hole. In this embodiment, for example, as shown in (a) of Fig. 1, a glass substrate 40 can be prepared, which has a glass substrate 1 with a through hole 30 and a metal coating 2 provided on the wall surface of the through hole and on the surface of the glass substrate 1. The through hole 30 communicates with both main surfaces of the glass substrate 40. An example will be described in which a conductive via is provided in this glass substrate 40.

[0069] The thickness of the glass substrate 1 may be 100 μm or more, 200 μm or more, or 300 μm or more from the viewpoint of suppressing warping of the substrate after sintering, and may be 800 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less from the viewpoint of reducing the weight and increasing the density of the substrate.

[0070] The average linear thermal expansion coefficient α of the glass substrate 1 is 0.3×10 -6 ~10×10 -6 K -1 may be 2 x 10 -6 ~8×10 -6 K -1 may be also possible.

[0071] The upper limit of the hole diameter of the through hole 30 may be 200 μm or less, 100 μm or less, or 60 μm or less from the viewpoint of increasing the density of the resulting semiconductor device, and the lower limit of the hole diameter of the through hole 30 is not particularly limited, but may be 20 μm or more, 30 μm or more, or 50 μm or more.

[0072] The number of through holes 30 provided in the glass substrate 40 is set per 1 cm 2 of the main surface of the substrate in order to increase the density of the resulting semiconductor device. 2 There may be 100 or more, 200 or more, or 300 or more per unit area.

[0073] The metal coating 2 may be provided on both main surfaces of the glass substrate 1 and on the wall surface of the through hole 30, or may be provided on at least one of the main surfaces of the glass substrate 1 and on the wall surface of the through hole 30, or may be provided only on the wall surface of the through hole 30, or may not be provided at all. In the embodiment shown in (a) of Fig. 1, a glass substrate 40 is provided with a metal coating 2 on both main surfaces of the glass substrate 1 and on the wall surface of the through hole 30. Note that a primer layer of epoxy resin or the like may be formed on both main surfaces of the glass substrate 1 and on the wall surface of the through hole 30, and the metal coating 2 may be provided on the surface of the primer layer.

[0074] Examples of the metal coating 2 include titanium, nickel, chromium, copper, aluminum, palladium, platinum, and gold. From the viewpoint of adhesion, the metal coating 2 is preferably a coating in which titanium, nickel, and copper are layered in this order. Adhesion is improved by oxidizing the surface of the glass substrate 1 to silicon oxide and forming a titanium layer on the silicon oxide. Furthermore, by providing a nickel layer on the titanium layer and providing a copper layer on the nickel layer, diffusion of copper into the glass substrate 1 can be suppressed compared to the case where a copper layer is provided directly on the titanium layer. Furthermore, by providing a copper layer on the surface, adhesion between the copper layer and the copper particles in the metal paste is improved, improving reliability.

[0075] 1(b), when preparing a glass substrate 41 having non-through holes 31 as holes, a conductive via serving as a through electrode can be formed by grinding the side of the glass substrate opposite to the side having the non-through holes 31 after step a, step b, step c, or step d. Grinding methods include, for example, mechanical polishing and chemical mechanical polishing.

[0076] As shown in Figures 2(a) to (c), the metal paste portion 3 can be provided, for example, by producing a metal particle film on a support film 7, in which a metal particle-containing layer 3p made of the metal paste of the present embodiment described above is provided, and then pressing this metal particle film against a substrate.

[0077] Examples of the support film 7 include a polyimide film, a polyethylene naphthalate film, and a polyethylene terephthalate film. From the viewpoint of workability for forming the metal particle-containing layer by coating, the thickness of the support film may be 20 to 200 μm, 25 to 175 μm, or 30 to 150 μm.

[0078] The composition of the metal particles and the volatile solvent in the metal particle-containing layer can be appropriately set so as to satisfy the conditions of the metal paste of the present embodiment described above. The thickness of the metal particle-containing layer may be 100 μm or less. From the viewpoint of easily ensuring sufficient filling of the through holes or non-through holes, the thickness of the metal particle-containing layer may be 30 μm or more, 40 μm or more, or 50 μm or more.

[0079] From the viewpoint of suppressing the generation of voids in the through holes or non-through holes, the metal particle-containing layer may have a waviness (height difference) on the surface opposite to the support film of 20 μm or less, or may have a waviness (height difference) of 10 μm or less. By reducing the waviness (height difference), when the metal particle film is pressed to fill the holes in the base with the metal particle composition, it becomes easier to simultaneously fill the through holes or non-through holes present in the base, and it becomes easier to reduce the number of through holes or non-through holes that are completely unfilled and the number of through holes or non-through holes where voids are partially generated. The waviness (height difference) can be evaluated by a non-contact method using a laser displacement meter or the like.

[0080] The above-mentioned metal particle film can be produced by applying the metal paste of the above-mentioned embodiment onto a support film to form a metal particle-containing layer in which the concentration of metal particles is 95.0 mass % or more, or by applying a metal paste in which the content of volatile solvent has been increased (for example, increased to an amount such that the concentration of metal particles is less than 94.0 mass %) and drying the applied film to form a metal particle-containing layer in which the concentration of metal particles is 95.0 mass % or more.

[0081] Methods for applying the metal paste include, for example, screen printing, transfer printing, offset printing, jet printing, and methods using a dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, slit coat, letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithography, bar coat, applicator, particle deposition method, spray coater, spin coater, dip coater, etc.

