Chip resistor and method for manufacturing the same

Abstract

To provide a chip resistor suitable for power improvement.SOLUTION: A chip resistor 1 comprises: an insulation substrate 2 having a rectangular parallelepiped shape; a pair of front electrodes 3 provided at both end parts in a longitudinal direction on a surface of the insulation substrate 2; two resistive elements 4 connected in parallel between the pair of front electrodes 3; a pre-coating layer 5 formed on the resistive elements 4; a pair of rear electrodes 6 provided at both end parts in the longitudinal direction on a rear face of the insulation substrate 2; a pair of end surface electrodes 7 provided on both end surfaces in the longitudinal direction of the insulation substrate 2; and a protection coating layer 8 formed so as to cover the pre-coating layer 5. Each resistive element 4 has a notch 10 at a connection position with the front electrode 3. A trimming groove (a trimming trace) 9 is formed linearly in an inter-electrode direction, starting from the notch 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a chip resistor whose resistance value is adjusted by irradiating a resistor element provided on an insulating substrate with laser light to form a trimming groove (trimming mark), and to a method for manufacturing such a chip resistor. [Background technology]

[0002] A chip resistor is mainly composed of a rectangular insulating substrate, a pair of front electrodes arranged opposite each other with a specified distance on the surface of the insulating substrate, a pair of back electrodes arranged opposite each other with a specified distance on the back surface of the insulating substrate, end electrodes bridging the front electrodes and the back electrodes, a resistive element bridging the pair of front electrodes, and a protective film covering the resistive element.

[0003] Generally, when manufacturing such chip resistors, a large number of electrodes, resistors, protective films, etc. are formed on a large sheet-like substrate at once, and then the large substrate is divided along grid-like dividing lines (e.g., dividing grooves) to obtain a large number of chip resistors. In the manufacturing process of such chip resistors, a large number of resistors are formed on one side of the large substrate by printing and firing a resistive paste, but since it is difficult to avoid slight variations in the size and film thickness of each resistor due to misalignment or bleeding during printing or uneven temperature in the firing furnace, a resistance value adjustment work is performed in which trimming grooves are formed in each resistor while the substrate is still in the large substrate and the resistors are trimmed up to the desired resistance value.

[0004] Trimming grooves are formed by irradiating the resistor with laser light, and known shapes include an I-cut (single cut) shape that starts on one side of the resistor in the width direction and extends in a straight line in a direction perpendicular to the inter-electrode direction, an L-cut shape in which an I-cut is turned 90 degrees halfway and extended in the inter-electrode direction, and a W-cut shape made up of two I-cuts of different lengths.

[0005] When a current is applied to a chip resistor configured in this way, the tip of the trimming groove in the resistor becomes a location where the current concentrates and generates localized heat (hot spot: the highest heat generation), and the heat generating portion is prone to concentrated deterioration due to long-term use, etc. In particular, when the chip resistor is used under a large power load, there is a problem that destruction occurs starting from the heat generating portion, which ultimately leads to destruction of the entire chip resistor.

[0006] Therefore, a chip resistor has been proposed in which two resistors are connected in parallel between a pair of electrodes to disperse hot spots that generate heat, as described in Patent Document 1. These two resistors are formed by screen printing a resistive paste, and trimming grooves are formed in each resistor after firing to adjust the resistance values ​​of the resistors to be substantially the same.

[0007] In the chip resistor described in Patent Document 1, two resistive elements are connected in parallel between a pair of electrodes, which divides the resistive element into two elements and distributes hot spots, thereby making it possible to reduce the power load per element. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2013-219259 A Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the chip resistor described in Patent Document 1, two resistors are formed by screen printing within a limited effective area on an insulating substrate, and therefore it is necessary to ensure a sufficient gap between each resistor when screen printing so that the resistors do not come into contact with each other due to paste dripping during printing, etc. Therefore, the overall area of ​​the resistors is limited by the gap, and in particular, when the effective area of ​​the insulating substrate itself becomes narrower as the chip resistor is made smaller, the proportion of the gap in the effective area increases, so that it is necessary to relatively reduce the overall area of ​​the resistors, making it difficult to improve power.

