Glass paste and use thereof

Abstract

To provide a glass paste capable of achieving both baking property and printing property even when baked in an inert gas atmosphere.SOLUTION: In the glass paste for forming an insulating protective film by firing in an inert gas atmosphere, a glass component and an organic vehicle are combined, 50 mass% or more of the glass component is composed of glass beads, and a (meth) acrylic resin is contained in the organic vehicle. The insulating protective film may be a film for protecting a base metal-based conductor film and / or a base metal-based resistive film. The central particle diameter D50 of the glass beads may be 1 to 30 μm. The glass beads may include at least one selected from the group consisting of borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass. A ratio of an alkali metal component in the glass beads may be 10% by mass or less. The glass paste may be applied to a base metal-based conductor film and / or a base metal-based resistance film and fired in an inert gas atmosphere to produce an insulating protective film.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a glass paste suitable for forming an insulating protective film for a base metal conductive film or a resistive film, and to uses thereof. [Background technology]

[0002] In electronic components and substrates that have a conductive film or resistive film formed on a substrate such as glass or ceramic, an insulating protective film is formed to protect the conductive film or resistive film. Glass is commonly used for this insulating protective film when heat resistance is required. A glass paste is printed on the conductive film or resistive film, dried, and then fired to form a glass insulating protective film (fired body). This glass paste is a paste-like composition in which glass particles are blended with an organic vehicle (resin component, organic solvent).

[0003] Traditionally, precious metal materials such as Ag, AgPd, and AgPt were mainly used for the conductive film, and AgPd and RuO2 for the resistive film. However, in recent years, precious metal materials have been avoided due to rising prices of precious metals and issues such as sulfur resistance and migration resistance, and furthermore, applications such as chip resistors require resistive films with ultra-low resistance and a small temperature coefficient of resistance (TCR), so base metal materials such as Cu are increasingly being used for the conductive film, and CuNi for the resistive film.

[0004] However, in the case of insulating protective films, the following problems arise when applying glass paste, which has conventionally been widely used for precious metal conductor films and resistive films, to base metal conductor films and resistive films.

[0005] Because precious metals do not oxidize, glass pastes used for precious metal conductor films and resistive films can be fired in air. However, because base metals are prone to oxidation, firing in a nitrogen atmosphere is essential for glass pastes used for precious metal conductor films and resistive films. During the firing process, the organic vehicle (resin components, organic solvents) contained in the glass paste is removed, and then the glass components melt and solidify to form the insulating protective film. In this process, it is important to completely decompose and remove the resin components so that they do not remain in the insulating protective film. If the resin components in the glass paste are not completely decomposed and remain in the insulating protective film, the densification of the fired glass body is hindered, resulting in reduced protective performance and poor appearance. In particular, firing glass pastes in a nitrogen atmosphere can easily result in incomplete decomposition of the resin components in the glass paste, resulting in soot on the insulating protective film after firing. Furthermore, even if thermal decomposition occurs, the decomposition is slow, and if decomposition gas remains up to the temperature at which the glass melts, the resulting bubbles will remain in the insulating protective film, reducing its protective performance (electrical insulation and barrier properties against oxygen, humidity, etc.).

[0006] To address these issues, Japanese Patent Application Laid-Open No. 2000-276946 (Patent Document 1) uses a combination of ethyl cellulose resin, which has excellent printability, and acrylic resin, which has excellent decomposition properties, as resin components, thereby improving printability and baking properties in a nitrogen atmosphere.

[0007] Furthermore, in Japanese Patent Laid-Open Publication No. 5-129739 (Patent Document 2), a metal oxide such as CeO2 is added to the paste as an oxidizing agent to promote decomposition of the resin component and improve sinterability in a nitrogen atmosphere. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-276946 [Patent Document 2] Japanese Patent Application Publication No. 5-129739 Summary of the Invention [Problem to be solved by the invention]

[0009] However, even if attempts are made to achieve both printability and sinterability simply by adjusting the resin components, as in Patent Document 1, the use of acrylic resin significantly reduces the fluidity of the glass paste, resulting in the problem of pinholes occurring when the glass paste is printed on a conductive film or resistive film. Therefore, when using acrylic resin, it is essential to adjust the rheology of the paste by adding a dispersant or the like to improve printability, and this dispersant often has an adverse effect on sintering in a nitrogen atmosphere, so the means in Patent Document 1 was not effective in solving the problem.

[0010] Furthermore, in Patent Document 2, a specific metal oxide is reduced and metallized in a nitrogen atmosphere as an oxidizing agent, which may remain in the insulating protective film and reduce its protective performance, or the metallized oxidizing agent may migrate to the resistive film and alter its performance, such as its resistance value and TCR. Thus, even if a metal oxide is added, the glass paste used to form the insulating protective film is not sufficient. Furthermore, the glass component of Patent Document 2 contains Pb, which is not practical from the viewpoint of a harmful substance.

[0011] As described above, glass pastes used for base metal conductor films and resistive films, which require firing in a nitrogen atmosphere where the thermal decomposition (removal) of the resin components is likely to be incomplete, must be able to achieve both sinterability (complete thermal decomposition of the resin components so that soot and bubbles do not form in the insulating protective film) and printability (good fluidity and no pinholes), without affecting the protective performance of the insulating protective film or the electrical properties of the conductor film or resistive film.

[0012] Therefore, an object of the present invention is to provide a glass paste that can achieve both sinterability and printability even when fired in an inert gas atmosphere, and uses thereof.

[0013] Another object of the present invention is to provide a glass paste capable of forming an insulating protective film that has excellent protective performance for a conductive film or a resistive film without significantly deteriorating the electrical properties of the conductive film or the resistive film, and uses thereof. [Means for solving the problem]

[0014] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that, in a glass paste for forming an insulating protective film by firing in an inert gas atmosphere, by combining a glass component with an organic vehicle, using glass beads as the main component of the glass component, and using a (meth)acrylic resin as a binder for the organic vehicle, it is possible to provide a glass paste that can be fired in an inert gas atmosphere while also achieving good printability. This finding led to the completion of the present invention.

[0015] That is, the present invention includes the following aspects.

[0016] Aspect [1]: A glass paste for forming an insulating protective film by firing in an inert gas atmosphere, comprising a glass component and an organic vehicle; The glass component contains glass beads in a proportion of 50% by mass or more, and The glass paste, wherein the organic vehicle contains a (meth)acrylic resin.

[0017] Aspect [2]: The glass paste according to aspect [1], wherein the insulating protective film is a film for protecting a base metal conductor film and / or a base metal resistive film.

[0018] Aspect [3]: The median particle size D of the glass beads 50 The glass paste according to the above aspect [1] or [2], wherein the particle size is 1 to 30 μm.

[0019] Aspect [4]: ​​The glass paste according to any one of Aspects [1] to [3], wherein the glass beads contain at least one selected from the group consisting of borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass.

[0020] Aspect [5]: The glass paste according to any one of Aspects [1] to [4], wherein the proportion of alkali metal components in the glass beads is 10 mass % or less.

[0021] Aspect [6]: The glass paste according to any one of Aspects [1] to [5], wherein the glass component further contains crushed glass powder.

[0022] Aspect [7]: The glass paste according to aspect [6], wherein the mass ratio of the glass beads to the crushed glass powder is 99 / 1 to 60 / 40.

[0023] Aspect [8]: A glass paste according to aspect [6] or [7], wherein the softening point of the pulverized glass powder is 100°C or more lower than the softening point of the glass beads, and the mass ratio of the glass beads to the pulverized glass powder is 85 / 15 to 65 / 35.

[0024] Aspect [9]: An insulating protective film formed from the glass paste according to any one of aspects [1] to [8].

[0025] Aspect

[10] : A method for producing an insulating protective film, comprising applying the glass paste according to any one of aspects [1] to [8] to a base metal conductor film and / or a base metal resistive film, and firing the paste in an inert gas atmosphere.

[0026] Aspect

[11] : A laminate comprising a ceramic substrate, a base metal conductive film, a base metal resistive film, and the insulating protective film according to aspect [9].