[0082] From the viewpoints of ease of application and uniformity of the applied film thickness, the metal paste can be applied onto the support film by screen printing.

[0083] The thickness of the coating film may be 1 μm or more, 2 μm or more, 3 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more, and may be 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less.

[0084] The step of drying the coating film to form the metal particle-containing layer can be carried out at room temperature or at a temperature between room temperature and 100° C. or lower, and the atmosphere may be air or nitrogen.

[0085] In step a, the above-mentioned metal particle film is pressed against the glass substrate 40 so that the metal particle-containing layer 3p of the metal particle film is in contact with the glass substrate 40, and the through-holes 30 of the glass substrate 40 are filled with a metal paste. In this case, for example, as shown in FIG. 2(b), the metal particle film and the glass substrate 40 can be sandwiched and pressed from above and below by a pressing tool A. The pressing tool A is not particularly limited, and may be a commercially available one, and may also be made using a metal member having a flat portion. For example, the pressing tool having two or more of the above-mentioned metal members can press the metal particle film against the glass substrate by sandwiching the metal particle film and the glass substrate between the metal members arranged so that the flat portions face each other. The pressing tool A may have a mechanism for adjusting the pressure applied to the metal particle film and the glass substrate. A spring or the like can be used as the pressure adjusting means.

[0086] The pressing conditions may be, for example, a temperature of room temperature to 50° C. or less, and the atmosphere may be a vacuum, air, or nitrogen. For the purpose of reducing voids, the metal particle film may be pressed onto the glass substrate after being held at a vacuum of 1000 Pa or less, or at a vacuum of 200 Pa or less. The pressure of the pressing tool when pressing the metal particle film onto the glass substrate may be within a range in which the glass substrate does not crack, and may be, for example, 0.01 MPa or more, 0.1 MPa or more, or 1 MPa or more.

[0087] The metal paste portion 3 may be any portion that fills the inside of the hole while covering at least the surface of the substrate surrounding the hole, but as shown in Figures 2(b) and (c), the metal paste portion may extend beyond the opening of the through hole (VP0 in Figure 2(a)) located on the opposite side to the side where the metal particle film of the substrate is pressed, to cover the surface surrounding the hole.

[0088] [Step b] In this step, the metal paste portion is heated to remove a part of the volatile solvent, in other words, the metal paste portion is heated so that a part of the volatile solvent remains. In addition, when the above-mentioned metal particle film is used, the metal paste portion can be heated after peeling off the support film.

[0089] For heating, for example, a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, a steam heating furnace, a hot plate press device, etc. can be used.

[0090] The atmosphere for heating may be air, an oxygen-free atmosphere such as nitrogen and rare gas, or a reducing atmosphere such as hydrogen and formic acid. In the case of air, when the heating temperature exceeds 100°C, the copper particles are easily oxidized. However, if the metal paste portion contains the above-mentioned high vapor pressure solvent as a volatile solvent, a part of the volatile solvent can be removed at a temperature of less than 100°C, 95°C or less, or 90°C or less. In addition, if the metal paste portion does not contain a high vapor pressure solvent as a volatile solvent, for example, if it contains only the above-mentioned low vapor pressure solvent, the oxidation of the copper particles can be suppressed while removing a part of the volatile solvent by heating at 110°C or more, 130°C or more, or 150°C or more in an oxygen-free atmosphere or a reducing atmosphere.

[0091] When the metal paste portion contains a high vapor pressure solvent, the heating temperature may be 70°C or more and less than 100°C, or 80°C or more and 95°C or less, from the viewpoint of suppressing oxidation of the copper particles, and the heating time may be 5 to 60 minutes, or 10 to 30 minutes, from the viewpoint of suppressing oxidation of the copper particles.

[0092] In addition, from the viewpoint of suppressing volumetric shrinkage before and after firing the conductive via precursor (for example, between step c of forming the conductive via precursor and step d of firing the conductive via precursor) and suppressing voids and cracks, the metal paste portion may be heated so that the concentration of metal particles becomes 96 mass% or more, 97.5 mass% or more, or 98 mass% or more.

[0093] [Process c] In this step, as shown in (a) to (d) of Fig. 3, the metal paste portion 3a after heating obtained in step b is planarized (or smoothed) while removing the metal paste covering the surface of the substrate, thereby forming a conductive via precursor 3b having a planarized exposed surface VP1 and containing metal particles and a remainder of the volatile solvent inside the hole (through hole 30) (Fig. 3(d)).

[0094] The metal paste portion can be removed using a rubber squeegee 42, for example, as shown in (b) and (d) of Fig. 3. This allows a part of the metal paste portion (the metal paste covering the surface of the substrate and the metal paste protruding from the holes) to be removed so that the surface SP0 of the glass substrate 40 and the exposed surface VP1 of the conductive via precursor 3b are flush with each other. Another method is removal using a metal squeegee such as SUS.

[0095] The step between the surface SP0 of the glass substrate 40 and the exposed surface VP1 of the conductive via precursor 3b may be 5 μm or less, or may be 3 μm or less, in a direction perpendicular to the substrate surface. The average step calculated by the following method may be in the above range. (Average step height) An image of a cross section passing through the center of the hole (via) is obtained, and the cross-sectional image is binarized to determine the cross-sectional area Sa surrounded by the inner wall of the hole (via), the exposed surface of the conductive via precursor, and the opening surface of the hole (via), and the average step is calculated by dividing this by the spacing Wa of the inner walls of the hole.

