Patent Application
20210249164
The present invention relates to a chip resistor in which trimming grooves are formed on a resistor provided on an insulating substrate so as to adjust a resistance value, and a manufacturing method thereof.
A chip resistor is configured to mainly include a rectangular parallelepiped insulating substrate, a pair of front electrodes oppositely disposed on a front surface of the insulating substrate with a predetermined interval therebetween, a pair of back electrodes oppositely disposed on a back surface of the insulating substrate with a predetermined interval therebetween, end face electrodes for bridging the front electrodes and the corresponding back electrodes, a resistor for bridging the pair of front electrodes, and a protective film for covering the resistor.
Generally, in a case of manufacturing this type of a chip resistor, after multi-piece electrodes, resistors, protective films, etc. are collectively formed on a large-sized substrate, the large-sized substrate is divided along grid-like division lines (for example, division grooves) to obtain multi-piece chip resistors. The process of manufacturing this type of the chip resistor includes the step of printing and sintering resistance paste on one of the surfaces of the large-sized substrate to obtain multi-piece chip resistors, which makes it difficult to avoid occurrence of a little variation in size and film thickness of each resistor due to such as positional deviation and bleeding during printing, or influence of temperature unevenness in a sintering furnace. Accordingly, a resistance value adjustment operation, in which trimming grooves are formed on each resistor in a state where they are on the large-sized substrate to set a resistance value to be a desired resistance value, is performed in the process above.
When surge voltage generated by static electricity, power supply noise, or the like is applied to the chip resistor configured as above, the characteristic of the resistor is affected by excessive electrical stress, and in the worst case, the resistor may be destroyed. It has been known that, in order to improve the surge characteristic, when the resistor is formed into a meander shape to lengthen the total length thereof, the potential drop becomes smooth and thus the surge characteristic can be improved.
As prior art of this type of a resistor, as illustrated in
As another prior art, as illustrated in
According to the prior art described in Patent Literature 1, since the total length of the resistor 102 is increased by using printing technique in combination with trimming work, it is possible to improve the surge characteristic. Furthermore, since formation of the trimming groove 103 also serves as adjustment of the resistance value, it is possible to improve accuracy of the resistance value. However, the trimming groove 103 is provided in a direction to narrow the cross-sectional area of current in the resistor 102, and accordingly, the amount of change in the resistance value which increases in accordance with increase in a cutting amount of the trimming groove 103 becomes large. In this way, in Patent Literature 1, although the accuracy of the resistance value can be improved to some extent, the resistance value cannot be finely adjusted with high accuracy.
On the other hand, according to the prior art described in Patent Literature 2, since each of the trimming grooves 103 can be provided in each of the rectangular portions 102a at both ends of the resistor 102 with the substantially S-shaped portion 102b interposed therebetween, an adjustment rate of the resistance value can be increased as compared with the chip resistor described in Patent Literature 1. However, the trimming grooves 103 of Patent Literature 2 are also provided in a direction to narrow the cross-sectional area of current in the resistor 102, and accordingly, the resistance value cannot be finely adjusted with high accuracy.
The present invention has been made in view of the circumstances of the prior art. A first object of the present invention is to provide a chip resistor capable of improving surge characteristic while finely adjusting a resistance value with high accuracy, and a second object is to provide a manufacturing method thereof.
In order to achieve the first object, the present invention provides a chip resistor comprising: an insulating substrate; a pair of electrodes which are oppositely disposed on the insulating substrate with a predetermined interval therebetween; and a resistor which bridges between the pair of electrodes, the resistor being provided with trimming grooves so as to adjust a resistance value, wherein the resistor comprises a print-forming body that consecutively connects the pair of electrodes, whereas the print-forming body having connecting portions each connected to the pair of electrodes and a rectangular shaped adjustment portion, whereas the adjustment portion is located between the connecting portions, at least one of the connecting portions is a turn-shaped meandering portion, a first trimming groove for coarse adjustment is provided in the adjustment portion to lengthen a current path of the resistor and a second trimming groove for fine adjustment is formed into the meandering portion, when referring to a direction between the pair of electrodes as an X direction and referring to a direction perpendicular to the X direction as a Y direction, the meandering portion includes an extending portion extending in the Y direction, an outer turn portion extending in the X direction to connect between one end of the extending portion and one of the pair of electrodes, and an inner turn portion extending in the X direction to connect between the other end of the extending portion and the adjustment portion, the second trimming groove extends in the Y direction from one of the outer turn portion and the inner turn portion as a starting end position, and a distal end of the second trimming groove does not reach an imaginary line connecting the outer turn portion and the inner turn portion at a shortest distance.