[0027] Aspect

[12] : A method for producing a laminate, comprising applying the glass paste according to any one of aspects [1] to [8] onto a ceramic substrate having a base metal conductor film and a base metal resistive film laminated thereon, and firing the glass paste in an inert gas atmosphere.

[0028] In the present application, a numerical range expressed as "A to B" means "A or more and B or less," and is used in the sense that both the numerical values ​​A and B at the both ends are included.

[0029] In addition, in this application, the term "base metal" refers to a metal other than the noble metals Au, Ag, Pt, Pd, Ru, Os, and Ir. [Effects of the Invention]

[0030] In the present invention, a glass paste for forming an insulating protective film by firing in an inert gas atmosphere contains a glass component and an organic vehicle, the glass component being mainly composed of glass beads, and the organic vehicle containing a (meth)acrylic resin, so that both sinterability and printability can be achieved even in an inert gas atmosphere (e.g., a nitrogen atmosphere). Therefore, when an insulating protective film for a conductor film or a resistive film is formed using the glass paste of the present invention, an insulating protective film that has excellent protective performance for the conductor film or the resistive film can be formed without degrading the electrical properties of the conductor film or the resistive film. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic plan view of a laminate used in the evaluation tests of printability, sinterability, and dielectric strength voltage in the examples. [Figure 2] FIG. 2 is a schematic plan view of a laminate used in an evaluation test of the rate of change in resistance value in a humidity resistance test and the change in TCR due to baking of a glass film in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0032] [Glass components] The glass paste of the present invention is used to form an insulating protective film by firing in an inert gas atmosphere, and is characterized by containing glass beads as the main glass component. Glass beads are glass particles adjusted to a spherical or nearly spherical shape at high temperatures, with smooth surfaces and no corners. Those skilled in the art clearly distinguish them from pulverized glass powders such as glass frit, which are glass particles that are not adjusted in this way and do not have smooth surfaces. The glass particles used in ordinary glass pastes are pulverized glass powders such as glass frit, and glass beads are used in applications such as retroreflective materials for road signs, sandblasting, and fillers for resin molded products.

[0033] In the present invention, it is presumed that the advantages of glass beads (spherical or approximately spherical glass particles) are that they have a smooth surface and a small surface area compared to crushed glass powder such as glass frit.

[0034] In other words, the small surface area of ​​the glass beads can prevent the resin component of the organic vehicle from being adsorbed to the glass beads in the glass paste. It is easy to predict that the resin component is unlikely to be thermally decomposed when adsorbed to the glass component, so in the present invention, the low adsorption of the resin component to the glass beads, which are the main component of the glass component, can be assumed to promote the thermal decomposition of the resin component in the firing process, improving firing properties (suppression of soot and bubbles).

[0035] Specifically, the insulating protective film that protects the conductive film or resistive film is applied over a relatively large area to cover the conductive film or resistive film, as shown in Figures 1 and 2, which are evaluation samples for the examples described later. In this case, during firing, a large amount of the resin component in the paste applied over a large area must be decomposed and removed. In firing in an inert gas atmosphere, if the resin component is not fully decomposed and remains in the insulating protective film, soot will be generated, and if the decomposition gas remains in the insulating protective film, bubbles will be generated. In contrast, the use of glass beads as the glass component promotes the thermal decomposition of the resin component, thereby suppressing the generation of soot and bubbles. Therefore, the firing performance required for a glass paste for an insulating protective film fired in an inert gas atmosphere can be reliably achieved.

[0036] Furthermore, since glass beads have a small surface area, they also have a smaller interaction with the organic vehicle, so they do not impede the fluidity of the paste, which is presumably why they improve printability (fluidity and suppression of pinholes).

[0037] That is, as described above, the insulating protective film that protects the conductive film or resistive film is formed in a manner that covers the conductive film or resistive film, and therefore, there are steps due to the conductive film or resistive film on the substrate during printing. In this case, pinholes are particularly likely to occur near the steps compared to flat areas, but the use of glass beads as the glass component increases fluidity and can suppress the occurrence of pinholes. Therefore, the present invention can reliably achieve the printability required for a glass paste for an insulating protective film that protects the conductive film or resistive film.

[0038] In the present invention, the main component of the glass component is glass beads, and therefore the effect of the glass beads can be effectively exhibited.

[0039] The shape of the glass beads may be any shape as long as the surface is formed as a smooth curved surface without corners (especially acute corners), and specifically, may be spherical or approximately spherical. However, from the viewpoint of improving sintering properties and printability, spherical shapes are preferred, and true spheres are particularly preferred.

[0040] The average sphericity of the glass beads may be 1.9 or less, for example 1.8 or less, preferably 1.5 or less, further preferably 1.4 or less, even more preferably 1.3 or less, and most preferably 1.2 or less.

[0041] The maximum sphericity of the glass beads may be 2 or less, for example, 1.9 or less, preferably 1.8 or less, further preferably 1.7 or less, even more preferably 1.6 or less, and most preferably 1.5 or less.

[0042] In the present application, the sphericity of the glass component can be calculated as the ratio of the major axis to the minor axis by measuring the maximum diameter (major axis) of the particles observed with a scanning electron microscope (SEM) and the maximum diameter (minor axis) perpendicular to the major axis. Furthermore, the average and maximum sphericity values ​​can be determined based on the sphericity values ​​calculated for any 100 particles.

[0043] Glass bead median particle size D 50 The median particle size is, for example, 0.1 to 100 μm, preferably 0.3 to 70 μm, and more preferably 0.5 to 50 μm (particularly 0.5 to 30 μm). From the viewpoint of printability, it is, for example, 0.7 to 40 μm (particularly 0.8 to 35 μm), preferably 1 to 30 μm (particularly 1 to 20 μm), more preferably 2 to 20 μm (particularly 2 to 10 μm), more preferably 3 to 8 μm, and most preferably 4 to 7 μm. When the median particle size is within this range (particularly the range of 0.7 to 40 μm), it is possible to obtain a pinhole-free insulating protective film that is not affected by printing conditions. If the median particle size of the glass beads is too small, even if the particle surface of each glass bead is smooth, the total surface area of ​​the glass particles in the paste will be large, which may increase the amount of resin component adsorbed and impair the fluidity and sinterability of the paste. Conversely, if the median particle size is too large, for example, when used as a paste for screen printing, there is a risk that the printing conditions will be restricted, such as the mesh of the screen being clogged, causing problems.

[0044] 10% by volume particle diameter of glass beads D 10can be selected from the range of about 0.05 to 50 μm, for example, 0.1 to 30 μm, preferably 0.3 to 25 μm, further preferably 0.4 to 20 μm, more preferably 0.5 to 15 μm, even more preferably 1 to 5 μm, and most preferably 2 to 3 μm.

[0045] 90% volume particle diameter of glass beads D 90 can be selected from the range of about 0.5 to 200 μm, for example, 0.7 to 100 μm, preferably 1.5 to 55 μm, further preferably 2 to 50 μm, more preferably 3 to 30 μm, even more preferably 5 to 20 μm, and most preferably 8 to 10 μm.

[0046] In the present application, the median particle diameter D of the glass components (glass beads and crushed glass powder) 50 (or average particle size), 10% by volume particle size D 10 and 90% by volume particle diameter D 90 is the median particle size D based on the particle size distribution measured using a laser diffraction scattering particle size distribution analyzer. 50 (volume basis), 10% by volume particle size D 10 and 90% by volume particle diameter D 90 means.

[0047] The softening point of the glass beads may be in the range of 600 to 950° C., preferably 650 to 950° C., further preferably 650 to 900° C., even more preferably 700 to 850° C., and most preferably 750 to 850° C. If the softening point of the glass beads is too low, bubbles and cissing are likely to occur in the insulating protective film, while if it is too high, there is a risk that the conductor film or resistor film made of a base metal such as copper will melt.

[0048] In the present application, the softening point of the glass component can be determined by measuring the temperature of the fourth inflection point using a macro-type differential thermal analyzer (DTA).

[0049] The proportion of glass beads in the glass component may be 50% by mass or more, preferably 60% by mass or more, further preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 100% by mass. If the proportion of glass beads is too low, there is a risk that it will be difficult to achieve both sinterability and printability.

