JP5966224B2 - Current detection resistor mounting structure - Google Patents

Description

  The present invention relates to a mounting structure of a resistor used for current detection.

  A current detection resistor is used for the purpose of monitoring the charge / discharge current of the battery and controlling the charge / discharge current of the battery. The current detection resistor is inserted in the path of the current to be monitored, detects a voltage generated across the resistor by the current, and detects a current from a known resistance value. In such an application, a current detection resistor having a low resistance value of, for example, 10 mΩ or less may be used. In response to a request for a further low resistance value, the current detection resistors 15a and 15b are connected to the wiring pattern 11a, There may be a plurality of parallel mountings between 11b (see FIG. 1).

  As a current detection resistor suitable for such use, a structure described in Patent Document 1 is known. A combined resistance value of about 0.1 mΩ can be obtained by connecting two current detection resistors having a low resistance value of about 0.2 mΩ, for example, in parallel.

JP 2002-57009 A

  However, when the resistance value is as low as about 0.1 mΩ, the state of the current flowing through the wiring pattern cannot be ignored. For example, when a current flows from the end X of one wiring pattern 11a shown in FIG. 2A to the end Y of the other wiring pattern 11b, and from the end X of the wiring pattern 11a shown in FIG. When a current flows through the end Z of the wiring pattern 11b, the current flowing through the two resistors 15a and 15b is biased. As a result, an error occurs in the detection voltage as compared with the case where current flows uniformly through the two resistors 15a and 15b.

  The present invention has been made based on the above-described circumstances, and reduces current bias of resistors connected in parallel based on the current path of the wiring pattern when detecting current by connecting resistors of low resistance value in parallel. Then, it aims at providing the mounting structure of the resistor for electric current detection which can reduce the error which arises in a detection voltage.

  The mounting structure of the current detection resistor of the present invention includes a wiring pattern including a pair of lands formed on a substrate, at least two current detection resistors mounted in parallel to the lands, and the pair of lands. And an adjustment element for lowering the resistance value of the wiring pattern in the vicinity of the mounting portion of one current detection resistor and in the vicinity of the mounting portion of the other current detection resistor. It is characterized by that.

  According to the present invention, the equivalent electrical resistivity of the wiring pattern is lowered at the site where the adjustment element is mounted. For this reason, even when the current direction is different, the adjustment element suppresses the potential around the resistor mounting portion from changing. Therefore, a current corresponding to each resistance value is shunted to each resistor connected in parallel, and the stability of the current detection accuracy is maintained.

It is a perspective view which shows the conventional mounting structure of the resistor for a current detection connected in parallel by two pieces. It is a top view of FIG. 1A. It is a figure which shows a current pathway with a broken line, (a) shows the case where an electric current flows from X to Y, (b) shows the case where an electric current flows from X to Z. It is a perspective view which shows the mounting structure of the resistor for electric current detection of one Example of this invention. FIG. 4 is a plan view of FIG. 3. It is explanatory drawing which shows the relationship between the X-axis of the graph used for description of this invention, and the voltage detection terminal extraction position S. It is a graph which shows the appearance resistance value with respect to the taking-out position S when the current path is X → Y (solid line) and when the current path is X → Z (dashed line) in the conventional mounting structure. It is a graph which shows the temperature coefficient of resistance (TCR) with respect to extraction position S when the current path is X → Y (solid line) and when the current path is X → Z (dashed line) in the conventional mounting structure. It is a graph which shows the appearance resistance value with respect to the taking-out position S when the current path is X → Y (solid line) and when the current path is X → Z (broken line) in the mounting structure of the present invention. It is a graph which shows the resistance temperature coefficient (TCR) with respect to the extraction position S when the current path is X → Y (solid line) and when the current path is X → Z (dashed line) in the mounting structure of the present invention. It is a perspective view which shows the mounting structure of the resistor for electric current detection of the 1st modification of this invention. It is a perspective view which shows the mounting structure of the resistor for electric current detection of the 2nd modification of this invention. It is a perspective view which shows the mounting structure of the resistor for electric current detection of the 3rd modification of this invention. It is a perspective view which shows the mounting structure of the resistor for electric current detection of the 4th modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 3 to 13. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

  3 and 4 show a mounting structure of a current detection resistor according to an embodiment of the present invention. In this embodiment, wiring patterns 11a and 11b including a pair of lands formed on a substrate and at least two current detection resistors 15a and 15b mounted in parallel between the lands are provided. Here, at least one of the wiring patterns 11a and 11b extends in a direction substantially perpendicular to the electrode arrangement direction of the current detection resistors 15a and 15b (not shown). That is, the current flowing through the current detection resistors 15a and 15b does not flow in and out linearly in the same direction as the electrode arrangement direction of the current detection resistors 15a and 15b, but the current inflow direction and / or outflow direction. However, it is different from the arrangement direction of the electrodes.