According to the chip resistor configured as above, since the first trimming groove is provided in the adjustment portion to lengthen the current path of the resistor, the resistance value is increased in accordance with increase in a cutting amount of the first trimming groove. As a result, it is possible to improve the surge characteristic while coarsely adjusting the resistance value. Furthermore, since the second trimming groove is provided in an area of the meandering portion in which a current distribution is small, it is possible to finely adjust the resistance value with high accuracy.
In the chip resistor configured as above, only one of the two connecting portions connected to the pair of electrodes may be a turn-shaped meandering portion. Meanwhile, it is preferable when both the two connecting portions are meandering portions having the turn-shape and the second trimming groove is provided in one of the meandering portions. With this configuration, the total length of the resistor becomes large, thereby further improving the surge characteristic.
In order to achieve the second object, the present invention provides a manufacturing method of a chip resistor, the chip resistor including an insulating substrate, a pair of electrodes which are oppositely disposed on the insulating substrate with a predetermined interval therebetween; and a resistor which bridges between the pair of electrodes, the resistor being provided with trimming grooves so as to adjust a resistance value, wherein the resistor comprises a print-forming body that consecutively connects the pair of electrodes, whereas the print-forming body having connecting portions each connected to the pair of electrodes and a rectangular shaped adjustment portion, whereas the adjustment portion is located between the connecting portions, at least one of the connecting portions is a turn-shaped meandering portion, and when referring to a direction between the pair of electrodes as an X direction and referring to a direction perpendicular to the X direction as a Y direction, the meandering portion includes an extending portion extending in the Y direction, an outer turn portion extending in the X direction to connect between one end of the extending portion and one of the pair of electrodes, and an inner turn portion extending in the X direction to connect between the other end of the extending portion and the adjustment portion, the manufacturing method comprising the steps of: forming a first trimming groove for coarse adjustment in the adjustment portion to lengthen a current path of the resistor; forming a second trimming groove for fine adjustment which extends in the Y direction from one of the outer turn portion and the inner turn portion as a starting end position, and setting a distal end of the second trimming groove to a position which does not reach an imaginary line connecting the outer turn portion and the inner turn portion at a shortest distance.
In the manufacturing method of a chip resistor including the steps described above, after print-forming the resistor having a meander shape in which at least one meandering portion is consecutively connected to the adjustment portion, a first trimming groove is provided in the adjustment portion to lengthen the current path of the resistor. With this configuration, the resistance value is increased in accordance with increase in the cutting amount of the first trimming groove, and accordingly, it is possible to coarsely adjust the resistance value while improving the surge characteristic. Furthermore, since the second trimming groove is provided in an area of one of the meandering portions in which the current distribution is small after forming the first trimming groove, it is possible to finely adjust the resistance value with high accuracy.
According to the present invention, it is possible to provide a chip resistor capable of improving surge characteristic while finely adjusting a resistance value with high accuracy.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The resistor 5 is formed into a meander shape, in which a first meandering portion 6 and a second meandering portion 7 at both ends are consecutively connected across an adjustment portion 8 located at the center. The meander shape described above is defined by printing of resistor paste. In
The second meandering portion 7 includes an extending portion 7a extending in the Y direction, an outer turn portion 7b extending in the X direction to connect between a lower end of the extending portion 7a and the second front electrode 4 illustrated on the right side of
The adjustment portion 8 is formed into a rectangular shape, and the pattern width thereof is larger than the pattern width of the first meandering portion 6 and the second meandering portion 7. The inner turn portion 6c of the first meandering portion 6 and the inner turn portion 7c of the second meandering portion 7 are connected to mutually opposing upper end sides of the adjustment portion 8. The adjustment portion 8 is provided with two first trimming grooves 9 which are formed along the Y direction from the upper side of the adjustment portion 8. The first trimming grooves 9 are extended to form an I-cut shape so as to lengthen a current path of the resistor 5, whereby a resistance value of the resistor 5 is coarsely adjusted to bring it close to a target resistance value. In the case of forming the first trimming grooves 9 in the adjustment portion 8, since the resistor 5 which has been formed into a printed shape having the two meandering portions 6, 7 is further meandered and thus turns at three times in total, the total length of the resistor 5 can be increased by the amount of turn.