[0050] The glass component may further contain ground glass powder such as glass frit, in order to compensate for the low softening fluidity of the glass beads, which are the main component.

[0051] The shape of the pulverized glass powder is not particularly limited, and may be a shape having corners (particularly acute angles) on the surface, specifically, a substantially spherical shape, an ellipsoid (oval sphere), a polyhedron (triangular pyramid, regular hexahedron or cube, rectangular parallelepiped, octahedron, etc.), a plate shape (flat, scale, or thin plate, etc.), a rod shape, a fiber shape, an irregular shape, etc. The shape of the pulverized glass powder is usually an ellipsoid, a polyhedron, an irregular shape, etc.

[0052] In the present application, a shape having corners means a shape that is not formed only by curved surfaces (that is, a shape other than a shape formed only by curved surfaces such as a sphere or an oval sphere).

[0053] The average sphericity of the pulverized glass powder may be greater than 1.2 (preferably greater than 1.5, and even more preferably greater than 1.9), for example, greater than 1.3 and not greater than 5, preferably greater than 1.5 and not greater than 3, even more preferably greater than 1.7 and not greater than 2.5, more preferably greater than 1.8 and not greater than 2.3, and most preferably greater than 1.9 and not greater than 2.1.

[0054] The maximum value of the sphericity of the pulverized glass powder may be greater than 1.5 (preferably greater than 1.7, and even more preferably greater than 2), for example, greater than 1.5 and not greater than 4, preferably greater than 2 and not greater than 4, even more preferably greater than 2.5 and not greater than 3.5, more preferably greater than 2.8 and not greater than 3.2, and most preferably greater than 2.9 and not greater than 3.1.

[0055] Center particle size D of crushed glass powder 50is, for example, 0.1 to 100 μm, preferably 0.3 to 70 μm, and more preferably 0.5 to 50 μm (particularly 0.5 to 30 μm), and from the viewpoint of printability, is, for example, 0.7 to 40 μm (particularly 0.8 to 35 μm), preferably 1 to 30 μm (particularly 1 to 20 μm), more preferably 2 to 20 μm (particularly 2 to 10 μm), more preferably 3 to 8 μm, and most preferably 4 to 7 μm. If the median particle size of the pulverized glass powder is too small, the fluidity and sinterability of the paste may be impaired, and if it is too large, the printability may be reduced.

[0056] The softening point of the pulverized glass powder is not particularly limited as long as it is 950° C. or lower, but is, for example, 350 to 900° C., preferably 400 to 800° C., further preferably 450 to 750° C., even more preferably 500 to 700° C., and most preferably 550 to 650° C. If the softening point of the pulverized glass powder is too low, bubbles and cissing are likely to occur in the insulating protective film, and if it is too high, there is a risk that the softening fluidity of the glass component cannot be adjusted.

[0057] The softening point of the pulverized glass powder is preferably at least 100°C (particularly at least 150°C) lower than that of the glass beads, in order to compensate for the low softening and flow of the glass beads, which are the main component, while also suppressing the entrapment of decomposition gases, and may be, for example, 100 to 300°C (particularly 150 to 250°C) lower. If the softening point of the pulverized glass powder is adjusted to fall within this range, the glass beads, which are the main component, do not soften and flow in the temperature range in which decomposition gases of the resin component are generated, allowing the decomposition gases to easily escape from the paste film, and only the pulverized glass powder begins to flow appropriately, filling in the fine gaps in the paste film, which presumably results in a dense insulating protective film.

[0058] The mass ratio of glass beads to pulverized glass powder (former / latter) can be selected within the range of 100 / 0 to 50 / 50, preferably 100 / 0 to 60 / 40, and more preferably 100 / 0 to 70 / 30. If the proportion of pulverized glass powder is too high, there is a risk that sinterability and printability cannot be achieved at the same time.

[0059] The mass ratio of glass beads to crushed glass powder is 100 / 0 to 60 / 40, preferably 100 / 0 to 70 / 30, more preferably 100 / 0 to 80 / 20, and even more preferably 100 / 0 to 90 / 10, in order to easily achieve both sinterability and printability.

[0060] The mass ratio of glass beads to pulverized glass powder is 99 / 1 to 60 / 40, preferably 95 / 5 to 65 / 35, more preferably 90 / 10 to 60 / 40, even more preferably 85 / 15 to 65 / 35, and most preferably 80 / 20 to 70 / 30, from the viewpoint of improving the protective properties of the insulating protective film. If the proportion of pulverized glass powder is too low, the effect of improving the protective properties of the insulating protective film may be reduced, while if the proportion is too high, it may be difficult to achieve both sinterability and printability. In particular, the mass ratio of glass beads to pulverized glass powder is most preferably in the range in which pulverized glass powder is an essential component, from the viewpoint of achieving both sinterability and printability and improving the protective properties of the insulating protective film.

[0061] The composition of the glass that constitutes the glass component is not particularly limited, but it is preferable that the composition is mainly composed of non-reducing oxides and is not easily reduced during firing. If the glass is reduced, metal components generated by reduction may remain in the insulating protective film after firing, reducing the insulating properties, or the metal components may migrate to the resistive film during firing, causing changes in the resistance value, temperature coefficient of resistance (TCR), etc.

[0062] Furthermore, the glass composition preferably does not contain a large amount of alkali metal components. If the glass composition contains a large amount of alkali metal components, ion exchange occurs with Cu, etc. in the conductive film or resistive film, and Cu, etc. diffuses into the insulating protective film, which may result in a decrease in insulation. On the other hand, alkaline earth metal components may be contained because they do not have the same effect of decreasing insulation as alkali metal components.

[0063] Examples of glasses that make up the glass component include borosilicate glass represented by the composition formula SiO2-B2O3-MO, aluminosilicate glass represented by the composition formula Al2O3-SiO2-MO, aluminoborosilicate glass represented by the composition formula Al2O3-SiO2-B2O3-MO, zinc borosilicate glass represented by the composition formula ZnO-SiO2-B2O3-MO, bismuth-based glass represented by the composition formula Bi2O3-B2O3-MO, vanadium-based glass represented by the composition formula V2O5-MO, phosphate-based glass represented by the composition formula P2O5-MO, and lead glass represented by the composition formula PbO2-B2O3-MO.

[0064] In the composition formula, M means all elements other than those explicitly stated in the composition formula (for example, elements other than Si and B in the case of borosilicate glass, and elements other than Al and Si in the case of aluminosilicate glass).

[0065] These glasses can be used alone or in combination of two or more. Among these, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, borosilicate zinc glass, bismuth-based glass, and vanadium-based glass are preferred.

[0066] Borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass have non-reducing glass compositions, whereas bismuth-based glass and vanadium-based glass have reducing glass compositions. In the glass compositions of bismuth-based glass and vanadium-based glass, Bi and V are reducing elements, so the proportion of Bi2O3 and V2O5 in the glass composition is preferably not more than 10 mass%, more preferably not more than 8 mass%, and even more preferably not more than 5 mass%.

[0067] Borosilicate zinc glass is a glass with intermediate properties between non-reducing and reducing properties, and the proportion of ZnO is preferably not too high, and may be 50 mass % or less in the glass composition, preferably 40 mass % or less, further preferably 30 mass % or less, even more preferably 20 mass % or less, and most preferably 15 mass % or less.

[0068] As the glass, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, borosilicate zinc glass in which the proportion of ZnO in the glass composition is 50 mass% or less, bismuth-based glass in which the proportion of Bi2O3 in the glass composition does not exceed 10 mass%, and vanadium-based glass in which the proportion of V2O5 in the glass composition does not exceed 10 mass%, are preferred, as they can achieve both sinterability and printability.

[0069] In particular, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass are most preferred as the glass because they have a non-reducing glass composition and can achieve a high level of both sinterability and printability. Using at least one glass selected from the group consisting of borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass makes it difficult to reduce during firing in an inert gas atmosphere, preventing metal components generated by reduction from remaining in the insulating protective film after firing, thereby improving insulation. Furthermore, migration of reduced metal components to the resistive film during firing can be prevented, preventing changes in properties such as the resistance value and temperature coefficient of resistance (TCR) of the resistive film.

