Chip resistor

Abstract

A chip resistor according to the present invention comprises an insulating substrate, a first upper surface electrode, a second upper surface electrode, a resistor, a first back surface electrode, a second back surface electrode, a first end surface electrode, and a second end surface electrode. The first back surface electrode and the second back surface electrode each contain silver particles (B) and a cured product of a hydroxyphenyl-based epoxy resin (A). The content of the silver particles (B) with respect to the first back surface electrode and the content of the silver particles (B) with respect to the second back surface electrode are each 30-65 mass%.

Description

Chip resistor

[0001] This disclosure relates to chip resistors used in various electronic devices.

[0002] Patent Document 1 discloses a chip-shaped electronic component comprising a substrate and an end-face electrode layer disposed on the end face of the substrate, wherein the end-face electrode layer is composed of a mixed material containing a conductive substance (a'), whisker-like particles (b) coated with the conductive substance (a'), conductive flake-like particles (c), and a tetrafunctional hydroxyphenyl type epoxy resin (d) having a molecular weight of 450 or more and less than 800, and the mass ratio of the flake-like particles (c) to the whisker-like particles (b) being 1 is 3 / 7 or more and 9 or less.

[0003] International Publication No. 2019 / 131352

[0004] The chip-shaped electronic components described above may further include a resistor and an electrode on the opposite side of the substrate from the side where the resistor is located, distinct from the end-face electrode layer. In this case, it is desirable to suppress cracks that occur at the point where the electrode contacts the substrate.

[0005] A chip resistor according to one aspect of the present disclosure comprises an insulating substrate, a first upper electrode and a second upper electrode disposed on a first main surface of the insulating substrate, a resistor electrically connecting the first upper electrode and the second upper electrode, a first back electrode and a second back electrode disposed on a second main surface of the insulating substrate opposite to the first main surface, a first end electrode electrically connected to the first upper electrode and the first back electrode, and a second end electrode electrically connected to the second upper electrode and the second back electrode. Each of the first back electrode and the second back electrode contains a cured product of hydroxyphenyl type epoxy resin (A) and silver particles (B). The content of silver particles (B) in the first back electrode and the content of silver particles (B) in the second back electrode are each 30% by mass or more and 65% by mass or less.

[0006] According to this disclosure, it is possible to provide a chip resistor that is less prone to cracking at the points where the first back electrode and the second back electrode contact the insulating substrate.

[0007] A chip resistor according to another aspect of the present disclosure comprises an insulating substrate, a first upper electrode and a second upper electrode disposed on a first main surface of the insulating substrate, a resistor electrically connecting the first upper electrode and the second upper electrode, a first back electrode and a second back electrode disposed on a second main surface of the insulating substrate opposite to the first main surface, a first end electrode electrically connected to the first upper electrode and the first back electrode, and a second end electrode electrically connected to the second upper electrode and the second back electrode. Each of the first back electrode and the second back electrode contains a cured product of a hydroxyphenyl type epoxy resin (A) and silver particles (B). The content of silver particles (B) in the first back electrode and the content of silver particles (B) in the second back electrode are each 30% by mass or more and 65% by mass or less.

[0008] According to this disclosure, it is possible to provide a chip resistor that is less prone to cracking at the points where the first back electrode and the second back electrode contact the insulating substrate.

[0009] Figure 1 is a cross-sectional view of a chip resistor according to Embodiment 1. Figure 2 is a cross-sectional view of a chip resistor according to Embodiment 2.

[0010] (Embodiment 1) 1. Overview Embodiment 1 of this disclosure will be described with reference to the figures. Figure 1 is a cross-sectional view of a chip resistor 10 according to Embodiment 1. Note that Embodiment 1 described below is only a part of the various embodiments of this disclosure. Furthermore, the embodiments described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. The figures referred to below are schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. The arrows indicating direction in the drawings are not intended to define the direction in which the chip resistor 10 is used, but are merely included to make the explanation easier to understand and do not have any actual meaning. In this disclosure, the vertical direction is also called the thickness direction, and viewing along the thickness direction is called a plan view.

[0011] The chip resistor 10 according to Embodiment 1 comprises an insulating substrate 1, a first upper electrode 411 and a second upper electrode 421 disposed on a first main surface 81 of the insulating substrate 1, a resistor 2 electrically connecting the first upper electrode 411 and the second upper electrode 421, a first back electrode 412 and a second back electrode 422 disposed on a second main surface 82 opposite to the first main surface 81 of the insulating substrate 1, a first end electrode 413 electrically connected to the first upper electrode 411 and the first back electrode 412, and a second end electrode 423 electrically connected to the second upper electrode 421 and the second back electrode 422. Each of the first back electrode 412 and the second back electrode 422 contains a cured product of hydroxyphenyl type epoxy resin (A) and silver particles (B). The silver particles are dispersed in the cured product. The content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are each 30% by mass or more and 60% by mass or less. In Embodiment 1, cracks are less likely to occur at the locations where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. The reason why the chip resistor 10 according to Embodiment 1 can exhibit the above effect has not been precisely revealed, but it is presumed to be due to the following reasons.

[0012] In Embodiment 1, each of the first back electrode 412 and the second back electrode 422 contains a cured product of hydroxyphenyl-type epoxy resin (A). The cured product of hydroxyphenyl-type epoxy resin (A) may have high chemical stability in high-temperature environments, mechanical rigidity to withstand large deformation loads, and flexibility to deform appropriately to prevent fracture under repeated stress loads. Furthermore, in Embodiment 1, the content of silver particles (B) contained in each of the first back electrode 412 and the second back electrode 422 is moderately reduced. In other words, the content of resin components contained in each of the first back electrode 412 and the second back electrode 422 is moderately increased. As a result, the above-mentioned effects derived from the cured product of hydroxyphenyl-type epoxy resin (A) are more efficiently exerted, and it is presumed that cracks are less likely to occur at the locations where each of the first back electrode 412 and the second back electrode 422 contacts the insulating substrate 1.

[0013] A chip resistor 10 equipped with such a first back electrode 412 and a second back electrode 422 can have high reliability even in harsh environments. For example, even if the chip resistor 10 according to Embodiment 1 is placed in an environment where the temperature repeatedly changes from relatively low temperatures (e.g., -55°C) to relatively high temperatures (e.g., 200°C), cracks are less likely to occur at the points where the first back electrode 412 and the second back electrode 422 contact the insulating substrate 1, and as a result, the destruction of the chip resistor 10 can be prevented.

[0014] In Embodiment 1, the content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are moderately reduced. Even in this case, peeling of the first back electrode 412 from the first plating film 414 is suppressed, and peeling of the second back electrode 422 from the second plating film 424 is suppressed. In addition, even at high temperatures, the first back electrode 412 and the second back electrode 422 can maintain high adhesion to the first plating film 414 and the second plating film 424, respectively, or to the insulating substrate 1. Therefore, damage to the chip resistor 10 is unlikely to occur.

[0015] 2. The chip resistor 10 according to the detailed embodiment 1 will be described with reference to the drawings.

[0016] 2.1 Configuration of the Chip Resistor The specific components of the chip resistor 10 according to Embodiment 1 will be described below.

[0017] (Insulating Substrate) The chip resistor 10 includes an insulating substrate 1. The insulating substrate 1 has a rectangular shape when viewed from above. Therefore, the insulating substrate 1 has two opposing surfaces in the thickness direction, namely a first main surface 81 and a second main surface 82 on the opposite side of the first main surface 81. The distance between the first main surface 81 and the second main surface 82 is the thickness of the insulating substrate 1. For example, the thickness of the insulating substrate 1 is 100 μm or more and 600 μm or less.

[0018] In Embodiment 1, the insulating substrate 1 is made of alumina (Al ２ O ３The insulating substrate 1 contains a sintered body. In addition, the insulating substrate 1 may contain components other than the alumina sintered body. The content of the alumina sintered body in the insulating substrate 1 is preferably 96% by mass or more, more preferably 99% by mass or more, and even more preferably 100% by mass.