Here, the number of the first trimming grooves 9 to be provided in the adjustment portion 8 is not limited to two, and may be one or more than three. In such a case, when forming the one or more first trimming grooves 9 so that the current path of the adjustment portion 8 with the one or more first trimming grooves 9 is larger than the minimum pattern width of a current path (6a,6b,6c,7b,7c) which does not have any trimming grooves defined by printing, load in the pattern can be concentrated on portions formed by printing. Accordingly, even when microcracks are generated in the first trimming grooves 9, it is possible to reduce an adverse effect on a resistance value.
Furthermore, the second meandering portion 7 is provided with a second trimming groove 10 which is formed into an L-cut shape from an upper side of the inner turn portion 7c toward the inside of the extending portion 7a. A distal end of the second trimming groove 10 is set to a position which does not cross over an imaginary line E connecting the outer turn portion 7b and the inner turn portion 7c at the shortest distance. Here, a portion where current flows the most in the extending portion 7a is the imaginary line E, and the second trimming groove 10 is provided in an area of the second meandering portion 7 in which current distribution is small. Accordingly, a change amount of the resistance value corresponding to a cutting amount of the second trimming groove 10 is very small. As a result, the resistance value of the resistor 5 can be finely adjusted with high accuracy by the second trimming groove 10 so as to be made coincide with the target resistance value.
The shape of the second trimming groove 10 is not limited to the L-cut shape, and may be an I-cut shape. In such a case, when forming the second trimming groove 10 so that a current path of the extending portion 7a of the second meandering portion 7 with the second trimming groove 10 is larger than the minimum pattern width of the current path (6a,6b,6c,7b,7c) which does not have any trimming grooves defined by printing, load in the pattern can be concentrated on portions formed by printing. Accordingly, even when microcracks are generated in the first trimming grooves 9, it is possible to reduce an adverse effect on a resistance value.
Next, a manufacturing process of the chip resistor 1 configured as above will be described with reference to
The first step of the manufacturing process of the chip resistor 1 is to prepare a large-sized substrate from which multi-piece insulating substrates 2 are obtained. In the large-sized substrate, primary division grooves and secondary division grooves extending in longitudinal and lateral directions are provided in advance to form a grid pattern, and each one of the grids divided by the primary dividing grooves and the secondary dividing grooves serves as a single chip region.
That is, as illustrated in
As illustrated in
Here, in
Next, after forming a pre-coat layer (not illustrated) for covering the resistor 5 by screen-printing glass paste over the resistor 5 and drying and sintering the printed glass paste, a step for irradiating a laser beam from above the pre-coat layer is performed to form the two I-cut shaped first trimming grooves 9 in the adjustment portion 8 (first trimming forming step) as illustrated in
Subsequently, as illustrated in
Next, the step of screen-printing epoxy resin paste over the first trimming groove 9 and the second trimming groove 10 and heating and curing the screen-printed paste is performed so as to form the protective coating layer (not illustrated) for covering the whole of the resistor 5 (protective coating layer forming step).
The steps up to here are collectively performed with respect to the large-sized substrate 2A from which multi-piece insulating substrates are obtained. In the next step, primary break processing for dividing the large-sized substrate 2A into strips along the primary division grooves is performed so as to obtain strip-shaped substrates (not illustrated) provided with multi-piece chip regions (primary dividing step). Then, the step of applying the Ag paste on divided surfaces of the strip-shaped substrate and then drying and sintering the applied paste, or sputtering Ni/Cr thereon instead of the Ag paste is performed so as to form end face electrodes (not illustrated) for bridging the first and second front electrodes 3, 4 and the corresponding back electrodes (end face electrode forming step).
