JP6484797B2 - Manufacturing method of chip resistor - Google Patents

Description

The present invention relates to a method of manufacturing a chip resistor composed of a small and low-resistance metal plate used for detecting a current value of various electronic devices.

  As shown in FIG. 8, a conventional chip resistor of this type includes a resistor 1 made of a plate-like metal, a protective film 2 formed on the center of one surface of the resistor 1, and this protection. An electrode 3 is formed by plating on both ends of the one surface of the resistor 1 with the film 2 interposed therebetween, and a plating layer 4 formed so as to cover the electrode 3. Another protective film 2a is formed on the other surface.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2010-161401 A

  In the conventional chip resistor, since the electrodes 3 are formed at both ends of one surface of the resistor 1, the current density in the vicinity of one surface of the resistor 1 is high as shown in FIG. As a result, the current density is reduced, and even if the thickness of the resistor 1 is increased in order to reduce the resistance value, the resistance value is difficult to decrease. In order to reduce the resistance value, the resistance value must be further increased. However, it has been difficult to reduce the resistance value. In FIG. 9, only the resistor 1 and the electrode 3 are shown, the arrows indicate the direction in which the current flows, and the thickness of the line indicates the magnitude of the flowing current.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a chip resistor that can easily reduce the resistance value and a manufacturing method thereof.

  In order to achieve the above object, the present invention has the following configuration.

According to the first aspect of the present invention, there is provided a sheet-like resistor made of metal, a step of forming a plurality of recesses in a strip shape at regular intervals on the sheet-like resistor, and a metal paste inside the recesses Forming a plurality of strip electrodes by filling and baking, and cutting the sheet-like resistor formed with the strip electrodes in a direction intersecting the plurality of strip electrodes, and forming the plurality of strip electrodes And cutting the portion substantially parallel to the plurality of strip electrodes to divide the sheet resistor into individual pieces. According to this manufacturing method, the pair of electrodes is used as a resistor. Since it forms in the provided recessed part, the effect that a pair of electrode can be comprised easily in the thickness direction of a resistor is acquired.

The invention according to claim 2 of the present invention has an inclined portion in which the concave portion expands toward the opening, and according to this manufacturing method, it is easy to fill the metal paste. Is obtained.

  As described above, the chip resistor according to the present invention forms a pair of electrodes on both end faces of the resistor, and thus the pair of electrodes is configured in the thickness direction of the resistor, so that only near the upper surface of the resistor. In addition, since the current density can be made uniform inside the resistor, a large amount of current flows uniformly between the pair of electrodes, the resistance value can be easily lowered, and the pair of electrodes contains a metal. Since it is configured by printing and baking a paste, it has an excellent effect that it is easy to reduce the size and improve productivity.

Sectional drawing of the chip resistor in one embodiment of this invention Sectional view when mounting the chip resistor The figure which shows the manufacturing method of the same chip resistor The figure which shows the manufacturing method of the same chip resistor The figure which shows the manufacturing method of the same chip resistor Sectional view showing current flow of the chip resistor The figure which shows the relationship between the electrode opposing length and resistance value of the same chip resistor Sectional view showing a conventional chip resistor Sectional view showing current flow of the chip resistor

  FIG. 1 is a cross-sectional view of a chip resistor according to an embodiment of the present invention.

  As shown in FIG. 1, a chip resistor according to an embodiment of the present invention includes a resistor 11 made of a plate-like or foil-like metal, and a pair of electrodes 12 formed on both end faces of the resistor 11. And a plating layer 13 formed so as to cover the pair of electrodes 12, and a protective film 14 formed between the plating layers 13 on the upper surface of the resistor 11.

  And a pair of electrode 12 is comprised by printing the paste containing a metal.

  In the above configuration, the resistor 11 is made of a metal containing Cu such as plate-like or foil-like CuNi, CuMn.

  The pair of electrodes 12 are provided so as to be continuous over the both end surfaces of the resistor 11 and the upper surfaces of both end portions of the resistor 11. That is, the pair of electrodes 12 is also formed on both end faces of the resistor 11 facing the longitudinal direction. Furthermore, a part of the resistor 11 is located on the lower surface of the pair of electrodes 12 so that a part of the end face of the resistor 11 is exposed from the pair of electrodes 12. The upper surfaces of the pair of electrodes 12 protrude upward from the upper surface of the resistor 11. In addition, the pair of electrodes 12 is formed by printing and drying a metal paste mainly containing Cu that does not contain glass frit, and baking it at 800 ° C. to 900 ° C. in a nitrogen atmosphere.

  The pair of electrodes 12 may be formed on the entire surface of both ends of the resistor 11, or the upper surface of the resistor 11 and the upper surface of the pair of electrodes 12 are flush with each other without being provided on the upper surface of the resistor 11. You may do it.