[0019] (Electrodes) In Embodiment 1, the chip resistor 10 includes a first upper electrode 411 and a second upper electrode 421. Each of the first upper electrode 411 and the second upper electrode 421 is arranged on the first main surface 81 of the insulating substrate 1. For example, the first upper electrode 411 and the second upper electrode 421 are electrically connected to the left and right ends of the resistor 2, respectively. Each of the first upper electrode 411 and the second upper electrode 421 also contains a metal. For example, the metal includes at least one selected from the group consisting of silver, copper, gold, nickel, tin, and palladium. Each of the first upper electrode 411 and the second upper electrode 421 is formed from a conductive paste containing the above-mentioned metal. In addition to the metal, the conductive paste includes at least one selected from the group consisting of a resin component and a glass component.

[0020] In Embodiment 1, the chip resistor 10 includes a first back electrode 412 and a second back electrode 422. Each of the first back electrode 412 and the second back electrode 422 is arranged on the second main surface 82 of the insulating substrate 1.

[0021] The thickness of the first back electrode 412 and the second back electrode 422 is preferably 5 μm or more and 30 μm or less. In this case, cracks are less likely to occur at the locations where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. A thickness of 8 μm or more is more preferable. A thickness of 15 μm or less is even more preferable.

[0022] The number average molecular weight of the hydroxyphenyl-type epoxy resin (A) is preferably 450 or more and 800 or less. In this case, both the rigidity and flexibility of the cured product of the hydroxyphenyl-type epoxy resin (A) are enhanced. As a result, fatigue failure is less likely to occur in each of the first back electrode 412 and the second back electrode 422.

[0023] The hydroxyphenyl-type epoxy resin (A) preferably has 2 or more epoxy groups in one molecule, more preferably 3 or more, and still more preferably 4 or more. In other words, the hydroxyphenyl-type epoxy resin (A) preferably includes a tetrafunctional hydroxyphenyl-type epoxy resin (A1). For example, the tetrafunctional hydroxyphenyl-type epoxy resin (A1) includes a compound represented by formula (1).

[0024]

[0025] In Embodiment 1, it is preferable that the storage elastic moduli of the first back electrode 412 and the second back electrode 422 satisfy a specific range. Specifically, in a temperature range of 25°C or higher and 200°C or lower, the storage elastic moduli of the first back electrode 412 and the second back electrode 422 are 1.0×10 ７ Pa or more and 3.0×10 ８ Pa or less. In this case, cracks are less likely to occur at portions of each of the first back electrode 412 and the second back electrode 422 that are in contact with the insulating substrate 1. The storage elastic moduli of the first back electrode 412 and the second back electrode 422 are 5.0×10 ７ Pa or more, more preferably 1.0×10 ８ Pa or more. Further, the storage elastic moduli of the first back electrode 412 and the second back electrode 422 are 2.8×10 ８ Pa or less, more preferably 2.5×10 ８ Pa or less, and even more preferably.

[0026] Each of the content of the hydroxyphenyl-type epoxy resin (A) relative to the first back electrode 412 and the content of the hydroxyphenyl-type epoxy resin (A) relative to the second back electrode 422 is preferably 35% by mass or more and 70% by mass or less. In this case, cracks are less likely to occur at portions of each of the first back electrode 412 and the second back electrode 422 that are in contact with the insulating substrate 1. This content is more preferably 40% by mass or more. Further, this content is more preferably 50% by mass or less.

[0027] As already mentioned, each of the first back electrode 412 and the second back electrode 422 contains silver particles (B). The content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are 30% by mass or more and 65% by mass or less. From the viewpoint of ensuring the conductivity of the first back electrode 412 and the second back electrode 422, it is preferable that this content is 50% by mass or more. From the viewpoint of further suppressing cracks that occur in each of the first back electrode 412 and the second back electrode 422, it is preferable that this content is 60% by mass or less.

[0028] The silver particles (B) preferably include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2). If each of the first back electrode 412 and the second back electrode 422 contains whisker-shaped silver particles (B1), the resistance values ​​of the first back electrode 412 and the second back electrode 422 can be lowered. If each of the first back electrode 412 and the second back electrode 422 contains flake-shaped silver particles (B2), the adhesion of the first back electrode 412 to the first plating film 414 and the adhesion of the second back electrode 422 to the second plating film 424 can be improved.

[0029] Examples of whisker-shaped silver particles (B1) include whisker-shaped inorganic fillers coated with silver. For example, the inorganic filler contains potassium titanate. The shape of the whisker-shaped silver particles (B1) is not particularly limited, but for example, the average fiber diameter of the whisker-shaped silver particles (B1) may be 0.3 μm or more and 0.6 μm or less, the average fiber length of the whisker-shaped silver particles (B1) may be 5 μm or more and 30 μm or less, and the aspect ratio of the whisker-shaped silver particles (B1) may be 8.3 or more and 100 or less.

[0030] Flake-shaped silver particles (B2) can be manufactured by plastically deforming spherical silver particles (A) using a ball mill or the like. The shape and size of the flake-shaped silver particles (B2) are not particularly limited, but the aspect ratio of the flake-shaped silver particles (B2) is 2 or greater.

[0031] Furthermore, if the silver particles (B) include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2), it is preferable that the whisker-shaped silver particles (B1) and flake-shaped silver particles (B2) are mixed in an appropriate ratio. In this case, the first back electrode 412 and the second back electrode 422 each maintain effective conductivity, and even under harsh conditions, the breakdown of the first back electrode 412 and the second back electrode 422 is less likely to occur. Also, even under relatively high temperature conditions, the first back electrode 412 and the second back electrode 422 can maintain high bonding strength with the first plating film 414 and the second plating film 424, respectively. This makes it less likely for the breakdown of the first back electrode 412 and the second back electrode 422 to occur at the points where they contact the insulating substrate 1. Specifically, it is preferable that the mass ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) is 50 / 65 or more and 50 / 35 or less.

[0032] For example, the first back electrode 412 and the second back electrode 422 are made from a conductive paste (hereinafter also referred to as conductive paste (P)) containing a hydroxyphenyl type epoxy resin (A) and silver particles (B).

[0033] Furthermore, the conductive paste (P) may contain, in addition to the hydroxyphenyl-type epoxy resin (A) or the hydroxyphenyl-type epoxy resin (A) and silver particles (B), at least one selected from the group consisting of a curing agent (C), a solvent (D), and a curing catalyst (E).

[0034] For example, the curing agent (C) includes at least one selected from the group consisting of imidazole-based curing agents such as phenylimidazole and cyanoimidazole, and dicyandiamide. Note that if the curing agent (C) contains both an imidazole-based curing agent and dicyandiamide simultaneously, the curing of the conductive paste (P) may be accelerated. The content of the curing agent (C) is not particularly limited, but is between 1 and 10 parts by mass per 100 parts by mass of the hydroxyphenyl-type epoxy resin (A).

[0035] For example, solvent (D) is not particularly limited, but includes at least one selected from the group consisting of ether-based solvents such as ethyl carbitol and butyl carbitol acetate, and alcohol-based solvents such as benzyl alcohol.

[0036] For example, the curing catalyst (E) includes at least one selected from the group consisting of tin-based curing catalysts such as dioctyl tin dilaurate and stannous 2-ethylhexylate, and phosphorus-based curing catalysts such as triphenylphosphine and triparathylphosphine.

[0037] For example, conductive paste (P) is manufactured by mixing a mixture of materials containing the above-mentioned components and kneading it into a uniform paste using a kneading device. Examples of kneading devices include a kneader mixer, a planetary mixer, or a three-roll mixer.

