Patent Grant
11646136
The present invention relates to a chip resistor whose resistance value is adjusted by forming trimming grooves in a resistive element provided on an insulated substrate and a method of manufacturing such a chip resistor.
A chip resistor is principally comprised of an insulated substrate having a rectangular parallelepiped shape, a pair of front electrodes placed opposing each other across a certain distance on a front surface of the insulated substrate, a pair of back electrodes placed opposing each other across a certain distance on a back surface of the insulated substrate, end face electrodes to bridge the front and back electrodes, a resistive element to bridge the front electrodes paired with each other, a protective layer to cover the resistive element, etc.
Typically, when manufacturing chip resistors as above, forming a large number of electrodes, resistive elements, protective coating layers, etc. onto a large-sized substrate in a single sequence is followed by separating the large-sized substrate along grid-like separation lines (e.g., separation trenches) into a large number of chip resistors. In the process of manufacturing such chip resistors, a large number of resistive elements are formed by printing and firing a resistive paste on one side of the large-sized substrate. It is inevitable that slight variation in the size and film thickness of each resistive element arises due to the influence of misalignment and blurry in printing or temperature irregularity inside a firing furnace among others. Therefore, resistance value adjustment work that forms trimming grooves in each resistive element and sets its resistance to a desired resistance value is performed for the resistive elements being on the large-sized substrate.
When a surge voltage that is produced by, inter alia, static electricity or power supply noise is applied to a chip resistor configured as above, excessive electric stress would occur and have an impact on the resistor characteristics and may destroy the resistor in the worst case. In order to improve anti-surge characteristics, it is known that making a resistive element in a meandering shape to elongate its entire length moderates a potential drop and anti-surge characteristics can be improved.
As related art of this kind, a chip resistor configured as below is proposed (refer to Japanese Unexamined Patent Application Publication No. 2019-201142). As is depicted in
In the related art disclosed in Japanese Unexamined Patent Application Publication No. 2019-201142, by forming the first trimming grooves 106 in the adjustment part 102 of the resistive element 105 formed in a meandering shape by printing, the resistance value of the resistive element 105 is roughly adjusted to approximate to the target resistance value. After that, by forming the L-cut shaped second trimming groove 107 in the second meandering portion 104, the resistance value of the resistive element 105 is finely adjusted to make it match the target resistance value. Thus, the resistance value can be adjusted at high precision with improved anti-surge characteristics.
In the chip resistor described in Japanese Unexamined Patent Application Publication No. 2019-201142, current passes across the second meandering portion 104 of the resistive element 105 through the shortest path which is depicted by an imaginary line E in
The present invention has been developed in view of actual circumstances as noted above. A first object of the invention resides in providing a chip resistor capable of improving anti-surge characteristics and making a fine resistance value adjustment at high precision. A second object of the invention resides in providing a method of manufacturing such a chip resistor.
In order to achieve the foregoing first object, a chip resistor according to the present invention includes an insulated substrate having a rectangular parallelepiped shape, a pair of electrodes placed opposing each other across a certain distance on the insulated substrate, and a resistive element making a bridge connection between the pair of the electrodes with a trimming groove extending linearly in the resistive element to make a resistance value adjustment. The resistive element is an element formed by printing having connecting portions connecting to the pair of the electrodes and an adjustment part which is rectangular in shape positioned between both the connecting portions. In the adjustment part, a first trimming groove for rough adjustment is formed to elongate a current path of the resistive element and a second trimming groove for fine adjustment is formed to adjust a resistance value after being roughly adjusted by the first trimming groove. A straight line along a direction in which the second trimming grove extends is angled with respect to a straight line along a direction in which the first trimming groove extends.