  A pair of lead wires 12a and 12b are led out from the pair of lands and function as voltage detection terminals. By measuring the line voltage, the voltage between the electrodes of the two resistors 15a and 15b connected in parallel, That is, the current flowing through the resistors 15a and 15b can be measured.

  The resistors 15a and 15b have a structure in which electrodes of a highly conductive material such as copper are joined to both ends of a flat resistor made of a metal resistance material such as a copper nickel alloy or a copper manganese nickel alloy. As an example, resistors 15a and 15b have a width of 8 mm and a length of 10 mm. Each resistor has a resistance value of 0.2 mΩ, and a combined resistance value of 0.1 mΩ can be obtained by connecting two resistors in parallel.

  The pair of wiring patterns 11a and 11b include adjustment elements for reducing the resistance value of the wiring pattern in the vicinity of the mounting portion of one current detection resistor 15a and in the vicinity of the mounting portion of the other current detection resistor 11b. 21a and 21b. That is, in this embodiment, in the wiring pattern 11a, the adjustment elements 21a and 21b are arranged in the vicinity of the mounting portions at both ends of the resistors 15a and 15b in a direction substantially perpendicular to the arrangement direction of the electrodes.

  The adjustment elements 21a and 21b are manufactured using a highly conductive material such as Cu or Al, and have an electric resistivity lower than that of the wiring pattern or the resistor. As shown in the figure, the adjustment element is thicker than the wiring pattern and thicker than the resistor electrode. The adjustment elements 21a and 21b are mounted on the wiring pattern by soldering or welding. In the case of performing soldering, soldering is facilitated if there is a surface treatment such as Sn or Ni at a portion where the adjustment element contacts the wiring pattern.

  In the portion where the adjustment elements 21a and 21b are mounted, the equivalent electrical resistivity of the wiring pattern is low. For this reason, even if the current direction changes due to a change in the power supply position of the wiring pattern, etc., the adjustment element suppresses changes in the potential around the resistor mounting part, and the stability of the current detection accuracy of the resistors connected in parallel Is maintained. The lower the resistance value of the adjusting element itself, the higher the potential adjusting effect.

  Next, the effects of the conventional mounting structure that does not include the adjustment element (see FIG. 1) and the mounting structure that includes the adjustment element of the present invention (see FIG. 3) will be compared. First, as shown in FIG. 2A, when the power path is U-shaped from X to Y because the power is connected to one end X, Y side of the wiring patterns 11a, 11b. It is. In this case, it is considered that the current of the outer resistor 15a decreases and the current of the inner resistor 15b increases in the two resistors 15a and 15b due to the resistance of the wiring pattern. That is, the current distribution is biased in the two resistors 15a and 15b.

  On the other hand, as shown in FIG. 2B, the current path flows from X to Z in the same direction in the wiring patterns 11a and 11b. In this case, it is considered that current flows through the two resistors 15a and 15b substantially evenly.

  In order to verify the effect of the adjustment element, it was verified how the characteristics change depending on the lead-out position of the voltage detection terminal S when the current path is X → Y and X → Z. Specifically, the voltage detection terminal extraction position S from the wiring pattern shown in the lower part of FIG. 5 is set to 0.00 at the center position of both resistors 15a and 15b, and the extraction position S is left and right with both resistors fixed. The appearance resistance value and the temperature coefficient of resistance (TCR) were measured. In the graph shown in the upper part of FIG. 5, the horizontal axis is the voltage detection terminal extraction position S and the vertical axis is the appearance resistance value (mΩ) or the resistance temperature coefficient (ppm / ° C.). The change of resistance temperature coefficient was investigated.