[0010] The present invention has been made in consideration of the current state of the prior art, and has a first object to provide a chip resistor that is suitable for improving power, and a second object to provide a method for manufacturing such a chip resistor. [Means for solving the problem]

[0011] In order to achieve the above object, the sulfide detection sensor of the present invention is a chip resistor comprising an insulating substrate having a rectangular parallelepiped shape, a pair of electrodes provided on both opposing sides of the insulating substrate, and a resistor bridging the pair of electrodes, the resistor being irradiated with laser light to form trimming marks for adjusting the resistance value, The above Resistor The pair of electrodes and both connection At the end A notch is formed, the resistor has a narrow portion narrowed by the notch and a wide portion where the notch is not present, The trimming marks are , on the other hand Starting from the notch In the range ending at the other notch It is characterized by extending linearly in the inter-electrode direction.

[0012] In a chip resistor configured in this way, The resistor has a notch formed at each end connected to the pair of electrodes. Starting from the notch In the range ending at the other notch, The trimming mark (trimming groove) created by irradiating laser light is formed so as to extend linearly in the direction between the electrodes. This allows the resistance value of the resistor to be adjusted with high precision using the trimming mark, while also alleviating current concentration at the tip of the trimming mark, thereby improving power.

[0013] In addition, as one means for achieving the second object, a manufacturing method for a chip resistor according to the present invention comprises an insulating substrate, a pair of electrodes arranged opposite each other on the insulating substrate with a predetermined distance therebetween, and a resistor bridging the pair of electrodes, and the resistance value of the resistor is adjusted by irradiating the resistor with laser light to trim and cut it, and is characterized in that the method includes the steps of: printing and forming a resistor having a shape in which both ends connected to the pair of electrodes are narrow portions and the area sandwiched between the narrow portions is a wide portion; and scanning and cutting the wide portion by irradiating laser light linearly along the inter-electrode direction from one narrow portion through the wide portion to the other narrow portion, thereby adjusting the resistance value of the resistor.

[0014] In a manufacturing method for chip resistors that includes such steps, the wide portion sandwiched between the two narrow portions of the resistor is scan-cut to adjust the resistance value. This means that the tip of the trimming mark does not remain on the resistor, preventing current concentration, and since the range in which scan-cutting can be performed is wide, the resistance value can be adjusted with high precision.

[0015] In addition, as another means for achieving the second object, a manufacturing method for a chip resistor according to the present invention includes an insulating substrate, a pair of electrodes arranged opposite each other on the insulating substrate with a predetermined distance therebetween, and a resistor bridging the pair of electrodes, and the resistance value is adjusted by irradiating the resistor with laser light to trim and cut it, the method comprising the steps of: printing and forming a rectangular resistor having a notch in the center of the width direction of both ends connected to the pair of electrodes; irradiating a laser beam from one notch to the other notch to divide the resistor in two; and irradiating each of the divided resistors with laser light so as to scan in a straight line from one of the notches in the direction between the electrodes, thereby adjusting the resistance value.

[0016] In the manufacturing method of chip resistors including such steps, a rectangular resistor having notches at both ends is printed and then divided into two by irradiating the resistor with laser light, so that the two resistors are connected in parallel between a pair of electrodes, thereby increasing the effective area of ​​the resistor as a whole and improving power. Moreover, each resistor after division has notches at both ends, and when adjusting the resistance value of such a resistor, laser light is irradiated along a straight line extending from one of the notches toward the interelectrode direction, so that the resistance value of each resistor can be adjusted with high precision, and current concentration at the tip of the trimming mark can be alleviated, improving power. Effect of the Invention

[0017] According to the present invention, it is possible to provide a chip resistor suitable for improving power since it is possible to reduce current concentration at the tip of the trimming mark. [Brief description of the drawings]

[0018] [Figure 1] 1 is a plan view of a chip resistor according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] 3 is an explanatory diagram of a resistor provided in the chip resistor. FIG. [Figure 4] 4 is a flowchart showing a manufacturing process of the chip resistor. [Diagram 5] 5A to 5C are plan views showing a manufacturing process of the chip resistor. [Figure 6] 10A to 10C are explanatory diagrams showing modified examples of the resistor element provided in the chip resistor. [Figure 7] FIG. 4 is a plan view of a chip resistor according to a second embodiment of the present invention. [Figure 8] 3 is an explanatory diagram of a resistor provided in the chip resistor. FIG. [Figure 9] 4 is a flowchart showing a manufacturing process of the chip resistor. [Figure 10]5A to 5C are plan views showing a manufacturing process of the chip resistor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a chip resistor according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.

