Resistor paste and chip resistor

Abstract

The present invention suppresses a change in the resistance value. This resistor paste includes: metal particles that contain copper and nickel; insulating particles that contain at least one of aluminum oxide, zirconium oxide, zinc oxide, and boron nitride; and glass particles. The glass particles contain barium oxide, boron oxide, and aluminum oxide. With respect to the glass particles, the ratio of barium oxide is 10 wt% or more and 30 wt% or less, the ratio of boron oxide is 20 wt% or more and 30 wt% or less, and the ratio of aluminum oxide is 1 wt% or more and 10 wt% or less.

Description

Resistor paste and chip resistors

[0001] The present disclosure relates generally to resistor pastes and chip resistors, and more particularly to resistor pastes containing metal particles and chip resistors having resistors made from the resistor paste.

[0002] Patent Document 1 describes a resistor paste containing inorganic components and an organic vehicle. The inorganic components contained in the resistor paste include a metal component, a low-melting-point glass, and a high-melting-point glass.

[0003] Japanese Patent Application Laid-Open No. 2022-140207

[0004] In resistor pastes such as those described in Patent Document 1, there is a demand for suppressing changes in resistance value due to oxidation and moisture absorption at high temperatures.

[0005] An object of the present disclosure is to provide a resistor paste and a chip resistor that can suppress changes in resistance value due to oxidation and moisture absorption at high temperatures.

[0006] A resistor paste according to one embodiment of the present disclosure includes metal particles containing copper and nickel, insulating particles containing at least one of aluminum oxide, zirconium oxide, zinc oxide, and boron nitride, and glass particles. The glass particles contain barium oxide, boron oxide, and aluminum oxide. In the glass particles, the barium oxide content is 10 wt % or more and 30 wt % or less, the boron oxide content is 20 wt % or more and 30 wt % or less, and the aluminum oxide content is 1 wt % or more and 10 wt % or less.

[0007] A chip resistor according to another aspect of the present disclosure comprises a substrate, a resistor, an upper surface electrode, a lower surface electrode, an end surface electrode, a protective film, and a plating layer. The substrate has a first surface and a second surface facing each other, and a third surface connecting the first surface and the second surface. The resistor is formed on the first surface using the resistor paste of the above aspect. The upper surface electrode is formed on the first surface in contact with the resistor. The lower surface electrode is formed on the second surface. The end surface electrodes are formed on the third surface and electrically connect the upper surface electrode and the lower surface electrode. The protective film covers at least a portion of the resistor. The plating layer covers at least a portion of the upper surface electrode, the lower surface electrode, and the end surface electrodes.

[0008] Glass particles according to yet another aspect of the present disclosure are used in a resistor paste. The glass particles contain barium oxide, boron oxide, and aluminum oxide. The barium oxide content of the glass particles is 10 wt % or more and 30 wt % or less, the boron oxide content is 20 wt % or more and 30 wt % or less, and the aluminum oxide content is 1 wt % or more and 10 wt % or less.

[0009] According to the resistor paste and chip resistor according to the above aspects of the present disclosure, it is possible to suppress changes in resistance value due to oxidation and moisture absorption at high temperatures.

[0010] Fig. 1 is a cross-sectional view of a chip resistor according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional photograph of a chip resistor of a comparative example. Fig. 3 is a cross-sectional photograph of a chip resistor according to an embodiment of the present disclosure. Fig. 4 is a graph showing the resistance change rate of a chip resistor according to an embodiment of the present disclosure.

[0011] The resistor paste and chip resistor according to the embodiment will be described below with reference to the drawings. The figures referred to in the following embodiments are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the figures do not necessarily reflect the actual dimensional ratios. Furthermore, the embodiment and modified examples described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiment and modified examples. Various modifications other than these embodiment and modified examples are possible depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure.

[0012] (1) Overview Fig. 1 is a cross-sectional view of a chip resistor 1 according to an embodiment of the present disclosure. As shown in Fig. 1, the chip resistor 1 according to this embodiment includes a substrate 11 and a resistor element 13.

[0013] First, an overview of the resistor paste of this embodiment will be described.

[0014] The resistor paste of this embodiment includes metal particles containing copper and nickel, insulating particles containing at least one of aluminum oxide, zirconium oxide, zinc oxide, and boron nitride, and glass particles. The glass particles include barium oxide, boron oxide, and aluminum oxide. In the glass particles, the proportion of barium oxide is 10 wt% or more and 30 wt% or less, the proportion of boron oxide is 20 wt% or more and 30 wt% or less, and the proportion of aluminum oxide is 1 wt% or more and 10 wt% or less. Here, wt% represents weight percentage.

