JP7670489B2 - Chip resistor and method for manufacturing the same - Google Patents

Description

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

A chip resistor is mainly composed of a rectangular insulating substrate, a pair of front electrodes arranged facing each other with a specified distance on the surface of the insulating substrate, a pair of rear electrodes arranged facing each other with a specified distance on the rear surface of the insulating substrate, end electrodes bridging the front and rear electrodes, a resistor bridging the pair of front electrodes, and a protective film covering the resistor.

In general, 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. However, 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, so 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.

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 midway and extended in the inter-electrode direction, and a W-cut shape made up of two I-cuts of different lengths.

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), making the heat-generating area prone to concentrated deterioration over long periods of use. In particular, when the chip resistor is used under heavy power loads, destruction can occur starting from the heat-generating area, ultimately leading to destruction of the entire chip resistor.

As described in Patent Document 1, 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. 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 value of each resistor to be substantially the same.

In the chip resistor described in Patent Document 1, two resistors are connected in parallel between a pair of electrodes, dividing the resistor into two elements and dispersing hot spots, making it possible to reduce the power load per element.

JP 2013-219259 A

However, the chip resistor described in Patent Document 1 has two resistors formed by screen printing within a limited effective area on an insulating substrate, and so it is necessary to ensure sufficient gaps between the resistors when screen printing to prevent them from coming into contact with each other due to paste dripping during printing. This limits the overall area of the resistors by the gaps, and in particular, when the effective area of the insulating substrate itself becomes narrower as chip resistors are made smaller, the proportion of the gaps in the effective area increases, so that the overall area of the resistors must be made smaller in relative terms, making it difficult to improve power.

The present invention was made in consideration of the current state of the prior art, and its first objective is to provide a chip resistor suitable for improving power output, and its second objective is to provide a method for manufacturing such a chip resistor.

In order to achieve the above-mentioned 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, and in which trimming marks for adjusting resistance value are formed by irradiating the resistor with laser light, notches are formed at both connection ends of the resistor to the pair of electrodes, the resistor has a narrow portion narrowed by the notches and a wide portion without the notches, and the trimming marks extend linearly between the electrodes in a range starting from one of the notches and ending at the other notch .

In a chip resistor configured in this manner, notches are formed at both connection ends of the resistor to a pair of electrodes, and trimming marks (trimming grooves) made by irradiating laser light are formed so as to extend linearly in the direction between the electrodes in the range starting from one notch and ending at the other notch. This makes it possible to adjust the resistance value of the resistor with high precision by using the trimming marks, and also to alleviate current concentration at the tips of the trimming marks, thereby improving power.

As one means for achieving the second object, the method for manufacturing a chip resistor according to the present invention includes an insulating substrate, a pair of electrodes arranged on the insulating substrate at a predetermined distance from each other, 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 it. 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 irradiating a laser beam linearly along the inter-electrode direction from one narrow portion through the wide portion to the other narrow portion, thereby scanning and cutting the wide portion to adjust the resistance value of the resistor.

In a manufacturing method for chip resistors that includes such steps, the wide portion of the resistor sandwiched between the two narrow portions is scanned and 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 the wide range in which scanning and cutting can be performed allows the resistance value to be adjusted with high precision.

As another means for achieving the second object, the method for manufacturing a chip resistor according to the present invention includes an insulating substrate, a pair of electrodes arranged on the insulating substrate at a predetermined distance from each other, and a resistor bridging the pair of electrodes, and the resistor is trimmed and cut with a laser beam to adjust its resistance value. The method includes the steps of: printing a rectangular resistor having a notch at the center of the width of both ends connected to the pair of electrodes; irradiating the laser beam from one of the notches to the other of the notches to divide the resistor into two; and irradiating the laser beam to each of the divided resistors in a linear manner starting from one of the notches in the inter-electrode direction to adjust the resistance value.

In a manufacturing method for chip resistors that includes such steps, a rectangular resistor with 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 entire resistor 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 that starts at one of the notches and extends toward the electrodes. This makes it possible to adjust the resistance value of each resistor with high precision, and also alleviates current concentration at the tip of the trimming mark, improving power.