In the chip resistor thus configured, the first trimming groove is formed in the adjustment part to elongate the current path of the resistive element, so that the resistance value increases depending on the cut depth of the first trimming groove. Thus, the resistance value can be roughly adjusted with improved anti-surge characteristics. In addition, the second trimming groove is formed in an area where there is less current distribution in the adjustment part and, thereby, the resistance value can be finely adjusted at high precision. Moreover, the straight line along the direction in which the second trimming grove extends is angled with respect to the straight line along the direction in which the first trimming groove extends. Thereby, the second trimming groove can be formed to extend long alongside the shortest current path and, therefore, it is possible to make yield improvement with reduced maladjustment of the resistance value.
In the chip resistor configured as above, although both the connecting portions of the resistive element may be a pattern extending linearly, making at least one of the connecting portions as a turn segment extending in a meandering shape elongates the current path of the resistive element and makes it possible to improve anti-surge characteristics.
In addition, in the chip resistor configured as above, although both the first and second trimming grooves may be formed in a single adjustment part, with the adjustment part having a first region and a second region continuing in series via a jointing portion, the first trimming groove formed in the first region, and the second trimming groove formed in the second region, the region where the trimming groove for rough adjustment is formed and the region where the trimming groove for fine adjustment is formed are separated. Consequently, this allows a more precise resistance value adjustment, elongates the current path of the resistive element, and makes it possible to further improve anti-surge characteristics.
In this case, it is preferable to form a plurality of first trimming grooves that are I-cut shaped and have different length dimensions in the first region and doing so allows a rough adjustment of the resistance value of the resistive element at high precision, though there is no particular limitation to the number of first trimming grooves that are formed in the first region.
Here, in a case where two first trimming grooves are formed in the first region, although a second one of the first trimming grooves may be formed in parallel with a first one of the first trimming grooves, one of the first trimming grooves may be angled with respect to the other one of the first trimming grooves. Alternatively, the two first trimming grooves may be formed to extend in opposite directions to each other originating from top and bottom opposing sides of the first region.
Furthermore, in order to achieve the forgoing second object, a method of manufacturing a chip resistor according to the present invention is a method of manufacturing a chip resistor including an insulated substrate, a first electrode and a second electrode placed opposing each other across a certain distance on the insulated substrate, and a resistive element making a bridge connection between the first electrode and the second electrode with a trimming groove extending linearly in the resistive element to make a resistance value adjustment. The resistive element includes an element formed by printing having a turn segment connecting to the first electrode and extending in a meandering shape, a first region which is rectangular in shape and connects to the turn segment, a second region which is rectangular in shape and connects to the second electrode, and a jointing portion making a connection between the first region and the second region. The method includes forming in the first region a first trimming groove for rough adjustment to elongate a current path of the resistive element, subsequently forming in the second region a second trimming groove extending in a direction angled with respect to a straight line along a direction in which the first trimming groove extends, and thereby making a fine adjustment of a resistance value after being roughly adjusted by the first trimming groove so that the resistance value falls within a target resistance value range.
In the method of manufacturing a chip resistor including steps as above, after printing and forming the meandering shaped resistive element with the first region and the second region continuing in series via the jointing portion, the first trimming groove is formed to elongate the current path of the resistive element in the first region, so that the resistance value increases depending on the cut depth of the first trimming groove. Thus, the resistance value can be roughly adjusted with improved anti-surge characteristics. Then, after the first trimming groove is formed, the second trimming groove is formed in the second region in a direction angled with respect to the first trimming groove. Thereby, the second trimming groove can be formed to extend long alongside the shortest current path and, therefore, it is possible to make a fine adjustment of the resistance value at high precision and make yield improvement with reduced maladjustment of the resistance value.
According to the present invention, it is possible to provide a chip resistor capable of improving anti-surge characteristics and making a fine resistance value adjustment at high precision.
Embodiments of the present invention will be described in detail based on the following figures, wherein:
Embodiments of the invention are described below with reference to the drawings.