[0015] According to the above-mentioned configuration, the inclusion of glass particles of the above-mentioned composition can suppress slight surface oxidation of the resistor 13 made of the resistor paste and improve moisture resistance, thereby suppressing changes in resistance value due to oxidation and moisture absorption of the chip resistor 1 in which the resistor 13 is used.

[0016] (2) Configuration of Resistor Paste Next, the configuration of the resistor paste of this embodiment will be described.

[0017] The resistor paste is the material of the resistor 13 of the chip resistor 1 and is used to form the resistor 13 .

[0018] The resistor paste includes metal particles, insulating particles, glass particles, and metal silicide.

[0019] The metal particles include copper (Cu) and nickel (Ni). More specifically, the metal particles are a combination of copper particles and nickel particles. The metal particles are not limited to a combination of copper particles and nickel particles, but may also be alloy particles of copper and nickel. Furthermore, the metal particles may be a combination of copper particles and alloy particles, a combination of nickel particles and alloy particles, or a combination of copper particles, nickel particles and alloy particles. The metal particles form a conductive path in the resistor 13 after firing. The metal particles are only required to contain copper and nickel, and may further contain other metals.

[0020] The insulating particles are aluminum oxide (Al ２ O ３ ), zirconium oxide (ZrO ２ ), zinc oxide (ZnO), and boron nitride (BN). In the following description, aluminum oxide may be referred to as alumina, and zirconium oxide may be referred to as zirconia.

[0021] In this embodiment, the insulating particles include alumina and zirconia, which reduce the content of metal particles in the fired resistor 13 to increase the resistance value, and suppress the melting and flow of glass particles (described later) to prevent disconnection of the conductive path.

[0022] The glass particles may be, for example, silicon oxide (e.g., SiO ２ The glass particles may contain additives in addition to silicon oxide. Additives added to the glass particles include barium oxide (BaO), boron oxide (B ２ O ３ ) and aluminum oxide, etc.

[0023] The glass particles are added to the resistor paste. More specifically, the glass particles enhance the wettability and adhesion to the substrate 11 described below, and melt and solidify throughout the resistor 13 to form a strong resistor 13. Furthermore, the glass particles are an insulator, and therefore also have the function of adjusting the resistance value.

[0024] The resistor paste contains titanium silicide (TiSi ２), zirconium silicide (ZrSi ２ ), hafnium silicide (HfSi ２ ), niobium silicide (NbSi ２ ), tantalum silicide (TaSi ２ ), chromium silicide (CrSi ２ ), tungsten silicide (WSi ２ ), molybdenum disilicide (MoSi ２ ), iron silicide (FeSi ２ ), magnesium silicide (Mg ２ Si), sodium silicate (Na ２ The resistor paste according to the embodiment includes at least one of zirconium silicide (PtSi) and platinum silicide (PtSi). The resistor paste according to the embodiment includes zirconium silicide as the metal silicide.

[0025] In the resistor paste according to the embodiment, the metal silicide reacts with the metal particles (copper and nickel) by firing, and this reaction changes the composition of copper and nickel in the metal particles, and nickel silicide (Ni ３１ Si １２ As a result, it is possible to increase the temperature coefficient of resistance (hereinafter abbreviated as TCR) of the resistor 13 formed by firing. In other words, it is possible to suppress the decrease in TCR that accompanies an increase in the amount of insulating particles added.

[0026] (3) Configuration of Chip Resistor Next, the configuration of the chip resistor 1 according to the first embodiment will be described with reference to FIG.

[0027] 1 , the chip resistor 1 according to the first embodiment includes a substrate 11, a plurality of (two in the illustrated example) upper surface electrodes 12, a resistor 13, a protective film 14, a plurality of (two in the illustrated example) lower surface electrodes 15, and a plurality of (two in the illustrated example) end surface electrodes 16. The chip resistor 1 according to the first embodiment also includes a plurality of (two in the illustrated example) first plating layers 17, a plurality of (two in the illustrated example) second plating layers 18, and a plurality of (two in the illustrated example) third plating layers 19. That is, the chip resistor 1 according to the first embodiment includes the substrate 11 and the resistor 13.