[0096] [Step d] In this step, the conductive via precursor 3b formed in step c is fired. This allows the conductive via 3c made of a metal body to be formed. The metal body may include a copper sintered body having a porous structure. The porosity of the conductive via may be 7% or less, 1.0 to 6.5%, or 1.5 to 5.0%, from the viewpoint of suppressing the penetration of a chemical solution into the copper sintered body when immersed in a chemical solution such as a resist stripping solution or a plating pretreatment solution in a later step and improving reliability. When the conductive via is made of a copper sintered body, the porosity of the copper sintered body may be in the above range. The porosity can be determined by the method described in the examples.

[0097] The calcination can be carried out by a heating treatment, for example, using a heating means such as a hot plate, a hot air dryer, a hot air heating furnace, a nitrogen dryer, an infrared dryer, an infrared heating furnace, a far-infrared heating furnace, a microwave heating device, a laser heating device, an electromagnetic heating device, a heater heating device, or a steam heating furnace.

[0098] The atmosphere during firing may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the copper sintered body, or a reducing atmosphere from the viewpoint of removing the surface oxide of the copper particles in the conductive via precursor. Examples of the oxygen-free atmosphere include the introduction of an oxygen-free gas such as nitrogen or a rare gas, or under vacuum. Examples of the reducing atmosphere include pure hydrogen gas, a mixed gas of hydrogen and nitrogen represented by forming gas, nitrogen containing formic acid gas, a mixed gas of hydrogen and a rare gas, and a rare gas containing formic acid gas. When the conductive via precursor is sintered by heating without pressurization, it is preferably in pure hydrogen gas or a mixed gas of hydrogen and nitrogen represented by forming gas, and preferably in pure hydrogen gas. By heating in pure hydrogen gas, it is possible to lower the sintering temperature of the copper particles. When pure hydrogen gas is used, even if the thickness of the substrate is as thick as 600 μm and the diameter of the through hole 30 is as small as 10 μm, the gas reaches the center of the through hole 30, making it easy to obtain a metal body containing a copper sintered body.

[0099] The maximum temperature reached during the heat treatment may be 150°C or higher, and may be 350°C or lower, 300°C or lower, or 260°C or lower, from the viewpoint of reducing thermal damage to each component and improving yield. If the maximum temperature reached is 150°C or higher, sintering tends to proceed sufficiently when the maximum temperature reached is held for 60 minutes or less. From the viewpoint of volatilizing all the volatile solvent and improving yield, the maximum temperature reached may be held for 1 minute or more, and may be 60 minutes or less, 40 minutes or less, or 30 minutes or less.

[0100] In this embodiment, by using the metal paste of this embodiment, sintering can be performed in an atmosphere containing formic acid gas at a low temperature of 300° C. or less, 200° C. or less, or 150° C. or less, and firing may be performed at 100 to 300° C., 100 to 200° C., or 100 to 150° C. In this case as well, a conductive via with excellent conductivity and connection reliability can be formed.

[0101] The conductive via precursor may be fired without pressure or with pressure. In the latter case, the pressure may be 0.05 MPa or more, 0.1 MPa or more, or 0.3 MPa or more in an atmosphere containing pure hydrogen gas, and 20 MPa or less, 15 MPa or less, or 10 MPa or less. In addition, the pressure may be 1 MPa or more, or 3 MPa or more, and 20 MPa or less, 15 MPa or less, or 10 MPa or less in an atmosphere containing nitrogen gas.

[0102] By setting the pressure to 0.05 MPa or more when pure hydrogen gas is used and 1 MPa or more when nitrogen gas is used, it becomes easier to suppress the generation of voids in the conductive via formed in the center of the through hole 30, and it becomes easier to obtain a conductive via with good conductivity. Furthermore, by setting the pressure to the above-mentioned lower limit or more, in the case where the glass substrate 40 has a metal coating 2, it becomes easier to improve the bonding strength between the metal coating 2 and the conductive via.

[0103] In addition, if the pressure applied during firing is within the above range, a special pressure device is not required, and the yield is not impaired, and voids can be reduced, and the bonding strength and connection reliability can be further improved. Examples of methods for applying pressure to the glass substrate having the conductive via precursor formed in the through hole include a method of placing a weight, a method of applying pressure using a pressure device, and a method of applying pressure using a fixed jig for applying pressure.

[0104] The copper sintered body contained in the metal body may have a copper element ratio of 95 mass% or more, 97 mass% or more, 98 mass% or more, or 100 mass% among the constituent elements excluding light elements. If the copper element ratio in the copper sintered body is within the above range, the formation of intermetallic compounds or the precipitation of different elements at the metallic copper crystal boundaries can be suppressed, the properties of the metallic copper constituting the copper sintered body are likely to be strong, and even better connection reliability is likely to be obtained.

[0105] In step d, the conductive via precursor has an exposed surface VP1 that is flat and has a sufficiently small difference in height from the substrate surface, and has a composition that is not prone to volumetric shrinkage upon firing, so that the difference in height between the surface SP0 of the substrate 40 and the exposed surface VP2 of the conductive via 3c can be made sufficiently small.