As is depicted in
The resistive element 5 is formed in a meandering shape with a first region 8 and a second region 9 continuing in series via a jointing section 10 between a pair of connecting portions 6 and 7. Such a meandering shape is defined by a shape into which paste of the resistive element is printed. A connecting portion 6 depicted at left is a turn segment formed in a meandering shape, and this connecting portion 6 makes a connection between the first front electrode 3 and the top edge of the first region 8. In addition, a connecting portion 7 depicted at right is a linear pattern, and this connecting portion 7 makes a connection between the second front electrode 4 and a lower end portion of the second region 9. The first region 8 and the second region 9 are an adjustment part for adjusting the resistance value of the resistive element 5, and these first region 8 and second region 9 are both formed in a rectangular shape. The top edge of the first region 8 and the top edge of the second region 9 are connected via the jointing section 10. The jointing section 10 and both the connecting portions 6 and 7 are set to have a substantially equal pattern width.
Two first trimming grooves 11 with different dimensions in length are formed in the first region 8, and the resistance value of the resistive element 5 is roughly adjusted to approximate to a target resistance value by these first trimming grooves 11. A first longer one of the first trimming grooves 11 is an I-cut shaped slit extending in the Y direction from the top side toward the bottom side of the first region 8. Forming the first trimming groove 11 like this in the first region 8 makes the resistive element 5 in a three-turn meandering shape and elongates the current path. A second shorter one of the first trimming grooves 11 is also an I-cut shaped slit extending in the Y direction from the top side toward the bottom side of the first region 8. The first and second ones of the first trimming grooves 11 extend in parallel with each other. However, the number of the first trimming grooves 11 that are formed in the first region 8 is not limited to two grooves and may be one groove or three or more grooves.
In the second region 9, an I-cut shaped second trimming groove 12 is formed which extends from the top side toward the bottom side of the second region 8 in a direction angled with respect to the Y direction. The resistance value of the resistive element 5 is finely adjusted to approximate to the target resistance value by this second trimming groove 12. Here, the extremity of the second trimming groove 12 is set to a position where it does not cross an imaginary line E connecting the jointing section 10 and the connecting portion 7 depicted at right at the shortest distance. Because a location where the largest amount of current flows within the second region 9 is along the imaginary line E, the second trimming groove 12 is formed in an area where there is less current distribution in the second region 9. Moreover, because the direction in which the second trimming groove 12 extends is angled with respect to the direction (Y direction) in which the first trimming grooves 11 extend, the second trimming groove 12 can be formed to extend long alongside the shortest current path (the imaginary line E). Accordingly, the amount of change in the resistance value depending on the cut depth of the second trimming groove 12 becomes small. It is possible to make a fine adjustment of the resistance value of the resistive element 5 at high precision and make yield improvement with reduced maladjustment of the resistance value.
Next, a description is provided about a process of manufacturing the chip resistor 1 configured as described above, while referring to
First, the process prepares a large-sized substrate that is separated into a large number of insulated substrates 2. This large-sized substrate is provided beforehand with a grid of primary and secondary separation trenches extending vertically and horizontally, and each of cells defined by both separation trenches corresponds to one chip area. A large-sized substrate 2A as a representative portion corresponding to one chip area is illustrated in
Specifically, as is illustrated in
Next, as is illustrated in
Here, in
Next, the process forms a precoating layer (omitted from the depiction) to cover the resistive element 5 by screen printing a glass paste from over the resistive element 5 and drying and firing the paste. After that, by irradiation with laser light from over the precoating layer, the process forms a first one of the first trimming grooves 11 in the first region 8, as is illustrated in
Subsequently, the process forms a second one of the first trimming grooves 11 which is shorter than the first one of the first trimming grooves 11 in the first region 8, as is illustrated in
Next, the process forms the I-cut shaped second trimming groove 12 in the second region 9, as is illustrated in
Here, a location where the largest amount of current flows within the second region 9 is along the imaginary line E. The second trimming groove 12 is formed in an area where there is less current distribution in the second region 9, and the direction in which it extends is angled with respect to the direction (Y direction) in which the first trimming grooves 11 extend. Owing to this, the second trimming groove 12 can be formed to extend long alongside the shortest current path (the imaginary line E). Accordingly, the amount of change in the resistance value depending on the cut depth of the second trimming groove 12 becomes small. It is possible to make a fine adjustment of the resistance value of the resistive element 5 at high precision. Additionally, it is preferable that the angle θ of inclination of the second trimming groove 12 with respect to the Y direction, in other words, the angle θ of inclination of a straight line along the direction in which the second trimming groove 12 extends with respect to a straight line along the direction (Y direction) in which the first trimming grooves 11 extend falls within a range from 1° to 3° (1°≤θ≤3°). If the angle θ of inclination becomes larger than the range, the amount of change in the resistance value per unit length depending on the cut depth of the second trimming groove 12 would become too small. This may result in that variation remaining after a rough adjustment of the resistance value by the first trimming grooves 11 cannot be finely adjusted satisfactorily by the second trimming groove 12.