The present invention can reduce current concentration at the tip of the trimming mark, providing a chip resistor that is suitable for improving power.

1 is a plan view of a chip resistor according to a first embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line II-II in FIG. 3 is an explanatory diagram of a resistor provided in the chip resistor. FIG. 4 is a flowchart showing a manufacturing process of the chip resistor. 5A to 5C are plan views showing a manufacturing process of the chip resistor. 10A to 10C are explanatory diagrams showing modified examples of the resistor element provided in the chip resistor. FIG. 6 is a plan view of a chip resistor according to a second embodiment of the present invention. 3 is an explanatory diagram of a resistor provided in the chip resistor. FIG. 4 is a flowchart showing a manufacturing process of the chip resistor. 5A to 5C are plan views showing a manufacturing process of the chip resistor.

The following describes an embodiment of the invention 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. 1.

As shown in Figures 1 and 2, the chip resistor 1 according to 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 precoat 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 precoat layer 5, and each resistor 4 has a trimming groove 9 formed therein.

The insulating substrate 2 is a large substrate, which will be described later, divided along primary and secondary dividing grooves that run vertically and horizontally in a grid pattern into multiple 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.

The pair of surface electrodes 3 are formed by screen printing a silver-based paste containing silver as the main component, followed by drying and firing. These surface electrodes 3 are formed at both ends of the insulating substrate 2 in the longitudinal direction (X direction) so as to face each other with a certain distance between them. The pair of surface electrodes 3 are divided into two at the center in the Y direction on the surface of the insulating substrate 2, but are electrically conductive via the end electrodes 7 formed on the end faces of the insulating substrate 2.

The two resistors 4 are formed by screen printing a resistor paste such as ruthenium oxide, drying and firing, and these two resistors 4 are connected in parallel between a pair of surface electrodes 3. Details will be described later, but the two resistors 4 are formed by printing a resistor between a pair of surface electrodes 3, and then dividing the resistor into two in the Y direction by irradiating it with laser light, and a roughly circular cutout portion 10 is formed at the connection point between these resistors 4 and the corresponding surface electrodes 3.

The two resistors 4 each have a trimming groove 9, which adjusts the resistance of each resistor 4 to a predetermined value. 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 interelectrode 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 interelectrode direction (X direction) from the left notch 10 to the right notch 10.

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

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 straight line in the inter-electrode direction (X direction) starting from the left notch 10. At this time, the trimming groove 9 is formed in the area Wb-1 (hatched area in FIG. 3) between the pair of notches 10 in the wide portion Wb. Since the ratio of the resistance increase to the increment in the cutting amount of the trimming groove 9 is small in this area 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 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 to the right notch 10.

The precoat layer 5 is made by screen printing a glass paste, then drying and baking it. This precoat layer 5 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 the trimming groove 9 in the resistor element 4 after division, 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.

The pair of back electrodes 6 are made by screen printing a silver-based paste whose main component is silver, then drying and firing the silver-based paste. These back electrodes 6 are formed in positions corresponding to the front electrodes 3 on the front side of the insulating substrate 2.

The end electrode 7 is formed by sputtering Ni/Cr on the end face of the insulating substrate 2. This end electrode 7 conducts 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 electrode 3 and back electrode 6 on both the front and back sides of the insulating substrate 2. Although not shown in the figure, this end electrode 7, 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.

The protective coating layer 8 is made 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 with trimming grooves 9 from the external environment, such as humidity and corrosive gases.

Next, the manufacturing process of 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. 5.

First, a large substrate 2A is prepared, which has primary and secondary dividing grooves that extend in a grid pattern. These primary and secondary dividing grooves divide the front and back surfaces of the large substrate 2A into numerous chip formation regions, and each of these chip formation regions becomes one insulating substrate 2. Although one chip formation region is shown as a representative example in Figure 5, in reality, many such chip formation regions are arranged in a grid pattern.

Next, in step S1 of FIG. 4, a silver-based paste is screen-printed on the surface of the large-format substrate 2A, and then dried and fired to form a pair of front electrodes 3 facing each other at a predetermined distance 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, which is connected to a semicircular cutout 3b. At the same time or before or after this, a silver-based paste is screen-printed on the back surface of the large-format substrate 2A, which is then dried and fired to form a pair of back electrodes (see FIG. 2) facing each other at a predetermined distance at both ends of the longitudinal direction of each chip-forming region (electrode formation process).

