Method for manufacturing chip resistors

Abstract

To provide a chip resistor that can make the remaining width of a resistor after trimming longer, can dissipate heat from hot spots, can reduce the effect of printing bleeding when forming a top electrode on the top surface of the resistor, and can reduce an overlapping area between the resistor and the top electrode.SOLUTION: A top electrode 14 is formed on the top surface of a resistor 12, and in a side portion 12a and a side portion 12b, which are a pair of side portions formed between the pair of top electrodes 14 in the resistor 12, one side portion has a curved shape bulging toward the opposite side of the other side portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a chip resistor, and particularly to the shape of a resistor body in a chip resistor.

Background Art

[0002] Conventionally, the shape of the resistor body in a chip resistor is usually rectangular in a plan view, and the widths in the direction perpendicular to the direction between electrodes in the resistor body are formed to be the same. That is, the resistor body is formed with the same width in the direction between electrodes.

[0003] For example, in the chip resistor disclosed in Patent Document 1 related to the applicant's application, the shape of the chip resistor is rectangular in a plan view, the long sides which are the side portions in the direction between electrodes are formed parallel to each other, and the resistor body is formed with the same width in the direction between electrodes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a chip resistor, when a trimming groove is formed in the resistor body, if the trimming groove in the direction perpendicular to the direction between electrodes is long, the remaining width of the resistor body after trimming becomes short, and there is a problem that it cannot withstand a high-power load.

[0006] Furthermore, when the resistor is formed with the same width in the direction between electrodes, the area where the trimming groove is provided becomes a narrow area, and the remaining width after trimming is prone to becoming a hot spot. Since the trimming groove is formed near the center in the direction between electrodes, as a result, the hot spot is formed near the center of the resistor in the direction between electrodes. If the hot spot is formed near the center of the resistor in the direction between electrodes, heat dissipation from the hot spot becomes difficult, which may cause fluctuations in the resistance value.

[0007] Furthermore, when forming top electrodes on the upper surface of a resistor, if the edges of the resistor in the direction between electrodes are close to the edge of the insulating substrate (the insulating substrate for one chip resistor), the top electrode paste printed on the top surface of the resistor may flow from the top surface of the resistor, a phenomenon known as printing bleeding during top electrode printing, which can cause it to flow into the area of ​​the adjacent chip resistor.

[0008] Furthermore, if the area where the resistor overlaps with the top electrode is large, the TCR becomes large. In particular, with small chip resistors, the size of the top electrode becomes large relative to the area of ​​the resistor, and the overlapping area between the resistor and the top electrode becomes large, which tends to result in a large TCR.

[0009] Therefore, the present invention aims to provide a chip resistor that can increase the remaining width of the resistor after trimming, enable heat dissipation of hot spots, reduce the effect of printing bleeding when forming an upper electrode on the upper surface of the resistor, and further reduce the overlapping area between the resistor and the upper electrode. [Means for solving the problem]

[0010] The present invention was created to solve the above problems, and firstly comprises an insulating substrate (10), a resistor (12) provided on the upper surface of the insulating substrate, and a pair of electrode portions (40) connected to the resistor, each electrode portion of the pair of electrode portions having an upper electrode (14) that overlaps the upper surface of the resistor and the upper surface of the insulating substrate, and the resistor has a first side portion (12a) provided on one side in the direction perpendicular to the direction between electrodes, and a second side portion (12b) provided on the other side in the direction perpendicular to the direction between electrodes, and the direction between electrodes A method for manufacturing a chip resistor having a shape enclosed by a third side (12c) provided on one side and located between one end of the first side and one end of the second side, and a fourth side (12d) provided on the other side in the direction between electrodes and located between the other end of the first side and the other end of the second side, wherein the first side and the second side are formed between a pair of upper electrodes, the first side has a curved shape that bulges out on the opposite side from the second side, and the second side has a curved shape that bulges out on the opposite side from the first side, A primary slit formation step on the upper surface of a substrate body that serves as the base for an insulating substrate in a chip resistor, having at least the size of multiple insulating substrates, is performed by laser scribing a primary slit for primary division on the upper surface of the substrate body, and the primary slit is formedThe resistor formation process involves forming resistors on the upper surface of a substrate by printing a resistive paste in a strip in the direction perpendicular to the direction between electrodes, thereby printing the resistive paste for multiple chip resistors at once. This causes the area near the edges of the resistive paste to flow outwards, resulting in a resistive paste that is raised towards the center in the direction between electrodes and thinner towards the edges. The resistive paste removal process involves scanning the printed resistive paste linearly in the direction between electrodes with a laser beam to remove the area between adjacent resistors in the direction perpendicular to the electrodes. The resistor forming process comprises: a resistor paste removal process, in which, due to the reduced thickness, the thinner areas are removed more than the thicker areas in a plan view, and the edges of the resistor paste perpendicular to the electrodes are formed to curve in an arc shape; a resistor paste firing process, in which the resistor paste remaining on the upper surface of the substrate after the resistor paste removal process is fired to form a resistor in which the edges perpendicular to the electrodes are curved in an arc shape; and an upper electrode forming process, in which, for upper electrodes laminated on the upper surface of the resistor, upper electrode paste is printed in a single printing area for two upper electrodes adjacent in the direction between electrodes, and then dried and fired to form the upper electrodes.