[0106] The step between the surface SP0 of the glass substrate 40 and the exposed surface VP2 of the conductive via 3c (or the recess of the conductive via 3c) may be 5 μm or less in the direction perpendicular to the substrate surface, or may be 3 μm or less. Also, the average step calculated by the following method may be in the above range. (Average step height) An image of a cross section passing through the center of the hole (via) is obtained, and the cross-sectional image is binarized to determine the cross-sectional area Sb surrounded by the inner wall of the hole (via), the exposed surface of the conductive via, and the opening surface of the hole (via), and the average step is calculated by dividing this by the spacing Wb of the inner walls of the hole.

[0107] Through the above-mentioned steps a to d, a glass substrate 50 with conductive vias can be obtained. In the glass substrate 50 with conductive vias, the exposed surfaces of the conductive vias are flat (smooth) and the step between the surface SP0 of the glass substrate 40 is sufficiently small, so that wiring can be easily formed and the glass substrate 50 can exhibit a sufficiently low connection resistance even after wiring formation.

[0108] The method for manufacturing a glass substrate with conductive vias of the present embodiment may further include a step e of forming wiring, in which case the method may be used as a method for manufacturing a wiring substrate with conductive vias.

[0109] [Process e] This process can include the steps of resist formation, plating, resist removal, and etching, which are described below.

[0110] <Resist formation process> In the resist formation process, for example, as shown in (a) and (b) of Figures 4, a negative photosensitive dry film 8 for etching resist is laminated on the main surface of the glass substrate 40 and the conductive via 3c, and then a light-transmitting photomask is placed over the wiring shape, exposed to ultraviolet light, and the unexposed areas are removed with a developer to form an etching resist 8a.

[0111] Other methods for forming the etching resist 8a include, for example, a method of silk-screen printing resist ink and a method of laminating a dry film resist with a laminator.

[0112] <Plating process> In the plating step, for example, as shown in FIG. 4(c), the wiring 9 can be formed in the openings of the etching resist 8a by a method such as electrolytic plating or electroless plating.

[0113] <Resist removal process> In the resist removal step, for example, as shown in FIG. 4(d), the etching resist 8a can be removed by a method such as stripping by a wet process using an alkaline aqueous solution or an organic solvent-based chemical liquid such as an organic amine-based liquid such as TMAH or a ketone-based liquid such as acetone, or stripping by a dry process using plasma, ozone, or the like.

[0114] <Etching process> In the etching step, the metal coating 2 in the portion not covered by the wiring 9 can be removed by etching. In this embodiment, parts of the metal coating 2 provided on both main surfaces of the glass substrate 1 are removed by etching.

[0115] Examples of the etching method include a method using a chemical etching solution typically used for wiring boards, such as a solution of cupric chloride and hydrochloric acid, a ferric chloride solution, a solution of sulfuric acid and hydrogen peroxide, or an ammonium persulfate solution.

[0116] By the above step e, a wiring board 52 with conductive vias as shown in FIG. 4(e) can be obtained.

[0117] In the above-mentioned method, a step of removing at least a part of the conductor such as the sintered body of the metal base or the metal coating 2 remaining on the main surface of the glass substrate 40 may be provided prior to the step e.

[0118] The means for removing the conductor include chemical polishing, mechanical polishing, chemical mechanical polishing, fly-cutting, plasma treatment, etc. Fly-cutting means cutting and flattening with a surface planer.

[0119] According to the manufacturing method of a glass substrate with conductive vias of this embodiment, it is possible to obtain a substrate with conductive vias in which the main surface of the substrate (e.g., metal coating 2) is fully exposed and the conductive vias have a sufficiently small step between the main surface of the substrate, so that a process for smoothing the main surface of the substrate, such as the process of removing the conductor described above, can be omitted.

[0120] In step e of this embodiment, a resin layer forming step may be further provided for forming a resin layer on the wiring board with conductive vias. This allows a resin layer to be formed to cover the wiring 9, and more effectively prevents cracks from occurring around the conductive vias and reduces the adhesion between the glass and the wiring in a reliability test, thereby further improving the connection reliability of the wiring board.

[0121] The resin layer may be formed by coating a resin composition or by attaching a resin film. The resin composition and the resin film may be used as an interlayer insulating material. The resin layer may be cured by heating. EXAMPLES

[0122] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0123] [Preparation of metal paste] (Preparation Examples A to J and Comparative Preparation Example A) The raw materials shown below were mixed in the ratios (parts by mass) shown in Tables 1 and 2 using a three-roll mill to prepare metal pastes.

[0124] <First copper particle> (Wet copper powder) Spherical copper particles W1:1050Y (Mitsui Kinzoku Co., Ltd., average particle size (D50): 0.81 μm, spherical) Spherical copper particles W2: 1100Y (Mitsui Kinzoku Co., Ltd., average particle size (D50): 1.1 μm, spherical) Spherical copper particles W3: 1200Y (Mitsui Kinzoku Co., Ltd., average particle size (D50): 2.1 μm, spherical) Spherical copper particles W4:1300Y (Mitsui Kinzoku Co., Ltd., average particle size (D50): 3.5 μm, spherical) Flat copper particles W1: 1100YP (manufactured by Mitsui Kinzoku, average particle size (D50): 1.4 μm, flat) Flat copper particles W2: 1200YP (Mitsui Kinzoku, average particle size (D50): 3.1 μm, flat) (Atomized copper powder) Spherical copper particles A1: MA-C02K (manufactured by Mitsui Kinzoku Co., Ltd., average particle size (D50): 1.8 μm, spherical) Spherical copper particles A2: MA-C025K (Mitsui Kinzoku Co., Ltd., average particle size (D50): 2.4 μm, spherical) Spherical copper particles A3: MA-C03K (manufactured by Mitsui Kinzoku Co., Ltd., average particle size (D50): 3.4 μm, spherical)

