JP6150593B2 - Chip resistor - Google Patents

Description

  The present invention relates to a chip resistor.

  Along with the downsizing of electronic equipment, in order to increase the mounting density of the circuit board, chip resistors that are surface-mounted components are also required to be small and low-profile. In response to this requirement, Patent Documents 1 and 2 disclose a chip resistor in which a resistor is embedded in a recess provided on the surface of a ceramic substrate.

  An example of the structure of this conventional chip resistor is shown in FIGS. The conventional chip resistor includes a ceramic substrate 1 having a recess at the center of the surface, a first surface electrode 4a and a second surface electrode 4b formed from both ends of the surface of the ceramic substrate 1 to a part of the recess 2, and first And a resistor 3 filled in the recess 2 so as to fill a part of the first surface electrode 4a and the second surface electrode 4b. The first surface electrode 4 a and the second surface electrode 4 b are formed on the side surfaces of the ceramic substrate 1 and the first and second back electrodes 5 a and 5 b having the same polarity formed on the back surface of the ceramic substrate 1. The first side electrode 6a and the second side electrode 6b are connected to each other.

  The first back surface electrode 5a and the second back surface electrode 5b of the ceramic substrate 1 are electrically connected to the wiring conductor of the external electric circuit substrate, so that the first side surface electrode 6a and the second side surface electrode 6b are connected to the first side electrode 6b. A voltage is applied to the resistor 3 through the surface electrode 4a and the second surface electrode 4b.

JP 2002-343601 A JP2004-146848

  When the conventional chip resistor was mounted on an external electric circuit board and a voltage was applied, the heat generated by the resistor itself could not be dissipated efficiently, and the electric resistance value of the resistor was not constant. And since the fixed electrical resistance value is not obtained, the reliability as a chip resistor may be impaired.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a chip resistor that can efficiently dissipate heat generated by a resistor when a voltage is applied while reducing the size and height. There is to do. And let it be a subject to achieve the said objective.

  In order to solve the above-mentioned problems, the present inventors have intensively studied and found that the temperature of the resistor near the center between the first surface electrode and the second surface electrode is the highest, and the first surface electrode and the second surface electrode As a result, it was found that the heat generated by the resistor is mainly dissipated through the surface electrode. Therefore, the present inventors have conducted further intensive studies to arrive at the present invention.

In order to solve the above problems, a chip resistor according to the present invention includes a ceramic substrate having a recess formed on a surface thereof, a resistor filled in the recess, an electrical connection with the resistor, and the resistor A chip resistor including a first surface electrode and a second surface electrode that are a pair of electrodes that are in contact with and opposed to both ends of the ceramic substrate, and when the ceramic substrate is viewed in plan view from the surface side, The recess includes a first recess region that overlaps at least a part of the first surface electrode, a second recess region that overlaps at least a part of the second surface electrode, the first surface electrode, It extends a predetermined width in the opposing direction of the second surface electrode, wherein the third recessed areas in which the first recessed region for connecting the second concave region has a second recessed area between said first recessed area Is wider than the predetermined width of the third recessed region. And said that no.

In such a chip resistor, when viewed in plan from the surface side of the ceramic substrate, the first surface region and the second surface region overlap the first surface region and the second surface region. It is wider than the third recessed region provided between the electrodes. For this reason, the contact area between the resistor and the electrode filled in the concave portion becomes wider as compared with the conventional case, and heat is easily dissipated to the electrode. In other words, the chip resistor of the present invention can secure a wider heat dissipation path by widening the first recessed area and the second recessed area to increase the contact area between the surface electrode and the resistor. The heat generated by the resistor is efficiently dissipated.
Therefore, according to the chip resistor of the present invention, it is possible to efficiently dissipate heat generated by the resistor when a voltage is applied while reducing the size and height.

  In addition, when the ceramic substrate is viewed in plan from the surface side, the first recessed region that does not overlap the first surface electrode is between the first surface electrode and the third recessed region, and the second It is preferable that the second recessed region that does not overlap with the surface electrode exists between the second surface electrode and the third recessed region.