[0011] Therefore, According to the manufactured chip resistor, Because the first and second sides of the resistor have a curved shape that bulges outward, the area near the center in the direction between electrodes is large. Therefore, even if the length of the trimming groove is short, the resistance value of the resistor increases easily, and the length of the trimming groove can be shortened to reach the desired resistance value, thus increasing the remaining width of the resistor.

[0012] Furthermore, the first and second sides of the resistor have a curved shape that bulges outward, and the width of the resistor is short in the end region in the direction between electrodes. As a result, hot spots are easily formed in the end region in the direction between electrodes, and since the top electrodes are connected to the end region of the resistor, this leads to improved heat dissipation and reduces the risk of resistance fluctuations.

[0013] Furthermore, because the first and second sides of the resistor have a curved shape that bulges outward, the width of the resistor is short in the end region in the direction between electrodes. Even if printing bleeding occurs during printing of the top electrode, the top electrode paste will not flow into the area of ​​the adjacent chip resistor.

[0014] Furthermore, in the end region in the direction between electrodes, the width of the resistor is short, so the area in which the resistor overlaps with the upper electrode can be reduced, and thus, an increase in TCR can be prevented.

[0015] Secondly, in the above-mentioned first configuration, The process includes: a cover coat formation step, in which a cover coat is formed by printing glass paste onto the upper surface of the resistor and firing it after the upper electrode formation step; a resistance value adjustment step, in which the resistance value is adjusted by forming trimming grooves on the resistor and performing trimming; a protective film formation step, in which a protective film is formed to cover a part of the upper electrode and the cover coat; a primary division step, in which the substrate body is first divided to form a strip-shaped substrate; a side electrode formation step, in which side electrodes are formed on the strip-shaped substrate; a secondary division step, in which the strip-shaped substrate on which the side electrodes are formed is secondarily divided; and a plating formation step, in which plating is formed on the secondarily divided substrate. It is characterized by having the following features.

[0016] Furthermore, thirdly, in the configuration of the first or second above, On the lower surface of the substrate, primary slits for primary division are formed perpendicular to the electrodes, and secondary slits for secondary division are formed in the direction between the electrodes. Characterized by being formed 。 [Effects of the Invention]

[0019] This invention Manufactured using the chip resistor manufacturing method. In the case of chip resistors, the first and second sides of the resistor have a curved shape that bulges outward, so the area near the center in the direction between electrodes is large. Therefore, even if the length of the trimming groove is short, the resistance value of the resistor increases easily, and the length of the trimming groove can be shortened to reach the desired resistance value, thus increasing the remaining width of the resistor.

[0020] Furthermore, the first and second sides of the resistor have a curved shape that bulges outward, and the width of the resistor is short in the end region in the direction between electrodes. As a result, hot spots are easily formed in the end region in the direction between electrodes, and since the top electrodes are connected to the end region of the resistor, this leads to improved heat dissipation and reduces the risk of resistance fluctuations.

[0021] In addition, since the first side portion and the second side portion of the resistor have a curved shape that bulges outward, in the end region in the direction between the electrodes, the width of the resistor is short. Even if printing bleeding occurs during the printing of the upper electrode, the upper electrode paste does not flow to the region of the adjacent chip resistor.

[0022] Furthermore, in the end region in the direction between the electrodes, since the width of the resistor is short, the region where the resistor overlaps with the upper electrode can be reduced, and thus, an increase in TCR can be prevented.

Brief Description of the Drawings

[0023] [Figure 1] It is a plan view of a chip resistor. [Figure 2] It is a cross-sectional view taken along the line A-A of FIG. 1. [Figure 3] It is a cross-sectional view taken along the line B-B of FIG. 1. [Figure 4] It is a flowchart showing the manufacturing process of a chip resistor. [Figure 5] It is an explanatory diagram showing the manufacturing process of a chip resistor. [Figure 6] It is an explanatory diagram showing the manufacturing process of a chip resistor. [Figure 7] It is an explanatory diagram showing the manufacturing process of a chip resistor. [Figure 8] It is an explanatory diagram showing the manufacturing process of a chip resistor.