[0020] As shown in Figures 1 and 2, the chip resistor 1 of the first embodiment is mainly composed of a rectangular insulating substrate 2, a pair of front electrodes 3 provided at both longitudinal ends of the surface of the insulating substrate 2, two resistors 4 connected in parallel between the pair of front electrodes 3, a pre-coat layer 5 formed on each resistor 4, a pair of back electrodes 6 provided at both longitudinal ends of the back surface of the insulating substrate 2, a pair of end electrodes 7 provided at both longitudinal ends of the insulating substrate 2, and a protective coating layer 8 formed to cover the pre-coat layer 5, and each resistor 4 has a trimming groove 9 formed therein.

[0021] The insulating substrate 2 is a large substrate that is divided along primary and secondary dividing grooves that extend vertically and horizontally in a lattice pattern to produce a large number of pieces, and the large substrate is a ceramic substrate whose main component is alumina. In the following description, the longitudinal direction of the insulating substrate 2 may be referred to as the X-direction, and the lateral direction of the insulating substrate 2 may be referred to as the Y-direction.

[0022] The pair of front electrodes 3 are formed by screen printing a silver-based paste containing silver as the main component, followed by drying and firing, and these front electrodes 3 are formed at both ends in the longitudinal direction (X direction) of the insulating substrate 2 so as to face each other with a specified gap between them. The pair of front electrodes 3 are divided into two at the center in the Y direction on the surface of the insulating substrate 2, but are electrically connected via an end electrode 7 formed on the end face of the insulating substrate 2.

[0023] The two resistors 4 are formed by screen printing a resistor paste such as ruthenium oxide, followed by drying and baking, and these two resistors 4 are connected in parallel between a pair of surface electrodes 3. Although details will be described later, the two resistors 4 are formed by printing a single resistor between a pair of surface electrodes 3, and then dividing the resistor into two in the Y direction by irradiating the resistor with laser light, and approximately circular notches 10 are formed at the connection points between these resistors 4 and the corresponding surface electrodes 3.

[0024] A trimming groove 9 is formed in each of the two resistors 4, and the resistance value of each resistor 4 is adjusted to a predetermined value by the trimming groove 9. The trimming groove 9 is a cut (trimming mark) made in the resistor 4 by irradiation with laser light, and the trimming grooves 9 formed in the two resistors 4 extend linearly in opposite directions starting from one of the notches 10. In the case of this embodiment, the trimming groove 9 formed in the resistor 4 shown in the upper part of FIG. 1 extends in the inter-electrode direction (X direction) from the right notch 10 to the left notch 10, and the trimming groove 9 formed in the resistor 4 shown in the lower part extends in the inter-electrode direction (X direction) from the left notch 10 to the right notch 10.

[0025] Fig. 3 is an explanatory diagram showing a resistor (the lower resistor 4 in Fig. 1) before forming trimming grooves 9. As shown in Fig. 3, notches 10 are formed in each of the connection ends between a pair of front electrodes 3 and resistor 4, so that resistor 4 has a pair of narrow width portions Wa whose dimension in the Y direction is narrowed by the notches 10, and a wide width portion Wb located between these narrow width portions Wa where no notches 10 exist.

[0026] As described above, the resistance value of the resistor 4 is adjusted to a predetermined value by irradiating the resistor 4 with a laser beam in a linear manner starting from the left notch 10 in the inter-electrode direction (X direction). At this time, the trimming groove 9 is formed in the region Wb-1 (hatched portion in FIG. 3) between the pair of notches 10 in the wide portion Wb. Since the ratio of the resistance value increase to the increment in the cutting amount of the trimming groove 9 is small in this region Wb-1, the resistance value can be finely adjusted with high precision by extending the cutting amount of the trimming groove 9 in the X direction. The same is basically true when adjusting the resistance value of the upper resistor 4 in FIG. 1, except that the starting point of the trimming groove 9 is changed from the left side to the right side notch 10.

