Patent Application
20220375661
The present invention relates to a chip resistor in which trimming grooves are formed on a resistor provided on an insulating substrate for the purpose of adjustment of a resistance value.
A chip resistor is designed to mainly include a rectangular parallelepiped insulating substrate, a pair of front electrodes oppositely disposed on the front surface of the insulating substrate with a predetermined interval therebetween, a pair of back electrodes oppositely disposed on the back surface of the insulating substrate with a predetermined interval therebetween, end face electrodes that bridges the front electrodes and the corresponding back electrodes, a resistor that bridges the pair of front electrodes, and a protective film for covering the resistor.
Generally, in the case of producing this type of chip resistor, after multi-piece electrodes, resistors, protective films, and the like 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. In the processes of producing this type of chip resistor, multi-piece chip resistors are obtained by printing the resistance pastes on one of the surfaces of the large-sized substrate and sintering the printed pastes. However, due to positional deviation and/or bleeding during printing, or influence of temperature unevenness in a sintering furnace, a little variation in size and film thickness among the resistors is caused. 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 so that a resistance value can be set to a desired resistance value, is performed in the processes above.
When surge voltage generated by static electricity, power supply noise, or the like is applied to the chip resistor designed as above, the characteristics of the resistor are affected by excessive electrical stress, and in the worst case, the resistor may be destroyed. It has been known that lengthening the resistor totally by forming it into a meandering shape causes the potential drop to be smoothed, thereby improving the surge characteristics.
As prior art of this type of chip resistor, as illustrated in
In the prior art disclosed in Patent Literature 1, the first trimming groove 106 is provided in the adjustment portion 102 of the resistor 105 which is print-formed in a meandering shape, whereby the resistance value of the resistor 105 is adjusted to be close to the target resistance value, and thereafter, the L-cut shaped second trimming groove 107 is provided in the second meandering portion 104, whereby the resistance value of the resistor 105 is adjusted to match the target resistance value. This enables improvement of the surge characteristics and adjustment of the resistance value with high accuracy.
Patent Literature 1: JP-A-2019-201142
In the chip resistor described in Patent Literature 1, an electric current flows through within the second meandering portion 104 of the resistor 105 in the shortest path indicated by an imaginary line E of
The present invention has been made in view of such a circumstance of the prior art, and an object thereof is to provide a chip resistor capable of improving surge characteristics, and also finely adjusting a resistance value with high accuracy.
In order to achieve the object describe above, the present invention provides a chip resistor comprising: a rectangular parallelepiped insulating substrate; a first electrode and a second electrode that are oppositely disposed on the insulating substrate with a predetermined interval therebetween; and a resistor that bridges the first electrode and the second electrode, the resistor being provided with trimming grooves for adjusting a resistance value, wherein the resistor is a print-formed body in which a first region, a linking portion, and a second region are consecutively formed, the first region being connected to the first electrode and extending in a meandering shape, the second region being connected to the second electrode, and the linking portion being positioned between the first region and the second region, the resistor is provided with a first trimming groove for rough adjustment and a second trimming groove for fine adjustment, the first trimming groove being provided in the first region to make an electric current path of the resistor long, and the second trimming groove being provided in the second region, in the second region, a connecting portion located at a diagonal position of the linking portion overlaps the second electrode, and also a substantially triangular space with the connecting portion as an apex is provided between the second region and the second electrode, and where a distance between the first electrode and the second electrode is an X-direction and a direction perpendicular to the X-direction is an Y-direction, the second trimming groove is an L-cut shaped slit including a straight portion and a turn portion, the straight portion extending in the Y-direction from, as a start point, a side located on an extension line of the linking portion, and the turn portion extending in the X-direction from a distal end of the straight portion toward the space
In the chip resistor designed as described above, the first trimming groove for making the electric current path of the resistor long is formed in the first region that is connected to the first electrode, whereby the resistance value increases in accordance with the trimming amount of the first trimming groove. This enables improvement of the surge characteristics, and also rough adjustment of the resistance value. Furthermore, the L-cut shaped second trimming groove is formed in the second region that is connected to the second electrode, whereby the resistance value can be finely adjusted with high accuracy. Still further, the space having a substantially triangular shape with the connecting portion as the apex is provided between the second region and the second electrode, and the space designed as described above is positioned at a distal end of the turn portion of the second trimming groove to face thereto. This increases, in accordance with extension of the straight portion of the second trimming groove, the area where the turn portion is able to be formed. Accordingly, even in the case where the initial resistance value of the resistor is too low and thus the second trimming groove should be made long, a possibility that the turn portion separates a part of the resistor is reduced, and as a result, it is possible to reduce failure of adjustment of the resistance value.
In the chip resistor designed as described above, in the case where a resistor width serving as an electric current path of the first region defined by the first trimming groove, a resistor width serving as an electric current path of the second region defined by the second trimming groove, and a resistor width of the linking portion in the Y-direction are set substantially equal to each other, the resistor is made long in the entire length from the first region to the second region through the linking portion. This enables improvement of the surge characteristics. And moreover, since the resistor width serving as the electric current path is made substantially equal among the first region, the second region, and the linking portion, it is possible to suppress the amount of change in the resistance value with respect to the overload.