[0028] (3.1) Substrate The substrate 11 is, for example, a ceramic substrate. The material of the ceramic substrate is, for example, an alumina sintered body with an alumina content of 96% or more. The substrate 11 is formed in a rectangular shape when viewed from a first direction D1. As shown in FIG. 1 , the substrate 11 has a first main surface (upper surface) 111, a second main surface (lower surface) 112, and an outer peripheral surface 113. The first main surface 111 and the second main surface 112 face each other in the first direction D1. Each of the first main surface 111 and the second main surface 112 is a flat surface extending along a second direction D2 perpendicular to the first direction D1. The outer peripheral surface 113 includes four side surfaces extending along the first direction D1. The four side surfaces included in the outer peripheral surface 113 connect the first main surface 111 and the second main surface 112. The first direction D1 is a direction parallel to the thickness direction of the substrate 11 (the vertical direction in FIG. 1 ). The second direction D2 is a direction parallel to the longitudinal direction or width direction (short-side direction) of the substrate 11 (the left-right direction in FIG. 1).

[0029] (3.2) Top Electrode The multiple top electrodes 12 are formed on the first main surface 111 of the substrate 11 in contact with the resistor 13. In the example of Fig. 1 , the multiple top electrodes 12 are formed on both ends of the first main surface 111 of the substrate 11 in the second direction D2. The multiple top electrodes 12 are made of, for example, a Cu (copper) alloy. The multiple top electrodes 12 are formed, for example, by printing a thick film material and then firing it.

[0030] (3.3) Resistor The resistor 13 is formed on the first main surface 111 of the substrate 11 using resistor paste as its material. In the example of FIG. 1 , the resistor 13 is formed in the center of the first main surface 111 of the substrate 11. The material of the resistor 13 is, for example, the resistor paste described above. The resistor 13 is in contact with the plurality of upper surface electrodes 12 at both ends in the second direction D2 and is electrically connected to the plurality of upper surface electrodes 12. The resistor 13 has, for example, a rectangular shape when viewed in a plan view from the first direction D1, but can have any shape to match the desired resistance value of the resistor 13.

[0031] (3.4) Protective Film The protective film 14 is a film for protecting the resistor 13. The protective film 14 covers at least a portion of the resistor 13. In the example of FIG. 1 , the protective film 14 covers the entire area (whole) of the resistor 13. The material of the protective film 14 is, for example, epoxy resin. The protective film 14 is formed, for example, in a rectangular shape when viewed from a plane in the first direction D1, but can have any shape to match the shape of the resistor 13. The material of the protective film 14 is not limited to epoxy resin, and may be, for example, polyimide resin.

[0032] (3.5) Lower Electrodes A plurality of lower electrodes (rear electrodes) 15 are formed on the second main surface 112 of the substrate 11. In the example of FIG. 1 , the plurality of lower electrodes 15 are formed on both ends of the second main surface 112 of the substrate 11 in the second direction D2. The plurality of lower electrodes 15 correspond one-to-one to the plurality of upper electrodes 12. The material of the plurality of lower electrodes 15 is, for example, a Cu-based alloy. The plurality of lower electrodes 15 are formed, for example, by printing a thick film material and then firing it.

[0033] (3.6) End Electrodes A plurality of end electrodes 16 are formed on the outer peripheral surface 113 of the substrate 11. In the example of FIG. 1 , the plurality of end electrodes 16 are formed to cover both side surfaces in the second direction D2 of the four side surfaces included in the outer peripheral surface 113 of the substrate 11. The plurality of end electrodes 16 correspond one-to-one to the plurality of upper electrodes 12 and the plurality of lower electrodes 15. The material of the plurality of end electrodes 16 is, for example, a mixture of carbon powder, silver (Ag), and epoxy resin. Each of the plurality of end electrodes 16 contacts a corresponding upper electrode 12 among the plurality of upper electrodes 12 at a first end (upper end) in the first direction D1, and contacts a corresponding lower electrode 15 among the plurality of lower electrodes 15 at a second end (lower end). As a result, the plurality of upper electrodes 12 are electrically connected to the plurality of lower electrodes 15 via the plurality of end electrodes 16, respectively. In other words, the end electrodes 16 electrically connect the upper electrodes 12 to the lower electrodes 15 , respectively.

[0034] (3.7) First Plating Layer The multiple first plating layers 17 are made of, for example, copper (Cu) plating. In the example of FIG. 1 , the multiple first plating layers 17 cover at least a portion (in this embodiment, the entirety) of the multiple upper electrodes 12, the multiple lower electrodes 15, and the multiple end electrodes 16 at both ends of the substrate 11 in the second direction D2. The multiple first plating layers 17 also contact the surface of the protective film 14. In the chip resistor 1 according to embodiment 1, providing the first plating layers 17 makes it possible to adjust the resistance value of the chip resistor 1. Note that the first plating layers 17 may be omitted.