[0027] The precoat layer 5 is formed by screen printing a glass paste, followed by drying and baking, and is formed so as to cover the resistor element 4 before it is divided into two. When dividing the resistor element 4 into two and when forming trimming grooves 9 in the divided resistor element 4, a laser beam is irradiated from above the precoat layer 5, but at that time, the resistor element 4 is protected from the heat of the laser beam by the precoat layer 5 made of a glass material.

[0028] The pair of back electrodes 6 are formed by screen printing a silver-based paste containing silver as the main component, followed by drying and firing. These back electrodes 6 are formed at positions corresponding to the front electrodes 3 on the front side of the insulating substrate 2 .

[0029] The end electrode 7 is formed by sputtering Ni / Cr on the end face of the insulating substrate 2. This end electrode 7 provides electrical continuity to the front electrode 3, which is divided into two in the Y direction on the surface of the insulating substrate 2, and also bridges the corresponding front electrodes 3 and back electrodes 6 on the front and back surfaces of the insulating substrate 2. Although not shown in the figure, this end electrode 7, the back electrode 6, and the surface of the front electrode 3 exposed from the protective coating layer 8 are covered with an external electrode made of a Ni-Sn plating layer.

[0030] The protective coating layer 8 is formed by screen-printing a resin paste such as epoxy or polyimide and then heating and hardening it. This protective coating layer 8 protects the two resistor elements 4 having trimming grooves 9 from the external environment such as humidity and corrosive gases.

[0031] Next, a manufacturing process for the chip resistor 1 according to the first embodiment will be described with reference to the flow chart shown in FIG. 4 and the plan view shown in FIG.

[0032] First, a large-sized substrate 2A is prepared, which has primary and secondary dividing grooves extending in a lattice pattern. These primary and secondary dividing grooves divide the front and back surfaces of the large-sized substrate 2A into numerous chip-forming regions, and each of these chip-forming regions becomes one insulating substrate 2. Although one chip-forming region is shown representatively in Fig. 5, in reality, many such chip-forming regions are arranged in a lattice pattern.

[0033] Next, in step S1 of Fig. 4, a silver-based paste is screen-printed on the surface of the large-sized substrate 2A, and then dried and baked to form a pair of front electrodes 3 facing each other at a predetermined interval at both ends of the longitudinal direction of each chip-forming region, as shown in Fig. 5(a). These front electrodes 3 are divided into two at the center of the short side of the chip-forming region via a slit 3a, and this slit 3a is connected to a semicircular cutout portion 3b. Simultaneously or before or after this, a silver-based paste is screen-printed on the rear surface of the large-sized substrate 2A, and then this is dried and baked to form a pair of rear electrodes (see Fig. 2) facing each other at both ends of the longitudinal direction of each chip-forming region at a predetermined interval (electrode formation process).

[0034] 4, a resistive paste containing ruthenium oxide or the like is screen-printed on the surface of large-sized substrate 2A, which is then dried and fired to form a substantially rectangular resistor 4A with both ends overlapping front electrode 3 (resistor formation step). This resistor 4A has a semicircular cutout 4a in the center in the short side direction, and cutout 4a is continuous with cutout 3b of front electrode 3 to form a substantially circular cutout 10 in the center in the short side direction of the chip formation area.

[0035] Next, in step S3 of FIG. 4, a glass paste is screen-printed on the resistor 4A, and then the glass paste is dried and fired to form a precoat layer 5 that covers the entire resistor 4A, as shown in FIG. 5(c) (precoat layer formation process).

[0036] Next, in step S4 of Fig. 4, a laser beam is irradiated onto the precoat layer 5 to form a dividing slit 5a, thereby dividing the resistor 4A into two resistors 4 as shown in Fig. 5(d) (resistor dividing step). At this time, since the slit 3a is formed in the center of the front electrode 3, the resistor 4A can be divided into two resistors 4 simply and reliably by irradiating the laser beam along the slit 3a.