Next, the process forms the protective coating layer, which is not depicted, to cover the whole of the resistive element 5 by screen printing a resin paste from over the first trimming grooves 11 and the second trimming groove 12 and thermally curing the paste (a step of forming the protective coating layer).
All the steps up to here are those of processing in a single sequence for the large-sized substrate 2A prepared to be separated into a large number of substrates. In the next step, the process performs primary breaking that separates the large-sized substrate 2A into strips along the primary separation trenches and obtains strip-like substrates, which are not depicted, each being provided with a plurality of chip areas (a primary separation step). Then, the process forms the end face electrodes, which are not depicted, to bridge the first and second front electrodes 3 and 4 and their mating back electrodes by sputtering a Ni/Cr layer onto the cut surfaces of the strip-like substrates (a step of forming the end face electrodes).
After that, the process performs secondary breaking that separates the strip-like substrates along the secondary separation trenches and thus obtains single chips, each of which is equivalent to the chip resistor 1 in size (a secondary separation step). Finally, the process applies electroplating (Ni plating and Sn plating) to the both longitudinal ends of the insulated substrate 2 of each of the single chips which are discrete ones and thus forms the external electrodes, which are not depicted, to cover the end face electrodes, the back electrodes, and the first and second front electrodes 3 and 4 exposed out of the protective coating layer. Thus, the chip resistor 1 as depicted in
As described hereinbefore, in the chip resistor 1 relevant to the first embodiment, after printing and forming the resistive element 5 having the first region 8 and the second region 9 which are rectangular in shape, the manufacturing process forms the first trimming grooves 11 in the first region 8 to elongate the current path of the resistive element 5. With improved anti-surge characteristics, the resistance value of the resistive element 5 can be roughly adjusted to approximate to the target value. Then, after the rough adjustment of the resistance value, the process forms the second trimming groove 12 in an area where there is less current distribution in the second region 9. In forming the groove, the direction in which the second trimming groove 12 extends is angled with respect to the direction in which the first trimming grooves 11 extend. Thereby, the second trimming groove 12 can be formed to extend long alongside the shortest current path (the imaginary line E). This results in a gradual change in the resistance value depending on the cut of the second trimming groove 12, and it is possible to make a fine adjustment of the resistance value at high precision and make yield improvement with reduced maladjustment of the resistance value.
In addition, in the chip resistor 1 relevant to the first embodiment, the first region 8 and the second region 9 which are the adjustment part are connected via the jointing section 10, and the area where the first trimming grooves 11 for rough adjustment are formed and the area where the second trimming groove 12 is formed are separate. Thus, a highly precise adjustment of the resistance value can be performed, the current path of the resistive element 5 becomes longer, and anti-surge characteristics can be improved. Furthermore, owing to the fact that the resistance value is roughly adjusted by the two first trimming grooves 11 formed in the region 8 and the second one of the first trimming grooves 11 is set shorter than the first one of the first trimming grooves 11, the chip resistor 1 with excellent withstand voltage (surge withstanding characteristics) can be realized.