[0125] <Second copper particles> Spherical copper particles W5: CH0200L1 (Mitsui Kinzoku Co., Ltd., average particle size (D50): 200 nm, spherical)

[0126] <Resin component> Resin R1: "KFA-2000" (acrylic binder manufactured by GOO Chemical Industry Co., Ltd.) as an organic binder and a mixture of carbitol and terpineol as an organic solvent (mass ratio of carbitol to terpineol in the mixture [carbitol:terpineol] = 1:1) mixed in a mass ratio of 1:2

[0127] <Volatile solvent> (High vapor pressure solvent: vapor pressure between 4 Pa ​​and 30 Pa at 20°C) α-Terpineol: Fujifilm Wako Pure Chemical Industries, Ltd., vapor pressure at 20°C: 6.5 Pa (Low vapor pressure solvent: vapor pressure of less than 4 Pa ​​at 20°C) Diethylene glycol mono-n-butyl ether: Showa Chemical Co., Ltd., vapor pressure at 20°C: 1.3 Pa

[0128] The metal pastes obtained in Preparation Examples A to J and Comparative Preparation Example A were evaluated for viscosity, printability, bondability, and volume resistivity of the sintered body according to the following methods.

[0129] <Viscosity> The viscosity of the metal paste was measured using a microspiral viscometer PCU-02V (product name, manufactured by Malcom Co., Ltd.) The measurement conditions were a rotation speed of 10 rpm and a temperature of 25°C.

[0130] <Printability> In the <Preparation of Metal Particle Film> described later, when printing was performed on a 100 μm thick PET film using a screen printer, the number of pinholes that were not applied to the PET film side was counted. Based on the number of pinholes, the printability was evaluated according to the following criteria. Evaluations A to D were considered to be good. (Judgment criteria) A: 0 pinholes B: The number of pinholes is 1 or more but less than 3 C: The number of pinholes is 3 or more but less than 5 D: The number of pinholes is 5 or more but less than 10 E: The number of pinholes is 10 or more but less than 20 F: 20 or more pinholes

[0131] In addition, in the <Preparation of Metal Particle Film> described later, after printing on a 100 μm-thick PET film using a screen printer, the coating amount (g) of an 8-inch φ size was measured.

[0132] <Zygosity> According to the following method, a bonded sample for a shear strength test was prepared, and the die shear strength was measured, and the bondability was evaluated according to the following criteria. The bondability was evaluated as A to C as good.

[0133] (Preparation of joint samples for shear strength test) 3×3mm 2 Using a 100 μm thick stainless steel mask and squeegee with a square opening, the metal paste was stencil printed on a copper plate with a size of 25 × 20 × 3 mm thick. After drying at 90 ° C for 10 minutes using a hot plate, it was placed in a tube furnace (manufactured by AVC Co., Ltd.) and argon gas was flowed at a flow rate of 1 L / min to replace the air in the tube furnace with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised to 225 ° C in 10 minutes, and the metal paste was sintered by performing a sintering process at 225 ° C for 60 minutes. Then, argon gas was flowed at a flow rate of 0.3 L / min to cool it, and it was taken out into the air at 50 ° C or less, and a substrate with a metal body formed on the copper plate was obtained as a joint sample for shear strength test.

[0134] (Measurement of die shear strength) For the bonded samples for shear strength testing, a universal bond tester (4000 series, Daisy Japan Co., Ltd.) equipped with a DS-100 load cell was used to press the metal body or Cu plate horizontally under the following measurement conditions: measurement speed: 5 mm / min, measurement height: 50 μm, and the die shear strength was measured. The average value of 10 points was calculated and used as the average bond strength. (Judgment criteria) A: Average joint strength is 50N or more B: Average joint strength is 40N or more and less than 50N C: Average joint strength is 20N or more but less than 40N D: Average joint strength is 10N or more but less than 20N E: The average bonding strength is less than 10N

[0135] <Volume resistivity measurement> The metal paste prepared above was applied to a glass wafer with a thickness of 1 mm using an automatic film applicator (manufactured by Allgood Co., Ltd.) so that the coating thickness was about 150 μm. The coating area was about 5 cm × about 10 cm. Next, the wafer with the coating film was dried at 90 ° C for 10 minutes using a hot plate, and then placed in a tube furnace (manufactured by AVC Co., Ltd.), and argon gas was flowed at 1 L / min to replace the air in the tube furnace with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised to 225 ° C in 10 minutes, and sintering treatment was performed at 225 ° C for 60 minutes to sinter the metal paste. Then, argon gas was flowed at a flow rate of 0.3 L / min to cool it, and it was taken out into the air at 50 ° C or less to obtain a sample with a metal body formed on the wafer.

[0136] The volume resistivity of the metal body in the above samples was calculated from the sheet resistance measured with a four-point needle sheet resistance meter (Loresta GP, manufactured by Mitsubishi Analytech Co., Ltd.) and the film thickness determined with a non-contact surface / layer cross-sectional shape measurement system (VertScan, manufactured by Ryoka Systems Co., Ltd.).

[0137] [Table 1]

[0138] [Table 2]

[0139] [Preparation of glass substrate with conductive vias] (Examples 1 to 13 and Comparative Examples 1 to 4) A glass substrate with conductive vias was produced by the following procedure.