[0035] (3.8) Second Plating Layer The second plating layers 18 are made of, for example, nickel (Ni) plating. In the example of Fig. 1, the second plating layers 18 cover the first plating layers 17 at both ends of the substrate 11 in the second direction D2. The second plating layers 18 are in contact with the surface of the protective film 14.

[0036] (3.9) Third Plating Layer The third plating layers 19 are made of, for example, tin (Sn) plating. In the example of Fig. 1, the third plating layers 19 cover the second plating layers 18 at both ends of the substrate 11 in the second direction D2. The third plating layers 19 are in contact with the surface of the protective film 14.

[0037] (4) Method for Manufacturing Chip Resistor Next, a method for manufacturing the chip resistor 1 according to the first embodiment will be described.

[0038] The method for manufacturing the chip resistor 1 includes first to ninth steps.

[0039] In the first step, the substrate 11 is prepared. More specifically, in the first step, a substrate body is prepared, which will be the basis for each of the substrates 11 of the multiple chip resistors 1. The substrate body is, for example, a ceramic substrate. The material of the ceramic substrate that will become the substrate body is, for example, an alumina sintered body with an alumina content of 96% or more.

[0040] In the second step, a plurality of lower electrodes 15 for each of the plurality of chip resistors 1 are formed on the second main surface of the substrate body. More specifically, in the second step, a Cu-based alloy film is formed on the second main surface of the substrate body by, for example, printing a thick film material and then firing it, thereby forming a plurality of lower electrodes 15 for each of the plurality of chip resistors 1. The second main surface of the substrate body is the surface that becomes the second main surface 112 of the substrate 11 of each of the plurality of chip resistors 1.

[0041] In the third step, a plurality of top electrodes 12 are formed on the first main surface of the substrate body. The first main surface of the substrate body is the surface that becomes the first main surface 111 of the substrate 11 of each of the plurality of chip resistors 1. More specifically, in the third step, a Cu-based alloy film is formed on the first main surface of the substrate body by, for example, printing a thick film material and then firing it, thereby forming the plurality of top electrodes 12 on each of the plurality of chip resistors 1.

[0042] In the fourth step, the resistor 13 of each of the plurality of chip resistors 1 is formed. More specifically, in the fourth step, a resistor paste is printed on the first main surface of the substrate body, and then the resistor 13 is formed by firing. At this time, in the resistor 13, a metal silicide (titanium silicide) reacts with metal particles (copper and nickel), thereby generating a metal silicide (nickel silicide) different from the metal silicide (titanium silicide). That is, in the chip resistor 1 according to the first embodiment, the resistor 13 contains nickel silicide.

[0043] In the fifth step, the protective film 14 is formed on each of the plurality of chip resistors 1. More specifically, in the fifth step, epoxy resin is applied so as to cover the entire resistor 13, and then the epoxy resin is thermally cured to form the protective film 14. As shown in FIG. 1 , the protective film 14 also covers the contact portions between the plurality of upper surface electrodes 12 and the resistor 13.

[0044] In the sixth step, the plurality of chip resistors integrally formed in the first to fifth steps, excluding the end surface electrodes 16, the first plating layer 17, the second plating layer 18, and the third plating layer 19, are divided into a plurality of strip-shaped chip resistors excluding the end surface electrodes 16, the first plating layer 17, the second plating layer 18, and the third plating layer 19. More specifically, in the sixth step, for example, the plurality of integrally formed chip resistors are divided into a plurality of strip-shaped chip resistors by applying stress from rollers (not shown) provided above and below.

[0045] In the seventh step, a plurality of end electrodes 16 are formed on each of the plurality of strip-shaped chip resistors. More specifically, in the seventh step, for example, an end electrode paste (not shown) made of the mixture is formed on a stainless steel roller (not shown), and the roller is then rotated to form a plurality of end electrodes 16 on each of the plurality of strip-shaped chip resistors. As a result, in each of the plurality of strip-shaped chip resistors, the plurality of top electrodes 12 and the plurality of bottom electrodes 15 are electrically connected via the plurality of end electrodes 16.

[0046] In an eighth step, the roller is rotated to separate the plurality of strip-shaped chip resistors into individual chip resistors.