[0070] The glass preferably has a low proportion of alkali metal components, and the proportion of alkali metal components (particularly Na2O) in the glass composition is preferably 10 mass% or less, more preferably 7 mass% or less, and even more preferably 5 mass% or less. If the proportion of alkali metal components is too high, there is a risk of a decrease in insulating properties. So-called soda-lime glass is known as glass containing alkali metal components, and soda-lime glass containing alkali metal components in the above proportions is preferred.

[0071] The proportion of the glass component in the glass paste may be 10% by mass or more, for example, 10 to 95% by mass, preferably 30 to 90% by mass, further preferably 50 to 85% by mass, more preferably 60 to 83% by mass (particularly 60 to 80% by mass), and most preferably 62 to 82% by mass (particularly 65 to 75% by mass). If the proportion of the glass component is too low, there is a risk that the protective performance will decrease.

[0072] [Organic vehicle] The glass paste of the present invention further contains an organic vehicle. The present invention is characterized in that the organic vehicle contains a (meth)acrylic resin as an organic binder. In the present invention, the sinterability of the glass paste can be improved by the organic vehicle containing a (meth)acrylic resin. It is presumed that because (meth)acrylic resins are easily thermally decomposed even in an inert gas atmosphere, the thermal decomposition of the resin component is promoted during the sintering process, suppressing the generation of soot and bubbles, thereby improving the sinterability.

[0073] In the present application, "acrylic" and "methacrylic" are collectively referred to as "(meth)acrylic."

[0074] Examples of the (meth)acrylic resin include polyalkyl (meth)acrylates such as polymethyl (meth)acrylate, polyethyl (meth)acrylate, polypropylene (meth)acrylate, polybutyl (meth)acrylate, and polyisobutyl (meth)acrylate. The molecular weight of the (meth)acrylic resin is not particularly limited and may be adjusted as desired according to the physical properties, such as viscosity, required for the glass paste.

[0075] These (meth)acrylic resins can be used alone or in combination of two or more. 1-8 Alkyl-(meth)acrylates are preferred, and polyC 2-6 Alkyl-(meth)acrylates are more preferred, and poly(C) such as polyisobutyl methacrylate. 3-5 Alkyl-methacrylates are particularly preferred.

[0076] The proportion of the (meth)acrylic resin in the organic binder may be 10% by mass or more, for example, 30% by mass or more, preferably 50% by mass or more, further preferably 80% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass. If the proportion of the (meth)acrylic resin is too low, there is a risk that the sinterability will decrease.

[0077] The organic binder may contain other organic binders in addition to the (meth)acrylic resin, as long as the effects of the present invention are not impaired.

[0078] Examples of other organic binders include thermoplastic resins other than (meth)acrylic resins (olefin resins, vinyl resins, styrene resins, polyether resins, polyester resins, polyamide resins, cellulose derivatives, etc.), thermosetting resins (thermosetting (meth)acrylic resins, epoxy resins, phenolic resins, unsaturated polyester resins, polyurethane resins, etc.), rubbers (polybutadiene, polyisoprene, etc.), etc. These other organic binders can be used alone or in combination of two or more.

[0079] Of these other organic binders, thermoplastic resins are preferred, and cellulose ethers such as ethyl cellulose are more preferred.

[0080] The proportion of the other organic binder may be 90% by mass or less of the organic binder, for example, 70% by mass or less, preferably 50% by mass or less, further preferably 20% by mass or less, more preferably 10% by mass or less, and most preferably 0% by mass. If the proportion of the other organic binder is too high, there is a risk that the sinterability will decrease.

[0081] The organic vehicle may further contain an organic solvent in addition to the (meth)acrylic resin as the organic binder. The organic vehicle containing an organic solvent is a solution of the organic binder containing the (meth)acrylic resin in the organic solvent, and may be a viscous liquid in which the organic binder containing the (meth)acrylic resin is dissolved in the organic solvent.

[0082] The organic solvent is not particularly limited, and may be an organic compound that imparts appropriate viscosity and fluidity to the glass paste and that can be easily volatilized by a drying process after the glass paste is applied to a substrate, and may also be a high-boiling organic solvent.

[0083] Examples of such organic solvents include aromatic hydrocarbons (toluene, xylene, etc.), esters (ethyl lactate, etc.), ketones (isophorone, etc.), amides (dimethylformamide, etc.), aliphatic alcohols (octanol, decanol, diacetone alcohol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates (ethyl cellosolve acetate, butyl cellosolve acetate, etc.), carbitols (carbitol, methyl carbitol, ethyl carbitol, etc.), carbitol acetates (methyl carbitol acetate, ethyl carbitol acetate, butyl carbitol acetate, etc.), and C 1-6 Examples of suitable organic solvents include alkyl carbitol acetates, aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, triethylene glycol, glycerin, etc.), alicyclic alcohols (e.g., cycloalkanols such as cyclohexanol; terpene alcohols (monoterpene alcohols) such as terpineol and dihydroterpineol), aromatic alcohols (metacresol, etc.), aromatic carboxylic acid esters (dibutyl phthalate, dioctyl phthalate, etc.), and nitrogen-containing heterocyclic compounds (dimethylimidazole, dimethylimidazolidinone, etc.). These organic solvents may be used alone or in combination of two or more.

[0084] Among these organic solvents, C such as butyl carbitol acetate is preferred from the viewpoint of the fluidity of the glass paste. 1-4 Alkyl-carbitol acetates are preferred.

[0085] The proportion of the organic binder (particularly, the (meth)acrylic resin) relative to 100 parts by mass of the organic solvent is, for example, 1 to 200 parts by mass, preferably 3 to 100 parts by mass, even more preferably 5 to 50 parts by mass, even more preferably 8 to 30 parts by mass, and most preferably 10 to 20 parts by mass.

[0086] The proportion of the organic vehicle is, for example, 1 to 100 parts by mass, preferably 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, and most preferably 30 to 50 parts by mass, relative to 100 parts by mass of the glass component. The proportion of the organic vehicle in the glass paste is 5 to 80% by mass, preferably 8 to 70% by mass, more preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and most preferably 20 to 35% by mass. If the proportion of the organic vehicle is too low, handling may be impaired, while if it is too high, sintering and printability may not be compatible.

[0087] (filler) The glass paste of the present invention may further contain a filler to adjust the expansion coefficient of the insulating protective film, the viscosity of the glass paste, the glass fluidity during firing, the ability to remove bubbles, etc., within a range that does not impair the effects of the present invention.

[0088] The type of filler is not particularly limited. Examples of fillers include carbides such as SiC, TiC, and B4C; nitrides such as Si3N4, AlN, and TiN; and metal oxides with high melting points that are difficult to reduce (e.g., SiO2, Al2O3, TiO2, ZrO, and CaO) and their composite metal oxides. These fillers are stable even during firing under an inert gas atmosphere, do not lose their shape due to melting, and do not metallize upon reduction, affecting the insulating properties of the insulating protective film or the electrical characteristics of the resistive film. Examples of composite metal oxides include CaAl2O4, CaTiO3, CaZrO3, MgAl2O4, MgTiO3, and MgZrO3. These fillers can be used alone or in combination. Of these, SiO2, Al2O3, and TiO2 are preferred due to their excellent thermal and chemical stability.

[0089] The shape of the filler is not particularly limited, and may be spherical, needle-like, flake-like, polygonal, or the like, with spherical or nearly spherical shapes being preferred in terms of dispersibility in the paste.

[0090] Filler central particle size D 50is, for example, 0.05 to 30 μm, preferably 0.1 to 20 μm, and more preferably 0.2 to 10 μm. If the median particle size is too small, there is no problem when a small amount is added, but if a large amount is added, the printability of the paste may decrease and pinholes may occur, and conversely, if it is too large, the smoothness of the obtained insulating protective film may decrease.

[0091] In the present application, the median particle size (or average particle size) of a filler means the median particle size (volume basis) based on a particle size distribution measured using a laser diffraction / scattering particle size distribution measuring device.