[0038] In Embodiment 1, the chip resistor 10 includes a first end electrode 413 electrically connected to a first top electrode 411 and a first back electrode 412, and a second end electrode 423 electrically connected to a second top electrode 421 and a second back electrode 422. Each of the first end electrode 413 and the second end electrode 423 is arranged to cover the left and right edges of the insulating substrate 1. Each of the first end electrode 413 and the second end electrode 423 is formed from a conductive paste containing a resin component, carbon particles, and silver powder. The resin component includes at least one selected from the group consisting of phenoxy resin and epoxy resin. The carbon particles can enhance the conductivity of the first end electrode 413 and the second end electrode 423. For example, the silver powder may be the same as the silver particles (B) contained in the first back electrode 412 and the second back electrode 422.

[0039] In Embodiment 1, the chip resistor 10 comprises a first plating film 414 covering a first top electrode 411, a first back electrode 412, and a first end electrode 413, and a second plating film 424 covering a second top electrode 421, a second back electrode 422, and a second end electrode 423.

[0040] Furthermore, in Embodiment 1, the first plated film 414 includes a first intermediate electrode 4141 and a first external electrode 4142 that covers the first intermediate electrode 4141. The first intermediate electrode 4141 covers the first top surface electrode 411, the first back surface electrode 412, and the first end surface electrode 413 so as to be in direct contact with the first top surface electrode 411, the first back surface electrode 412, and the first end surface electrode 413. The first external electrode 4142 is not in direct contact with the first top surface electrode 411, the first back surface electrode 412, and the first end surface electrode 413, and covers the first top surface electrode 411, the first back surface electrode 412, and the first end surface electrode 413 via the first intermediate electrode 4141.

[0041] Furthermore, in Embodiment 1, the second plated film 424 includes a second intermediate electrode 4241 and a second external electrode 4242 that covers the second intermediate electrode 4241. The second intermediate electrode 4241 covers the second top surface electrode 421, the second back surface electrode 422, and the second end surface electrode 423 so as to be in direct contact with the second top surface electrode 421, the second back surface electrode 422, and the second end surface electrode 423. The second external electrode 4242 is not in direct contact with the second top surface electrode 421, the second back surface electrode 422, and the second end surface electrode 423, and covers the second top surface electrode 421, the second back surface electrode 422, and the second end surface electrode 423 via the second intermediate electrode 4241.

[0042] (Resistor) The chip resistor 10 includes a resistor 2. The resistor 2 is electrically connected to the first top surface electrode 411 and the second top surface electrode 421. In Embodiment 1, the resistor 2 is arranged on one of the opposing surfaces of the insulating substrate 1 in the thickness direction, that is, on the first main surface 81. The shape of the resistor 2 in plan view is, for example, a rectangular shape such as a rectangle. The resistor 2 is made of, for example, RuO ２ , AgPd, CuNi, or the like.

[0043] In Embodiment 1, for example, the resistor 2 can be formed from a thin film conductor obtained by a thin film process. In other words, the chip resistor 10 according to Embodiment 1 is a thin film chip resistor. For example, the thickness of the resistor 2 is 10 nm or more and 1000 nm or less. In this case, the effect of Embodiment 1 is particularly likely to be exhibited.

[0044] (Protective film) For example, the chip resistor 10 is equipped with a protective film 6. In Embodiment 1, the protective film 6 includes an inorganic protective layer 62 and a resin layer 63 disposed on the inorganic protective layer 62.

[0045] The inorganic protective layer 62 is positioned to cover a portion of the resistor 2. The inorganic protective layer 62 is in direct contact with the resistor 2. When viewed from above, the inorganic protective layer 62 covers the resistor 2. In this case, fluctuations in the resistance value of the resistor 2 can be suppressed. The inorganic protective layer 62 is made of an inorganic material. Examples of inorganic materials include glass materials, metal oxides, and metal nitrides. Examples of glass materials include crystal glass and quartz glass. Examples of metal oxides include Al ２ O ３ Examples include alumina.

[0046] The resin layer 63 can protect the resistor 2 and the inorganic protective layer 62. For example, the resin layer 63 is arranged to cover the entire inorganic protective layer 62, in which case fluctuations in the resistance value of the resistor 2 can be suppressed. The resin layer 63 is formed from a resin composition containing a resin component such as epoxy resin. In addition to the resin component, the resin composition may contain at least one selected from the group consisting of silica particles and silicone rubber particles. In this case, the stress generated in the resin layer 63 due to heat, etc., can be relieved compared to the case where the resin layer 63 is formed from only the resin component. As a result, the resin layer 63 becomes less likely to peel off from the inorganic protective layer 62.

[0047] 2.2 Method for Manufacturing Chip Resistors A brief description will be given of the method for manufacturing the chip resistor 10 according to Embodiment 1.

[0048] First, a conductive paste containing metal is applied to the first main surface 81 of the insulating substrate 1 by printing, and the first upper electrode 411 and the second upper electrode 421 are formed by firing.

[0049] Next, a thin film conductor is formed on the first main surface 81 of the insulating substrate 1 by a thin film process such as sputtering. Then, the resistor 2 is formed by removing the unnecessary portion of the thin film conductor by a photolithography process.

[0050] Next, a protective film 6 is formed. First, an inorganic material is placed to cover the resistor 2. Then, an inorganic protective layer 62 is formed by firing the placed inorganic material. Subsequently, an epoxy resin composition is applied to the inorganic protective layer 62, and the epoxy resin composition is heated and cured. This forms a resin layer 63 that covers the inorganic protective layer 62.

[0051] Next, the conductive paste (P) described above is applied to the second main surface 82 of the insulating substrate 1. Then, the first back surface electrode 412 and the second back surface electrode 422 are formed by heating and curing this paste.

[0052] Next, a conductive paste containing resin components, carbon particles, and silver powder is applied to each of the left and right sides of the insulating substrate 1. Then, by heating and curing this paste, the first end face electrode 413 and the second end face electrode 423 are formed, respectively.

[0053] Then, a first plating film 414 is formed covering the first upper electrode 411, the first back electrode 412, and the first end electrode 413, and a second plating film 424 is formed covering the second upper electrode 421, the second back electrode 422, and the second end electrode 423. In Embodiment 1, the first intermediate electrode 4141 and the second intermediate electrode 4241 are formed by applying Ni plating so as to cover the first end electrode 413 and the second end electrode 423, respectively. Furthermore, the first external electrode 4142 and the second external electrode 4242 are formed by applying Sn plating so as to cover the first intermediate electrode 4141 and the second intermediate electrode 4241, respectively.

[0054] The chip resistor 10 according to Embodiment 1 can be manufactured by following these steps. However, the above method is merely one example of a method for manufacturing the chip resistor 10 according to Embodiment 1. For example, the first upper electrode 411 and the second upper electrode 421 do not necessarily have to be manufactured at the same time. More specifically, when manufacturing the first upper electrode 411 and the second upper electrode 421, first, the lower portion of the first upper electrode 411 and the lower portion of the second upper electrode 421 are manufactured on the first main surface 81 of the insulating substrate 1, followed by the manufacture of the resistor 2 and the inorganic protective layer 62. After that, a conductive paste may be applied so as to cover a part of the resistor 2 and a part of the inorganic protective layer 62, and then heated to manufacture the upper portion of the first upper electrode 411 and the upper portion of the second upper electrode 421, respectively (see Figure 1). In this case, both ends of the resistor 2 in the left-right direction may be covered by the first upper electrode 411 and the second upper electrode 421, respectively.

[0055] 2.3 Modified Examples Modified examples of the chip resistor 10 will be described. The modified examples are examples of variations in which the configuration of Embodiment 1 is partially changed, added, or deleted. Furthermore, regarding the modified examples, the same configuration as the chip resistor 10 of Embodiment 1 will not be described.