[0140] <Preparing the glass substrate> Glass substrate A: A glass substrate "D263Teco" (manufactured by SCHOTT, product name, material: borosilicate glass, average linear thermal expansion coefficient α: 7.2×10) having a through hole and on both main surfaces and the wall surface of the through hole, a titanium layer (thickness 100 nm) and a copper layer (thickness 300 nm) formed in this order. -6 K -1 The glass substrate had a diameter of 6 inches and a thickness of 300 μm, and the titanium layer and copper layer were formed in that order by sputtering, with through holes having a hole diameter (via diameter) of 90 μm provided therein. Glass substrate B: A glass substrate "OA-10G" (manufactured by Nippon Electric Glass, material: alkali-free glass, average linear thermal expansion coefficient α: 3.8×10) with through holes and a titanium layer (thickness 100 nm) and a copper layer (thickness 300 nm) formed in that order on both main surfaces and on the wall surfaces of the through holes. -6 K -1 The glass substrate had a diameter of 6 inches and a thickness of 300 μm, and the titanium layer and copper layer were formed in that order by sputtering, with through holes having a hole diameter (via diameter) of 90 μm provided therein.

[0141] <Preparation of metal particle film> The metal paste prepared above was printed on a 100 μm thick PET film with an 8-inch diameter (circular shape with a diameter of 20 cm) using a screen printing plate (line diameter: 23 μm, mesh number: 400, mesh size: 41 μm, void ratio: 41 μm) using a screen printer to obtain a metal particle film with a metal particle-containing layer.

[0142] <Conductive via formation> Using a bonding device VJ-35 (manufactured by Ayumi Industries Co., Ltd.), the metal particle film was bonded to the glass substrate from the metal particle-containing layer side, and the laminate was vacuum-pressed at room temperature and a pressure of 3 MPa to fill the through holes with the metal paste. At this time, the metal paste was protruded to the opposite side of the glass substrate from the side to which the metal particle film was bonded. Note that glass substrate A was used in Examples 1 to 11 and Comparative Examples 1 and 2, and glass substrate B was used in Examples 12 to 13 and Comparative Examples 3 and 4.

[0143] Next, the PET film was peeled off from the laminate, and the laminate was dried in the air for 10 minutes at 90° C. The concentration (mass%) of metal particles in the metal paste portion before and after drying is shown in the table.

[0144] For the dried laminate, as shown in (a) to (d) of Figure 3, the metal paste on the main surface of the glass substrate on which the metal particle film was bonded was removed using a rubber squeegee, and then the metal paste protruding from the side opposite the side on which the metal particle film was bonded to the glass substrate was removed using a rubber squeegee.

[0145] Next, the glass substrate with the conductive via precursor formed in the through hole by the above-mentioned process was placed in a tube furnace (manufactured by AVC Corporation), and argon gas was flowed at 1 L / min to replace the air in the tube furnace with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised to 300°C in 10 minutes, and sintering treatment was performed at 300°C for 60 minutes to sinter the conductive via precursor. Then, argon gas was flowed at a flow rate of 0.3 L / min to cool, and the substrate was taken out into the air at 50°C or less to obtain a glass substrate with conductive vias.

[0146] <Evaluation of glass substrates with conductive vias> The glass substrates with conductive vias obtained above were evaluated for the presence or absence of cracks and voids in the conductive vias, the porosity of the conductive vias, and the depressions after sintering according to the following methods.

[0147] (Presence or absence of cracks in conductive vias) The cross-sections of the conductive vias in the glass substrate with conductive vias were exposed by cross-section polishing, and 30 conductive vias were observed using a digital microscope (VHX-6000, Keyence Corporation) to check for the presence or absence of cracks (length 10 μm or more).

[0148] (Presence or absence of voids in conductive vias) The cross-sections of the conductive vias in the glass substrate with conductive vias were exposed by cross-section polishing, and 30 conductive vias were observed using a digital microscope (VHX-6000, Keyence Corporation) to check for the presence or absence of voids (diameter 5 μm or more).

[0149] (dent after sintering) The cross sections of the conductive vias of the glass substrate with conductive vias were exposed by cross-section polishing, and 30 conductive vias were observed using a digital microscope (VHX-6000, manufactured by Keyence Corporation), and the average step height was calculated using the following method. [Average step height] An image of a cross section passing through the center of the via was obtained and then binarized to determine the cross-sectional area Sb enclosed by the inner wall of the via, the exposed surface of the conductive via, and the opening surface of the via. The average step difference (=Sb / Wb) was calculated by dividing this by the spacing Wb between the inner walls of the hole. The average value of the average step height at 30 points was calculated, and the dents after sintering were evaluated according to the following criteria. Note that a rating of C or higher can be judged as good. (Judgment criteria) A: The average step height is less than 1 μm B: The average step height is 1 μm or more and less than 3 μm C: The average step height is 3 μm or more and less than 5 μm D: The average step height is 5 μm or more and less than 10 μm E: The average step height is 10 μm or more

[0150] (Porosity of conductive vias) The glass substrate with conductive vias that had been subjected to mechanical polishing was cut in the thickness direction, and the cross section of the central portion of the conductive via of the glass substrate was exposed by a focused ion beam, and this cross section was observed. When observing the cross section of the central portion of the through hole of the glass substrate, a range of ±5 μm from the central portion of the through hole in the thickness direction of the glass substrate and ±5 μm in the direction perpendicular to the thickness direction of the glass substrate was observed. The focused ion beam processing observation device used was MI4050 (manufactured by Hitachi High-Technologies Corporation). For the observation, a scanning electron microscope S-3700N (manufactured by Hitachi High-Technologies Corporation) was used at a magnification of 5000 times, and a cross-sectional image (about 10 μm square) of the conductor was taken. Five observation points were made. The obtained cross-sectional image was binarized using image analysis software (Adobe Photoshop (registered trademark) Elements) so that the sintered copper portion and the porous (vacant hole) portion were separated. For each of the five observation points, the ratio of the area of ​​the porous portion to the total area of ​​the cross section of the conductive via was calculated, and this was taken as the porosity. The average value of the porosities at the five observation points was taken as the porosity of the conductive via.