  According to such a chip resistor, there is a recessed area wider than the third recessed area between the first surface electrode and the third recessed area and between the second surface electrode and the third recessed area. A wider heat dissipation path can be secured for the contact portion between the surface electrode and the resistor. Therefore, before the heat | fever which a resistor emits is dissipated through the contact part of a surface electrode and a resistor, it can dissipate more efficiently by dissipating more heat to the contact part beforehand.

  The back surface of the ceramic substrate further comprises a first back electrode electrically connected to the first surface electrode, and a second back electrode electrically connected to the second surface electrode, and the ceramic substrate is When viewed from the front side, it is preferable that the formation region of the first back electrode and the second back electrode overlap the formation region of the resistor.

  Thus, according to the chip resistor, by forming the first back electrode and the second back electrode immediately below the resistor, the resistor is emitted not only through the first surface electrode and the second surface electrode. Heat can be efficiently dissipated also to the first back electrode and the second back electrode.

  ADVANTAGE OF THE INVENTION According to this invention, the chip resistor which dissipates efficiently the heat | fever which a resistor emits at the time of voltage application is provided, reducing size and height.

It is a figure which shows a mode when 1st Embodiment of this invention is planarly viewed. It is a figure which shows the recessed part 2 in FIG. It is AA 'sectional drawing of FIG. It is a figure which shows a mode when 2nd Embodiment of this invention is planarly viewed. It is BB 'sectional drawing of FIG. It is a figure which shows a mode when the conventional chip resistor is planarly viewed. It is CC 'sectional drawing of FIG.

  Hereinafter, embodiments of a chip resistor according to the present invention will be described in detail with reference to FIGS. In the drawings, the same or corresponding members or elements are described with the same reference numerals. In order to facilitate understanding of the embodiment, the protective layer is not shown in FIGS. 1 and 4.

  Hereinafter, a first embodiment of the present invention will be described in detail. FIG. 1 is a diagram showing a state when the first embodiment is viewed from the surface side of a ceramic substrate. FIG. 2 is a view showing the recess 2 in FIG. FIG. 3 is a cross-sectional view taken along the line AA ′ of the chip resistor in FIG.

<About chip resistors>
The chip resistor 11 includes a ceramic substrate 1 having a recess 2, a resistor 3 filled in the recess 2, a first surface electrode 4a and a second surface electrode 4b, a first back electrode 5a and a second back electrode. 5b, the 1st side electrode 6a and the 2nd side electrode 6b, and the protective layer 7 are provided as a main component.

<About ceramic substrate 1>
The ceramic substrate 1 has a flat plate shape, and has a surface on which a resistor 3 and a protective layer 7 to be described later are formed, and a back surface facing the surface. Furthermore, it has a pair of opposed short side surfaces and a pair of opposed long side surfaces. And in the center part of the ceramic substrate 1, it has the recessed part 2 depressed in the thickness direction.

<About the recess 2>
As shown in FIGS. 1 and 2, the recess 2 includes a first recess region 2 a, a second recess region 2 b, and a third recess region 2 c when viewed from the surface side of the ceramic substrate 1.

  Moreover, as shown in FIG. 3, the cross-sectional shape of the recess 2 is substantially T-shaped. The bottom surface of each recessed area is a plane substantially parallel to the surface of the ceramic substrate 1. The depths of the first recess region 2a and the second recess region 2b are shallower than the depth of the third recess region. The depth is the distance from the bottom surface of each recessed area to the surface of the ceramic substrate 1. In addition, the side surface of each recessed region is an inclined surface that extends toward the surface of the ceramic substrate 1.

  In the present embodiment, the side surface of each recessed region is an inclined surface, but may be a plane perpendicular to the surface of the ceramic substrate 1.

<Regarding the first recessed area 2a>
The first recessed area 2a is an area including a portion overlapping the first surface electrode 4a and is wider than a third recessed area 2c described later. The first recessed region 2a includes a first gradually opened region 2aA that gradually spreads from the third recessed region 2c toward the end of the recessed portion 2 on the first surface electrode 4a side, and the first gradually opened region 2aA to the recessed portion 2 A first parallel region 2aB extending in parallel with the long side direction of the ceramic substrate 1 toward the end portion. As shown in FIG. 2, a part of the first parallel region 2aB overlaps the first surface electrode 4a, and the first gradually opened region 2aA is disposed between the third recessed region 2c and the first parallel region 2aB. The In the present embodiment, the width is the length of the ceramic substrate 1 in the short side direction.