[0092] The proportion of the filler is, for example, 100 parts by mass or less (for example, 1 to 100 parts by mass), preferably 50 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of the glass component.

[0093] (Other additives) The glass paste of the present invention may further contain conventional additives as other additives, provided that the effects of the present invention are not impaired. Examples of conventional additives include curing agents (e.g., curing agents for (meth)acrylic resins), colorants (e.g., dyes and pigments), hue modifiers, dye fixatives, gloss-imparting agents, metal corrosion inhibitors, stabilizers (e.g., antioxidants, UV absorbers), surfactants or dispersants (e.g., anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants), dispersion stabilizers, viscosity or rheology modifiers, moisturizers, thixotropy-imparting agents, leveling agents, antifoaming agents, and bactericides. These additives can be used alone or in combination.

[0094] The proportion of other additives is, for example, 50 parts by mass or less (eg, 0.1 to 50 parts by mass), preferably 30 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the glass component.

[0095] [Protective insulating film] The insulating protective film of the present invention is not particularly limited as long as it is formed from the glass paste and is an insulating protective film for protecting an object to be protected obtained by firing a raw material containing a base metal, such as a base metal conductor film and / or a base metal resistive film.

[0096] (Conductive and resistive films) A base metal-based conductor film or resistive film refers to a conductor film or resistive film containing a base metal as its main component. The base metal-based conductor film or resistive film may be a conductor film or resistive film that may be oxidized during firing to form an insulating protective film by laminating a base metal or resistive film on the conductor film or resistive film in air, resulting in electrical effects such as a change in resistance value. Specifically, the base metal-containing conductor film or resistive film is preferably a conductor film or resistive film containing a base metal as its main component, or a conductor film or resistive film having a base metal present at least on its surface. When the conductor film or resistive film has a laminate structure of different metals, at least the outermost surface of the film may be a conductor film or resistive film formed from a base metal-based metallic element. The conductor film or resistive film may be a conductor film or resistive film formed inside a substrate, such as an internal conductor, internal resistor, or via, with a portion exposed on the surface of the substrate.

[0097] Preferred base metals include, for example, Period 3 metals such as Al; Period 4 metals such as Ti, Cr, Mn, Fe, Ni, and Cu; Period 5 metals such as Mo and Sn; and Period 6 metals such as La, Ta, and W. These base metals can be used alone or in combination. Among them, Period 4 metals in Groups 8 to 11 such as Ni and Cu; and Period 6 metals in Groups 3 to 5 such as La are preferred.

[0098] The method for manufacturing the conductive film or resistive film is not particularly limited, and examples include methods of forming the conductive film or resistive film using a paste for forming the conductive film or resistive film by screen printing, dipping, dispensing, inkjet, etc., thin film (sputtering) methods, plating methods, etc.

[0099] Preferred conductive films include, for example, conductive films formed by applying a Ni or Cu paste to the surface of a glass or ceramic substrate by screen printing to form an electrode or wiring pattern; conductive films formed by dipping a glass or ceramic part into a Ni or Cu paste to form an end electrode; conductive films formed by forming a Cu film on the outermost surface by sputtering (particularly, conductive films formed by printing or filling a green sheet with Cu, W, Mo, Mn, etc. as an internal conductor, and then co-firing the green sheet and the conductor, and sputtering Ti, Pd, and Cu in that order on the exposed conductor portions of the resulting co-fired substrate and on the surface of the substrate, to form a Cu film on the outermost surface); and conductive films formed by forming a Cu film on the surface of a substrate by electrolytic or electroless plating.

[0100] The thickness (average thickness) of the conductor film may be 3 μm or more (for example, 3 to 200 μm), for example, 3 to 100 μm, preferably 5 to 50 μm, and more preferably 10 to 25 μm.

[0101] Preferred resistive films include, for example, resistive films obtained by screen-printing resistive pastes such as CuNi paste, NiCr paste, LaB6 paste, and TaSn paste; and metal plate resistors formed by welding a metal plate conductor and a resistive element to form a chip resistor.

[0102] The thickness (average thickness) of the resistive film may be 5 μm or more (for example, 5 to 200 μm), for example, 5 to 100 μm, preferably 10 to 50 μm, and more preferably 15 to 30 μm.

[0103] (Method of manufacturing insulating protective film) The insulating protective film of the present invention is obtained by applying (coating) the glass paste to a target surface to be coated and firing it in an inert gas atmosphere in order to protect a base metal conductor film and / or a base metal resistive film.

[0104] The method for coating the glass paste is not particularly limited, and examples thereof include flow coating, spin coating, spray coating, screen printing, flexographic printing, casting, bar coating, curtain coating, roll coating, gravure coating, dipping, slit coating, photolithography, and inkjet coating.

[0105] The glass paste is usually applied so as to cover all or part of the conductive film or resistive film. The drawing method (or printing method) for drawing the pattern (coating layer) is not particularly limited as long as it is a printing method capable of forming a pattern, and examples thereof include screen printing, inkjet printing, intaglio printing (e.g., gravure printing), offset printing, intaglio offset printing, and flexographic printing. Of these methods, screen printing is preferred.

[0106] After coating, the coating may be dried naturally or by heating. The heating temperature can be selected depending on the type of organic solvent and is, for example, 50 to 200° C., preferably 100 to 150° C. The heating time is, for example, 5 to 60 minutes, preferably 10 to 30 minutes.

[0107] The insulating protective film is obtained by subjecting the glass paste coating to a firing step in which the coating is heated (heat treated) at a predetermined temperature.

[0108] The firing temperature (maximum temperature reached) of the coating film is, for example, 650 to 1,000°C, preferably 700 to 950°C, and more preferably 750 to 900°C. If the firing temperature is too low, the film will harden before the decomposition gas of the resin component in the glass paste is fully generated, and there is a risk of the decomposition gas being trapped inside as bubbles. If the firing temperature is too high, the firing temperature will approach (or exceed) the melting point of the metal that forms the conductive film or resistive film, and there is a risk of the conductive film or resistive film being over-sintered or melting.

[0109] The firing temperature of the coating film is preferably higher than the softening point of the glass beads, which are the main component, and specifically may be 50 to 350°C (preferably 100 to 300°C, more preferably 150 to 250°C) higher than the softening point. If the difference between the firing temperature and the softening point is too small, the insulating protective film will not be sintered sufficiently, leaving gaps and reducing its density, which may impair its protective performance. If the difference between the firing temperature and the softening point is too large, the softened glass may flow too much and be repelled by the base film (conductive film or resistive film), exposing the conductive film or resistive film, which may impair its insulating and protective performance.

[0110] The heat treatment time (heating time at the maximum temperature) is, for example, 1 to 60 minutes, and preferably about 5 to 20 minutes.

[0111] The firing is carried out in an inert gas atmosphere (such as nitrogen gas, argon gas, helium gas, etc.) to prevent oxidation of the base metal to be protected, and is preferably carried out in a nitrogen atmosphere.

[0112] The average thickness of the insulating protective film obtained after firing can be appropriately selected, for example, from the range of 5 to 300 μm, preferably 10 to 200 μm, and more preferably 20 to 100 μm, depending on the application. If the average thickness is too thin, there is a risk that the insulating and protective properties will be reduced. If the average thickness is too thick, there is a risk that when trimming the resistive film with a laser to adjust the resistance, the insulating protective film will be too thick and the laser energy will not reach the resistive film, making trimming impossible.

[0113] The obtained insulating protective film is not particularly limited as long as it is in a form that protects a base metal conductor film and / or a base metal resistive film, but it may be in a form that protects, for example, a base metal conductor film and a base metal resistive film laminated on a ceramic substrate.

[0114] Examples of materials for the ceramic substrate include alumina, alumina-zirconia, aluminum nitride, silicon nitride, silicon carbide, etc. Among these, alumina, aluminum nitride, and silicon nitride are preferred, aluminum nitride and alumina are more preferred, and alumina is most preferred.

[0115] The thickness of the ceramic substrate may be appropriately selected depending on the application, and is, for example, 0.001 to 10 mm, preferably 0.01 to 5 mm, more preferably 0.05 to 3 mm, and even more preferably 0.1 to 1 mm. [Example]

[0116] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Details of the materials used in the examples are shown below.