[0151] [Fabrication and evaluation of wiring board] (Examples 1 to 13 and Comparative Examples 1 to 4) Wiring was formed on the glass substrate with conductive vias prepared in the same manner as above in the following manner to obtain a wiring substrate, which was then evaluated.

[0152] On the surface of the glass substrate with conductive vias obtained above, a dry film for ultraviolet curing etching resist H-W425 (trade name, manufactured by Resonac Corporation) was pressed with a laminator. Then, a photomask was aligned to expose the wiring pattern, and resist development was performed. Next, electrolytic plating was performed on the resist openings, and then the resist was peeled off and the seed layer was etched to form wiring having a wiring pattern of 300 μm × 600 μm, thereby obtaining a test piece 55 (wiring board) as shown in FIG. 5. The wiring pattern was finished so that the thickness was about 10 μm after etching the seed layer. In the test piece 55, the conductive vias formed in the through holes are electrically connected by wiring provided on the surface of the substrate.

[0153] In addition, in Examples 11 and 13 and Comparative Examples 2 and 4, ABF films "ABF GX92" (manufactured by Ajinomoto Fine-Techno Co., Ltd.) were attached by heat pressing to both sides of the test piece 55 on which the wiring pattern was formed, to prepare a test piece with a resin layer. The thickness of the resin layer was about 30 μm.

[0154] The test pieces obtained above were evaluated for initial resistance, connection reliability, the presence or absence of cracks in the substrate, and dents in the conductive vias after resist peeling, according to the following methods.

[0155] (Initial resistance value) The initial resistance of the test piece 55 (or the test piece with the resin layer) was measured by connecting 1000 vias with a diameter of 90 μm. Based on this connected resistance, the initial resistance was evaluated according to the following criteria. A rating of B or higher was deemed to be good. (Number of vias) 90μmφ: 1000 pieces (Judgment criteria) A: Resistance is less than 6Ω B: Resistance is 6Ω or more and less than 10Ω C: Resistance is 10Ω or more and less than 20Ω D: Resistance is 20Ω or more and less than 50Ω E: Resistance is 50Ω or more

[0156] (Connection reliability) Test piece 55 (or test piece with resin layer) was set in a temperature cycle tester (TSA-72SE-W, manufactured by Espec Corporation), and a temperature cycle connection reliability test was performed under the following conditions: low temperature side: -55°C, 15 minutes, room temperature: 2 minutes, high temperature side: 125°C, 15 minutes, defrost cycle: automatic, number of cycles: 50, 100, 300, 500, 1000 cycles. The resistance value of the connection of the above number of vias was measured for the test pieces that had undergone each number of cycles. Based on this connected connection resistance value, the connection reliability was evaluated according to the following criteria. (Judgment criteria) A: Resistance change rate is less than 1% of the initial resistance value B: Resistance change rate is 1% or more and less than 3% of the initial resistance value C: Resistance change rate is 3% or more and less than 5% of the initial resistance value D: Resistance change rate is 5% or more and less than 10% of the initial resistance value E: Resistance change rate is 10% or more but less than 20% of the initial resistance value F: Resistance change rate is 20% or more compared to the initial resistance value G: Poor continuity occurs

[0157] (Cracked circuit board) The test piece 55 (or the test piece with the resin layer) was visually inspected to check for the presence or absence of cracks in the glass substrate.

[0158] (Dent after resist removal) In preparing the test piece 55 (or the test piece with the resin layer), the resist was peeled off, and then the cross section of the conductive via was exposed by cross-sectional polishing. 30 conductive vias were observed using a digital microscope (VHX-6000, manufactured by Keyence Corporation), and the average value of the average step height was calculated in the same manner as in the evaluation of the dents after sintering. The dents after the resist peeling were then evaluated according to the following criteria. Note that evaluations of C or higher can be judged as good. (Judgment criteria) A: The average step height is less than 1 μm B: The average step height is 1 μm or more and less than 3 μm C: The average step height is 3 μm or more and less than 5 μm D: The average step height is 5 μm or more and less than 10 μm E: The average step height is 10 μm or more

[0159] [Table 3]

[0160] [Table 4]

[0161] [Observation and consideration of conductive vias] (Observation 1) For the glass substrate with conductive vias produced in Example 1, a focused ion beam processing and observation device (manufactured by Hitachi High-Technologies Corporation, product name: MI4050) was used to expose the cross section of the center of the conductive via of the glass substrate with conductive vias by a focused ion beam, and the cross section was observed. For the observation, a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name: S-3700N) was used to take cross-sectional images of the copper sintered body at magnifications of 5,000 times and 20,000 times (see FIG. 6). The images shown in FIG. 6 are (a) an image at a magnification of 5,000 times, and (b) an image at a magnification of 20,000 times. As shown in FIG. 6(b), the copper sintered body has a structure in which the first copper particles are filled between the second copper particles, and the particles are bonded together. It is believed that the formation of such a dense copper sintered body and the suppression of the occurrence of voids and cracks and the suppression of dents due to the suppression of shrinkage during sintering can show a sufficiently low connection resistance value even after wiring is formed, and the obtained wiring board can have excellent connection reliability.