[0037] Next, in step S5 of Fig. 4, a measurement probe (not shown) is brought into contact with the front electrode 3 exposed from the precoat layer 5, and in this state, the resistance value of the resistor 4 is measured while laser light is irradiated from above the precoat layer 5, thereby forming trimming grooves 9 in the two resistors 4 and adjusting the resistance value to a target resistance value (trimming step) as shown in Fig. 5(e). At this time, the laser light is irradiated so as to scan linearly from one notch 10 as a starting point toward the other notch 10, so that the trimming groove 9 is formed in the portion of the resistor 4 sandwiched between both notches 10 (region Wb-1 in Fig. 3). Since the ratio of the resistance value increment to the increment in the cutting amount of the trimming groove 9 is small in this portion of the resistor 4, the resistance value can be finely adjusted with high precision by extending the cutting amount of the trimming groove 9 in the X direction.

[0038] Since the initial resistance of the two resistors 4 is determined when the resistor 4A is divided into two along the dividing slit 5a, if the size of the resistor 4A to be printed is determined in advance, the initial resistance of the divided resistor 4 can be set to a value somewhat lower than the target resistance. Therefore, the trimming groove 9 can be formed thereafter to adjust the resistance of each resistor 4 to the target resistance. However, the width of the dividing slit 5a may be increased or decreased to adjust the width dimension (length in the Y direction) of the resistor 4. In this case, even if there is variation in the size and film thickness of the resistor 4A when printed, the initial resistance of the divided resistor 4 can be adjusted (coarsely adjusted) to a value lower than the target resistance.

[0039] Next, in step S6 of FIG. 4, a resin paste such as epoxy or polyimide is screen-printed on top of the precoat layer 5, and the resin paste is heated and cured to form a protective coat layer 8 that covers the entire precoat layer 5 including the dividing slits 5a and part of the front electrode 3, as shown in FIG. 5(f) (protective coat layer formation process).

[0040] The steps up to this point are batch processing of the large-sized substrate 2A, but next, in step S7 of Figure 4, the large-sized substrate 2A is primarily divided (broken) along the primary division grooves to obtain multiple rectangular substrates 2B from the large-sized substrate 2A (primary division step).

[0041] Next, in step S8 of Fig. 4, a plurality of rectangular substrates 2B are stacked vertically, and then Ni / Cr is sputtered on the divided surfaces of each rectangular substrate 2B in this state to form end electrodes 7 bridging the front electrodes 3 and the back electrodes (not shown) as shown in Fig. 5(g) (end electrode forming step). The end electrodes 7 provide electrical continuity to the front electrodes 3, which are divided into two on the surface of the insulating substrate 2 via the slits 3a.

[0042] Next, in step S9 of FIG. 4, the rectangular substrate 2B is secondarily divided (broken) along the secondary dividing grooves to obtain individual pieces (single chips) having the same size as the chip resistor 1 (secondary dividing step).

[0043] Finally, in step S10 of FIG. 4, electrolytic plating is performed on each individual chip to form external electrodes consisting of a Ni-Sn plating layer covering the front electrode 3, the back electrode 6, and the end electrode 7, thereby completing the chip resistor 1 shown in FIGS. 1 and 2.

[0044] As described above, in the chip resistor 1 of the first embodiment, a notch 10 is formed at the connection point between the front electrode 3 and the resistor 4, and a trimming groove (trimming mark) 9 is formed to extend linearly from this notch 10 toward the inter-electrode direction, thereby alleviating current concentration at the tip of the trimming groove 9 and improving power.

[0045] In the chip resistor 1 according to the first embodiment, the resistor 4 has a pair of narrow portions Wa whose lateral dimension is narrowed by the notches 10, and a wide portion Wb between the narrow portions Wa where no notches 10 exist. By irradiating the resistor 4 with laser light along a scanning line from one notch 10 to the other notch 10, a trimming groove 9 is formed in a region Wb-1 in the wide portion Wb of the resistor 4 that is sandwiched between the pair of notches 10. Since the ratio of the resistance value increment to the increment in the cutting amount of the trimming groove 9 is small in the region Wb-1, the resistance value can be finely adjusted with high precision by extending the cutting amount of the trimming groove 9 in the X direction.