[0117] [Materials used] Glass beads A: SiO2-B2O3, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 800°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads B: Al2O3-SiO2, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 840°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads C: Al2O3-SiO2-B2O3, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 830°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads D: ZnO-SiO2-B2O3 (ZnO 46 mass%), median particle size (D 50 ) 5 μm, 10% by volume particle size (D 10) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 630°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads E: Al2O3-SiO2-B2O3 (Na2O 12 mass%), median particle size (D 50 ) 5 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 790°C, no sharp edges, average sphericity 1.2, maximum sphericity 1.5 Glass beads F: SiO2-B2O3, central particle size (D 50 ) 0.5 μm, 10% by volume particle size (D 10 ) 0.3 μm, 90% by volume particle size (D 90 ) 0.9 μm, softening point 800 ° C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads G: SiO2-B2O3, central particle size (D 50 ) 1.0 μm, 10% by volume particle size (D 10 ) 0.5 μm, 90% by volume particle size (D 90 ) 1.8 μm, softening point 800 ° C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads H: SiO2-B2O3, central particle size (D 50 ) 30.0 μm, 10% by volume particle size (D 10 ) 15.0 μm, 90% by volume particle size (D 90 ) 54.0 μm, softening point 800°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5 Glass beads I: SiO2-B2O3, median particle size (D 50 ) 50.0 μm, 10% by volume particle size (D 10 ) 25.0 μm, 90% by volume particle size (D 90 ) 90.0 μm, softening point 800°C, no sharp corners, average sphericity 1.2, maximum sphericity 1.5

[0118] Glass frit a: SiO2-B2O3, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90) 9.0 μm, softening point 600°C, sharp corners, average sphericity 2.0, maximum sphericity 3.0 Glass frit b: SiO2-B2O3, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 800°C, sharp corners, average sphericity 2.0, maximum sphericity 3.0 Glass frit c: ZnO-SiO2-B2O3 (ZnO 67 mass%), central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 550°C, sharp corners, average sphericity 2.0, maximum sphericity 3.0 Glass frit d: SiO2-B2O3-PbO, central particle size (D 50 ) 5.0 μm, 10% by volume particle size (D 10 ) 2.5 μm, 90% by volume particle size (D 90 ) 9.0 μm, softening point 490°C, sharp corners, average sphericity 2.0, maximum sphericity 3.0

[0119] Methacrylic resin A: Polyisobutyl methacrylate Methacrylic resin B: Polymethyl methacrylate Ethyl cellulose: Ethyl cellulose resin BCA: butyl carbitol acetate

[0120] [Average and maximum sphericity of glass particles] The sphericity of glass particles (glass beads or glass frit) was measured by observing 100 glass particles using a scanning electron microscope (JEOL JSM-IT300LA) and measuring the maximum diameter (major diameter) of the particles and the maximum diameter (minor diameter) perpendicular to the major diameter, thereby calculating the sphericity defined as the ratio of major diameter to minor diameter. The average sphericity and maximum sphericity were calculated from the obtained sphericity values ​​of 100 glass particles of each type.

[0121] [Presence or absence of corners in glass components] The presence or absence of corners in the glass components was determined by visually observing the shape of each glass component using a scanning electron microscope (JSM-IT300LA manufactured by JEOL Ltd.), and if the glass component was an approximately spherical particle with no corners on its surface, it was determined to have no corners.

[0122] Examples 1 to 21 and Comparative Examples 1 to 4 [Preparation of glass paste] Glass pastes were prepared by blending the raw materials according to the blending examples shown in Tables 1 and 2. Specifically, first, predetermined amounts of each powder material and organic vehicle were weighed out into containers using an electronic balance. Next, the powder material and organic vehicle were uniformly mixed using a planetary (rotation-revolution) degassing mixer, and then passed through a triple roll mill to obtain the respective glass pastes (paste compositions).

[0123] [Table 1]

[0124] [Table 2]

[0125] [Preparation of evaluation samples] 1 and 2 show schematic plan views of the evaluation sample (laminate) produced.

[0126] Evaluation sample 1 shown in Fig. 1 is a sample for two-terminal measurement used to evaluate printability, sinterability, and dielectric strength. For evaluation sample 1, a conductive film 3, a resistive film 4, and an insulating protective film 5 were formed on the surface of substrate 2 in the arrangement shown in Fig. 1 by the method described below, using the materials shown in Tables 11 to 13.

[0127] First, Cu paste was screen-printed on the surface of the substrate (alumina substrate) 2 in a 6 mm x 9 mm rectangular pattern to form a conductive film precursor. Next, CuNi paste was printed in a 3 mm wide x 90 mm long U-shaped pattern, overlapping the center of the edge of the conductive film precursor, to form a resistive film precursor. The intermediate body, in which the conductive film precursor and resistive film precursor were layered on the substrate 2, was fired in a tunnel furnace (continuous furnace) in a nitrogen atmosphere at a maximum temperature of 900°C, maintaining the temperature for 10 minutes, to form a Cu conductive film 3 (film thickness 15 μm) and a CuNi resistive film 4 (film thickness 20 μm). The total firing time, including the temperature rise and fall times, was 60 minutes. The glass paste was printed twice in an area of ​​30 mm × 120 mm so as to cover a portion of the Cu conductor film 3 thus obtained and the CuNi resistive film 4, and then fired in a nitrogen atmosphere using the same tunnel furnace (maximum temperature holding time: 10 minutes, total firing time: 60 minutes) to form an insulating protective film 5. The maximum firing temperature was set to the temperatures shown in Tables 11 to 13. In addition, by adjusting the viscosity using a solvent, the thickness of the insulating protective film 5 after firing was made uniform to about 30 μm for all pastes.

[0128] Eighteen evaluation patterns were formed on one evaluation sample 1, and the spacing between the patterns was set to 15 mm.

[0129] Evaluation sample 11 shown in Figure 2 is a four-terminal measurement sample used to evaluate the rate of change in resistance value during a humidity test and the change in TCR due to glass film firing. For evaluation sample 11, a conductor film 13, a resistive film 14, and an insulating protective film 15 were formed on the surface of substrate 12 in the arrangement shown in Figure 2 using the materials shown in Tables 11 to 13 under the same conditions (printing conditions, firing conditions, and thickness) as evaluation sample 1. Conductive film 13 had four square sections (5 mm x 5 mm) for forming joints with terminals, and two pairs of opposing square sections were connected by a connecting section. Resistive film 14 had a shape (1 mm x 10 mm) that spanned the centers of the opposing connecting sections. Furthermore, insulating protective film 15 had a roughly rectangular shape large enough to cover conductor film 13, and the corners of the roughly rectangular shape were shaped to expose conductor film 13 for forming joints with terminals.

[0130] [Evaluation and Judgment] For each test piece (Example, Comparative Example), in order to determine whether a glass paste capable of resolving the problem of the present application was obtained, the printability (whether it has excellent fluidity and does not produce pinholes), sinterability (whether soot or bubbles do not form in the insulating protective film even when fired in a nitrogen atmosphere), protective performance (performance of the insulating protective film against conductive films and resistive films), and changes in electrical properties (whether firing the glass paste in a nitrogen atmosphere does not change the properties of the resistive film).

[0131] [Pinhole] (Test Method) The glass paste was screen-printed and the dried film was observed under a microscope (100x magnification). Pinholes with a diameter of φ50 μm or more, through which the underlying conductive film or resistive film could be seen, were defined as pinholes.

[0132] (Judgment criteria) Pinholes were evaluated according to the criteria shown in Table 3.

[0133] [Table 3]

[0134] [Printability] From the viewpoint of suitability (printability) for practical use in this application, glass pastes with a pinhole rating of C or higher were deemed to pass.

[0135] [Soot] (Test Method) The color of the insulating protective film after firing was observed under a microscope (100x magnification) and compared with the white background of the alumina substrate to determine the presence of soot.

[0136] (Judgment criteria) The soot was evaluated according to the criteria shown in Table 4.