[0056] In Embodiment 1, the insulating substrate 1 is made of alumina (Al ２ O ３ ) contains a sintered body, but is not limited to this. For example, the insulating substrate 1 is made of alumina (Al ２ O ３ It may also contain a sintered body of a different metal oxide than alumina (Al). ２ O ３ In addition to sintered bodies, aluminum nitride (AlN), zirconia (ZrO ２ ) and silicon nitride (Si ３ Ni ４ It contains at least one sintered body selected from the group consisting of the following:

[0057] In Embodiment 1, the first intermediate electrode 4141 and the second intermediate electrode 4241 were each made by Ni plating, and the first external electrode 4142 and the second external electrode 4242 were each made by Sn plating, but the invention is not limited to these. That is, each of the first plating film 414 and the second plating film 424 may contain, in addition to nickel (Ni) and tin (Sn), at least one element selected from the group consisting of copper (Cu), chromium (Cr), lead (Pb), zinc (Zn), indium (In), bismuth (Bi), gold (Au), silver (Ag), palladium (Pd), and platinum (Pt).

[0058] In Embodiment 1, composition (M) contained a hydroxyphenyl-type epoxy resin (A). However, for example, composition (M) may contain a resin different from the hydroxyphenyl-type epoxy resin (A), as long as it does not impair the effects of Embodiment 1. In this case, the insulating film 3 contains a cured product of a resin different from the hydroxyphenyl-type epoxy resin (A) in addition to the cured product of the hydroxyphenyl-type epoxy resin (A).

[0059] The chip resistor 10 may have an insulating film on its second main surface 82. If the chip resistor 10 has an insulating film on its second main surface 82, the insulating film may be interposed between each of the first back electrode 412 and the second back electrode 422 and the insulating substrate 1.

[0060] 3. Embodiments As is clear from Embodiment 1 above, this disclosure includes the following embodiments. Hereafter, reference numerals are enclosed in parentheses solely to indicate their correspondence with Embodiment 1.

[0061] A chip resistor (10) according to a first aspect of the present disclosure comprises an insulating substrate (1), a first upper electrode (411) and a second upper electrode (421) disposed on a first main surface (81) of the insulating substrate (1), a resistor (2) electrically connecting the first upper electrode (411) and the second upper electrode (421), a first back electrode (412) and a second back electrode (422) disposed on a second main surface (82) of the insulating substrate (1) opposite to the first main surface (81), a first end electrode (413) electrically connected to the first upper electrode (411) and the first back electrode (412), and a second end electrode (423) electrically connected to the second upper electrode (421) and the second back electrode (422). Each of the first back electrode (412) and the second back electrode (422) contains a cured product of a hydroxyphenyl type epoxy resin (A) and silver particles (B). The content of silver particles (B) in the first back electrode (412) and the content of silver particles (B) in the second back electrode (422) are each 30% by mass or more and 65% by mass or less.

[0062] According to this embodiment, a chip resistor (10) can be provided in which cracks are less likely to occur at the locations where the first back electrode (412) and the second back electrode (422) are in contact with the insulating substrate (1).

[0063] In the first embodiment, the chip resistor (10) according to a second aspect of the present disclosure comprises silver particles (B) including whisker-shaped silver particles (B1) and flake-shaped silver particles (B2).

[0064] In the third aspect of the present disclosure, the chip resistor (10) has, in the first or second aspect, a ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) of 50 / 65 or more and 50 / 35 or less.

[0065] A chip resistor (10) according to a fourth aspect of the present disclosure, in any one of the first to third aspects, has a storage modulus of 1.0 × 10⁻¹⁰ of the first back electrode (412) and the second back electrode (422). ７ The above 3.0 x 10 ８ The following applies:

[0066] (Embodiment 2) 1. Overview Embodiment 2 of this disclosure will be described with reference to the figures. Figure 2 is a cross-sectional view of a chip resistor 10A according to Embodiment 2. Note that Embodiment 2 described below is only a part of the various embodiments of this disclosure. Furthermore, Embodiment 2 described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. The figures referred to below are schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. The arrows indicating direction in the drawings are not intended to define the direction in which the chip resistor 10A is used, but are merely included to make the explanation easier to understand and do not have any actual meaning. In the following description, the thickness direction of the insulating substrate 1 is referred to as the vertical direction, and in the vertical direction, the side on which the resistor 2 is arranged relative to the insulating substrate 1 is referred to as the top, and the opposite side is referred to as the bottom. Furthermore, the direction perpendicular to the vertical direction, where the first upper electrode 411 and the second upper electrode 421 are aligned, is called the left-right direction. In the left-right direction, the side of the second upper electrode 421 relative to the first upper electrode 411 is called the right, and the side of the first upper electrode 411 relative to the second upper electrode 421 is called the left. Viewing along the thickness direction is called a plan view.

[0067] The chip resistor 10A according to Embodiment 2 comprises an insulating substrate 1, a first upper electrode 411 and a second upper electrode 421 disposed on the first main surface 81 of the insulating substrate 1, a resistor 2 electrically connecting the first upper electrode 411 and the second upper electrode 421, a first back electrode 412 and a second back electrode 422 disposed on the second main surface 82 opposite to the first main surface 81 of the insulating substrate 1, a first end electrode 413 electrically connected to the first upper electrode 411 and the first back electrode 412, and a second end electrode 423 electrically connected to the second upper electrode 421 and the second back electrode 422. Each of the first back electrode 412 and the second back electrode 422 contains a cured product of hydroxyphenyl type epoxy resin (A) and silver particles (B). The silver particles are dispersed in the cured product. The content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are each 30% by mass or more and 60% by mass or less. In Embodiment 2, cracks are less likely to occur at the locations where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. The reason why the chip resistor 10A according to Embodiment 2 can exhibit the above effect has not been precisely revealed, but it is presumed to be due to the following reasons.

[0068] In Embodiment 2, each of the first back electrode 412 and the second back electrode 422 contains a cured product of hydroxyphenyl-type epoxy resin (A). The cured product of hydroxyphenyl-type epoxy resin (A) may have high chemical stability in high-temperature environments, mechanical rigidity to withstand large deformation loads, and flexibility to deform appropriately to prevent fracture under repeated stress loads. Furthermore, in Embodiment 2, the content of silver particles (B) contained in each of the first back electrode 412 and the second back electrode 422 is moderately reduced. In other words, the content of resin components contained in each of the first back electrode 412 and the second back electrode 422 is moderately increased. As a result, the above-mentioned effects derived from the cured product of hydroxyphenyl-type epoxy resin (A) are more efficiently exerted, and it is presumed that cracks are less likely to occur at the locations where each of the first back electrode 412 and the second back electrode 422 contacts the insulating substrate 1.

[0069] A chip resistor 10A equipped with such a first back electrode 412 and a second back electrode 422 can have high reliability even in harsh environments. For example, even if the chip resistor 10A according to Embodiment 2 is placed in an environment where the temperature repeatedly changes from relatively low temperatures (e.g., -55°C) to relatively high temperatures (e.g., 200°C), cracks are less likely to occur at the points where the first back electrode 412 and the second back electrode 422 contact the insulating substrate 1, and as a result, the failure of the chip resistor 10A can be prevented.

[0070] In Embodiment 2, the content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are moderately reduced. Even in this case, peeling of the first back electrode 412 from the first plating film 414 is suppressed, and peeling of the second back electrode 422 from the second plating film 424 is suppressed. In addition, even at high temperatures, the first back electrode 412 and the second back electrode 422 can maintain high adhesion to the first plating film 414 and the second plating film 424, respectively, or to the insulating substrate 1. Therefore, damage to the chip resistor 10A is unlikely to occur.

[0071] 2. The chip resistor 10A according to the detailed embodiment 2 will be described with reference to the drawings.

[0072] 2.1 Configuration of the Chip Resistor The specific components of the chip resistor 10A according to Embodiment 2 will be described below.