Embodiments for Carrying Out the Invention

[0024] In the present invention, in a chip resistor, the remaining width of the resistor after trimming can be increased, heat dissipation of hot spots can be performed, the influence of printing bleeding when forming an upper electrode on the upper surface of the resistor can be reduced, and furthermore, the overlapping region between the resistor and the upper electrode can be reduced. The object of providing such a resistor is achieved as follows.

[0025] In an embodiment of the present invention, the chip resistor 1 is formed as shown in Figures 1 to 3, and the chip resistor 1 includes an insulating substrate 10, a resistor (which may also be called a "resistor layer") 12, an upper electrode (which may also be called an "upper electrode layer") 14, a cover coat 18, a protective film (which may also be called a "protective layer") 20, a lower electrode 22, a side electrode 24, and a plating 26.

[0026] To further explain the chip resistor 1, the insulating substrate 10 is an insulator made of alumina with a content of approximately 96%. This insulating substrate 10 has a rectangular parallelepiped shape, and when viewed from above, it has a roughly rectangular shape. This insulating substrate 10 is used as the base material, or substrate, of the chip resistor 1.

[0027] Furthermore, since slits are formed in the insulating substrate 10 by laser scribing, in reality, notches formed by dividing the slits formed by laser scribing are formed at the corners of the insulating substrate 10. In other words, in the present invention, primary and secondary slits are formed on the upper surface of the insulating substrate, and primary and secondary slits are also formed on the lower surface. Therefore, in the cross-sectional view shown in Figure 2, notches are formed at the upper and lower corners of the insulating substrate 10 (not shown), and in the side surfaces on the Y1 and Y2 sides in Figure 3, notches are formed at the upper and lower corners (not shown).

[0028] Furthermore, as shown in Figure 2, the resistor 12 is provided on the upper surface (planar upper surface) of the insulating substrate 10. In other words, as shown in Figure 1, the resistor 12 is formed in a strip shape in the direction between electrodes (the direction of current flow, which may also be the longitudinal direction) (X1-X2 direction (see Figure 1)), and specifically has edges 12a and 12b provided between a pair of electrodes, and a pair of edges 12c and 12d. In other words, the resistor 12 has a shape enclosed by a side portion (first side portion) 12a provided on one side (Y1 side) in the direction perpendicular to the direction between electrodes (direction perpendicular to the direction between electrodes) (Y1-Y2 direction), a side portion (second side portion) 12b provided on the other side (Y2 side) in the direction perpendicular to the direction between electrodes, a side portion (third side portion) 12c provided on one side (X1 side) in the direction between electrodes and provided between one end of side portion 12a and one end of side portion 12b, and a side portion (fourth side portion) 12d provided on the other side (X2) in the direction between electrodes and provided between the other end of side portion 12a and the other end of side portion 12b. Side portions 12a and 12b face each other, and side portions 12c and 12d face each other.

[0029] The edges 12a and 12b have an outward-bulging (or "bulging out") arc shape, with the edge 12a on the Y1 side bulging towards Y1 and the edge 12b on the Y2 side bulging towards Y2. In other words, in the pair of edges 12a and 12b provided between a pair of electrodes, one edge bulges in the opposite direction from the other edge. In planar perspective, the edges 12a and 12b are formed symmetrically (or approximately symmetrically) along the center line perpendicular to the distance between the electrodes. The edges 12a and 12b are formed between a pair of upper electrodes 14.

[0030] Furthermore, the edges 12c and 12d are formed in a straight line perpendicular to the distance between the electrodes. In other words, the edges 12c and 12d are parallel to each other.

[0031] As a result, in a planar perspective view, the resistor 12 is formed symmetrically with respect to the center line in the direction between electrodes, except for the trimming groove 50, and also symmetrically with respect to the center line perpendicular to the direction between electrodes.

[0032] As described above, the resistor 12 is formed such that its width (width in the Y1-Y2 direction) increases from the ends in the direction between electrodes (the end on the X1 side and the end on the X2 side) towards the center. The resistor 12 is shortest at the ends in the direction between electrodes, and longest at the central position P in the direction between electrodes, with the width decreasing from the center towards the ends in the direction between electrodes. The width of the resistor 12 in the direction perpendicular to the electrodes (maximum width) is shorter than the width of the insulating substrate 10 in the direction perpendicular to the electrodes, and a gap is provided between the resistor 12 and the long side (side in the direction between electrodes) of the insulating substrate 10.

[0033] Furthermore, the length of the resistor 12 in the direction between electrodes is shorter than the length of the insulating substrate 10 in the direction between electrodes, and a gap is formed between the resistor 12 and the short side of the insulating substrate 10.

[0034] Although the shape of the edges 12a and 12b is described as being arc-shaped, any curved shape that bulges outward and whose width decreases from the center towards the ends in the direction between electrodes may be approximately arc-shaped, elliptical arc-shaped, or approximately elliptical arc-shaped.