Thereafter, secondary break processing for dividing the strip-shaped substrate along the secondary division grooves is performed to obtain a chip unit having the same dimension as that of the chip resistor 1 (secondary dividing step). The final step is to apply electrolytic plating such as Ni, Au, or Sn on both of the end faces of the insulating substrate 2 in its longitudinal direction for each divided chip unit so as to form an external electrode (not illustrated) for covering the end face electrodes, the back electrodes, and the first and second front electrodes 3, 4 exposed from the protective film. In this way, the chip resistor 1 as illustrated in
As described above, according to the chip resistor 1 of the first embodiment, after print-forming the resistor 5 having the meander shape in which the first meandering portion 6 is consecutively connected to the second meandering portion 7 across the rectangular shaped adjustment portion 8, the step of forming the first trimming grooves 9 in the adjustment portion 8 is performed. As a result, it is possible to lengthen the current path of the resistor 5 and improve the surge characteristics while coarsely adjusting the resistance value of the resistor 5 so as to bring it close to the target resistance value. Furthermore, thereafter, by forming the second trimming groove 10 in an area of the second meandering portion 7 where the current distribution is small, the resistance value of the resistor can be finely adjusted to be made coincide with the target resistance value in accordance with the cutting amount of the second trimming groove 10. As a result, it is possible to adjust the resistance value with high accuracy while improving the surge characteristics.
The second embodiment differs from the first embodiment in that the pattern width of the adjustment portion 8 which is narrowed by formation of the first trimming grooves 9 is made substantially the same as the pattern of the first meandering portion 6. The configuration of the chip resistor 20 other than the above is basically the same as that of the chip resistor 1 illustrated in
That is, as illustrated in
According to the chip resistor 20 of the second embodiment configured as above, since the first trimming groove 9 is formed in the adjustment portion 8 printed in the rectangular shape, the pattern width is made substantially the same as the width W from the first meandering portion 6 to the inner turn portion 7c of the second meandering portion 7 through the adjustment portion 8. With this configuration, it is possible to distribute hot spots, thereby realizing equalization of the entire pattern of the resistor 5.
In the chip resistor 20 according to the second embodiment, the number of the first trimming groove 9 to be provided in the adjustment portion 8 may be two or more. In such a case, the width dimension of the adjustment portion 8 may be changed at the time of print-forming in accordance with the number of the first trimming groove 9.
Furthermore, in each of the embodiments described above, the second trimming groove 10 is provided in the second meandering portion 7 from the upper side of the inner turn portion 7c to the inside of the extending portion 7a. Meanwhile, as long as the distal end of the second trimming groove 10 does not cross over the imaginary line E connecting the outer turn portion 7b and the inner turn portion 7c at the shortest distance, the second trimming groove 10 may be provided in the second meandering portion 7 from a lower side of the outer turn portion 7b to the inside of the extending portion 7a.
Still further, in each of the embodiments described above, an example in which the second trimming groove 10 is provided in the second meandering portion 7 connected to the second front electrode 4, which is consecutively connected to the first meandering portion 6 across the adjustment portion 8, has been described. Meanwhile, the second trimming groove 10 may be provided in the first meandering portion 6 connected to the first front electrode 3 to finely adjust the resistance value. In such a case, it is preferable to set the pattern width of the extending portion 6a of the first meandering portion 6 larger than the pattern width of the extending portion 7a of the second meandering portion 7.
Still further, in each of the embodiments described above, as each connecting portion of the resistor 5 respectively connected to the first front electrode 3 and the second front electrode 4, the first meandering portion 6 and the second meandering portion 7 both having a turn-shape are employed. Meanwhile, as either one of the connecting portions, a connecting portion having a straight shape, without being bended in the turn shape, may be employed. That is, the chip resistor 1 illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-095499 | May 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/015269 | 4/8/2019 | WO | 00 |