[0046] In addition, in the chip resistor 1 of the first embodiment, two resistors 4 are connected in parallel between a pair of surface electrodes 3, and these two resistors 4 are divided via a dividing slit 5a extending linearly in the inter-electrode direction, and the cutout portions 10 formed at both ends of the two resistors 4 are each connected to the dividing slit 5a. Therefore, by dividing the resistor 4 into two elements, hot spots are dispersed and the power load per element can be reduced.

[0047] Moreover, since the dividing slit 5a between the two resistors 4 is formed by irradiating them with laser light, the gap required between the two resistors 4 can be made as narrow as possible, and accordingly the total area of ​​the resistors 4 that occupies the effective area of ​​the insulating substrate 2 can be made larger, which also reduces the power load.

[0048] Furthermore, in the chip resistor 1 according to the first embodiment, since the slit 3a is formed in the center of the front electrode 3, when dividing the resistor 4A after printing into two resistors 4, the dividing slit 5a can be easily formed by irradiating the resistor 4A with laser light using the slit 3a in the front electrode 3 as a position reference. However, it is also possible to form the front electrode 3 without the slit 3a, and in that case, the irradiation position of the laser light can be determined by performing image recognition of the resistor 4A before forming the dividing slit 5a.

[0049] In the chip resistor 1 according to the first embodiment, as long as a notch 10 is formed at the connection point between the front electrode 3 and the resistor 4, and the trimming groove (trimming mark) 9 is formed to extend linearly in the inter-electrode direction starting from the notch 10, various modifications are possible. For example, instead of forming the notch 10 in the inner part of the resistor 4 that contacts the dividing slit 5a, the notch 10 may be formed in the outer part of the resistor 4 located on the opposite side to the dividing slit 5a, and the trimming groove 9 may be formed starting from such a notch 10. In addition, the shape of the notch 10 is not limited to a circular arc shape, and may be another shape such as a rectangular shape.

[0050] 6, the resistor 4 may be formed in a rectangular shape with a constant width, with the cutout 10 formed on the front electrode 3 side at the connection point with the resistor 4, and the trimming groove 9 may be formed in the resistor 4 having such a shape. In this case, the resistor 4 does not have a narrow portion with a narrow width, but the region of the resistor 4 where the trimming groove 9 is formed (the region sandwiched between a pair of cutouts 10) is a portion where the ratio of the resistance value increase to the cut-in amount increase of the trimming groove 9 is small, so that the resistance value can be finely adjusted with high precision by extending the cut-in amount of the trimming groove 9 in the inter-electrode direction.

[0051] FIG. 7 is a plan view of a chip resistor 20 according to a second embodiment of the present invention, and FIG. 8 is an explanatory diagram of a resistor element provided in the chip resistor 20.

[0052] As shown in Figure 7, the chip resistor 20 of the second embodiment is mainly composed of a rectangular insulating substrate 21, a pair of front electrodes 22 provided at both longitudinal ends of the surface of the insulating substrate 21, a resistor 23 connected between the pair of front electrodes 22, a pre-coat layer 24 formed on the resistor 23, a protective coating layer 25 formed to cover the pre-coat layer 24, a pair of back electrodes (not shown) provided at both longitudinal ends of the back surface of the insulating substrate 21, and a pair of end electrodes 26 provided at both longitudinal end faces of the insulating substrate 21.

[0053] Resistor 23 is made by screen printing a resistor paste such as ruthenium oxide, followed by drying and baking, and as shown in Fig. 8, notches 27 are formed in the four corners of resistor 23 when printed. These notches 27 form resistor 23 into a pair of narrow width portions Wa in which the dimension in the width direction (Y direction) is narrowed, and a wide width portion Wb located between these narrow width portions Wa where no notches 27 exist.

[0054] Here, both ends in the width direction (Y direction) of the wide portion Wb of resistor 23 are adjustment portions 23a, and by irradiating these adjustment portions 23a with laser light in the inter-electrode direction (X direction) to form trimming grooves, adjustment portions 23a are scanned and cut to adjust the resistance value of resistor 23 to a predetermined value. That is, adjustment portions 23a hatched in Fig. 8 are removed portions of resistor 23 where trimming grooves are formed during scan cut, and as shown in Fig. 7, the width dimension of resistor 23 after scan cut is shortened by an amount equivalent to the removal of adjustment portions 23a accompanying the formation of trimming grooves.