[0035] Furthermore, although it was stated that the width of the resistor 12 is longest at the central position P in the direction between electrodes, the width of the resistor 12 may be maximized in the region including the central position P in the direction between electrodes (the central region). In other words, the width of the resistor 12 may be maximized at a position slightly offset from the central position P in the direction between electrodes. In this case, the resistor 12 is not symmetrical with respect to the center line perpendicular to the direction between electrodes, but it can be said to be approximately symmetrical. The central region is the region including the central position P, and the length of the central region in the direction between electrodes can be considered to be, for example, about 1 / 10 of the length of the resistor 12 in the direction between electrodes, with the central position being located at the center along the direction between electrodes within the central region.

[0036] Furthermore, in the sides 12a and 12b shown in Figure 1, side 12a has a curved shape that bulges out on the opposite side from side 12b, and side 12b also has a curved shape that bulges out on the opposite side from side 12a. The width of the resistor 12 in the direction perpendicular to the electrodes decreases from the center to the ends in the direction perpendicular to the electrodes of the resistor 12, and the width perpendicular to the electrodes is maximum in the central region including the center position in the direction perpendicular to the electrodes of the resistor 12.

[0037] Furthermore, even if there are areas with the same width in a portion of the region in the direction between electrodes, it is sufficient if the overall shape is a curved shape that bulges outward and has a width-changing region where the width decreases from the center to the ends in the direction between electrodes. In other words, the shape of the resistor 12 shown in Figure 1 can be said to be a width-changing region because the width decreases from the center to the ends in the direction between electrodes over the entire region. However, for example, the resistor 12 may have a region of the same width in the central part in the direction between electrodes (that is, the edges of this region are parallel to each other in the direction between electrodes), and width-changing regions with arc-shaped edges are provided on both the left and right sides of this region.

[0038] Specifically, this resistor 12 is a ruthenium oxide-based thick film (for example, a ruthenium oxide-based metal glaze thick film). This resistor 12 is a functional element that provides the electrical characteristics of the chip resistor 1.

[0039] Furthermore, when manufacturing the chip resistor 1, the resistive element 12 is formed in a strip shape in the primary direction (see W4 in Figure 6). Therefore, in the resistive element 12 of a single chip resistor 1, the thickness is greatest at the center in the direction between electrodes, and decreases towards the ends in the direction between electrodes. On the other hand, in the direction perpendicular to the electrodes, the resistive element 12 is formed to be approximately the same thickness.

[0040] In other words, the thickness of the resistor 12 decreases from the center towards the edges in the direction between the electrodes of the resistor 12, and the thickness is maximum in the central region including the central position in the direction between the electrodes of the resistor 12.

[0041] Furthermore, as shown in Figure 1, the top electrodes 14 are mainly formed in pairs at both ends of the upper surface of the resistor 12 in the longitudinal direction (X1-X2 direction (see Figure 1)). In other words, the top electrodes 14 are formed to a predetermined length from the X1 side end of the upper surface of the insulating substrate 10, and also from the X2 side end of the upper surface of the insulating substrate 10. Specifically, these top electrodes 14 are formed of a silver-based thick film (silver-palladium-based metal glaze thick film). In a plan view, the top electrodes 14 are formed in a strip shape perpendicular to the distance between the electrodes, and specifically, in a rectangular shape. The two top electrodes 14 are formed symmetrically with respect to a center line in the direction between the electrodes.

[0042] Furthermore, the width 14L of the upper electrode 14 in the direction perpendicular to the electrodes is longer than the width 12L in the direction perpendicular to the electrodes of the region of the resistor 12 that overlaps with the upper electrode 14, and is even longer than the maximum width of the resistor 12 in the direction perpendicular to the electrodes. Also, the width 14L is smaller than the width of the insulating substrate 10 in the direction perpendicular to the electrodes. As a result, the upper electrode 14 is basically formed by stacking it on the upper surface of the resistor 12, but a portion of the upper electrode 14 (i.e., the regions on both sides in the width direction (Y1-Y2 direction) and the end sides in the direction between electrodes) is stacked on the upper surface of the insulating substrate 10.

[0043] Furthermore, the cover coat 18 is formed in a layer on the upper surface of the resistor 12 to mitigate thermal shock to the resistor 12 during trimming and to prevent microcracks at the tip of the trimming groove. In the direction between electrodes, the cover coat 18 covers the area where the trimming groove is formed and is formed in contact with the upper electrode 14, so that the resistor 12 is covered by the upper electrode 14 and the cover coat 18. The length of the cover coat 18 in the width direction is formed to be approximately the same as (strictly speaking, slightly shorter than) the length of the insulating substrate 10 in the width direction. This cover coat 18 is formed of a glass-based material, specifically a thick lead borosilicate glass film. Trimming grooves 50 are formed in the resistor 12 and the cover coat 18.