[0073] (Insulating Substrate) The chip resistor 10A includes an insulating substrate 1. The insulating substrate 1 has a rectangular shape when viewed from above. Therefore, the insulating substrate 1 has two surfaces facing each other in the thickness direction, namely a first main surface 81 (top surface) and a second main surface 82 (bottom surface) opposite to the first main surface 81. The distance between the first main surface 81 and the second main surface 82 is the thickness of the insulating substrate 1. For example, the thickness of the insulating substrate 1 is 100 μm or more and 600 μm or less.

[0074] In Embodiment 2, the insulating substrate 1 is made of alumina (Al ２ O ３The insulating substrate 1 contains a sintered body. In addition, the insulating substrate 1 may contain components other than the alumina sintered body. The content of the alumina sintered body in the insulating substrate 1 is preferably 96% by mass or more, more preferably 99% by mass or more, and even more preferably 100% by mass.

[0075] (Electrodes) In Embodiment 2, the chip resistor 10A includes a first upper electrode 411 and a second upper electrode 421. Each of the first upper electrode 411 and the second upper electrode 421 is arranged on the first main surface 81 of the insulating substrate 1. For example, the first upper electrode 411 is arranged on the first main surface 81 at one end (left side) of the insulating substrate 1. The second upper electrode 421 is arranged on the first main surface 81 at the end of the insulating substrate 1 opposite to the first upper electrode 411 (right side). There is a gap between the first upper electrode 411 and the second upper electrode 421 in the direction in which the first upper electrode 411 and the second upper electrode 421 are aligned (left-right direction). For example, the first upper electrode 411 and the second upper electrode 421 are electrically connected to the left-right ends of the resistor 2, respectively. Each of the first upper electrode 411 and the second upper electrode 421 also contains metal. For example, the metal includes at least one selected from the group consisting of silver, copper, gold, nickel, tin, and palladium. Each of the first upper electrode 411 and the second upper electrode 421 is formed from a conductive paste containing the above-mentioned metal. In addition to the metal, the conductive paste includes at least one selected from the group consisting of resin components and glass components.

[0076] In Embodiment 2, the chip resistor 10A includes, for example, a first connecting electrode 415 and a second connecting electrode 425. The first connecting electrode 415 electrically connects the first end face electrode 413 and the first top surface electrode 411, and the second connecting electrode 425 electrically connects the second end face electrode 423 and the second top surface electrode 421.

[0077] The first connecting electrode 415 is placed on top of the first upper electrode 411 so as to contact the portion of the outer (left) end of the first upper electrode 411 that is not covered by the resistor 2. That is, the first connecting electrode 415 contacts the portion of the upper surface of the first upper electrode 411 that is not covered by the resistor 2. Furthermore, the first connecting electrode 415 may also cover the left end of the protective film 6. The second connecting electrode 425 is placed on top of the second upper electrode 421 so as to contact the portion of the outer (right) end of the second upper electrode 421 that is not covered by the resistor 2. That is, the second connecting electrode 425 contacts the portion of the upper surface of the second upper electrode 421 that is not covered by the resistor 2. Furthermore, the second connecting electrode 425 may also cover the right end of the protective film 6.

[0078] Each of the first connecting electrode 415 and the second connecting electrode 425 can be formed from a thin film conductor obtained by a thin film process such as sputtering. The thin film conductor for forming each of the first connecting electrode 415 and the second connecting electrode 425 contains at least one selected from the group consisting of, for example, CuNi and Cr.

[0079] In Embodiment 2, the chip resistor 10A includes a first back electrode 412 and a second back electrode 422. Each of the first back electrode 412 and the second back electrode 422 is arranged on the second main surface 82 of the insulating substrate 1.

[0080] For example, the first back electrode 412 is positioned on the second main surface 82 at the end of the insulating substrate 1 on the side of the first top electrode 411 (left side). The second back electrode 422 is positioned on the second main surface 82 at the end of the insulating substrate 1 on the opposite side (right side) from the first back electrode 412. There is a gap between the first back electrode 412 and the second back electrode 422 in the direction in which the first back electrode 412 and the second back electrode 422 are aligned (left-right direction).

[0081] The outer (left) end of the first back electrode 412 is located, for example, at the outer (left) end of the second main surface 82 of the insulating substrate 1. Alternatively, the outer end of the first back electrode 412 may extend from the outer (left) end of the second main surface 82 toward the first main surface 81 (upward) and be positioned on the left end face of the insulating substrate 1. In this case, the outer end of the first back electrode 412 does not reach the first upper electrode 411; that is, there is a vertical gap between the first upper electrode 411 and the first back electrode 412 on the left end face of the insulating substrate 1. The outer (right) end of the second back electrode 422 is located, for example, at the outer (right) end of the second main surface 82 of the insulating substrate 1. Alternatively, the outer end of the second back electrode 422 may extend from the outer (right) end of the second main surface 82 toward the first main surface 81 (upward) and be positioned on the right end face of the insulating substrate 1. In this case, the outer end of the second back electrode 422 does not reach the second top electrode 421, meaning that there is a vertical gap between the second top electrode 421 and the second back electrode 422 on the right end face of the insulating substrate 1.

[0082] The thickness of the first back electrode 412 and the second back electrode 422 is preferably 5 μm or more and 30 μm or less. In this case, cracks are less likely to occur at the locations where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. A thickness of 8 μm or more is more preferable. A thickness of 15 μm or less is even more preferable.

[0083] The number average molecular weight of the hydroxyphenyl-type epoxy resin (A) is preferably 450 or more and 800 or less. In this case, both the rigidity and flexibility of the cured product of the hydroxyphenyl-type epoxy resin (A) are enhanced. As a result, fatigue failure is less likely to occur in each of the first back electrode 412 and the second back electrode 422.

[0084] The hydroxyphenyl-type epoxy resin (A) preferably has two or more epoxy groups in one molecule, more preferably three or more, and even more preferably four or more. In other words, the hydroxyphenyl-type epoxy resin (A) preferably contains a tetrafunctional hydroxyphenyl-type epoxy resin (A1). For example, the tetrafunctional hydroxyphenyl-type epoxy resin (A1) contains a compound represented by formula (2).

[0085]

[0086] In Embodiment 2, it is preferable that the storage modulus of the first back electrode 412 and the second back electrode 422 satisfy a specific range. Specifically, in a temperature range of 25°C to 200°C, the storage modulus of the first back electrode 412 and the second back electrode 422 is 1.0 × 10⁻⁶. ７ Pa or more 3.0×10 ８ It is preferable that the pressure is Pa or less. In this case, cracks are less likely to occur at the points where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. The storage modulus of the first back electrode 412 and the second back electrode 422 is 5.0 × 10⁻⁶. ７ It is more preferable that the pressure be Pa or higher, and 1.0 × 10 ８ It is even more preferable that the pressure be Pa or higher. Furthermore, the storage modulus of the first back electrode 412 and the second back electrode 422 is 2.8 × 10⁻⁶. ８ It is more preferable that it be Pa or less, and 2.5 × 10 ８ It is even more preferable that it be Pa or less.

[0087] The content of hydroxyphenyl-type epoxy resin (A) in the first back electrode 412 and the content of hydroxyphenyl-type epoxy resin (A) in the second back electrode 422 are preferably 35% by mass or more and 70% by mass or less. In this case, cracks are less likely to occur at the locations where the first back electrode 412 and the second back electrode 422 are in contact with the insulating substrate 1. This content is more preferably 40% by mass or more. Furthermore, this content is more preferably 50% by mass or less.

[0088] As already mentioned, each of the first back electrode 412 and the second back electrode 422 contains silver particles (B). The content of silver particles (B) in the first back electrode 412 and the content of silver particles (B) in the second back electrode 422 are 30% by mass or more and 65% by mass or less. From the viewpoint of ensuring the conductivity of each of the first back electrode 412 and the second back electrode 422, it is preferable that this content is 50% by mass or more. From the viewpoint of further suppressing cracks that occur in each of the first back electrode 412 and the second back electrode 422, it is preferable that this content is 60% by mass or less.