  6 and 7 are graphs of the appearance resistance value and the temperature coefficient of resistance (TCR) in a mounting structure in which no adjustment element is present. The solid line shows the case where the current is passed from X to Y, and the broken line shows the case where the current is passed from X to Z. As shown in this graph, when the voltage detection terminal extraction position S is 0 mm, that is, between the two resistors 15a and 15b connected in parallel, the appearance resistance value and the resistance temperature coefficient are stabilized. However, when the current path indicated by the solid line is X → Y, the appearance resistance value and the temperature coefficient of resistance greatly change at a position away from this. Therefore, the characteristics are likely to change due to variations in the mounting position of the resistor, making it difficult to detect current with stable accuracy.

  8 and 9 are graphs of the appearance resistance value and the resistance temperature coefficient (TCR) in the mounting structure of the present invention in which the adjustment element is mounted. As shown in this graph, the divergence between the graphs in the X → Y direction and the X → Z direction is suppressed as compared with the case where no adjustment element is provided. In particular, the appearance resistance value and the resistance temperature coefficient in the X → Y direction are suppressed. It can be seen that the slope of the graph in FIG. Therefore, by arranging the adjusting elements 21a and 21b, the current distribution of both resistors is less biased, and the current detection accuracy varies due to the displacement of the resistor mounting position or the voltage detection terminal extraction position S. It can be seen that it can be suppressed. The present invention is highly effective when a lower resistance value is required. In particular, a current detection resistor of 5 mΩ or less, more preferably a current detection resistor of 1 mΩ or less is mounted and used in parallel. It is suitable for the case.

  FIG. 10 shows a mounting structure of a first modification of the present invention. In this modified example, adjustment elements 22a and 22b having a shape obtained by bending a material having a low resistivity such as Cu or Al into a crank shape are employed. This is a bridge-shaped adjusting element having a size extending from the end of the electrode of one resistor 15a to the end of the electrode of the other resistor 15b along the direction in which the resistors are arranged. Compared to the above embodiment, the mounting area is small, so that the mountability is improved. That is, when soldering, if the mounting area becomes large, the generation of voids is a concern. However, since the mounting area is small, such a concern is reduced.

  FIG. 11 shows the mounting structure of the second modification of the present invention. In this modification, adjustment elements 23a and 23b having a shape bent in a crank shape are employed as in the first modification. This adjustment element is shorter than the adjustment element of the first modification along the direction in which the resistors are arranged.

  FIG. 12 shows the mounting structure of the third modified example of the present invention. In this modification, adjustment elements 24a and 24b having a shape bent in a crank shape are employed as in the first modification. This adjusting element is similarly arranged along the direction in which the resistors are arranged, but there is a connecting portion of the adjusting element before the portion where the current flows into and out of one resistor 15a, and the other connecting portion of the adjusting element. However, it is arranged long so as to be in front of the part where the current flows into and out of the other resistor 15b.

  FIG. 13 shows the mounting structure of the fourth modified example of the present invention. In this modification, adjustment elements 25a and 25b having a shape bent in a crank shape are employed as in the first modification. This adjustment element is similarly arranged along the direction in which the resistors are arranged, but the width of the adjustment element is equal to the width of the wiring pattern. That is, before the current flows into and out of the resistor, the wiring pattern branches to the adjustment element, and a part of the current flows from the wiring pattern and flows into the resistor, and further from the adjustment element to the resistor. Yes.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a current detection resistor mounting structure in which low resistance resistors are connected in parallel.

Claims (3)

A wiring pattern including a pair of lands formed on a substrate;
At least two current sensing resistors mounted in parallel to the land;
A detection terminal derived from the pair of lands,
A current detecting resistor comprising an adjustment element for reducing a resistance value of a wiring pattern in the vicinity of a mounting portion of one current detecting resistor and in the vicinity of a mounting portion of another current detecting resistor Implementation structure.   2. The current detection resistor mounting structure according to claim 1, wherein at least one of the wiring patterns extends in a direction substantially perpendicular to an electrode arrangement direction of the current detection resistor.   A wiring pattern including a pair of lands formed on a substrate;
  And at least two current detection resistors mounted in parallel to the land,
  An adjustment element extending from the end of the electrode of one current detection resistor to the end of the electrode of the other current detection resistor, the adjustment element having an electric resistivity lower than that of the current detection resistor A mounting structure of a current detection resistor characterized by that.

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