  Further, the plating layer 13 is formed so as to cover the pair of electrodes 12 located on the upper surface and the end surface of the resistor 11 and the exposed end surface of the resistor 11. This plating layer 13 is constituted by nickel plating or tin plating.

  The protective film 14 is formed between the pair of electrodes 12 and between the plating layers 13 on the upper surface of the resistor 11, and is formed by applying and drying an epoxy resin or a silicon resin. Note that another protective film 14 a may be formed on the entire lower surface of the resistor 11.

  Further, a trimming groove 15 is formed in the central portion of the resistor 11. The trimming groove 15 is formed by irradiating a laser from above the resistor 11. The trimming groove 15 is formed on the bottom surface of the first trimming groove 15a so as to be narrower than the width of the first trimming groove 15a and not to protrude from the first trimming groove 15a in a top view. And a second trimming groove 15b. The interior of the trimming groove 15 is filled with a protective film 14.

  As described above, since the coarse adjustment can be performed by the first trimming groove 15a and the fine adjustment can be performed by the second trimming groove 15b, the resistance value accuracy is improved. Moreover, it is preferable that the front-end | tip part of the depth direction of the trimming groove | channel 15 is located above the lower surface of the thickness direction of a pair of electrode 12. FIG. This is because the change in resistance value is very small even when a portion where current hardly flows is trimmed.

  Here, as shown in FIG. 2, the mounting on the mounting substrate is generally performed with the side on which the protective film 14 is formed facing downward, but in this specification and the drawings, the protective film 14 is not shown for convenience. The explanation will be made with the formed side as the upper side.

  Hereinafter, a method for manufacturing a chip resistor according to an embodiment of the present invention will be described with reference to the drawings.

  First, as shown in FIG. 3 (a), a plurality of recesses 16 are formed in strips at regular intervals on a sheet-like resistor 11a in which a Cu-containing alloy such as CuNi or CuMn, or a metal is formed in a plate shape or a foil shape. To do. The sheet-like resistor 11a becomes the resistor 11 in a piece-like chip resistor. Here, the band shape means a band shape when viewed from above, and does not mean a shape viewed from the side. The recess 16 is formed by pressing the sheet resistor 11a so as not to penetrate the sheet resistor 11a.

  Further, the inner surface and the bottom surface of the recess 16 are perpendicular to each other. However, as shown in FIG. 3B, if the recess 16 is provided with an inclined portion that extends toward the opening, the metal paste is filled. It becomes easy.

  Next, as shown in FIG. 3C, a metal paste is filled in the recess 16 and baked to form a plurality of strip electrodes 12a. The strip electrode 12a is printed by printing a metal paste containing Cu as a main component and containing no glass frit on the surface of the sheet resistor 11a. And the paste which has this Cu as a main component is baked and formed at 700 to 900 degreeC in nitrogen atmosphere. The firing temperature is preferably 800 ° C to 900 ° C. Furthermore, the upper surface of the strip-shaped electrode 12a protrudes upward from the upper surface of the sheet-like resistor 11a. In addition, this strip | belt-shaped electrode 12a becomes a pair of electrode 12 in a piece-shaped chip resistor.

  At this time, the metal constituting the strip electrode 12a (a pair of electrodes 12) is the same metal as the material constituting the sheet resistor 11a, that is, Cu. As a result, Cu in the paste and Cu in the alloy containing Cu can be diffused and bonded at the portion where they are in contact with each other, so that the belt-like electrode 12a and the sheet-like resistor 11a are firmly joined. Because it can.

  Here, the recess 16 may be formed so as to penetrate the sheet-shaped resistor 11a, or the upper surface of the strip-shaped electrode 12a and the upper surface of the sheet-shaped resistor 11a may be flush with each other.

  The recess 16 does not penetrate the sheet resistor 11a, and the depth of the recess 16 is preferably 1/3 to 2/3 of the thickness of the sheet resistor 11a. This is because if the depth of the concave portion 16 is less than 1/3 of the thickness of the sheet-like resistor 11a, it is difficult to obtain an effect of reducing the resistance value, and the depth of the concave portion 16 is 2/3 of the thickness of the sheet-like resistor 11a. If it is larger, the thickness of the sheet-like resistor 11a where the concave portion 16 is formed becomes thin, the bending stress is deteriorated, and handling becomes difficult. Furthermore, it is preferable that the strip electrode 12a protrudes upward from the upper surface of the sheet resistor 11a. This is because a space can be created between the resistor 11 and the mounting substrate, so that the protective film 14 can be thickened.