[0089] The silver particles (B) preferably include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2). If each of the first back electrode 412 and the second back electrode 422 contains whisker-shaped silver particles (B1), the resistance values ​​of each of the first back electrode 412 and the second back electrode 422 can be lowered. If each of the first back electrode 412 and the second back electrode 422 contains flake-shaped silver particles (B2), the adhesion of the first back electrode 412 to the first plating film 414 and the adhesion of the second back electrode 422 to the second plating film 424 can be improved.

[0090] Examples of whisker-shaped silver particles (B1) include whisker-shaped inorganic fillers coated with silver. For example, the inorganic filler contains potassium titanate. The shape of the whisker-shaped silver particles (B1) is not particularly limited, but for example, the average fiber diameter of the whisker-shaped silver particles (B1) may be 0.3 μm or more and 0.6 μm or less, the average fiber length of the whisker-shaped silver particles (B1) may be 5 μm or more and 30 μm or less, and the aspect ratio of the whisker-shaped silver particles (B1) may be 8.3 or more and 100 or less.

[0091] Flake-shaped silver particles (B2) can be manufactured by plastically deforming spherical silver particles (A) using a ball mill or the like. The shape and size of the flake-shaped silver particles (B2) are not particularly limited, but the aspect ratio of the flake-shaped silver particles (B2) is 2 or greater.

[0092] Furthermore, if the silver particles (B) include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2), it is preferable that the whisker-shaped silver particles (B1) and flake-shaped silver particles (B2) are mixed in an appropriate ratio. In this case, each of the first back electrode 412 and the second back electrode 422 maintains effective conductivity, and even under harsh conditions, it becomes less likely for the first back electrode 412 and the second back electrode 422 to break down. Also, even under relatively high temperature conditions, the first back electrode 412 and the second back electrode 422 can maintain high bonding strength with the first plating film 414 and the second plating film 424, respectively. This makes it less likely for the first back electrode 412 and the second back electrode 422 to break down at the points where they contact the insulating substrate 1. Specifically, it is preferable that the mass ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) is 35 / 65 or more and 50 / 50 or less.

[0093] For example, the first back electrode 412 and the second back electrode 422 are made from a conductive paste (hereinafter also referred to as conductive paste (P)) containing a hydroxyphenyl type epoxy resin (A) and silver particles (B).

[0094] Furthermore, the conductive paste (P) may contain, in addition to the hydroxyphenyl-type epoxy resin (A) or the hydroxyphenyl-type epoxy resin (A) and silver particles (B), at least one selected from the group consisting of a curing agent (C), a solvent (D), and a curing catalyst (E).

[0095] For example, the curing agent (C) includes at least one selected from the group consisting of imidazole-based curing agents such as phenylimidazole and cyanoimidazole, and dicyandiamide. Note that if the curing agent (C) contains both an imidazole-based curing agent and dicyandiamide simultaneously, the curing of the conductive paste (P) may be accelerated. The content of the curing agent (C) is not particularly limited, but is between 1 and 10 parts by mass per 100 parts by mass of the hydroxyphenyl-type epoxy resin (A).

[0096] For example, solvent (D) is not particularly limited, but includes at least one selected from the group consisting of ether-based solvents such as ethyl carbitol and butyl carbitol acetate, and alcohol-based solvents such as benzyl alcohol.

[0097] For example, the curing catalyst (E) includes at least one selected from the group consisting of tin-based curing catalysts such as dioctyl tin dilaurate and stannous 2-ethylhexylate, and phosphorus-based curing catalysts such as triphenylphosphine and triparathylphosphine.

[0098] For example, conductive paste (P) is manufactured by mixing a mixture of materials containing the above-mentioned components and kneading it into a uniform paste using a kneading device. Examples of kneading devices include a kneader mixer, a planetary mixer, or a three-roll mixer.

[0099] In Embodiment 2, the chip resistor 10A includes a first end electrode 413 that is electrically connected to the first top electrode 411 and the first back electrode 412, and a second end electrode 423 that is electrically connected to the second top electrode 421 and the second back electrode 422. The first end electrode 413 and the second end electrode 423 are arranged to cover the left and right ends of the insulating substrate 1, respectively.

[0100] For example, the first end electrode 413 covers the end face of the insulating substrate 1 on the side of the first upper electrode 411 (left side). The second end electrode 423 covers the end face of the insulating substrate 1 on the side of the second upper electrode 421 (right side).

[0101] The lower end of the first end electrode 413 extends inward (to the right) and contacts the lower surface of the first back electrode 412 on the lower side of the insulating substrate 1, thereby electrically connecting to the first back electrode 412. The lower end of the second end electrode 423 extends inward (to the left) and contacts the lower surface of the second back electrode 422 on the lower side of the insulating substrate 1, thereby electrically connecting to the second back electrode 422. The upper end of the first end electrode 413 extends inward (to the right) and is positioned on the upper side of the insulating substrate 1 to cover the upper side of the first top electrode 411. The upper end of the second end electrode 423 extends inward (to the right) and is positioned on the upper side of the insulating substrate 1 to cover the upper side of the second top electrode 421.

[0102] A first connecting electrode 415 is interposed between the first end electrode 413 and the first upper electrode 411, and the first end electrode 413 and the first upper electrode 411 are electrically connected via the first connecting electrode 415. The upper end of the second end electrode 423 extends inward (to the left) and is positioned on the upper surface side of the insulating substrate 1 to cover the upper surface side of the second upper electrode 421. A second connecting electrode 425 is interposed between the second end electrode 423 and the second upper electrode 421, and the second end electrode 423 and the second upper electrode 421 are electrically connected via the second connecting electrode 425.

[0103] Each of the first end face electrode 413 and the second end face electrode 423 can be formed from a thin film conductor obtained by a thin film process such as sputtering. The thin film conductor for forming each of the first end face electrode 413 and the second end face electrode 423 contains, for example, a Ni-based alloy.

[0104] In Embodiment 2, the chip resistor 10A comprises a first plating film 414 covering the first connecting electrode 415, the first back electrode 412, and the first end electrode 413, and a second plating film 424 covering the second connecting electrode 425, the second back electrode 422, and the second end electrode 423.

[0105] In the second embodiment, the first plating film 414 includes a first intermediate electrode 4141 and a first external electrode 4142 that covers the first intermediate electrode 4141. The first intermediate electrode 4141 covers the first connecting electrode 415, the first back electrode 412, and the first end electrode 413 so as to be in direct contact with them. The first external electrode 4142 does not directly contact the first connecting electrode 415, the first back electrode 412, and the first end electrode 413, but covers the first connecting electrode 415, the first back electrode 412, and the first end electrode 413 via the first intermediate electrode 4141.

[0106] Furthermore, in Embodiment 2, the second plating film 424 includes a second intermediate electrode 4241 and a second external electrode 4242 that covers the second intermediate electrode 4241. The second intermediate electrode 4241 covers the second connecting electrode 425, the second back electrode 422, and the second end electrode 423 so as to be in direct contact with them. The second external electrode 4242 does not directly contact the second connecting electrode 425, the second back electrode 422, and the second end electrode 423, but covers the second connecting electrode 425, the second back electrode 422, and the second end electrode 423 via the second intermediate electrode 4241.

[0107] (Resistor) The chip resistor 10A includes a resistor 2. The resistor 2 is electrically connected to the first upper electrode 411 and the second upper electrode 421. In Embodiment 2, the resistor 2 is placed on one of the surfaces of the insulating substrate 1 that face each other in the thickness direction, that is, on the first main surface 81. The shape of the resistor 2 in plan view is, for example, rectangular. The resistor 2 is made of, for example, RuO ２ It is composed of AgPd, CuNi, etc.