[0055] Next, a manufacturing process for the chip resistor 20 according to the second embodiment will be described with reference to the flow chart shown in FIG. 9 and the plan view shown in FIG.

[0056] First, after preparing a large-sized substrate 21A having primary and secondary dividing grooves extending in a lattice pattern, in step S30 in Fig. 9, a silver-based paste is screen-printed on the surface of the large-sized substrate 21A, and then dried and fired to form a pair of front electrodes 22 facing each other at a predetermined interval at both ends of the longitudinal direction of each chip forming region of the large-sized substrate 21A, as shown in Fig. 10(a). At the same time or before or after this, a silver-based paste is screen-printed on the rear surface of the large-sized substrate 21A, and then dried and fired to form a pair of rear electrodes (not shown) facing each other at a predetermined interval at both ends of the longitudinal direction of each chip forming region (electrode formation process).

[0057] 9, a resistive paste containing ruthenium oxide or the like is screen-printed on the surface of large-sized substrate 21A, and then dried and fired to form resistor 23 with both ends overlapping front electrodes 22 (resistor formation step). Notches 27 are formed in the four corners of resistor 23, and resistor 23 has adjustment portions 23a at both ends in the width direction sandwiched between left and right notches 27 (see FIG. 8).

[0058] Next, in step S32 of FIG. 9, a glass paste is screen-printed on the resistor 23, and then the glass paste is dried and fired to form a precoat layer 24 that covers the entire resistor 23, as shown in FIG. 10(c) (precoat layer formation process).

[0059] 9, a measurement probe (not shown) is brought into contact with the front electrode 22 exposed from the precoat layer 24, and while measuring the resistance value of the resistor 23 in this state, a laser beam is irradiated onto the adjustment portion 23a of the resistor 23 from above the precoat layer 24, and the resistance value is adjusted to a target resistance value by performing a scan cut on the adjustment portion 23a of the resistor 23 (trimming step), as shown in FIG. 10(d). In this scan cut, the laser beam is irradiated onto the adjustment portion 23a in a range from either the left or right notch 27 to the other notch 27, and both the start and end of the trimming groove formed by the irradiation of the laser beam are located within the notch 27, so that the tip of the trimming groove (trimming mark) does not remain on the resistor 23, and current concentration can be avoided. Moreover, the adjustment portion 23a of the resistor 23 is a portion in which the ratio of the resistance value increase to the cut-in amount increase of the trimming groove is small, and scan cutting can be performed over the entire range of such adjustment portion 23a, so that the resistance value of the resistor 23 can be adjusted with high precision.

[0060] Next, in step S34 of FIG. 9, a resin paste such as epoxy or polyimide is screen-printed on top of the precoat layer 24, and this resin paste is heated and cured to form a protective coat layer 25 that covers the entire precoat layer 24 and part of the front electrode 22, as shown in FIG. 10(e) (protective coat layer formation process).

[0061] The processes up to this point are batch processing of the large-sized substrate 21A, but next, in step S35 of Figure 9, the large-sized substrate 21A is primarily divided (broken) along the primary division grooves to obtain multiple rectangular substrates 21B from the large-sized substrate 21A (primary division process).

[0062] Next, in step S36 of FIG. 9, multiple rectangular substrates 21B are stacked vertically, and then Ni / Cr is sputtered onto the divided surfaces of each rectangular substrate 21B in this state to form end electrodes 26 that bridge the front electrodes 22 and the back electrodes (not shown), as shown in FIG. 10(f) (end electrode formation process).

[0063] Next, in step S37 of FIG. 9, the rectangular substrate 21B is secondarily divided (broken) along the secondary dividing grooves to obtain individual pieces (single chips) having the same size as the chip resistors 20 (secondary dividing step).