[0044] Furthermore, the protective film 20 is provided so as to cover the cover coat 18 and a portion of the upper electrode 14. To describe the formation position of this protective film 20 in more detail, in the width direction it is formed to be approximately the same as the width of the insulating substrate 10 (therefore, it is also laminated on a portion of the upper surface of the insulating substrate 10), and furthermore, in the direction between electrodes it is formed to be approximately the same as the length of the resistor 12 (strictly speaking, slightly shorter). This protective film 20 is formed of a thick epoxy resin film. As described above, the protective film 20 mainly protects the resistor 12.

[0045] Furthermore, as shown in Figure 2, a pair of lower electrodes 22 are formed at both ends of the longitudinal direction (X1-X2 direction (see Figure 1)) of the lower surface of the insulating substrate 10. In other words, the lower electrodes 22 are formed to a predetermined length from the X1 side end of the lower surface of the insulating substrate 10, and also to a predetermined length from the X2 side end of the lower surface of the insulating substrate 10. The width of the lower electrodes 22 in the Y1-Y2 direction is formed to be approximately the same as (or may be the same as) the width of the insulating substrate 10 in the Y1-Y2 direction. These lower electrodes 22 are formed of a silver-based thick film (for example, a silver-based metal glaze thick film). The lower electrodes 22 may also be formed of a gold-based thin film.

[0046] Furthermore, the side electrodes 24 are formed in layers with a roughly U-shaped cross-section so as to cover a portion of the upper electrode 14, a portion of the lower electrode 22, and a portion of the side surface of the insulating substrate 10. These side electrodes 24 are provided at the X1 side end and the X2 side end, respectively. The upper end of the side electrodes 24 is in contact with the protective film 20. These side electrodes 24 are formed of a thin film, specifically a thin metal film.

[0047] Furthermore, the plating 26 is composed of nickel plating 28 and tin plating 30, and is provided at the end on the X1 side and the end on the X2 side, respectively.

[0048] The nickel plating 28 is formed to cover a portion of the upper electrode 14, the side electrode 24, and a portion of the lower electrode 22. The upper end of the nickel plating 28 is in contact with the protective film 20, and the lower end is in contact with the bottom surface of the insulating substrate 10. In other words, it is formed to cover the exposed portions of the upper electrode 14, the side electrode 24, and the lower electrode 22. This nickel plating 28 is applied with a substantially uniform film thickness by electroplating. This nickel plating 28 is made of nickel and is formed to prevent solder corrosion of internal electrodes such as the upper electrode 14. In addition to nickel, copper plating may also be used for this nickel plating 28.

[0049] Furthermore, the tin plating 30 is formed with a substantially uniform film thickness so as to cover the upper surface of the nickel plating 28, with the upper end of the tin plating 30 in contact with the protective film 20 and the lower end in contact with the bottom surface of the insulating substrate 10. This tin plating 30 is formed to facilitate good soldering of the chip resistor 1 to the wiring board. Note that in addition to tin plating 30, solder may also be used.

[0050] The electrode portion 40 is formed by the upper electrode 14, the lower electrode 22, the side electrode 24, and the plating 26. The portion of this electrode portion 40 located on the lower side of the insulating substrate 10 becomes the lower electrode portion 42.

[0051] Figure 1 shows the arrangement of each part of the chip resistor 1 when viewed from above. It illustrates the outermost outline of the resistor 12, top electrode 14, cover coat 18, and protective film 20 when viewed from above (or from a planar perspective). Parts that are actually hidden and not visible are represented by dotted lines.

[0052] The manufacturing method for the chip resistor 1 with the above configuration will be explained using Figures 4 to 8, etc. First, a plain alumina substrate (this alumina substrate is large enough to have at least the size of the insulating substrate for multiple chip resistors) (substrate body) 5 without primary or secondary slits is prepared, and a bottom electrode G22 is formed on the lower surface (which may also be the back surface or bottom surface) of this alumina substrate 5 (see S11 in Figure 4 and W1 in Figure 5, bottom electrode formation process). In other words, a paste for the bottom electrode is printed, dried, and fired. As shown in Figure 5, when forming this bottom electrode, the bottom electrode G22 is formed simultaneously for adjacent chip resistors. That is, for regions of the alumina substrate corresponding to two adjacent chip resistors in the X direction (this X direction is the direction of the secondary slit), the bottom electrode is formed in one printed area so as to straddle the boundary position (i.e., the position corresponding to the primary slit). Furthermore, in the Y direction (this Y direction is the direction of the primary slit and is perpendicular to the X direction), a continuous strip of bottom electrodes is formed. In other words, in the Y direction, multiple chip resistors are grouped together to form a series of bottom electrodes in a strip, and in the X direction, two adjacent bottom electrodes are grouped together to form the bottom electrodes. This bottom electrode G22 can be said to be multiple bottom electrodes 22. Note that W1 in Figure 5 is a diagram showing the alumina substrate viewed from the bottom side.