  Further, the first gradually opened region 2aA may have a stepped shape or may not be provided when viewed from the surface side of the ceramic substrate 1.

<About the second recessed region 2b>
The second recessed area 2b is an area that includes a portion overlapping the second surface electrode 4b and is wider than a third recessed area 2c described later. Further, the second recessed region 2b includes a second gradually opened region 2bA that gradually spreads from the third recessed region 2c toward the end of the recessed portion 2 on the second surface electrode 4b side, and a second gradually opened region 2bA to the recessed portion 2 A second parallel region 2bB extending in parallel with the long side direction of the ceramic substrate 1 toward the end is formed. As shown in FIG. 2, a part of the second parallel region 2bB overlaps the second surface electrode 4b, and the second gradually opened region 2bA is disposed between the third recessed region 3c and the second parallel region 2bB. The In the present embodiment, the width is the length of the ceramic substrate 1 in the short side direction.

  Further, the second gradually opened region 2bA may have a stepped shape or may not be provided when viewed in plan from the surface side of the ceramic substrate 1.

<About the third recessed area 2c>
The third recessed area 2c is an area connecting the first recessed area 2a and the second recessed area 2b, and the long side direction of the ceramic substrate 1 (the first surface electrode 4a and the second surface electrode 4b face each other). This is a region extending with a predetermined width in parallel with the direction.

<Regarding resistor 3>
The resistor 3 is formed by filling the recess 2. Therefore, the shape of the resistor 3 as viewed from the surface side of the ceramic substrate 1 is substantially the same as that of the recess 2 as shown in FIG. The shape of the cross section of the resistor 3 is substantially the same as that of the recess 2 as shown in FIG.

  As shown in FIG. 3, the thickness of the resistor 3 formed in the first recess region 2a and the second recess region 2b is smaller than the thickness of the resistor 3 formed in the third recess region 2c. Therefore, the cross-sectional area of the resistor 3 formed in the third concave region (the cross-sectional area cut by a plane parallel to the short side surface of the ceramic substrate 1) and the first concave region 2a and the second concave region 2b are formed. The difference from the cross-sectional area of the resistor 3 is reduced as compared with the case where the depths of the respective recessed regions are the same. In the present embodiment, the depth of each recess region is set so that the cross-sectional area of the resistor 3 formed in each recess region is substantially constant.

<About the first surface electrode 4a and the second surface electrode 4b>
The first surface electrode 4a and the second surface electrode 4b, which are a pair of electrodes made of a metal-based material, are opposed to both ends of the resistor 3 in the long side direction of the ceramic substrate 1 respectively. Abutted. Specifically, the first surface electrode 4a is disposed on the side surface and part of the bottom surface of the first recessed region 2a from the surface of the ceramic substrate 1. The second surface electrode 4b is disposed on the side surface and part of the bottom surface of the second recessed region 2b from the surface of the ceramic substrate 1. That is, in the case of this embodiment, a part of surface electrode is arrange | positioned in the state pinched | interposed into the ceramic substrate 1 and the resistor 3. FIG.

Moreover, the width | variety of the 1st surface electrode 4a and the 2nd surface electrode 4b is formed wider than the width | variety of the 3rd recessed part area | region 2c.
In order to increase the contact area between the first surface electrode 4a and the second surface electrode 4b and the resistor 3, the widths of the first surface electrode 4a and the second surface electrode 4b and the first parallel region of the recess 2 are used. The widths of 2aB and the second parallel region 2bB are preferably approximated.

<Regarding First Back Electrode 5a and Second Back Electrode 5b>
The first back surface electrode 5a and the second back surface electrode 5b made of a material containing metal as a main component are disposed apart from the back surface of the ceramic substrate 1. The first back electrode 5a has the same polarity as the first surface electrode 4a, and the second back electrode 5b has the same polarity as the second surface electrode 4b. These electrodes having the same polarity are electrically connected by side electrodes described later.