Next, in step S2 of FIG. 4, a resistive paste containing ruthenium oxide or the like is screen-printed on the surface of the large-sized substrate 2A, which is then dried and fired to form a substantially rectangular resistor 4A with both ends overlapping the front electrode 3 (resistor formation process). This resistor 4A has a semicircular cutout 4a in the center of the short side, and the cutout 4a is connected to the cutout 3b of the front electrode 3, forming a substantially circular cutout 10 in the center of the short side of the chip formation area.

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).

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 division step). At this time, since a slit 3a is formed in the center of the front electrode 3, the resistor 4A can be easily and reliably divided into two resistors 4 by irradiating the laser beam along this slit 3a.

Next, in step S5 of FIG. 4, a measuring 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, forming trimming grooves 9 in the two resistors 4 and adjusting the resistance value to the target resistance value, as shown in FIG. 5(e) (trimming process). 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 the trimming groove 9 is formed in the part of the resistor 4 sandwiched between both notches 10 (area Wb-1 in FIG. 3). Since the ratio of the resistance value increase to the increment in the cutting amount of the trimming groove 9 is small in this part 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.

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 (roughly adjusted) to a value lower than the target resistance.

Next, in step S6 of FIG. 4, a resin paste such as epoxy or polyimide is screen-printed on 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).

The above steps are a batch process for the large-sized substrate 2A, but next, in step S7 of FIG. 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).

Next, in step S8 of FIG. 4, multiple 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 that bridge the front electrodes 3 and the back electrodes (not shown) as shown in FIG. 5(g) (end electrode formation process). 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 slits 3a.

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

Finally, in step S10 of FIG. 4, electrolytic plating is performed on the individual chips to form external electrodes consisting of a Ni-Sn plating layer that covers 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.

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

In the chip resistor 1 according to the first embodiment, notches 10 are formed at both longitudinal ends of the resistor 4, and the resistor 4 has a pair of narrow width portions Wa whose lateral dimension is narrowed by the notches 10, and a wide width portion Wb located between the narrow width portions Wa and in which 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 the region Wb-1 in the wide width portion Wb of the resistor 4, which is sandwiched between the pair of notches 10. 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.

In addition, in the chip resistor 1 according to the first embodiment, two resistors 4 are connected in parallel between a pair of front electrodes 3, and these two resistors 4 are divided via a dividing slit 5a that extends linearly in the inter-electrode direction, and the notches 10 formed at both ends of the two resistors 4 each communicate with 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.

In addition, because 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 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.

In addition, in the chip resistor 1 according to the first embodiment, a slit 3a is formed in the center of the front electrode 3, so 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. In that case, the position for irradiating the resistor 4A with laser light can be determined by performing image recognition of the resistor 4A before forming the dividing slit 5a.

In the chip resistor 1 according to the first embodiment, a notch 10 is formed at the connection between the front electrode 3 and the resistor 4, and various modifications are possible as long as the trimming groove (trimming mark) 9 is formed to extend linearly from the notch 10 in the inter-electrode direction. 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 from such a notch 10 as the starting point. In addition, the shape of the notch 10 is not limited to an arc shape, and may be other shapes such as a rectangle.

Also, as in the modified example shown in FIG. 6, the resistor 4 may be formed in a rectangular shape with a constant width, with a notch 10 formed on the front electrode 3 side at the connection point with the resistor 4, and a trimming groove 9 may be formed in the resistor 4 of this 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 notches 10) is a portion where the ratio of the resistance value increase to the increment in the cutting amount of the trimming groove 9 is small, so the resistance value can be finely adjusted with high precision by extending the cutting amount of the trimming groove 9 in the inter-electrode direction.

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

As shown in FIG. 7, the chip resistor 20 according to 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 precoat layer 24 formed on the resistor 23, a protective coating layer 25 formed to cover the precoat 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 ends of the insulating substrate 21.