[0047] In the ninth step, a first plating layer 17 to a third plating layer 19 are formed on each of the plurality of chip resistors. More specifically, in the ninth step, three plating layers, the first plating layer 17, the second plating layer 18, and the third plating layer 19, are formed on each of the plurality of chip resistors in this order.

[0048] The chip resistor 1 can be manufactured by the first to ninth steps described above.

[0049] (5) Effects and Advantages Next, the effects and advantages of the chip resistor 1 using the resistor paste of this embodiment will be described.

[0050] The resistance value of the chip resistor 1 may change due to moisture absorption and oxidation caused by exposure of the resistive element 13 of the chip resistor 1 to the atmosphere containing moisture at high temperatures.

[0051] In this embodiment, the resistance change rate ΔR, which is the rate of change in the resistance value of the chip resistor 1 expressed as a percentage before and after leaving the chip resistor 1 in a constant temperature bath at 155°C for 500 hours, is used as an indicator of the ease with which the resistance value changes.

[0052] If the resistance change rate ΔR is equal to or greater than a reference value (e.g., 1.2%), the performance of the chip resistor 1 intended at the time of design may not be achieved when the chip resistor 1 is incorporated into a device, etc.

[0053] It has been experimentally confirmed that the resistance change rate ΔR increases as the porosity of the resistor 13 included in the chip resistor 1 increases. This is thought to be because the resistor 13 with a higher porosity is more susceptible to oxidation and moisture absorption.

[0054] It has also been experimentally confirmed that the porosity of the resistor 13 varies depending on the composition of the resistor paste. Fig. 2 is an SEM image of a comparative chip resistor 10 including a resistor 130 with a high porosity (over 5%). On the other hand, Fig. 3 is an SEM image of the chip resistor 1 of this embodiment including a resistor 13 in which the porosity has been reduced to 5% or less by adjusting the composition of the resistor paste.

[0055] Below, the effect of the composition of the resistor paste on the resistance change rate ΔR will be explained with reference to experimental results for three chip resistors 1 (first chip resistor, second chip resistor, third chip resistor) and a comparative chip resistor.

[0056] The first to third chip resistors and the comparative chip resistor are samples with different resistor pastes, as shown in Table 1. Specifically, the first to third chip resistors are samples created with the intention of suppressing the rate of resistance change ΔR, and the comparative chip resistor is a sample for comparison.

[0057]

[0058] As shown in Table 1, the first to third chip resistors are characterized by containing at least one of the first glass particles and the second glass particles as glass particles. On the other hand, the comparative chip resistor 10 does not contain either the first glass particles or the second glass particles as glass particles. In the following description, the first glass particles, the second glass particles, and the third glass particles, which have the same composition as the second glass particles but a different particle size, as described below, may be collectively referred to as "specific glass particles."

[0059] The first to fifth glass particles are all glass particles containing silicon oxide. The compositions of the first to fifth glass particles are shown in Table 2.

[0060]

[0061] As shown in Table 2, the third glass particles are glass particles having a different particle size from the second glass particles. Here, the particle size refers to the median diameter (D50) calculated from the particle size distribution obtained by dynamic light scattering or the like.

[0062] The first glass particles are glass particles characterized by containing barium oxide, boron oxide, and aluminum oxide, as shown in Table 2. More specifically, the first glass particles are glass particles characterized by having a barium oxide ratio of 10 wt % or more and 30 wt % or less, a boron oxide ratio of 20 wt % or more and 30 wt % or less, and an aluminum oxide ratio of 1 wt % or more and 10 wt % or less. In this embodiment, as an example, the first glass particles have a barium oxide ratio of 27 wt %, a boron oxide ratio of 25 wt %, and an aluminum oxide ratio of 7 wt %.

[0063] The fourth glass particles and the fifth glass particles also contain barium oxide, boron oxide, and aluminum oxide, but the ratios thereof are outside the above-mentioned ranges of the ratios in the first glass particles.

[0064] The second glass particles (and the third glass particles, which are different in particle size from the second glass particles) contain zinc oxide (ZnO), sodium oxide (NaO), in addition to barium oxide, boron oxide, and aluminum oxide. ２O) and potassium oxide (K ２ The second glass particles further contain 0. More specifically, the second glass particles are glass particles having a barium oxide ratio of 10 wt % or more and 30 wt % or less, a boron oxide ratio of 20 wt % or more and 30 wt % or less, and an aluminum oxide ratio of 1 wt % or more and 10 wt % or less. Furthermore, the second glass particles are glass particles having a zinc oxide ratio of 15 wt % or more and 20 wt % or less, a sodium oxide ratio of 1 wt % or more and 2 wt % or less, and a potassium oxide ratio of 0.1 wt % or more and 0.5 wt % or less. In this embodiment, as an example, the second glass particles have a barium oxide ratio of 14 wt %, a boron oxide ratio of 21 wt %, an aluminum oxide ratio of 2 wt %, a zinc oxide ratio of 17 wt %, a sodium oxide ratio of 2 wt %, and a potassium oxide ratio of 0.4 wt %.