[0137] [Table 4]

[0138] [Bubbles] (Test Method) The cross section of the insulating protective film after firing was observed using a microscope (100x magnification) and a scanning electron microscope (SEM) to determine whether or not bubbles were present.

[0139] (Judgment criteria) The bubbles were evaluated according to the criteria shown in Table 5.

[0140] [Table 5]

[0141] [Repel] (Test Method) The surface of the insulating protective film after firing was observed under a microscope (100x magnification) to determine whether or not repelling occurred.

[0142] (Judgment criteria) The cissing was evaluated according to the criteria shown in Table 6.

[0143] [Table 6]

[0144] [Baking property] From the perspective of suitability (firing ability) for practical use in this application, glass pastes that received a rating of C or higher in all evaluations of soot, bubbles, and repelling were deemed to be acceptable.

[0145] In addition, if any of the appearance evaluations up to this point has received a rating of 'D', the subsequent characteristic evaluations of [protective performance] and [electrical characteristic evaluation] will not be carried out.

[0146] [Moisture resistance test] (Test Method) The resistance value of the resistive film (CuNi) protected by the insulating protective film was measured at 25°C using a resistance meter before and after a humidity test (left to stand for 1,000 hours in an environment with a temperature of 85°C and humidity of 85%), and the protective performance of the insulating protective film was determined by the rate of change in resistance value before and after the humidity test.

[0147] (Judgment criteria) The protective performance of the insulating protective film was evaluated according to the criteria shown in Table 7.

[0148] [Table 7]

[0149] [Dielectric strength] (Test Method) Copper foil was placed over the entire surface of the insulating protective film, and a weight was placed on top to adhere the copper foil to the insulating protective film. In this state, a voltage was applied between the copper foil and the conductive film (Cu) formed on the evaluation sample, and the insulating properties of the insulating protective film in the thickness direction were evaluated. In detail, the voltage was increased in steps of 100 V starting from 100 V, and the voltage at the next step where insulation was lost and conduction occurred was recorded, and this voltage was taken as the dielectric strength voltage. The voltage application time at each voltage was 10 seconds.

[0150] (Judgment criteria) The dielectric strength was evaluated according to the criteria shown in Table 8.

[0151] [Table 8]

[0152] [Protection performance] From the perspective of suitability (protective performance) for practical use in this application, glass pastes with a rating of C or higher in all evaluations of moisture resistance test and dielectric strength voltage were deemed to pass.

[0153] [TCR change] (Test Method) The TCR (temperature coefficient of resistance) of the resistive film before firing the glass paste and the TCR of the resistive film after firing the glass paste were measured and the amount of change was evaluated. Here, TCR indicates how much the resistance value changes per 1°C change in temperature, and in this test, the TCR was used when the sample temperature was between 25°C and 155°C. The TCR of the resistive film before firing the glass paste was +50 ppm / °C.

[0154] (Judgment criteria) TCR changes were evaluated according to the criteria shown in Table 9.

[0155] [Table 9]

[0156] [Changes in electrical characteristics] From the perspective of suitability for practical use in this application (change in electrical characteristics), glass pastes with a TCR change rating of C or higher were deemed to pass.

[0157] [Overall Judgment] Based on the evaluation of each evaluation item, an overall evaluation was made according to the criteria shown in Table 10.

[0158] [Table 10]

[0159] [Verification results and discussion] The verification results are shown in Tables 11 to 13.

[0160] [Table 11]

[0161] [Table 12]

[0162] [Table 13]

[0163] (Comparative Examples 1 and 2) Comparative Example 1 is an example in which the glass paste used for air firing was directly fired in a nitrogen atmosphere. In Comparative Example 1, the resin component did not decompose during firing and remained in the insulating protective film, resulting in a soot rating of d, which failed the firing performance, and the overall evaluation was rank D. Comparative Example 2, in which the composition of the glass component was changed to borosilicate glass and the type of resin component was changed to methacrylic resin A, showed a slight improvement in firing performance and was ranked c. However, perhaps because the use of methacrylic resin A reduced the fluidity of the paste, the evaluation item for printability was ranked d (fail), resulting in the overall evaluation being rank D.

[0164] (Examples 1 to 6, Comparative Example 3) Example 1 is an example in which the glass component of Comparative Example 2 was changed from glass frit to glass beads. Perhaps because glass beads with a small surface area were used and the adsorption of resin components was reduced, significant improvements were observed in printability and sinterability, and the results were either graded a or graded b (pass) in all of printability, sinterability, protective performance, and electrical property changes, resulting in an overall ranking of B.

[0165] Examples 2 to 6 and Comparative Example 3 are examples based on Example 1, in which part of the glass component was changed from glass beads to glass frit, and the compounding ratio of glass beads to glass frit was changed.

[0166] Example 2, in which the mass ratio of glass beads to glass frit was 90 / 10, was not significantly different from Example 1 in each evaluation.

[0167] Examples 3 and 4, in which the glass beads / glass frit ratio was 80 / 20 and 70 / 30 (mass ratio), were rated a (pass) in all of the printability, sinterability, protective performance, and electrical property change, resulting in an overall rating of Rank A. The addition of glass frit with a low softening point allowed the glass frit to soften and flow, filling the small gaps created by the release of resin components during sintering, forming a dense insulating protective film, which is likely why the examples received the best result (Rank A) in the evaluation of protective performance.

[0168] In Example 5, in which the ratio of glass beads to glass frit was 60 / 40 (mass ratio), there was a slight decrease in printability and sinterability (rating c), possibly due to increased adsorption of the resin component to the glass component caused by the incorporation of glass frit, and the density of the insulating protective film was slightly reduced due to an increase in pinholes and air bubbles, resulting in somewhat inferior protective performance (rating c).However, all evaluation items were at a pass level, and the overall rating was Rank C. Furthermore, in Comparative Example 3, in which the ratio of glass frit was increased to glass beads to glass frit = 40 / 60 (mass ratio), there was an increase in adsorption of the resin component, possibly due to an increase in pinholes and air bubbles, which impaired the density of the insulating protective film, resulting in a rating of d (fail) in sintering performance, resulting in an overall rating of Rank D.

[0169] In Example 6, in which the glass frit of Example 3 was changed to zinc-based glass (ZnO 67% by mass), the protective performance and the change in electrical characteristics were slightly lower than in Example 3, possibly because the Zn component reduced by firing remained in the insulating protective film or migrated to the resistive film. However, the impact was minor, probably because the amount of ZnO in the entire glass component was small at around 10% by mass, and the overall evaluation was ranked B.

[0170] Specifically, when the glass component contains glass beads at a ratio of 50% by mass or more, the surface area of ​​the glass component is reduced, accelerating the decomposition of the resin component in the glass paste. As a result, the sinterability is improved when sintered in an inert gas atmosphere without sacrificing printability, and it was found that both sinterability and printability are achieved.

[0171] Furthermore, when the glass beads contain crushed glass powder with a softening point 100°C or more lower than the glass beads, and the mass ratio of glass beads / crushed glass powder is 80 / 20 to 70 / 30, the density of the insulating protective film is strengthened, and therefore it has been found that a glass paste can be obtained that is most suitable for forming an insulating protective film that protects base metal conductive films and resistive films by firing in an inert gas atmosphere, from the viewpoint of not altering the electrical properties of the conductive films and resistive films, as well as having excellent protective performance in addition to printability and sintering properties.

[0172] (Examples 7 to 10, Comparative Example 4) Examples 7 to 10 and Comparative Example 4 are examples based on Example 1, in which the type of resin component in the glass paste was changed.

[0173] Example 7, in which polymethyl methacrylate was used as the (meth)acrylic resin of the resin component, showed no significant difference in the evaluations from Example 1, in which polyisobutyl methacrylate was used.