[0108] The resistor 2 is positioned from at least a portion of the first upper electrode 411 to at least a portion of the second upper electrode 421. The insulating substrate 1, the first upper electrode 411, and the portion of the resistor 2 that overlaps with the first upper electrode 411 are stacked in this order. The insulating substrate 1, the second upper electrode 421, and the portion of the resistor 2 that overlaps with the second upper electrode 421 are stacked in this order.

[0109] The resistor 2 overlaps the insulating substrate 1, for example, between the first upper electrode 411 and the second upper electrode 421, so as to be in contact with the insulating substrate 1. The left end of the resistor 2 is positioned so as to be in contact with the upper surface of the first upper electrode 411, and the right end of the resistor 2 is positioned so as to be in contact with the upper surface of the second upper electrode 421. That is, for example, the insulating substrate 1, the first upper electrode 411, and one (left) end of the resistor 2 are stacked in this order, and the insulating substrate 1, the second upper electrode 421, and the other (right) end of the resistor are stacked in this order. The end of the resistor 2 on the first upper electrode 411 side (left) may reach the outer (left) end in the left-right direction of the upper surface of the first upper electrode 411, but the end of the resistor 2 may not reach the end of the first upper electrode 411, and there may be a portion where the resistor 2 is not positioned between the end of the resistor 2 on the upper surface of the first upper electrode 411 and the end of the first upper electrode 411. The end of the resistor 2 on the side of the second upper electrode 421 (right side) may reach the outer (right side) edge in the left-right direction of the upper surface of the second upper electrode 421, but the end of the resistor 2 may not reach the edge of the second upper electrode 421, and there may be a portion on the upper surface of the second upper electrode 421 between the end of the resistor 2 and the edge of the second upper electrode 421 where the resistor 2 is not positioned.

[0110] In Embodiment 2, for example, the resistor 2 can be formed from a thin-film conductor obtained by a thin-film process. In other words, the chip resistor 10A according to Embodiment 2 is a thin-film chip resistor. For example, the thickness of the resistor 2 is, for example, 10 nm or more and 1000 nm or less. In this case, the effects of Embodiment 2 are particularly easily demonstrated.

[0111] (Protective film) For example, the chip resistor 10A is provided with a protective film 6. In Embodiment 2, for example, the protective film 6 includes only a resin layer 63.

[0112] The protective film 6 covers, for example, at least a portion of the resistor 2. The protective film 6 covers at least the portion of the resistor 2 that does not overlap with the first upper electrode 411 and the second upper electrode 421. The protective film 6 may cover the entire upper surface of the resistor 2.

[0113] The resin layer 63 can protect the resistor 2. For example, the resin layer 63 is arranged to cover the entire resistor 2, in which case fluctuations in the resistance value of the resistor 2 can be suppressed. The resin layer 63 is formed from a resin composition containing a resin component such as epoxy resin. In addition to the resin component, the resin composition may contain at least one selected from the group consisting of silica particles and silicone rubber particles. In this case, the stress generated in the resin layer 63 due to heat, etc., can be relieved compared to the case where the resin layer 63 is formed from only the resin component. As a result, the resin layer 63 becomes less likely to peel off.

[0114] For example, the first connecting electrode 415 is in contact with the left side (first upper electrode 411 side) of the protective film 6 (resin layer 63), and the second connecting electrode 416 is in contact with the right side (second upper electrode 421 side) of the protective film 6 (resin layer 63). The inner (right) end of the first connecting electrode 415 in the left-right direction is in contact with, for example, the left side (first upper electrode 411 side) of the protective film 6 (resin layer 63). The inner (left) end of the second connecting electrode 425 in the left-right direction is in contact with, for example, the right side (second upper electrode 421 side) of the protective film 6 (resin layer 63). This further suppresses the intrusion of moisture into the resistor 2, and effectively suppresses fluctuations in the resistance value of the resistor 2.

[0115] Furthermore, for example, the first intermediate electrode 4141 is in contact with the left side (first upper electrode 411 side) of the protective film 6, and the second intermediate electrode 4241 is in contact with the right side (second upper electrode 421 side) of the protective film 6. For example, the inner (right) end of the first intermediate electrode 4141 in the upper part of the insulating substrate 1 is in contact with the left side (first upper electrode 411 side) of the resin layer 63. For example, the inner (left) end of the second intermediate electrode 4241 in the upper part of the insulating substrate 1 is in contact with the right side (second upper electrode 421 side) of the resin layer 63. This further suppresses the intrusion of moisture into the resistor 2, and effectively suppresses fluctuations in the resistance value of the resistor 2.

[0116] Furthermore, for example, the first external electrode 4142 is in contact with the end of the protective film 6 on the side of the first upper electrode 411 (left side), and the second external electrode 4242 is in contact with the end of the protective film 6 on the side of the second upper electrode 421 (right side). For example, the inner (right side) end of the first external electrode 4142 in the left-right direction is in contact with the end of the resin layer 63 on the side of the first upper electrode 411 (left side). For example, the inner (left side) end of the second external electrode 4242 in the left-right direction is in contact with the end of the resin layer 63 on the side of the second upper electrode 421 (left side). This further suppresses the intrusion of moisture into the resistor 2, and effectively suppresses fluctuations in the resistance value of the resistor 2.

[0117] The left-right position of the resin layer 63's end on the first upper electrode 411 side (left side) is, for example, the position from the inner (right) end to the outer (left) end of the first upper electrode 411 in the left-right direction. That is, the left-right end of the resin layer 63's end on the first upper electrode 411 side (left side) is not located inside the inner (right) end of the first upper electrode 411 in the left-right direction, and does not extend beyond the outer (left) end to reach the outer end face of the first upper electrode 411. If the left-right end of the resin layer 63's end on the first upper electrode 411 side (left side) is not located inside the inner end of the first upper electrode 411 in the left-right direction, the resin layer 63 can effectively suppress fluctuations in the resistance value of the resistor 2. If the left-right end of the resin layer 63's end on the first upper electrode 411 side (left side) does not reach the outer end face of the first upper electrode 411, the resin layer 63 can be prevented from hindering the electrical connection between the first end electrode 413 and the first upper electrode 411. If the end of the resin layer 63 on the side of the second upper electrode 421 (right side) is not located inside the inner end of the second upper electrode 421 in the left-right direction, the resin layer 63 can effectively suppress fluctuations in the resistance value of the resistor 2. If the end of the resin layer 63 on the side of the second upper electrode 421 (right side) does not reach the outer end face of the second upper electrode 421, the resin layer 63 can suppress interference with the electrical connection between the second end face electrode 423 and the second upper electrode 421.

[0118] 2.2 Method for Manufacturing Chip Resistors A brief description will be given of the method for manufacturing a chip resistor 10A according to Embodiment 2 of the chip resistor method.

[0119] First, for example, a conductive paste containing metal is applied to the first main surface 81 of the insulating substrate 1 by printing, and the first upper electrode 411 and the second upper electrode 421 are formed by firing.

[0120] Next, a thin film conductor is formed on the first main surface 81 of the insulating substrate 1 by a thin-film process such as sputtering. Then, if necessary, the resistor 2 is formed by removing the unnecessary portion of the thin film conductor by a process such as photolithography.

[0121] Next, a protective film 6 is formed. For example, an epoxy resin composition is applied to cover the resistor 2, and the epoxy resin composition is heated and dried. In this case, the heating temperature is, for example, about 120°C.

[0122] Next, the conductive paste (P) described above is applied to the second main surface 82 of the insulating substrate 1. Then, the conductive paste (P) and the dried epoxy resin composition described above are heated simultaneously. The heating temperature in this case is, for example, about 200°C. This hardens the conductive paste (P) to form the first back electrode 412 and the second back electrode 422, and hardens the epoxy resin composition to form a resin layer 63 that covers the resistor 2.