[0065] The resistance change rates ΔR of the first to third chip resistors, which contain at least one of the first glass particles and the second glass particles having the above characteristics, are 1.14%, 1.03%, and 1.17%, respectively, which are below the reference value of 1.2%. On the other hand, the resistance change rate ΔR of the comparative chip resistor 10, which does not contain either the first glass particles G1 or the second glass particles G2, is 1.57%, which is above the reference value of 1.2%.

[0066] In this way, by including at least one of the first glass particles and the second glass particles in the resistor paste used in the chip resistor 1, it is possible to suppress changes in the resistance value.

[0067] Furthermore, the first glass particles and the second glass particles are lead-free. This allows the chip resistor 1 using the first glass particles and the second glass particles to comply with the regulations set forth in laws regarding specific hazardous substances, such as the European RoHS Directive (Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment). Note that "lead-free" here means that the first glass particles and the second glass particles are substantially free of lead, and they may contain lead to an extent that satisfies the regulations set forth in laws regarding specific hazardous substances.

[0068] Next, the effect of the content of specific glass particles (first to third glass particles) on the resistance change rate ΔR will be explained with reference to experimental results for three chip resistors (fourth to sixth chip resistors).

[0069] As shown in Table 3, the fourth to sixth chip resistors are samples using resistor pastes with different contents of the second glass particles, which are specific glass particles.

[0070]

[0071] As shown in Table 3, the resistive paste used in the fourth chip resistor contains 6 wt% second glass particles, resulting in a resistance change rate ΔR of 0.63%. The resistive paste used in the fifth chip resistor contains 11 wt% second glass particles, resulting in a resistance change rate ΔR of 0.45%. The resistive paste used in the sixth chip resistor contains 16.3 wt% second glass particles, resulting in a resistance change rate ΔR of 0.41%.

[0072] Thus, the higher the content of specific glass particles in the resistor paste, the more effectively the change in resistance value can be suppressed. More specifically, the content of specific glass particles in the resistor paste is preferably 2.0 wt% or more. Furthermore, the content of specific glass particles in the resistor paste is even more preferably 6.0 wt% or more. In the fourth to sixth chip resistors, the content of specific glass particles is 6.0 wt% or more, and the rate of resistance change ΔR is a value (1% or less) that is even more preferable in terms of the performance of the chip resistor 1.

[0073] Next, the influence of the particle size of the specific glass particles on the rate of resistance change ΔR will be described with reference to the experimental results for two chip resistors (the seventh chip resistor and the eighth chip resistor).

[0074] The seventh chip resistor is a sample using a resistor paste containing the second glass particles, which are specific glass particles, as shown in Table 4. The eighth chip resistor is a sample using a resistor paste containing the third glass particles, which are specific glass particles. The content of the second glass particles in the seventh chip resistor and the content of the third glass particles in the eighth chip resistor are equal, and in this embodiment, both are 21.6 wt %.

[0075]

[0076] As described above, the third glass particles are glass particles having the same composition as the second glass particles but a different particle size. In this embodiment, the particle size of the second glass particles is 5.9 μm, as shown in Table 2. The particle size of the third glass particles is 1 μm.

[0077] As shown in Table 4, the resistance change rate ΔR of the seventh chip resistor is 0.2%, and the resistance change rate ΔR of the eighth chip resistor is 0.0046%.

[0078] Thus, the smaller the particle size of the specific glass particles, the more effectively the change in resistance value can be suppressed. More specifically, the particle size of the specific glass particles in the resistor paste is preferably 6.0 μm or less. Furthermore, the particle size of the specific glass particles in the resistor paste is more preferably 1.5 μm or less.

[0079] As described above, the resistor paste of this embodiment used in the first through eighth chip resistors contains at least one of the first through third glass particles, which are specific glass particles. As shown in Figure 4, the resistance change rate ΔR of the first through eighth chip resistors is below the reference value of 1.2%. Only the comparative chip resistor, which does not contain any of the first through third glass particles, has a resistance change rate ΔR equal to or greater than the reference value of 1.2%. In this way, the resistor paste used in the chip resistors contains specific glass particles, which can suppress changes in resistance value.