[0174] Furthermore, the results of Examples 8 to 10 and Comparative Example 4 showed that in each item related to sinterability, sinterability tended to decrease as the proportion of ethyl cellulose increased, possibly due to the use of ethyl cellulose, which has low decomposition properties under a nitrogen atmosphere, resulting in residual resin components in the insulating protective film after sintering. Specifically, Example 8, in which 25% by mass of the resin component was ethyl cellulose, received a C rating for sooting. Example 9, in which 50% by mass of the resin component was ethyl cellulose, also received a C rating for protective performance, possibly due to the resin components being insufficiently decomposed during sintering, preventing the densification of the insulating protective film. Furthermore, Example 10, in which 75% by mass of the resin component was ethyl cellulose, also received a C rating for bubbles. Thus, although Examples 8 to 10 received more items with poorer sinterability than Example 1 in each evaluation, they maintained a C rating overall, which is a passable level. However, in Comparative Example 4, in which the resin component was entirely ethyl cellulose, the decomposition of the resin component during firing under a nitrogen atmosphere was insufficient, and the resin component remained in the insulating protective film after firing, resulting in a soot evaluation rating of d (fail).

[0175] Example 11 Example 11 is an example in which part of the glass component of Example 1 was changed from glass beads A to glass frit b, resulting in a mass ratio of glass beads / glass frit = 50 / 50, and part of the resin component was changed from methacrylic resin A to ethyl cellulose, resulting in a mass ratio of methacrylic resin A / ethyl cellulose = 50 / 50. In Example 11, the inclusion of ethyl cellulose reduced the sinterability compared to Example 1, and the proportion of glass beads in the glass component was 50 mass%, which reduced the effect of promoting decomposition of the resin component during sintering and the effect of improving printability, resulting in a decrease in printability and sinterability to a C rating. As a result, the protective performance was also rated C, but the pass level C rank was maintained in all items.

[0176] The above results confirm that a glass paste that combines printability and sinterability can be obtained by including glass beads in a proportion of 50% by mass or more in the glass component and including a (meth)acrylic resin in the organic vehicle.

[0177] (Examples 12 to 13) Examples 12 and 13 are examples in which the concentration of the glass component in the glass paste was changed based on Example 1. Compared to Example 1, in which the glass component concentration (mass%) was 71.4%, Example 12, which had a glass component concentration of 80.0%, and Example 13, which had a glass component concentration of 62.5%, showed no significant differences in the evaluations. Therefore, it is presumed that the concentration of the glass component has little effect on printability, firing properties, protective performance, and changes in electrical properties, and can be applied over a relatively wide range.

[0178] (Examples 14 to 17) Examples 14 to 17 are examples in which the composition of the glass component of Example 1 was changed. In all of the examples, printability and sinterability were both rated a. In the evaluation items of protective performance and electrical property change, Examples 14 and 15, in which aluminosilicate glass or aluminoborosilicate glass was used instead of borosilicate glass as the glass component, were rated a or b for protective performance and electrical property change, similar to Example 1, which used borosilicate glass, and the overall evaluation was Rank B.

[0179] On the other hand, Example 16, which used zinc-based glass (ZnO 46% by mass), was rated C in the evaluation items of dielectric strength voltage and electrical characteristic change in protective performance, possibly because the Zn component reduced by firing remained in the insulating protective film or migrated to the resistive film, and the overall evaluation was Rank C. Example 17, which used soda-lime glass (NaO 12% by mass), was rated C in protective performance, possibly because ion exchange with Cu and the like in the conductor film and resistive film occurred during firing, resulting in a decrease in insulation, and the overall evaluation was Rank C.

[0180] (Examples 18 to 21) Examples 18 to 21 are examples based on Example 1, in which the particle diameter of the glass beads used as the glass component was changed. 50 Compared to Example 1, in which the particle size was 5.0 μm, Example 19, in which the particle size was reduced to 1.0 μm, and Example 20, in which the particle size was increased to 30.0 μm, showed no significant differences in the evaluations.

[0181] On the other hand, the central grain size D 50 In Example 18, where the diameter was reduced to 0.5 μm, the median particle size of the glass beads was reduced compared to Example 1, which increased the total surface area of ​​the glass particles. As a result, the interaction between the glass component and the resin component increased, which increased the amount of resin component adsorbed to the glass component. Furthermore, the glass beads' effect of promoting the flow of the paste and promoting the decomposition of the resin component was weakened, which is presumably why printability and sinterability deteriorated, resulting in a rating of C. Furthermore, as the sinterability deteriorated, the thermal decomposition of the resin component during sintering was incomplete, and the resin component remained in the insulating protective film, inhibiting densification of the insulating protective film, possibly resulting in a deterioration in protective performance (rating of C).

[0182] Also, the central particle size D 50 In Example 21, where the mesh size was increased to 50.0 μm, the paste could not pass through the mesh smoothly during screen printing, and printability deteriorated, resulting in a rating of C. Furthermore, the printability deteriorated, resulting in an increase in minute pinholes, which may have also reduced the protective performance of the insulating protective film, resulting in a rating of C in the evaluation of protective performance.

[0183] From the above results, it is found that the median particle size of glass beads D 50 It can be said that a range of 1.0 to 30 μm is preferable.

[0184] (Effects obtained) From all of the above verification results, it was found that in Examples 1 to 21, the problem of the present application was solved by the glass component containing glass beads in a proportion of 50 mass% or more and the organic vehicle containing a (meth)acrylic resin, and that a glass paste was obtained that could be fired in an inert gas atmosphere while achieving both sinterability (complete thermal decomposition of the resin component so that soot and bubbles do not form in the insulating protective film) and printability (excellent fluidity and no pinholes).

[0185] Furthermore, the median particle size of the glass beads D 50 In the case where the diameter of the glass beads is within the range of 1.0 to 30 μm, the glass beads are selected from borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass, and the proportion of alkali metal components in the glass beads is 10 mass % or less, the glass beads exhibit excellent sinterability, printability, and protective performance, and do not alter the electrical properties of conductive films or resistive films. Therefore, it was found that a glass paste suitable for forming an insulating protective film that protects base metal conductive films or resistive films by firing in an inert gas atmosphere can be obtained. [Industrial Applicability]

[0186] The glass paste of the present invention can be used to form an insulating protective film for protecting a base metal conductor film or a resistive film, and is useful as an insulating protective film for, for example, chip resistors, resistor-embedded modules, resistor-embedded substrates, ceramic heaters, LED mounting substrates, etc. [Explanation of symbols]

[0187] 1,11...Evaluation sample 2,12...Base material 3,13...Conductor film 4,14...Resistive film 5,15...Insulating protective film

Claims

1. A glass paste for forming an insulating protective film by firing in an inert gas atmosphere, comprising a glass component and an organic vehicle; The glass component contains glass beads in a proportion of 50% by mass or more, and The glass paste, wherein the organic vehicle contains a (meth)acrylic resin.

2. 2. The glass paste according to claim 1, wherein the insulating protective film is a film for protecting a base metal conductor film and / or a base metal resistive film.

3. The median particle diameter D of the glass beads ５０ 3. The glass paste according to claim 1, wherein the particle size is 1 to 30 μm.

4. 3. The glass paste according to claim 1, wherein the glass beads contain at least one material selected from the group consisting of borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass.

5. 3. The glass paste according to claim 1, wherein the proportion of alkali metal components in the glass beads is 10% by mass or less.

6. 3. The glass paste according to claim 1, wherein the glass component further comprises ground glass powder.

7. 7. The glass paste according to claim 6, wherein the mass ratio of the glass beads to the crushed glass powder is 99 / 1 to 60 / 40.

8. 7. The glass paste according to claim 6, wherein the softening point of the pulverized glass powder is 100° C. or more lower than the softening point of the glass beads, and the mass ratio of the glass beads to the pulverized glass powder is 85 / 15 to 65 / 35.

9. 3. An insulating protective film formed from the glass paste according to claim 1.

10. 3. A method for producing an insulating protective film, comprising applying the glass paste according to claim 1 or 2 to a base metal conductor film and / or a base metal resistive film, and firing the paste in an inert gas atmosphere.

11. A laminate comprising a ceramic substrate, a base metal conductive film, a base metal resistive film, and the insulating protective film according to claim 9.

12. 3. A method for producing a laminate, comprising applying the glass paste according to claim 1 or 2 to a ceramic substrate having a base metal conductor film and a base metal resistive film laminated thereon, and firing the resulting mixture in an inert gas atmosphere.

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