[0053] Next, primary slits J1 and secondary slits J2 are formed on the lower surface of the alumina substrate 5 by laser scribing (see S12 in Figure 4 and W2 in Figure 5, lower surface slit formation process). In other words, multiple primary slits J1 are formed in a groove-like manner in the Y direction, and multiple secondary slits J2 are formed in a groove-like manner in the X direction. In this case, since groove-shaped slits are formed on the lower surface of the alumina substrate 5, the lower surface electrode G22 will naturally be cut when the primary slits J1 and secondary slits J2 are formed.

[0054] Next, primary slits J1 are formed on the front surface (i.e., the top surface) of the alumina substrate 5 by laser scribing (see S13 in Figure 4 and W3 in Figure 6, top surface primary slit formation process). In other words, multiple primary slits J1 are formed in a groove-like manner in the Y direction. These primary slits J1 are naturally formed at the boundary positions with adjacent chip resistors in the X direction when the substrate is divided into multiple chip resistors, and are formed at positions corresponding to the primary slits J1 formed on the bottom surface of the alumina substrate 5.

[0055] Next, a resistor is formed on the front surface (i.e., the top surface) of the alumina substrate. To do this, a resistor paste is first printed onto the top surface of the alumina substrate and dried (see S14 in Figure 4 and W4 in Figure 6, resistor paste application and drying process). In other words, the resistor paste G12' is printed continuously in a strip in the Y direction (perpendicular to the electrodes) on the alumina substrate. Specifically, on the alumina substrate, in a series of regions of the insulating substrate 10 that are connected in the Y direction when they ultimately become individual chip resistors (this is referred to as the "aggregate region"; this aggregate region can also be described as a region in which multiple individual chip resistor formation regions on the substrate body are connected in a straight line), the resistor paste G12' is printed in a single strip from one end of the aggregate region to the other end. In other words, in the region between the primary slits, the resistor paste is printed in a series of strips in the direction of the primary slits, for multiple chip resistors at once. A gap is provided between the edges of the printed region along the primary slits and between the primary slits. In other words, gaps are formed between the primary slit and the resistor paste on both sides of the primary slit. In this case, the resistor paste is a ruthenium oxide-based paste (for example, a ruthenium oxide-based metal glaze paste), which forms a thick resistor film. The resistor paste is formed by printing, for example, screen printing.

[0056] When the resistor paste G12' is printed as described above, the area near the edges of the resistor paste G12' flows outwards, so it becomes more raised towards the center in the X direction and thinner towards the ends near the primary slit J1 (see the cross-sectional view in Figure 6(b)). Since the resistor paste G12' is formed to be long in the Y direction, the resistor paste G12' has approximately the same thickness in the Y direction, except for the ends in the Y direction.

[0057] Next, a portion of the resistor paste is removed with a laser (see S15 in Figure 4 and W5 in Figure 6, resistor paste removal step). That is, the region between adjacent resistors in the resistor paste in the Y direction is removed with a laser to form individual resistor pastes 12'. At this time, the laser beam is scanned linearly from one end of the alumina substrate 5 in the X direction toward the other end, and then the irradiation position of the laser beam is shifted in the Y direction and scanned linearly from the other end of the alumina substrate 5 toward the first end to remove the resistor paste. The output value of the laser beam is set to a lower value than usual.

[0058] As a result, thinner portions of the resistor paste G12' are removed more in a plan view than thicker portions, and the thickness of the resistor 12 decreases from the center to the edges. Therefore, as shown in Figure 6(c), the long sides of each resistor paste 12' are formed in an arc shape. In other words, even without scanning the laser beam in an arc shape, the long sides of the resistor paste 12' can be formed in an arc shape by scanning it in a straight line.

[0059] Next, the resistor paste 12' is baked to form the resistor 12 (see S16 in Figure 4 and W6 in Figure 7, resistor paste baking step). In this way, a resistor 12 with a shape in which the long side is curved in an arc can be formed.

[0060] In Figures 6 to 8, the resistor paste G12', resistor G12, and top electrode G14 are shown with hatching for clarity. Figures 6 to 8 also show the alumina substrate as viewed from the top.

[0061] Next, secondary slits J2 are formed on the front surface (i.e., the top surface) of the alumina substrate 5 by laser scribing (see S17 in Figure 4 and W7 in Figure 7, upper surface secondary slit formation process). In other words, multiple secondary slits J2 are formed in a groove-like manner in the X direction. These secondary slits J2 are naturally formed at the boundary positions with adjacent chip resistors in the Y direction when the substrate is divided into multiple chip resistors, and are formed at positions corresponding to the secondary slits J2 formed on the lower surface of the alumina substrate 5.