  Further, when viewed from the front side of the ceramic substrate 1, the formation region of the first back electrode 5a overlaps with the formation region of the first recess region 2a, and the formation region of the second back electrode 5b overlaps with the second recess region 2b. ing.

<Regarding First Side Electrode 6a and Second Side Electrode 6b>
The first side surface electrode 6a made of a metal-based material is formed on the short side surface of the ceramic substrate 1 on the first surface electrode 4a side, and the first back surface electrode 5a has the same polarity as the first surface electrode 4a. Are connected and electrically connected.
The second side surface electrode 6b made of a metal-based material is formed on the short side surface of the ceramic substrate 1 on the second surface electrode 4b side, and the second back surface electrode 5b having the same polarity as the second surface electrode 4b, Are connected and electrically connected.

<About protective layer>
The protective layer 7 made of an insulating film is formed so as to cover the resistor 3 in order to protect the resistor 3. The insulating film constituting the protective layer 7 is made of a material such as glass or resin.

  Each of the electrodes described so far is preferably made of a metal material having high thermal conductivity since it serves as a heat dissipation path for the heat generated by the resistor 3.

  According to the first embodiment, the heat generated by the resistor 3 in the vicinity of the center between the first surface electrode 4a and the second surface electrode 4b flows from the central portion of the resistor 3 to the end portion along the resistor 3 that gradually becomes wider. It is transmitted toward. Then, heat can be efficiently dissipated from the contact portion between the surface electrodes 4a and 4b and the resistor 3 having an increased area.

  Further, according to the first embodiment, the distance between the resistor 3 and the first back electrode 5a and the second back electrode 5b is shorter than that in the conventional example (see FIG. 7). Therefore, the heat generated by the lower part of the resistor 3 (the part located on the back side of the ceramic substrate 1) can be efficiently dissipated through the first back electrode 5a and the second back electrode 5b.

  Further, according to the first embodiment, since the cross-sectional area of the resistor 3 cut along a plane parallel to the short side surface of the ceramic substrate 1 becomes substantially constant, temperature deviation is eliminated in the entire resistor 3. Therefore, resistance value fluctuation is reduced, and the reliability as a chip resistor is improved.

  As described above, according to the first embodiment, it is possible to provide a chip resistor that can efficiently dissipate the heat generated by the resistor when power is applied while reducing the size and height.

  Next, a manufacturing example of the chip resistor of the present invention will be described.

  First, a ceramic green sheet containing alumina as a main component is formed with a recess by press molding, and then fired at about 1600 ° C. to obtain a ceramic substrate.

Next, a paste mainly composed of Ag—Pd is screen-printed at a predetermined position on the surface of the ceramic substrate. And the paste which has Ag-Pd as a main component is screen-printed in the predetermined position of the back surface of a ceramic substrate. Then, it bakes at about 850 degreeC, and forms the 1st surface electrode, the 2nd surface electrode, the 1st back electrode, and the 2nd back electrode.
Moreover, it is not limited to Ag-Pd paste, For example, you may use Ag paste.

  Next, the recess is filled with a resistor paste containing ruthenium oxide as a main component by screen printing, and then fired at about 850 ° C. to form a resistor. If necessary, perform laser trimming of the resistor to correct the resistance value.

  Next, a glass paste containing glass as a main component is screen-printed on the resistor, and then baked at about 650 ° C. to form a protective layer.

  The above processing is a batch processing of a large number of substrates, and then a process of dividing into strips is performed. After the division, side electrodes mainly composed of Ni · Cr are formed by sputtering on the exposed side surfaces of the ceramic substrate.

  Then, a process of dividing into single chips is performed. Thereby, a chip resistor is obtained.

  The second embodiment of the present invention will be described in detail below. FIG. 4 is a diagram showing a state when the second embodiment of the present invention is viewed in plan from the surface side of the ceramic substrate. FIG. 5 is a cross-sectional view of the chip resistor in FIG. 4 taken along the line BB ′.

  The chip resistor 11 according to the second embodiment is the same as the chip resistor 11 according to the first embodiment except that the first gradually opened region 2aA of the first recessed region 2a and the second gradually opened region 2bA of the second recessed region 2b are eliminated. The depths of the respective recessed regions of the recessed portion 2 are the same.