In this case, when the first trimming groove is an I-cut shaped slit that extends in the Y-direction from, as a start point, a central portion of the first region in the X-direction, and a length of the first region in the X-direction is set to about twice a length of the linking portion in the Y-direction, by forming the first trimming groove having a predetermined length at a predetermined position of the print-formed body, it is possible to easily form the first region in a meandering shape having the substantially equal resistance width.
According to the chip resistor of the present invention, it is possible to improve surge characteristics, and also possible to finely adjust a resistance value with high accuracy.
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Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The resistor 5 is formed in a meandering shape, in which a first region 8 is consecutively connected to a second region 9 between a pair of connecting portions 6, 7 via a linking portion 10. The meandering shape described above is defined by the shape of printed resistor pastes. The connecting portion 6 illustrated on the left side of
Each of the first region 8 and the second region 9 serves as an adjustment portion provided for adjusting a resistance value of the resistor 5, and an upper end portion of the first region 8 and an upper end portion of the second region 9 are connected to each other via the linking portion 10. The first region 8 is formed in a rectangular shape, and at an area which is between the first front electrode 3 and the first region 8 and is below the connecting portion 6, a rectangular shaped space S1 is provided. On the other hand, the second region 9 is formed in a polygonal shape having one oblique side 9a, and at an area between the second front electrode 4 and the oblique side 9a of the second region 9 and is above the connecting portion 7, a space S2 having a triangular shape with the connecting portion 7 as the apex is provided.
The first region 8 is provided with a first trimming groove 11, whereby a resistance value of the resistor 5 is roughly adjusted to be close to the target resistance value. The first trimming groove 11 is an I-cut shaped slit that extends in Y-direction from an upper side central portion of the first region 8 toward the lower side thereof. Forming the first trimming groove 11 designed as described above in the first region 8 causes the shape of the resistor 5 to meander twice, which makes an electric current path long.
The second region 9 is provided with a second trimming groove 12, whereby the resistance value of the resistor 5 is finely adjusted to be close to the target resistance value. The second trimming groove 12 is an L-cut shaped slit having a straight portion 12a and a turn portion 12b. The straight portion 12a extends in Y-direction from, as a start point, a position closer to the right side than an upper side central portion of the second region 9 toward the lower side. The turn portion 12b extends in X-direction from the distal end of the straight portion 12a toward the oblique side 9a.
Here, the distal end of the straight portion 12a of the second trimming groove 12 is set to be positioned not to go beyond an imaginary line E that connects the linking portion 10 and the connecting portion 7 illustrated on the right side of
Next, producing processes of the chip resistor 1 designed as described above will be explained with reference to each
The first process is to prepare a large-sized substrate from which multi-piece insulating substrates 2 are obtained. In the large-sized substrate, the primary division groove and the secondary division groove, which respectively extend vertically and horizontally, are provided beforehand to form a grid pattern, and each one of the grids divided by the primary division groove and the secondary division groove serves as a single chip region. Each
That is, as illustrated in
As illustrated in
Here, the first region 8 connected to the connecting portion 6 illustrated on the left side of
Next, after forming a pre-coat layer (not illustrated) for covering the resistor 5 by screen-printing the glass pastes over the resistor 5 and drying and sintering the printed glass pastes, a process of irradiating a laser beam from above the pre-coat layer is performed to form, as illustrated in
Next, as illustrated in
Here, a portion where the electric current flows the most in the second region 9 is the imaginary line E, and the second trimming groove 12 is formed in an area of the second region 9 in which an electric current distribution is small. Accordingly, the amount of change in the resistance value in accordance with the trimming amount of the second trimming groove 12 is very small, and as a result, the resistance value of the resistor 5 can be finely adjusted with high accuracy. Furthermore, the side of the second region 9 positioned in the direction toward which the turn portion 12b of the second trimming groove 12 extends is the oblique side 9a that inclines to approach the second front electrode 4 as it approaches the connecting portion 7. This increases, in accordance with extension of the straight portion 12a of the second trimming groove 12, the area where the turn portion 12b is able to extend. Accordingly, even in the case where the initial resistance value of the resistor 5 is too low and thus the second trimming groove 12 should be made long, a possibility that the turn portion 12b of the second trimming groove 12 goes beyond the oblique side 9 of the second region 9 and thus separates a part of the resistor 5 is reduced. As a result, it is possible to reduce failure of adjustment of the resistance value.
By forming the second trimming groove 12 in the second region 9, the distance between the linking portion 10 and the second trimming groove 12 defines an electric current path in the second region 9. In the present embodiment, the second trimming groove 12 is formed at a position closer to the second front electrode 4 than the upper side central portion of the second region 9 so that the resistor width of the electric current path in the second region 9 becomes substantially equal to the length-a of the linking portion 10 in Y-direction. Thus, forming the second trimming groove 12 for fine adjustment realizes the meandering shaped resistor 5 that is long in the entire length from the first region 8 to the second region 9 through the linking portion 10, and moreover, makes the resistor width serving as the electric current path substantially equal among the first region 8, the second region 9, and the linking portion 10.
Next, the process of screen-printing the epoxy resin pastes over the first trimming groove 11 and the second trimming groove 12 and heating and curing the screen-printed pastes is performed so as to form the protective coating layer (not illustrated) for covering the entire of the resistor 5 (protective coating layer forming process).
The processes 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 process, primary break processing for dividing the large-sized substrate 2A into strips along the primary division groove is performed so as to obtain strip-shaped substrates (not illustrated) provided with multi-piece chip regions (primary dividing process). Then, a process of sputtering Ni/Cr on divided faces of the strip-shaped substrate 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 process).
Thereafter, secondary break processing for dividing the strip-shaped substrate along the secondary division groove is performed to obtain a chip unit having the same dimension as that of the chip resistor 1 (secondary dividing process). The final process is to form electrolytic plating (Ni plating and Sn plating) layers on both of the end faces in its longitudinal direction of the insulating substrate 2 for each divided chip unit so as to form the external electrodes (not illustrated) for covering the end face electrodes, the back electrodes, and the first and second front electrodes 3, 4 exposed from the protective coating layer. Through the processes above, it is possible to obtain the chip resistor 1 as illustrated in
As described above, in the chip resistor 1 according to the first embodiment, the I-cut shaped first trimming groove 11 for making the electric current path of the resistor 5 long is formed in the first region 8 that is connected to the first front electrode 3, whereby the resistance value increases in accordance with the trimming amount of the first trimming groove 11. This enables improvement of the surge characteristics, and also rough adjustment of the resistance value. Furthermore, the L-cut shaped second trimming groove 12 is formed in the second region that is connected to the second front electrode 4, whereby the resistance value can be finely adjusted with high accuracy.
Still further, the space S having a substantially triangular shape with the connecting portion 7 as the apex is provided between the second region 9 and the second front electrode 4, and the space S2 designed as described above is positioned at a distal end of the turn portion 12b of the second trimming groove 12 to face thereto. This increases, in accordance with extension of the straight portion 12a of the second trimming groove 12, the area where the turn portion 12b is able to be formed. Accordingly, even in the case where the initial resistance value of the resistor 5 is too low and thus the second trimming groove 12 should be made long, a possibility that the turn portion 12b of the second trimming groove 12 goes beyond the oblique side 9 of the second region 9 and thus separates a part of the resistor 5 is reduced. As a result, it is possible to reduce failure of adjustment of the resistance value.
Still further, in the chip resistor 1 according to the first embodiment, after the resistor 5 is print-formed in such a manner that the first region 8 in X-direction becomes about twice the length of the linking portion 10 in Y-direction, the I-cut shaped first trimming groove 11 is formed at the central portion of the first region 8. This allows the first region 8 to have a meandering shape in which the resistor width of the first region 8 is substantially equal to that of the connecting portions 6, 7 and linking portion 10. Thereafter, the second trimming groove 12 is formed at a position closer to the second front electrode 4 than the second region 9, thereby making the resistor width serving as the electric current path substantially equal among the first region 8, the second region 9, and the linking portion 10. As a result, it is possible to suppress the amount of change in the resistance value with respect to the overload.
It should be noted that the present invention is not limited to the first embodiment described above, and various modifications are possible within the scope of the technical gist thereof.
For example, in the chip resistor 1 according to the first embodiment, the side of the second region 9 positioned in the direction toward which the turn portion 12b of the second trimming groove 12 extends is the oblique side 9a that linearly inclines toward the connecting portion 7. However, as in the case of a chip resistor 20 according to a second embodiment illustrated in FIG.3, the oblique side 9a may be formed in an arc shape with a gentle curve. That is, near an area where the connecting portion 7 of the second region 9 is to overlap the second front electrode 4, a step is caused by the film thickness of the second front electrode 4, and thus the extrusion of the pastes at the time of print-forming the resistor 5 including the second region 9 is likely to cause bleeding near the connecting portion 7. This makes it difficult to realize the space S2 having a triangular shape with the connecting portion 7 as the apex, however, as in the case of the chip resistor 20 according to the second embodiment, when the side of the second region 9 opposed to the second front electrode 4 is the oblique side 9a formed in an arc shape with a gentle curve, the space S2 can be easily provided since the oblique side 9a is apart from the second front electrode 4.
Still further, as in the case of a chip resistor 30 according to a third embodiment illustrated in
Still further, as in the case of a chip resistor 40 according to a fourth embodiment illustrated in
Still further, in each of the above-described embodiments, the first trimming groove 11 to be formed in the first region 8 is one piece of I-cut shaped slit. However, the first trimming groove 11 may be formed with two pieces of I-cut slits. In such a case, in order to make the resistor width of the first region after forming the first trimming groove 11 substantially equal to the resistor width of the linking portion 10, at the time of print-forming, the length-b of the first region 8 in X-direction may be made more than twice the length-a (b>2) by the amount corresponding to the increase in the number of slits to two.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-085360 | May 2021 | JP | national |