[0062] Next, the top electrode 14 is formed (see S18 in Figure 4 and W8 in Figure 7, top electrode formation process). That is, the top electrode paste is printed so that a portion of it is laminated onto the resistor, and then dried and fired. In this case, the top electrode paste is a silver-based paste (for example, a silver-palladium-based metal glaze paste). Note that, in the case of a chip resistor, the top electrodes of adjacent chip resistors that are adjacent to each other are formed in a single printed area.

[0063] Next, a cover coat 18 is formed (S19 in Figure 4, W9 in Figure 8, cover coat formation step). Specifically, a lead borosilicate glass paste is printed onto the upper surface of the region of the resistor 12 that is not covered by the upper electrode 14, and onto the upper surface of the region inside the upper electrode, and then fired to form the cover coat 18.

[0064] Next, the resistance value is adjusted by forming a trimming groove in the resistor 12 and performing trimming (S20 in Figure 4, W10 in Figure 8, resistor adjustment process). In other words, a trimming groove is formed in the resistor 12 by laser trimming. In the connection region between the resistor and the top electrode, since the top electrode is stacked on the top surface of the resistor, compared to the case where the resistor is stacked on the top surface of the top electrode, a sufficient area for contacting the probe (terminal) for resistance measurement during trimming can be secured, and accurate trimming can be performed.

[0065] Next, a protective film G20 is formed to cover the cover coat 18 and a portion of the upper electrode 14 (see S21 in Figure 4 and W11 in Figure 8, protective film formation step). In other words, the resin paste is printed in a strip shape in the Y direction and then dried and cured. That is, in the Y direction, a series of protective films are formed in a strip shape for multiple chip resistors. This protective film G20 can be said to be multiple parts of the protective film 20.

[0066] Next, the alumina substrate is divided along the primary slit J1 (see S22 in Figure 4, primary division step). For this division, for example, the alumina substrate is divided by bending it, with the bottom surface as the starting point. In other words, the strip-shaped substrates, which are made by arranging portions of the alumina substrate for one chip resistor in a straight line, are divided by bending them downwards from the top surface so as to bend them toward adjacent strip-shaped substrates.

[0067] Subsequently, side electrodes are formed on the strip-shaped substrate (see S23 in Figure 4, side electrode formation step). In other words, a thin metal film is formed by sputtering. Alternatively, a paste for the side electrodes may be printed, dried, and fired (or cured instead of fired) to form a thick film.

[0068] Subsequently, secondary division is performed along the secondary slit J2 (see S24 in Figure 4). Then, plating is formed to create a chip resistor (see S25 in Figure 4). In this way, chip resistor 1 is manufactured.

[0069] In the chip resistor 1 with the above configuration, the sides 12a and 12b of the resistor 12 are curved outwards, and the width of the resistor 12 is longest near the center in the direction between electrodes, so that a long remaining width of the resistor can be secured after trimming. In other words, although the trimming groove is formed near the center in the direction between electrodes of the resistor 12, the area occupied near the center in the direction between electrodes is large, so even if the length of the trimming groove is short, the resistance value of the resistor 12 can easily increase, and the length of the trimming groove can be shortened to reach the desired resistance value, thus allowing for a longer remaining width of the resistor.

[0070] Furthermore, the thickness is greatest at the center in the direction between electrodes, and decreases towards the ends in the direction between electrodes. This also means that the proportion of volume occupied near the center in the direction between electrodes is large, so even if the length of the trimming groove is short, the resistance value of the resistor 12 increases easily, and the length of the trimming groove can be shortened to reach the desired resistance value, thus increasing the remaining width of the resistor. Moreover, since the width of the resistor near the center is large to begin with, this also contributes to increasing the remaining width after trimming. Therefore, since the remaining width of the resistor after trimming can be increased, it can withstand high-power loads.

[0071] Furthermore, since the width of the resistor 12 is longer near the center in the direction between electrodes and shorter in the end region in the direction between electrodes, hot spots tend to form in the end region of the resistor 12 in the direction between electrodes when current is applied. However, since the upper electrode 14 is connected to the end region of the resistor 12 in the direction between electrodes, this leads to improved heat dissipation and reduces the risk of resistance fluctuations.

[0072] Furthermore, in the end region in the direction between electrodes, since the width of the resistor 12 is short, even if printing bleeding occurs during top electrode printing, the distance to the adjacent chip resistor (a chip resistor adjacent in the direction perpendicular to the electrodes) is long in the end region of the resistor 12 in the direction between electrodes, so the top electrode paste does not flow into the area of ​​the adjacent chip resistor. In particular, as in the chip resistor 1 of this embodiment, when the contour of the long side of the resistor 12 is formed by laser, the side surface along the long side of the resistor 12 becomes steep, making it prone to printing bleeding. However, since the distance to the adjacent chip resistor is long, even if printing bleeding occurs, the top electrode paste does not flow into the area of ​​the adjacent chip resistor.