[0064] Finally, in step S38 of FIG. 9, electrolytic plating is performed on each individual chip to form external electrodes consisting of a Ni-Sn plating layer covering the front electrode 22, the back electrode, and the end electrode 26, thereby completing the chip resistor 20 shown in FIG. 7.

[0065] In the chip resistor 20 of the second embodiment configured in this manner, notches 27 are formed in the four corners of the resistor 23 which are the connection points with the front electrode 22, and the resistance value is adjusted by scan-cutting the adjustment portion 23a of the resistor 23 sandwiched between the left and right cutout portions 27. This means that the tip of the trimming groove (trimming mark) does not remain on the resistor 23, preventing current concentration, and since the range in which scan-cutting can be performed is wide, the resistance value can be adjusted with high precision.

[0066] In the chip resistor 20 according to the second embodiment, the notches 27 are formed at the four corners on the resistor 23 side among the connection points between the front electrode 22 and the resistor 23, but such notches 27 may be formed on the front electrode 22 side instead of the resistor 23, or may be formed on both the front electrode 22 and the resistor 23. Furthermore, the shape of the notches 27 is not limited to an arc shape, and may be another shape such as a rectangle. [Explanation of symbols]

[0067] 1 Chip resistor 2. Insulating substrate 2A large board 2B Strip-shaped board 3 Surface electrode (electrode) 3a Slit 3b Notch 4,4A resistor 4a Notch 5 Pre-coat layer 5a Split slit 6 Back electrode 7 Edge electrode 8 Protective Coating Layer 9 Trimming groove (trimming mark) 10 Notch 20 Chip resistors 21 Insulating substrate 21A large board 21B Strip-shaped board 22 Surface electrode (electrode) 23 Resistor 23a Adjustment section 24 Pre-coat layer 25 Protective Coating Layer 26 End electrode 27 Notch Wa Narrow section Wb Wide section

Claims

1. A chip resistor comprising a rectangular parallelepiped insulating substrate, a pair of electrodes provided on both opposing sides of the insulating substrate, and a resistor bridging the pair of electrodes, the resistor being irradiated with laser light to form trimming marks for adjusting a resistance value, a notch is formed at each end of the resistor connected to the pair of electrodes, the resistor has a narrow portion narrowed by the notch and a wide portion where the notch is not present, The chip resistor is characterized in that the trimming mark extends linearly in the inter-electrode direction in a range starting from one of the notches and ending at the other notch.

2. A chip resistor as described in claim 1, characterized in that at least two of the resistors are connected in parallel between a pair of the electrodes, the two resistors are divided via a dividing slit extending linearly in the inter-electrode direction, and the notches formed at both ends of the two resistors are each connected to the dividing slit.

3. A chip resistor as described in Claim 2, characterized in that the trimming marks formed on the two resistors extend in opposite directions along the longitudinal direction of the slit.

4. A method for manufacturing a chip resistor comprising an insulating substrate, a pair of electrodes arranged on the insulating substrate facing each other with a predetermined distance therebetween, and a resistor bridging the pair of electrodes, the resistance value of which is adjusted by irradiating the resistor with a laser beam to trim it, a step of printing and forming a resistor having a shape in which both ends connected to the pair of electrodes are narrow portions and a region sandwiched between the narrow portions is a wide portion; a step of linearly irradiating a laser beam along a direction between the electrodes from one of the narrow portions through the wide portion to the other of the narrow portions, thereby scanning and cutting the wide portion and adjusting the resistance value of the resistor; A method for manufacturing a chip resistor comprising the steps of:

5. A method for manufacturing a chip resistor comprising an insulating substrate, a pair of electrodes arranged on the insulating substrate facing each other with a predetermined distance therebetween, and a resistor bridging the pair of electrodes, the resistance value of which is adjusted by irradiating the resistor with a laser beam to trim it, a step of printing and forming a rectangular resistor having a notch at the center in the width direction of both ends connected to the pair of electrodes; a step of dividing the resistor into two by irradiating a laser beam onto an area extending from one of the cutouts to the other of the cutouts; a step of adjusting a resistance value by irradiating a laser beam to each of the two divided resistors in a linear manner starting from one of the cutout portions toward an inter-electrode direction; A method for manufacturing a chip resistor comprising the steps of:

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