The resistor 23 is made by screen printing a resistor paste such as ruthenium oxide, drying and firing it, and as shown in FIG. 8, notches 27 are formed at the four corners of the resistor 23 when printed. These notches 27 give the resistor 23 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 the narrow width portions Wa where no notches 27 exist.

Here, both ends of the wide portion Wb of the resistor 23 in the width direction (Y direction) 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, the adjustment portions 23a are scanned and cut to adjust the resistance value of the resistor 23 to a predetermined value. That is, the hatched adjustment portions 23a in FIG. 8 are the removed portions of the resistor 23 where trimming grooves are formed during the scan cut, and as shown in FIG. 7, the width dimension of the resistor 23 after the scan cut is shortened by the amount of the adjustment portions 23a removed due to the formation of the trimming grooves.

Next, the manufacturing process of 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. 10.

First, a large-sized substrate 21A having a grid-like primary division groove and a secondary division groove is prepared. In step S30 of 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 distance at both ends of the longitudinal direction of each chip formation 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 distance at both ends of the longitudinal direction of each chip formation region (electrode formation process).

Next, in step S31 of FIG. 9, a resistive paste containing ruthenium oxide or the like is screen-printed on the surface of the large-sized substrate 21A, which is then dried and fired to form a resistor 23 with both ends overlapping the front electrodes 22 (resistor formation process). Notches 27 are formed in the four corners of this resistor 23, and the resistor 23 has adjustment sections 23a at both ends in the width direction sandwiched between the left and right notches 27 (see FIG. 8).

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).

9, a measuring probe (not shown) is brought into contact with the surface electrode 22 exposed from the precoat layer 24, and while measuring the resistance of the resistor 23 in this state, a laser beam is irradiated from above the precoat layer 24 onto the adjustment portion 23a of the resistor 23, and the resistance is adjusted to the target resistance value by performing a scan cut on the adjustment portion 23a of the resistor 23, as shown in FIG. 10(d) (trimming process). In this scan cut, the laser beam is irradiated onto the adjustment portion 23a in the 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 trimming groove cut-in amount increase is small, and scan cutting can be performed over the entire range of this adjustment portion 23a, so the resistance value of the resistor 23 can be adjusted with high precision.

Next, in step S34 of FIG. 9, a resin paste such as epoxy or polyimide is screen-printed on the precoat layer 24, and the 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).

The above steps are a batch process for the large-sized substrate 21A, but next, in step S35 of FIG. 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 step).

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).

Next, in step S37 of FIG. 9, the rectangular substrate 21B is secondarily divided (broken) along the secondary division grooves to obtain individual pieces (single chips) of the same size as the chip resistor 20 (secondary division process).

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

In the chip resistor 20 according to the second embodiment configured in this manner, notches 27 are formed at 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 notches 27. This means that the tip of the trimming groove (trimming mark) does not remain on the resistor 23, preventing current concentration, and the range over which scan-cutting can be performed is wide, allowing the resistance value to be adjusted with high precision.

In the chip resistor 20 according to the second embodiment, the notches 27 are formed at the four corners of the connection points between the front electrode 22 and the resistor 23 on the resistor 23 side, but such notches 27 may be formed on the front electrode 22 side instead of the resistor 23, or 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 other shapes such as a rectangle.

1 Chip resistor 2 Insulating substrate 2A Large substrate 2B Strip-shaped substrate 3 Front electrode (electrode)
3a Slit 3b Notch 4, 4A Resistor 4a Notch 5 Precoat layer 5a Dividing slit 6 Back electrode 7 End electrode 8 Protective coat layer 9 Trimming groove (trimming mark)
10: Notch 20: Chip resistor 21: Insulating substrate 21A: Large substrate 21B: Strip-shaped substrate 22: Front electrode (electrode)
23 resistor 23a adjustment portion 24 precoat layer 25 protective coat layer 26 end electrode 27 cutout portion Wa narrow width portion Wb wide width portion

Claims (5)

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 . The chip resistor 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 each communicate with the dividing slit . 3. The chip resistor according to claim 2, wherein the trimming marks formed on the two resistors extend in opposite directions along a longitudinal direction of the slit . 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: 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: