JP3688691B2 - Resistors and circuit boards - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resistor and a circuit board used for electronic equipment.
[0002]
[Prior art]
In a rectangular chip resistor used in an electronic circuit, there is a technique for reducing resistance variation by forming a resistor in a semicircular or semi-elliptical shape instead of a rectangular shape (for example, a patent) Reference 1).
[0003]
However, this conventional technology relates to a resistor manufacturing technique for reducing the resistance value variation of the resistor itself in the resistor, and consideration is given to the resistance value variation for circuit mounting. Not.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-102401
[Problems to be solved by the invention]
As described above, conventionally, in a resistor used in an electronic circuit, even though there is a resistor manufacturing technique for reducing the resistance value variation of the resistor itself, the resistance value variation in the circuit mounting is reduced. There is a problem that there is no effective technique for reduction.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resistor with a small resistance error and a circuit board that can reduce variations in resistance on circuit mounting.
[0007]
[Means for Solving the Problems]
In the present invention, in a resistor provided with a rectangular electrode, by specifying the shape of the electrode or the shape of the resistor including the electrode, variation in resistance value in circuit mounting is reduced. It is characterized by.
[0008]
That is, the present invention is characterized in that in a resistor provided with a rectangular electrode in the element body, at least a tip corner portion of the electrode on the side where current flows is rounded (that is, cut into an arc shape). To do. As a specific example, in a rectangular chip resistor in which a pair of rectangular electrodes are provided at both ends of the same surface of the rectangular chip resistor, the corners of the electrodes or the corners of the electrodes and the resistors are rounded off. Further, the present invention is characterized in that an error in resistance value due to local concentration of the current flowing through the resistor locally at the corner of the resistor is suppressed.
[0009]
Also, the present invention provides each of the patterns and resistors that form a current path in a circuit board in which a resistor is interposed between a pattern to which a voltage is applied and a pattern in which a current flows according to the applied voltage. In order to make the current distribution in the joint portion uniform, the resistor is provided with a rectangular electrode with a rounded chamfered corner, and the resistor and each pattern are joined and soldered via this electrode. It is characterized by that. This makes the current distribution at the junction between the resistor and the pattern uniform, eliminates the bias of the current distribution due to the local concentration of the current at the junction between the resistor and the pattern, and localizes the current. The resistance value error due to can be kept low.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a resistor and its mounting example in the first embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b) and FIG.
[0011]
FIGS. 1A, 1B and 2 show the configuration of the rectangular chip resistor in the first embodiment of the present invention, respectively. FIG. 1A is a plan view and FIG. Is a side view, and FIG. 2 is an external perspective view.
[0012]
The resistor 10 according to the first embodiment of the present invention includes a rectangular chip resistor 11 (R) having a substantially rectangular parallelepiped shape and a pair of rectangular electrodes 12 a provided at both ends of the lower surface of the resistor 11 (R). , 12b.
[0013]
In the first embodiment of the present invention, each corner of a rectangular chip resistor 11 (R) constituting the resistor 10 and a pair of electrodes 12 a and 12 b provided at both ends of the lower surface of the resistor 11 (R). As shown in the figure, each part is R chamfered (arc chamfered).
[0014]
As shown in FIG. 1B, the resistor 10 having the corners of the rectangular chip resistor 11 (R) and the pair of electrodes 12a and 12b having an R chamfer is formed on the lower surface of the rectangular chip resistor 11 (R). The pair of electrodes 12 a and 12 b provided are mounted on the circuit board 30 by being joined to the patterns Pa and Pb provided on the circuit board 30 by, for example, solder. At this time, the patterns Pa and Pb of the circuit board 30 to which the electrodes 12a and 12b of the resistor 10 are joined are wider than the electrodes 12a and 12b, and the electrodes 12a and 12b have a pattern Pa, Bonded to Pb.
[0015]
Thus, the current flowing through the resistor 10 is locally concentrated on the corners of the resistor 10 by the configuration in which the corners of the rectangular chip resistor 11 (R) and the pair of electrodes 12 a and 12 b are chamfered. The error of the resistance value due to this can be suppressed.
[0016]
In particular, when the electrodes and the resistor are left in a rectangular shape as in a conventional rectangular chip resistor, for example, when a current due to a rectangular voltage application flows into the resistor, the current flows in (source side). In the electrode portion of the electrode, the current is concentrated at the corners of the electrode, and the current distribution due to the local concentration of the current is significantly biased, and the current does not flow uniformly into the resistor. A value error occurs.
[0017]
At this time, as in the above-described embodiment, the corners of the rectangular chip resistor 11 (R) and the pair of electrodes 12a and 12b are configured to be chamfered, thereby eliminating the above-described current distribution bias. Current flows uniformly through the resistor, and a resistance value error due to current distribution bias can be reduced.
[0018]
Therefore, the above-described effect can be expected by chamfering the corner on the side where current flows only for the source side electrode (for example, 12a).
[0019]
On the current flow side (sink side), a resistance value error due to current distribution deviation occurs as in the source side, but the electrodes 12a and 12b provided on the rectangular chip resistor 11 (R). By adopting a configuration in which each corner portion is chamfered, the above-described current distribution bias is eliminated even on the sink side, and a resistance value error due to the current distribution bias can be reduced.
[0020]
Note that the current distribution at the electrode junction at this time varies depending on the direction of the resistor and the pattern. A difference in current distribution by simulation between the rectangular chip resistor in the conventional configuration based on this and the rectangular chip resistor according to the embodiment of the present invention will be described later with reference to FIGS.
[0021]
Next, a resistor and a mounting example thereof according to the second embodiment of the present invention will be described with reference to FIGS. 3 (a) and 3 (b) and FIG.
[0022]
FIGS. 3 (a), 3 (b) and 4 show the configuration of the rectangular chip resistor in the second embodiment of the present invention. FIG. 3 (a) is a plan view and FIG. 3 (b). Is a side view, and FIG. 4 is an external perspective view.
[0023]
The resistor 20 according to the second embodiment of the present invention includes a rectangular chip resistor 21 (R) having a substantially rectangular parallelepiped shape, and a pair of rectangular electrodes 22 a provided at both ends of the lower surface of the resistor 21 (R). , 22b.
[0024]
In the second embodiment of the present invention, the rectangular chip resistor 21 (R) constituting the resistor 20 remains rectangular as in the prior art, and the rectangular chip resistor 21 (R) constituting the resistor 20 is used. The corners of the pair of electrodes 22a and 22b provided at both ends of the lower surface of FIG.
[0025]
As shown in FIG. 3 (b), the resistor 20 in which the corners of the pair of electrodes 22a and 22b provided at both ends of the lower surface of the rectangular chip resistor 21 (R) are chamfered has a rectangular chip resistor 21 (R The pair of electrodes 22a and 22b provided on the lower surface of () is joined to the patterns Pa and Pb provided on the circuit board 30 by, for example, soldering, thereby mounting on the circuit board 30. At this time, the patterns Pa and Pb of the circuit board 30 to which the electrodes 22a and 22b of the resistor 10 are joined are wider than the electrodes 22a and 22b, and the electrodes 22a and 22b Bonded to Pb.
[0026]
As described above, the corners of the pair of electrodes 22a and 22b provided on the rectangular chip resistor 21 (R) are chamfered so that the corners of the electrodes 22a and 22b are joined to the patterns Pa and Pb. The error of the resistance value due to the current concentrated locally on the corners of the electrodes 22a and 22b can be suppressed. In particular, when the electrodes are left in a rectangular shape as in a conventional rectangular chip resistor, for example, when current due to rectangular voltage application flows into the resistor, the source side electrode portion into which the current flows flows. Since the current concentrates on the corners of the electrodes and the current does not flow uniformly into the electrodes 22a and 22b of the rectangular chip resistor 21 (R), a resistance value error occurs due to the bias of the current distribution. At this time, as in the above-described embodiment, each corner portion of the pair of electrodes 22a and 22b provided on the rectangular chip resistor 11 (R) is configured to have a chamfered shape so that the current distribution is biased. As a result, current flows uniformly through the resistor, and a resistance value error due to current distribution bias can be reduced. Further, on the sink side, as in the above-mentioned source side, a resistance value error occurs due to the bias of the current distribution. However, the current distribution described above can be obtained by making each corner of the electrodes 22a and 22b R-chamfered. The resistance value error due to the current distribution bias can be reduced. At this time, the current distribution also changes depending on the direction of the resistor and the pattern.
[0027]
Current distribution under various conditions of the above-described rectangular chip resistor having a rounded chamfered portion according to the embodiment of the present invention and various chip shapes including the rectangular chip resistor in the conventional configuration. The simulation results of these differences are shown in FIGS.
[0028]
Here, as a measurement condition, the basic shape of the square chip resistor is 6.35 mm (L) × 3.18 mm (W) × 4.7 mm (T), and the basic shape of the electrodes provided at both ends of the lower surface of the square chip resistor. Is a square chip resistor having a resistance value of 0.001Ω, a rated power of 1.0 W, and a rated current of 31.6 A, and 2.20 mm (d) × 3.18 mm (W) × 0.15 mm (T). To do. This rectangular chip resistor is indicated by a symbol R in FIGS. 5 to 25, and its electrode is indicated by a symbol Ta (Source side) and a symbol Tb (Sink side). The measurement ambient temperature is 25 ± 5 ° C., the measurement current is DC 1 A or less, and the measurement resolution is 0.1 μΩ.
[0029]
FIG. 5 to FIG. 8 show the arrangement conditions of the rectangular chip resistor (R) and the pattern (Pa, Pb) that includes the rectangular chip resistor (R) and forms the current path for measurement. Here, an example is shown in which an existing square chip resistor (R) whose corners are not rounded is arranged (circuit connected) on the pattern (Pa, Pb).
[0030]
FIGS. 5 to 7 are examples of arrangement of representative patterns (Pa, Pb) with respect to the rectangular chip resistor (R) when the rectangular chip resistor (R) is mounted on a circuit board for measurement (Pattern 1 to Pattern 2). Pattern 4) is shown.
[0031]
In the pattern arrangement example shown in FIG. 5, narrow patterns (Pa, Pb) and square chip resistors (R) are arranged on a straight line along the direction of current flow. The arrangement pattern is such that the accompanying current easily flows straight from the tip side of the electrode Ta (Source side) of the square chip resistor (R). Here, the arrangement pattern shown in FIG. 5 is referred to as “pattern 1”.
[0032]
In the pattern arrangement example shown in FIG. 6, the pattern (Pa, Pb) has a wide shape with respect to the electrodes Ta, Tb, and the current accompanying the voltage application of the pattern (Pa) is the electrode Ta of the rectangular chip resistor (R). The arrangement pattern is easier to flow from the tip of the (Source side) and its surroundings. Here, the arrangement pattern shown in FIG. 6 is referred to as “pattern 2”.
[0033]
In the pattern arrangement example shown in FIG. 7, a square chip resistor (R) is arranged at each tip portion of the juxtaposed patterns (Pa, Pb), and the current accompanying the voltage application of the pattern (Pa) is a square chip resistance. The arrangement pattern makes a U-turn to the pattern (Pb) through the vessel (R). Here, the arrangement pattern shown in FIG. 7 is referred to as “pattern 3”.
[0034]
The pattern arrangement example shown in FIG. 8 is a pattern in which square chip resistors (R) are crossed over patterns (Pa, Pb) having different extending directions, and the current accompanying the voltage application of the pattern (Pa) is the pattern ( Pb) is an arrangement pattern that flows in the Z direction. Here, the arrangement pattern shown in FIG. 8 is referred to as “pattern 4”.
[0035]
FIGS. 9 to 12 show current distributions measured by the pattern arrangements (pattern 1 to pattern 4) shown in FIGS. 5 to 7 with respect to a square chip resistor (R) having an existing shape whose corners are not chamfered. The state is shown, and the portion having the highest current density is indicated by d1, and the relatively high portion is indicated by d2.
[0036]
FIG. 9A shows the current distribution in the source-side electrode joint portion when the existing-shaped square chip resistor (R) whose corners are not rounded on the chamfer is arranged in the “pattern 1” shown in FIG. Yes. In this example, the current flowing into the rectangular chip resistor (R) is concentrated locally in one place.
[0037]
FIG. 9B shows the current distribution in the sink-side electrode junction portion when the existing-shaped square chip resistor (R) is arranged in the “pattern 1” shown in FIG. In this example, the current flowing through the pattern (Pb) is concentrated locally in one place.
[0038]
FIG. 10A shows the current distribution in the source-side electrode junction portion when the above-explained rectangular chip resistor (R) is arranged in the “pattern 2” shown in FIG. In this example, the current flowing into the square chip resistor (R) is concentrated locally at several locations.
[0039]
FIG. 10B shows the current distribution in the sink-side electrode junction portion when the above-explained rectangular chip resistor (R) is arranged in the “pattern 2” shown in FIG. In this example, the current flowing through the pattern (Pb) is concentrated locally in several places.
[0040]
FIG. 11A shows the current distribution in the source-side electrode junction portion when the above-described existing rectangular chip resistor (R) is arranged in the “pattern 3” shown in FIG. In this example, the current flowing into the rectangular chip resistor (R) is concentrated locally in one place.
[0041]
FIG. 11B shows the current distribution in the sink-side electrode junction portion when the above-explained rectangular chip resistor (R) is arranged in the “pattern 3” shown in FIG. In this example, the current flowing through the pattern (Pb) is concentrated locally in several places.
[0042]
FIG. 12A shows the current distribution in the source-side electrode junction portion when the above-explained rectangular chip resistor (R) is arranged in the “pattern 4” shown in FIG. In this example, the current flowing into the rectangular chip resistor (R) is concentrated locally in one place.
[0043]
FIG. 12B shows a current distribution in the sink side electrode junction portion when the above-explained rectangular chip resistor (R) is arranged in the “pattern 4” shown in FIG. In this example, the current flowing through the pattern (Pb) is concentrated locally in one place.
[0044]
As described above, in the square chip resistor (R) having the existing shape, as shown in FIGS. 9 to 12, in any pattern arrangement (Pattern 1 to Pattern 4), the current is at one place or several places. Since the current distribution is locally concentrated on the current and the current does not flow uniformly through the resistor, an error occurs in the resistance value.
[0045]
FIG. 13 to FIG. 16 show examples of the shape of the resistor to be measured. Here, examples of changing the shape of both the chip resistor and the electrode (resistance model 1 to resistance model 4) are shown. Show. 13 is a chip resistor formed in an oval shape, FIG. 14 is a chip resistor whose corners are gently curved (R chamfered at a radius of 600 μm), and FIG. 15 is an R chamfer according to the first embodiment of the present invention. FIG. 16 shows a chip resistor having a semicircular shape at both ends. Here, the chip resistor formed in the shape of an ellipse shown in FIG. 13 is “Resistance Model 1”, the chip resistor shown in FIG. 14 having a gently curved corner is “Resistance Model 2”, and FIG. The R-chamfered rectangular chip resistor (that is, the rectangular chip resistor 10 shown in FIGS. 1 and 2) according to the first embodiment of the present invention is formed as “resistance model 3”, and both ends shown in FIG. The chip resistor is referred to as “resistance model 4”.
[0046]
FIG. 17 to FIG. 24 show the state of current distribution when the resistors of the respective resistance models (resistance model 1 to resistance model 4) are measured by the pattern arrangements (pattern 1 to pattern 4) shown in FIG. 5 to FIG. In the figure, a portion with the highest current density is indicated by d1, and a relatively high portion is indicated by d2.
[0047]
FIG. 17 shows a current distribution in the source-side electrode junction portion when the chip resistor (R) of “resistance model 1” shown in FIG. 13 is arranged in “pattern 1” shown in FIG. In this example, the current flowing into the chip resistor (R) of “resistance model 1” is concentrated locally in one place.
[0048]
FIG. 18 shows the current distribution in the source-side electrode junction when the chip resistor (R) of “resistance model 1” shown in FIG. 13 is arranged in “pattern 2” shown in FIG. In this example, current flows relatively uniformly into the chip resistor (R) of “resistance model 1”.
[0049]
FIG. 19 shows a current distribution in the source-side electrode junction portion when the chip resistor (R) of “resistance model 2” shown in FIG. 14 is arranged in “pattern 1” shown in FIG. In this example, the current flowing into the chip resistor (R) of “Resistance Model 2” is small but concentrated locally in one place.
[0050]
FIG. 20 shows a current distribution in the source-side electrode junction portion when the chip resistor (R) of “resistance model 2” shown in FIG. 14 is arranged in “pattern 2” shown in FIG. In this example, a small amount of current flows into the chip resistor (R) of “resistance model 2”, but it is concentrated locally in several places.
[0051]
21 shows the rectangular chip resistor 10 according to the first embodiment of the present invention shown in FIGS. 1 and 2, ie, the chip resistor (R) of the “resistance model 3” shown in FIG. The current distribution of the source side electrode joint portion when arranged in the “pattern 1” is shown. In this example, current flows relatively uniformly into the chip resistor (R) of “resistance model 3”.
[0052]
FIG. 22 shows a current distribution in the source-side electrode junction portion when the chip resistor (R) of “resistance model 3” shown in FIG. 15 is arranged in “pattern 2” shown in FIG. In this example, current flows relatively uniformly into the chip resistor (R) of “resistance model 3”.
[0053]
FIG. 23 shows a current distribution in the source-side electrode junction portion when the chip resistor (R) of “resistance model 4” shown in FIG. 16 is arranged in “pattern 1” shown in FIG. In this example, the current flowing into the chip resistor (R) of “resistance model 4” is concentrated locally in one place.
[0054]
FIG. 24 shows the current distribution of the source-side electrode junction when the chip resistor (R) of “resistance model 4” shown in FIG. 16 is arranged in “pattern 2” shown in FIG. In this example, the current flowing into the chip resistor (R) of “resistance model 4” is concentrated locally in one place.
[0055]
The following results were obtained from the current distribution of each resistance model (resistance model 1 to resistance model 4) shown in FIGS.
That is, in the “resistance model 1” shown in FIG. 13, in the case of the “pattern 2” shown in FIG. 6, as shown in FIG. 18, a current is relatively uniformly applied to the chip resistor (R) of the “resistance model 1”. In the case of “Pattern 1” shown in FIG. 5, the current is concentrated locally as shown in FIG. 17, so that the current flows uniformly to the chip resistor (R) of “Resistance Model 1”. Absent. Therefore, the chip resistor (R) of “resistance model 1” shown in FIG. 13 has a large resistance value error in “pattern 1” shown in FIG.
[0056]
In “Resistance Model 2” shown in FIG. 14, in each of “Pattern 1” shown in FIG. 5 and “Pattern 2” shown in FIG. 6, as shown in FIG. 19 and FIG. Current concentration. From this result, it was found that when the corner of the electrode is chamfered in an arc shape, if the radius is large, the current is concentrated locally as in the “resistance model 1”.
[0057]
In the “resistance model 4” shown in FIG. 16, as shown in FIGS. 23 and 24, in each of the “pattern 1” shown in FIG. 5 and the “pattern 2” shown in FIG. Similar to “Model 1”, current concentration is observed locally at one location. From this result, it was found that even if the electrode ends were semicircular, the current was concentrated locally as in the “resistance model 1”.
[0058]
In the “resistance model 3” shown in FIG. 15, in both “pattern 1” shown in FIG. 5 and “pattern 2” shown in FIG. 6, as shown in FIGS. Concentration is not observed, and the current distribution is the most uniform among the resistance models of each shape described above.
[0059]
In order to investigate the current distribution of the “resistance model 3” in more detail, a simulation of the current distribution was performed when the wiring was “pattern 3” shown in FIG. The result is shown in FIG. Here, no local concentration of current as shown in FIG. 11 was observed, and it was confirmed that the current distribution in the electrode junction portion was uniform.
[0060]
From the above measurement results, it was found that the shape of the electrodes Ta and Tb being “resistance model 3” is most effective in reducing the resistance value error due to the current bias.
[0061]
The above-described electrode shape according to the present invention is not limited to a square chip resistor, but can be applied to various mounting impedance elements on a circuit board where high accuracy is required.
[0062]
【The invention's effect】
As described above in detail, according to the present invention, the current distribution at the junction between the resistor and the pattern is made uniform, and the current distribution due to the local concentration of the current at the junction between the resistor and the pattern is reduced. The bias can be eliminated, and the resistance value error due to the local concentration of current can be kept low.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of mounting a resistor and a resistor on a circuit board in the first embodiment of the present invention.
FIG. 2 is a perspective view showing an external shape of a resistor in the first embodiment.
FIG. 3 is a diagram showing an example of mounting the resistor and the resistor on the circuit board in the first embodiment of the present invention.
FIG. 4 is a perspective view showing an external shape of a resistor in the second embodiment.
FIG. 5 is a diagram showing a pattern arrangement (Pattern 1) when simulating the current distribution at the electrode joint portion in resistors of various shapes including the resistor of the present invention.
6 is a diagram showing a pattern arrangement (pattern 2) related to FIG.
7 is a diagram showing a pattern arrangement (pattern 3) related to FIG.
8 is a diagram showing a pattern arrangement (pattern 4) related to FIG.
FIG. 9 is a diagram showing a current distribution in an electrode junction portion of a pattern 1 in an existing square chip resistor.
FIG. 10 is a diagram showing a current distribution in an electrode junction portion of a pattern 2 in an existing square chip resistor.
FIG. 11 is a diagram showing a current distribution in an electrode junction portion of a pattern 3 in an existing square chip resistor.
FIG. 12 is a diagram showing a current distribution in an electrode junction portion of a pattern 4 in an existing square chip resistor.
FIG. 13 is a perspective view showing the external shape of a resistor (resistance model 1) to be measured.
FIG. 14 is a perspective view showing an external shape of a resistor (resistance model 2) to be measured.
FIG. 15 is a perspective view showing an external shape of a resistor (resistance model 3) to be measured.
FIG. 16 is a perspective view showing an external shape of a resistor (resistance model 4) to be measured.
FIG. 17 is a diagram showing a current distribution at an electrode junction portion of pattern 1 in resistance model 1;
FIG. 18 is a diagram showing a current distribution in an electrode junction portion of a pattern 2 in the resistance model 1;
FIG. 19 is a diagram showing a current distribution at an electrode junction portion of pattern 1 in resistance model 2;
20 is a diagram showing a current distribution at an electrode junction portion of a pattern 2 in the resistance model 2. FIG.
FIG. 21 is a diagram showing a current distribution in an electrode junction portion of a pattern 1 in a resistance model 3;
FIG. 22 is a diagram showing a current distribution in an electrode junction portion of a pattern 2 in the resistance model 3;
FIG. 23 is a diagram showing a current distribution at an electrode junction portion of a pattern 1 in the resistance model 4;
FIG. 24 is a diagram showing a current distribution in an electrode junction portion of a pattern 2 in the resistance model 4;
FIG. 25 is a diagram showing a current distribution at an electrode junction portion of a pattern 3 in the resistance model 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,20 ... Resistor, 11, 21 ... Rectangular chip resistor (R), 12a, 12b, 22a, 22b ... Electrode, 30 ... Circuit board.

Claims (7)

A resistor in which a rectangular electrode is provided on an element body, wherein at least a tip corner portion of the electrode on the side where current flows is rounded. The resistor according to claim 1, wherein the element body is a rectangular chip resistor, and a pair of electrodes are provided at both ends of the same surface of the rectangular chip resistor. The resistor according to claim 1 or 2, wherein corners of all the electrodes are rounded. The resistor according to claim 2, wherein a corner portion of the square chip resistor is rounded. A first pattern to which a voltage is applied;
A second pattern in which a current by an applied voltage of the first circuit pattern flows;
A pair of rectangular electrodes whose corners are rounded, and one of the electrodes is joined to the first pattern, and the other of the electrodes is joined to the second pattern. A circuit board characterized by that. The circuit board according to claim 5, wherein the resistor is configured by providing a pair of electrodes at both ends of the same surface of the rectangular chip resistor. The circuit board according to claim 6, wherein the square chip resistor has a rounded chamfer.

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