[0080] (6) Modifications The above embodiment is merely one of various embodiments of the present disclosure. This embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above embodiment are listed below. The modifications described below can be applied in appropriate combinations.

[0081] In the above embodiment, the resistor paste contains titanium silicide as the metal silicide, but the resistor paste may contain a metal silicide other than titanium silicide. The resistor paste may contain, for example, zirconium silicide, hafnium silicide, niobium silicide, tantalum silicide, chromium silicide, tungsten silicide, molybdenum silicide, iron silicide, magnesium silicide, sodium silicide, or platinum silicide as the metal silicide. The resistor paste may also contain two or more of the above materials as the metal silicide. In short, the resistor paste may contain at least one of titanium silicide, zirconium silicide, hafnium silicide, niobium silicide, tantalum silicide, chromium silicide, tungsten silicide, molybdenum silicide, iron silicide, magnesium silicide, sodium silicide, and platinum silicide as the metal silicide.

[0082] In the above embodiment, the resistor paste contains alumina and zirconia as insulating particles, but the resistor paste may contain at least one of alumina, zirconia, zinc oxide, and boron nitride as insulating particles.

[0083] In the above embodiment, each end electrode 16 has a U-shape when viewed in a direction orthogonal to both the first direction D1 and the second direction D2 (a direction perpendicular to the plane of the paper in FIG. 1 ). However, the shape of each end electrode 16 is not limited to a U-shape and may be, for example, an I-shape along the first direction D1. In this case, it is sufficient that the first end (upper end) of each end electrode 16 in the first direction D1 contacts the side surface of the top electrode 12, and the second end (lower end) of each end electrode 16 in the first direction D1 contacts the side surface of the bottom electrode 15. This allows the multiple top electrodes 12 and the multiple bottom electrodes 15 to be electrically connected via the multiple end electrodes 16.

[0084] (7) Summary The present specification discloses the following aspects.

[0085] A resistor paste according to a first aspect includes metal particles containing copper and nickel, insulating particles containing at least one of aluminum oxide, zirconium oxide, zinc oxide, and boron nitride, and glass particles. The glass particles include barium oxide, boron oxide, and aluminum oxide. In the glass particles, the barium oxide content is 10 wt % or more and 30 wt % or less, the boron oxide content is 20 wt % or more and 30 wt % or less, and the aluminum oxide content is 1 wt % or more and 10 wt % or less.

[0086] According to this aspect, it is possible to suppress changes in the resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0087] In the resistor paste according to the second aspect, the glass particles do not contain lead in the first aspect.

[0088] According to this aspect, it is possible to satisfy the regulations set forth in laws regarding specific hazardous substances, such as the European RoHS Directive.

[0089] In a resistor paste according to a third aspect, in the first or second aspect, the glass particles further contain zinc oxide, sodium oxide, and potassium oxide, wherein the ratio of zinc oxide in the glass particles is 15 wt % or more and 20 wt % or less, the ratio of sodium oxide in the glass particles is 1 wt % or more and 2 wt % or less, and the ratio of potassium oxide in the glass particles is 0.1 wt % or more and 0.5 wt % or less.

[0090] According to this aspect, it is possible to further suppress the change in resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0091] In the resistor paste according to a fourth aspect, in any one of the first to third aspects, the ratio of glass particles is 2.0 wt % or more.

[0092] According to this aspect, it is possible to further suppress the change in resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0093] In the resistor paste according to the fifth aspect, in any one of the first to fourth aspects, the ratio of the glass particles (G1 to G3) is 6.0 wt % or more.

[0094] According to this aspect, it is possible to further suppress the change in resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0095] In the resistor paste according to the sixth aspect, in any one of the first to fifth aspects, the particle size of the glass particles (G1 to G3) is 6.0 μm or less.

[0096] According to this aspect, it is possible to further suppress the change in resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0097] In the resistor paste according to the seventh aspect, in any one of the first to sixth aspects, the particle size of the glass particles (G1 to G3) is 1.5 μm or less.

[0098] According to this aspect, it is possible to further suppress the change in resistance value of the chip resistor (1) using the resistor paste due to oxidation and moisture absorption at high temperatures.

[0099] The resistor paste according to an eighth aspect is the resistor paste according to any one of the first to seventh aspects, further comprising a metal silicide.

[0100] According to this aspect, it is possible to suppress a decrease in TCR.