A point of difference of the second embodiment from the first embodiment lies in that two first trimming grooves 11 formed in the first region 8 do not extend in parallel with each other, and the second one of the first trimming grooves 11 is formed in a direction angled with respect to the first one of the first trimming grooves 11. The resistor structure other than this is basically the same as the chip resistor 1 depicted in
Specifically, as is depicted in
In the thus configured chip resistor 20 relevant to the second embodiment, because the second one of the first trimming grooves 11 extends in the direction angled with respect to the first one of the first trimming grooves 11, there occurs a gradual change in the resistance value depending on the cut of the second one of the first trimming grooves 11, and a rough adjustment of the resistance value can be performed at higher precision. In addition, because micro cracks that are produced in the extremity of the second one of the first trimming grooves 11 are oriented toward the first one of the first trimming grooves 11, spreading of the micro cracks produced in the second one of the first trimming grooves 11 can be absorbed by the first one of the first trimming grooves 11.
Furthermore, while the second one of the first trimming grooves 11 is angled with respect to the first one of the first trimming grooves 11 in the chip resistor 20 relevant to the second embodiment, after the first one of the first trimming grooves 11 is formed to extend from the top side of the first region 8 in a direction angled with respect to the Y direction, the second one of the first trimming grooves 11 may be formed to extend in the Y direction from the top side toward the bottom side of the first region 8, as in a chip resistor 30 relevant to a third embodiment which is depicted in
A point of difference of the fourth embodiment from the first embodiment lies in that two first trimming grooves 11 are formed toward opposite directions to each other, one originating from the top side of the first region 8 and the other originating from the bottom side of the first region 8, and that two second trimming grooves 12 are formed toward opposite directions to each other, one originating from the top side of the second region 9 and the other originating from the bottom side of the second region 9. The resistor structure other than this is basically the same as the chip resistor 1 depicted in
Specifically, as is depicted in
In addition, as for a fine adjustment of the resistance value, after a first one of the second trimming grooves 12 is formed to be angled with respect to the Y direction from the top side toward the bottom side of the second region 9, a second one of the second trimming grooves 12 is formed to be angled with respect to the Y direction from the bottom side toward the top side of the second region 9. Here, a location where the second one of the second trimming grooves 12 is formed is in an area where there is much less current distribution in the second region 9. Therefore, forming the second one of the second trimming grooves 12 allows a fine adjustment of the resistance value at extremely high precision. Furthermore, the second one of the second trimming grooves 12 is also set to a position where it does not cross the imaginary line E, and both the first and second ones of the second trimming grooves 12 are formed alongside the shortest current path (the imaginary line E).
A point of difference of the fifth embodiment depicted in
A point of difference of the sixth embodiment depicted in
Note that the present invention is not limited to the foregoing embodiments, and various modifications can be made thereto without departing from the technical scope of the invention. For example, the shape of the first trimming grooves 11 for rough adjustment is not limited to the I-cut shape and may be any shape with a linear slit, such as an L-cut shape or a J-cut shape having the turned extremity of the linear slit.
In addition, in the case of the chip resistor in which the resistive element has the meandering shaped connecting portion, as in the first or fourth embodiment, size reduction of the chip resistor narrows the clearance between the resistive element and the front electrodes and increases the influence of blurry in printing the resistive element. In such a case, the front electrodes may be placed farther away on the side of the connecting portions to widen the clearance (increase the distance) between the resistive element and the front electrodes.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2021-064208 | Apr 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5043694 | Higashi | Aug 1991 | A |
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| Number | Date | Country |
|---|---|---|
| 2019-201142 | Nov 2019 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20220319745 A1 | Oct 2022 | US |