[0162] [Observation and consideration of wiring board] The appearance and cross section of the wiring board produced in Example 1 were observed with an optical microscope. In the images shown in Fig. 7, (a) shows the appearance of the wiring board, (b) shows an enlarged view of a part of (a), and (c) shows a cross section of the wiring board. As shown in Fig. 7, the via part of the glass substrate is filled with the copper sintered body without voids, and the copper wiring is well formed in the conductive via part filled with the copper sintered body.

[0163] [Preparation of glass substrate with conductive vias] (Comparative Examples 5 to 8) A glass substrate with conductive vias was produced by the following procedure.

[0164] <Preparing the glass substrate> The same glass substrate A and glass substrate B as those described above were prepared.

[0165] <Conductive via formation> The glass substrate was immersed in a copper sulfate plating solution and electrolytic copper plating was performed to fill the vias with a diameter of 90 μm. Next, the copper plating film deposited on both sides of the glass substrate was polished using a CMP slurry to finish the copper on the glass substrate to a thickness of approximately 1 μm.

[0166] [Table 5]

[0167] [Observation and consideration of wiring board after temperature cycle test] The wiring boards produced in Example 12 and Comparative Example 7 were observed with an optical microscope for their substrate surfaces after a temperature cycle test (50 times). As shown in FIG. 8(a), the wiring board produced in Example 12 suppressed the occurrence of cracks even after the temperature cycle test. FIG. 8(b) is an enlarged view of a portion of FIG. 8(a). On the other hand, as shown in FIG. 9(a), the wiring board produced in Comparative Example 7 had cracks occurring in the glass substrate around the conductive vias. FIG. 9(b) is an enlarged view of a portion of FIG. 9(a).

[0168] [Young's modulus of sintered metal paste] For the metal paste of Preparation Example A, the Young's modulus of the sintered body was measured by the following method. (Young's modulus measurement) The metal paste was applied onto a glass substrate so that the dimensions after drying were 40 mm × 10 mm × 0.22 mm. Next, the metal paste coating was fired according to the following procedure. (a) The glass substrate having the metal paste coating was placed in a tube furnace (manufactured by AVC Corporation), and argon gas was flowed at 1 L / min to replace the air in the tube furnace with argon gas. (b) Next, while hydrogen gas was flowing at 300 mL / min, the temperature was raised to 300°C in 10 minutes, and sintering treatment was carried out at 300°C for 60 minutes. (c) Thereafter, argon gas was flowed at a flow rate of 0.3 L / min to cool the glass substrate, and the glass substrate on which the sintered body had been formed was taken out into the air at 50° C. or less. (d) The Young's modulus of the obtained sintered body is measured by a resonance method using a JE2-RT model manufactured by Nippon Technoplus Co., Ltd. under the conditions of a temperature of 23° C. and a resonance frequency of 278.4 Hz.

[0169] The metal paste of Preparation Example A had a Young's modulus of 27.4 GPa for the sintered body. This value is about one third of the Young's modulus of a typical electrolytic copper plating film, which is about 100 GPa. It is believed that filling the vias with a copper sintered body with such a low Young's modulus reduced the stress around the vias, and suppressed the occurrence of cracks around the vias after the temperature cycle test. [Explanation of symbols]

[0170] DESCRIPTION OF THE SYMBOLS 1...glass substrate, 2...metal coating, 3...metal paste portion, 3b...conductive via precursor, 3c...conductive via, 3p...metal particle-containing layer, 7...support film, 8a...etching resist, 9...wiring, 30...through hole, 31...non-through hole, 40, 41...glass substrate, 42...rubber squeegee, 50...glass substrate with conductive via, 52...wiring board with conductive via, 55...test piece, A...pressure jig.

Claims

1. a step a) of preparing a glass substrate having a hole formed therein, and providing a metal paste portion containing metal particles and a volatile solvent so as to fill the inside of the hole and cover at least the surface of the glass substrate around the hole; a step b of heating the metal paste portion to remove a portion of the volatile solvent; a step c) of removing a portion of the metal paste portion after heating so that the surface is exposed, thereby forming a conductive via precursor having a flattened exposed surface inside the hole, the conductive via precursor including the metal particles and the remainder of the volatile solvent; and step d) of firing the conductive via precursor; the metal particles include first metal particles having a volume average particle size of 0.8 μm or more and second metal particles having a volume average particle size of 0.5 μm or less, The metal particle concentration of the metal paste portion provided in the step a is 95.0 mass% or more, A method for manufacturing a glass substrate with conductive vias, wherein the content of the second metal particles in the metal paste portion provided in step a is 50 mass % or less based on the total amount of the metal particles.

2. The method for manufacturing a glass substrate with conductive vias according to claim 1 , wherein the first metal particles and the second metal particles are copper particles.

3. The method for manufacturing a glass substrate with conductive vias according to claim 1 or 2, wherein the first metal particles include flaky copper particles.

Images