[0101] A resistor paste according to a ninth aspect is the same as that of the eighth aspect, and contains, as the metal silicide, at least one of titanium silicide, zirconium silicide, hafnium silicide, niobium silicide, tantalum silicide, chromium silicide, tungsten silicide, molybdenum silicide, iron silicide, magnesium silicide, sodium silicide, and platinum silicide.

[0102] According to this aspect, it is possible to suppress a decrease in TCR.

[0103] A chip resistor (1) according to a tenth aspect includes a substrate (11), a resistor (13), an upper electrode (12), a lower electrode (15), an end electrode (16), a protective film (14), and a plating layer (17). The substrate (11) has a first surface (111) and a second surface (112) that face each other, and a third surface (113) that connects the first surface (111) and the second surface (112). The resistor (13) is formed on the first surface (111) using the resistor paste according to any one of the first to ninth aspects. The upper electrode (12) is formed on the first surface (111) in contact with the resistor (13). The lower electrode (15) is formed on the second surface (112). The end surface electrodes (16) are formed on the third surface (113) and electrically connect the upper surface electrode (12) and the lower surface electrode (15). The protective film (14) covers at least a portion of the resistor (13). The plating layer (17) covers at least a portion of the upper surface electrode (12), the lower surface electrode (15), and the end surface electrodes (16).

[0104] According to this aspect, it is possible to suppress changes in the resistance value of the chip resistor (1) due to oxidation and moisture absorption at high temperatures.

[0105] The configurations according to the second to ninth aspects are not essential for the resistor paste and can be omitted as appropriate.

[0106] The resistor paste and chip resistor of the present disclosure can suppress changes in resistance value due to oxidation and moisture absorption at high temperatures, making the resistor paste and chip resistor of the present disclosure industrially useful.

[0107] REFERENCE SIGNS LIST 1 chip resistor 11 substrate 12 upper electrode 13 resistor element 14 protective film 15 lower electrode 16 end electrode 17 first plating layer 18 second plating layer 19 third plating layer 111 first main surface 112 second main surface 113 outer peripheral surface

Claims

1. A resistor paste comprising: metal particles containing copper and nickel; insulating particles containing at least one of aluminum oxide, zirconium oxide, zinc oxide, and boron nitride; and glass particles, wherein the glass particles contain barium oxide, boron oxide, and aluminum oxide, and wherein the proportion of the barium oxide in the glass particles is 10 wt% or more and 30 wt% or less, the proportion of the boron oxide is 20 wt% or more and 30 wt% or less, and the proportion of the aluminum oxide is 1 wt% or more and 10 wt% or less.

2. The resistor paste according to claim 1, wherein the glass particles do not contain lead.

3. The resistor paste according to claim 1 or 2, wherein the glass particles further contain zinc oxide, sodium oxide, and potassium oxide, and in the glass particles, the ratio of the zinc oxide is 15 wt% or more and 20 wt% or less, the ratio of the sodium oxide is 1 wt% or more and 2 wt% or less, and the ratio of the potassium oxide is 0.1 wt% or more and 0.5 wt% or less.

4. The resistor paste according to claim 1 or 2, wherein the ratio of the glass particles is 2.0 wt % or more.

5. The resistor paste according to claim 1 or 2, wherein the ratio of the glass particles is 6.0 wt% or more.

6. The resistor paste according to claim 1 or 2, wherein the particle size of the glass particles is 6.0 μm or less.

7. The resistor paste according to claim 1 or 2, wherein the particle size of the glass particles is 1.5 μm or less.

8. The resistor paste according to claim 1 or 2, further comprising a metal silicide.

9. The resistor paste according to claim 8, wherein the metal silicide comprises at least one of titanium silicide, zirconium silicide, hafnium silicide, niobium silicide, tantalum silicide, chromium silicide, tungsten silicide, molybdenum silicide, iron silicide, magnesium silicide, sodium silicide, and platinum silicide.

10. A chip resistor comprising: a substrate having a first surface and a second surface opposing each other, and a third surface connecting the first surface and the second surface; a resistor made from the resistor paste described in claim 1 or 2 and formed on the first surface; an upper surface electrode formed on the first surface in contact with the resistor; a lower surface electrode formed on the second surface; an end surface electrode formed on the third surface and electrically connecting the upper surface electrode and the lower surface electrode; a protective film covering at least a portion of the resistor; and a plating layer covering at least a portion of the upper surface electrode, the lower surface electrode and the end surface electrode.

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