  As shown in FIG. 4, the first recessed area 2a entirely overlaps the first surface electrode 4a, and the second recessed area 2b entirely overlaps the second surface electrode 4b. In other words, a part of the third recessed area 2c overlaps the first surface electrode 4a and the second surface electrode 4b. For this reason, the cross-sectional area of the resistor 3 formed between the first surface electrode 4a and the second surface electrode 4b (cross-sectional area cut along a plane parallel to the short side surface of the ceramic substrate 1) is substantially constant.

  According to the second embodiment, the contact area between the resistor 3 and the first surface electrode 4a and the second surface electrode 4b is increased as compared with the conventional example (see FIG. 6). Heat can be efficiently dissipated to the electrode 4a and the second surface electrode 4b.

  Further, according to the second embodiment, the distance between the resistor 3 and the first back electrode 5a and the second back electrode 5b is shorter than that in the conventional example (see FIG. 7). Therefore, the heat generated by the lower part of the resistor 3 (the part located on the back side of the ceramic substrate 1) can be efficiently dissipated through the first back electrode 5a and the second back electrode 5b.

  Further, according to the second embodiment, since the cross-sectional area of the resistor 3 formed between the first surface electrode 4a and the second surface electrode 4b is constant, there is no temperature deviation in the entire resistor 3. . Therefore, resistance value fluctuation is reduced, and the reliability as a chip resistor is improved.

  As described above, according to the second embodiment, it is possible to provide a chip resistor that can efficiently dissipate heat generated by the resistor when power is applied while reducing the size and height.

  In the embodiment described so far, in a state where a part of the first surface electrode 4 a and the second surface electrode 4 b is sandwiched between the ceramic substrate 1 and the resistor 3, Arranged on a part of the bottom. The present invention is not limited to this. For example, the first surface electrode 4 a and the second surface electrode 4 b are arranged from the surface of the ceramic substrate 1 to the surface of the resistor in a state of straddling the surface of the ceramic substrate 1 and the resistor 3 filled in the recess 2. Also good.

  It goes without saying 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.

  The chip resistor of the present invention is improved in heat dissipation while being reduced in size and height, and can be used for various electronic devices.

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Recess 2a 1st recessed area 2aA 1st gradually opened area 2aB 1st parallel area 2b 2nd recessed area 2bA 2nd gradually opened area 2bB 2nd parallel area 2c 3rd recessed area 3 Resistor 4a 1st surface electrode 4b 2nd surface electrode 5a 1st back surface electrode 5b 2nd back surface electrode 6a 1st side surface electrode 6b 2nd side surface electrode 7 Protective layer 11 Chip resistor

Claims (3)

A ceramic substrate having a recess formed on the surface;
A resistor filled in the recess;
A first surface electrode and a second surface electrode, which are a pair of electrodes that are electrically connected to the resistor and are in contact with opposite ends of the resistor;
A chip resistor comprising:
When the ceramic substrate is viewed in plan from the surface side,
The recess is
A first recessed region at least partially overlapping a portion of the first surface electrode;
A second recessed region at least partially overlapping a portion of the second surface electrode;
A third recess region extending in a predetermined width in the opposing direction of the first surface electrode and the second surface electrode, and connecting the first recess region and the second recess region;
Have
The chip resistor characterized in that the width of the first recessed area and the second recessed area is wider than the predetermined width of the third recessed area. When the ceramic substrate is viewed in plan from the surface side,
The first recessed area that does not overlap the first surface electrode is between the first surface electrode and the third recessed area;
2. The chip resistor according to claim 1, wherein the second recessed region that does not overlap the second surface electrode is located between the second surface electrode and the third recessed region. On the back surface of the ceramic substrate,
A first back electrode electrically connected to the first surface electrode;
A second back electrode electrically connected to the second surface electrode;
Further comprising
When the ceramic substrate is viewed in plan from the surface side,
3. The chip resistor according to claim 1, wherein a formation region of the first back electrode and the second back electrode overlaps a formation region of the resistor. 4.

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