[0073] Furthermore, in the end region in the direction between electrodes, the width of the resistor 12 is short, so the area in which the resistor overlaps with the upper electrode is small, and thus it is possible to prevent the TCR from becoming large. In particular, even in the case of small chip resistors, it is possible to prevent the TCR from becoming large.

[0074] In the drawing, the Y1-Y2 direction is perpendicular to the X1-X2 direction, and the Z1-Z2 direction is perpendicular to both the X1-X2 and Y1-Y2 directions. Also, in the drawing, the Y direction is perpendicular to the X direction. [Explanation of Symbols]

[0075] 1. Chip resistor 5 Alumina substrate 10 Insulating substrate 12 Resistors 12a Edge 12b Edge 12c side 12d Edge 14 Top electrode 18 Cover Coat 20 Protective film 22 Bottom electrode 24 Side electrode 26 Plating 28 Nickel Plating 30 Tin-plated 40 Electrode part 42 Bottom side electrode part 50 trimming grooves J1 Primary Slit J2 Secondary Slit P center position

Claims

1. The device comprises an insulating substrate (10), a resistor (12) provided on the upper surface of the insulating substrate, and a pair of electrode portions (40) connected to the resistor. Each electrode portion of the pair of electrode portions has an upper electrode (14) that overlaps the upper surface of the resistor and the upper surface of the insulating substrate. The resistor has a first side portion (12a) provided on one side in the direction perpendicular to the direction between electrodes, a second side portion (12b) provided on the other side in the direction perpendicular to the direction between electrodes, and a first side portion provided on one side in the direction between electrodes. A method for manufacturing a chip resistor having a shape enclosed by a third side portion (12c) provided between one end of the portion and one end of the second side portion, and a fourth side portion (12d) provided on the other side in the direction between electrodes and provided between the other end of the first side portion and the other end of the second side portion, wherein the first side portion and the second side portion are formed between a pair of upper electrodes, the first side portion has a curved shape that bulges out on the opposite side from the second side portion, and the second side portion has a curved shape that bulges out on the opposite side from the first side portion, A primary slit formation step on the upper surface of a substrate body that serves as the base body for an insulating substrate in a chip resistor, wherein the substrate body has at least the size of multiple insulating substrates, and a primary slit for primary division is formed on the upper surface of the substrate body by laser scribing, In the resistor forming process, in which a resistor is formed on the upper surface of a substrate body in which a primary slit has been formed, A resistive paste printing process involves printing a resistive paste in a strip-like shape perpendicular to the direction between electrodes, thereby printing enough resistive paste for multiple chip resistors at once. This process causes the area near the edges of the resistive paste to flow outwards, resulting in a resistive paste that is raised towards the center in the direction between electrodes and thinner towards the edges in the direction between electrodes. In a resistor paste removal process, a laser beam is scanned linearly across the printed resistor paste in the direction between electrodes to remove the area between adjacent resistors perpendicular to the electrodes. Because the printed resistor paste becomes thinner towards the edges in the direction between electrodes, the thinner areas are removed more than the thicker areas in a plan view, resulting in the side of the resistor paste perpendicular to the electrodes being curved in an arc shape. A resistor forming step comprising: a resistor paste firing step, in which the resistor paste remaining on the upper surface of the substrate body after the resistor paste removal step is fired to form a resistor in which the side perpendicular to the electrodes is curved in an arc shape; The process involves forming upper electrodes by stacking them on the upper surface of a resistor, printing upper electrode paste in a single printing area for two upper electrodes adjacent to each other in the direction between electrodes, and then drying and firing the paste to form the upper electrodes. A method for manufacturing a chip resistor, characterized by having the following features.

2. After the upper electrode formation process, a cover coat formation process is performed by printing glass paste onto the upper surface of the resistor and firing it to form a cover coat. A resistance adjustment process involves adjusting the resistance value by forming a trimming groove in the resistor and performing trimming, A protective film formation step involves forming a protective film so as to cover a portion of the upper electrode and the cover coat, A primary division step involves dividing the substrate material into strip-shaped substrates, A side electrode formation step in which side electrodes are formed on a strip-shaped substrate, A secondary division process for dividing a strip-shaped substrate on which side electrodes have been formed into a secondary division, A plating process in which plating is formed on a substrate that has been divided into two sections, A method for manufacturing a chip resistor according to claim 1, characterized by having the following features.

3. A method for manufacturing a chip resistor according to claim 1 or 2, characterized in that a primary slit for primary division is formed on the lower surface of the substrate body in a direction perpendicular to the distance between electrodes, and a secondary slit for secondary division is formed in the direction between electrodes.

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