[0123] Next, the first connecting electrode 415 and the second connecting electrode 425 are fabricated by forming a thin film conductor using a thin film process such as sputtering. When forming this thin film conductor, the thin film process is carried out using a metal mask, for example, so that the thin film conductor is formed only in the desired locations.

[0124] Next, the first end face electrode 413 and the second end face electrode 423 are fabricated by forming a thin film conductor using a thin film process such as sputtering. When forming this thin film conductor, for example, a metal mask is used in the thin film process to ensure that the thin film conductor is formed only in the desired locations.

[0125] Then, a first plating film 414 is formed covering the first connecting electrode 415, the first back electrode 412, and the first end electrode 413, and a second plating film 424 is formed covering the second connecting electrode 425, the second back electrode 422, and the second end electrode 423. In Embodiment 2, for example, the first intermediate electrode 4141 and the second intermediate electrode 4241 are formed by applying Ni plating so as to cover the first end electrode 413 and the second end electrode 423, respectively. Furthermore, the first external electrode 4142 and the second external electrode 4242 are formed by applying Sn plating so as to cover the first intermediate electrode 4141 and the second intermediate electrode 4241, respectively.

[0126] The chip resistor 10A according to Embodiment 2 can be manufactured by following these steps. Note that the above method is merely one example of a method for manufacturing the chip resistor 10A according to Embodiment 2.

[0127] 2.3 Modified Examples Modified examples of chip resistor 10A will be described. Note that the modified examples are examples of variations in which the configuration of Embodiment 2 is partially changed, added, or deleted. Furthermore, regarding the modified examples, the same configuration as the chip resistor 10A of Embodiment 2 will not be described.

[0128] In Embodiment 2, the insulating substrate 1 is made of alumina (Al ２ O ３ ) contains a sintered body, but is not limited to this. For example, the insulating substrate 1 is made of alumina (Al ２ O ３ It may also contain a sintered body of a different metal oxide than alumina (Al). ２ O ３ In addition to sintered bodies, aluminum nitride (AlN), zirconia (ZrO ２ ) and silicon nitride (Si ３ Ni ４ It contains at least one sintered body selected from the group consisting of the following:

[0129] In Embodiment 2, the first intermediate electrode 4141 and the second intermediate electrode 4241 were each made by Ni plating, and the first external electrode 4142 and the second external electrode 4242 were each made by Sn plating, but are not limited to these. That is, each of the first plating film 414 and the second plating film 424 may contain, in addition to nickel (Ni) and tin (Sn), at least one element selected from the group consisting of copper (Cu), chromium (Cr), lead (Pb), zinc (Zn), indium (In), bismuth (Bi), gold (Au), silver (Ag), palladium (Pd), and platinum (Pt).

[0130] In Embodiment 2, composition (M) contained a hydroxyphenyl-type epoxy resin (A). However, for example, composition (M) may contain a resin different from the hydroxyphenyl-type epoxy resin (A), as long as it does not impair the effects of Embodiment 2. In this case, the insulating film 3 contains a cured product of a resin different from the hydroxyphenyl-type epoxy resin (A) in addition to the cured product of the hydroxyphenyl-type epoxy resin (A).

[0131] The chip resistor 10A may have an insulating film on its second main surface 82. If the chip resistor 10A has an insulating film on its second main surface 82, the insulating film may be interposed between each of the first back electrode 412 and the second back electrode 422 and the insulating substrate 1.

[0132] 3. Embodiments As is clear from Embodiment 2 above, this disclosure includes the following embodiments. Hereafter, reference numerals are enclosed in parentheses solely to indicate their correspondence with Embodiment 2.

[0133] A chip resistor (10A) according to a fifth aspect of the present disclosure comprises an insulating substrate (1), a first upper electrode (411) and a second upper electrode (421) disposed on a first main surface (81) of the insulating substrate (1), a resistor (2) electrically connecting the first upper electrode (411) and the second upper electrode (421), a first back electrode (412) and a second back electrode (422) disposed on a second main surface (82) of the insulating substrate (1) opposite to the first main surface (81), a first end electrode (413) electrically connected to the first upper electrode (411) and the first back electrode (412), and a second end electrode (423) electrically connected to the second upper electrode (421) and the second back electrode (422). Each of the first back electrode (412) and the second back electrode (422) contains a cured product of a hydroxyphenyl type epoxy resin (A) and silver particles (B). The content of silver particles (B) in the first back electrode (412) and the content of silver particles (B) in the second back electrode (422) are each 30% by mass or more and 65% by mass or less.

[0134] According to this embodiment, a chip resistor (10A) can be provided in which cracks are less likely to occur at the locations where the first back electrode (412) and the second back electrode (422) are in contact with the insulating substrate (1).

[0135] A chip resistor (10A) according to a sixth aspect of the present disclosure, in a fifth aspect, the silver particles (B) include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2).

[0136] In the seventh aspect of this disclosure, the chip resistor (10A) has, in the fifth or sixth aspect, a mass ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) of 35 / 65 or more and 50 / 50 or less.

[0137] A chip resistor (10A) according to the eighth aspect of this disclosure, in any one of the fifth to seventh aspects, has a storage modulus of 1.0 × 10⁻¹⁰ of the first back electrode (412) and the second back electrode (422). ７ Pa or more 3.0×10 ８ It is less than or equal to Pa.

[0138] 1. Insulating substrate 2. Resistor 10, 10A chip resistor 411. First top electrode 412. First back electrode 413. First end electrode 414. First plating film 421. Second top electrode 422. Second back electrode 423. Second end electrode 424. Second plating film 81. First main surface 82. Second main surface

Claims

1. A chip resistor comprising: an insulating substrate; a first upper electrode and a second upper electrode disposed on a first main surface of the insulating substrate; a resistor electrically connecting the first upper electrode and the second upper electrode; a first back electrode and a second back electrode disposed on a second main surface of the insulating substrate opposite to the first main surface; a first end electrode electrically connected to the first upper electrode and the first back electrode; and a second end electrode electrically connected to the second upper electrode and the second back electrode, wherein each of the first back electrode and the second back electrode contains a cured product of hydroxyphenyl type epoxy resin (A) and silver particles (B), and the content of silver particles (B) in the first back electrode and the content of silver particles (B) in the second back electrode are each 30% by mass or more and 65% by mass or less.

2. The chip resistor according to claim 1, wherein the silver particles (B) include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2).

3. The chip resistor according to claim 2, wherein the ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) is 50 / 65 or more and 50 / 35 or less.

4. The storage modulus of the first back electrode and the second back electrode is 1.0 × 10⁻⁶ ７ The above 3.0 x 10 ８ The chip resistor according to claim 1, which is as follows:

5. A chip resistor comprising: an insulating substrate; a first upper electrode and a second upper electrode disposed on a first main surface of the insulating substrate; a resistor electrically connecting the first upper electrode and the second upper electrode; a first back electrode and a second back electrode disposed on a second main surface of the insulating substrate opposite to the first main surface; a first end electrode electrically connected to the first upper electrode and the first back electrode; and a second end electrode electrically connected to the second upper electrode and the second back electrode, wherein each of the first back electrode and the second back electrode contains a cured product of hydroxyphenyl type epoxy resin (A) and silver particles (B), and the content of silver particles (B) in the first back electrode and the content of silver particles (B) in the second back electrode are each 30% by mass or more and 65% by mass or less.

6. The chip resistor according to claim 5, wherein the silver particles (B) include whisker-shaped silver particles (B1) and flake-shaped silver particles (B2).

7. The chip resistor according to claim 6, wherein the mass ratio of flake-shaped silver particles (B2) to whisker-shaped silver particles (B1) is 35 / 65 or more and 50 / 50 or less.

8. The storage modulus of the first back electrode and the second back electrode is 1.0 × 10⁻⁶ ７ Pa or more 3.0×10 ８ A chip resistor according to claim 5, wherein the current is Pa or less.

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