  Next, as shown in FIG. 3D, the sheet-like resistor 11a is diced in a direction orthogonal to the plurality of strip-like electrodes 12a to form dicing grooves 17. At this time, the dicing groove 17 is not provided in one of both end portions of the sheet-like resistor 11a.

  Next, as shown in FIG. 4A, while measuring the resistance value of the adjacent strip electrodes 12a, the sheet-shaped resistor 11a between the adjacent strip electrodes 12a is irradiated with a laser from above to adjust the resistance value. A trimming groove 15 is formed so as to have a predetermined resistance value. The trimming groove 15 is formed in a direction parallel to the plurality of strip-like electrodes 12a so as not to penetrate the sheet-like resistor 11a.

  In addition, the trimming groove 15 forms a first trimming groove 15 a so as to be exposed to the dicing groove 17. If the resistance value does not reach the predetermined resistance value, the first trimming groove 15a is extended until it reaches the opposing dicing groove 17, and the first trimming groove 15a is narrower than the first trimming groove 15a. A second trimming groove 15b is formed on the bottom surface of the trimming groove 15a.

  Next, as shown in FIG. 4B, an epoxy resin or a silicon resin is applied to the sheet-like resistor 11a exposed from the belt-like electrode 12a, and dried and cured to form a protective film 14. Further, another protective film 14a (not shown in FIG. 4) is formed on the entire lower surface of the sheet resistor 11a. The other protective film 14a may be formed before this step.

  Thereafter, the sheet-like resistor 11a is cut at a position where the plurality of strip-like electrodes 12a are formed substantially in parallel with the plurality of strip-like electrodes 12a (cut along the line XX in FIG. 4B), and a plurality of strip-like resistors are formed. Cut in the direction crossing the electrode 12a (along the dicing groove 17) (cut along line YY in FIG. 4B), and as shown in FIG. And is divided into individual pieces each having a pair of electrodes 12 formed on both end surfaces of the individual resistor 11 and the upper surfaces of both end portions of the resistor 11.

  Finally, as shown in FIG. 5B, nickel plating and tin plating are sequentially performed on the pair of electrodes 12 to form a plating layer 13, and a piece-like resistor as shown in FIG. 5C. Get.

  Here, FIGS. 3A, 3B, and 3C are side views, FIGS. 3D, 4, 5, 5A, and 5B are top views, and FIG. 5C is FIG. 5B. ZZ line sectional drawing of is shown. Furthermore, in FIGS. 3-5, although the strip | belt-shaped electrode 12a represents three things, other than three may be sufficient.

  In the chip resistor according to the embodiment of the present invention, since the pair of electrodes 12 are formed on both end faces of the resistor 11, the pair of electrodes 12 is configured in the thickness direction of the resistor 11, thereby Since the current density can be made uniform not only in the vicinity of the upper surface of the resistor 11 but also inside the resistor 11, a large amount of current flows uniformly between the pair of electrodes 12, and the resistance value can be easily lowered. .

  That is, by increasing the opposing length of the pair of electrodes 12 in the thickness direction of the resistor 11 (increasing the area), a current having a constant current density is caused to flow between the pair of electrodes 12. The resistance value is lowered.

  Therefore, as shown in FIG. 6, the current density does not decrease as the distance from the vicinity of one surface of the resistor 11 increases. FIG. 6 is a cross-sectional view showing only the resistor 11 and the pair of electrodes 12. The arrows indicate the direction in which the current flows, and the thickness of the line indicates the magnitude of the flowing current.

  Here, the relationship between the opposing length of the pair of electrodes 12 in the thickness direction of the resistor 11 and the rate of change of the resistance value is shown in FIG.

  In FIG. 7, a 6432 type chip resistor having a resistance 11 thickness of 1 mm is used, the horizontal axis indicates the length of the pair of electrodes 12 facing each other when the thickness of the resistance 11 is 100, and the vertical axis indicates The resistance value when the length of the pair of electrodes 12 facing each other is zero (the pair of electrodes 12 does not face each other) is represented as 100.

  As is apparent from FIG. 7, it can be seen that the resistance value decreases as the length of the pair of electrodes 12 facing each other in the thickness direction of the resistor 11 is increased (the opposing area is increased).

  In addition, since the pair of electrodes is formed by printing and baking a metal paste containing a metal, it is easy to downsize compared to forming the electrodes by welding or cladding, and further, the sheet-like resistor 11a. Therefore, productivity can be improved. In particular, when an electrode is provided by plating, it takes a long time to form a thick electrode by plating, and the productivity deteriorates.

  Further, since the pair of electrodes 12 are formed inside the recess 16 provided in the resistor 11, the pair of electrodes 12 can be easily configured in the thickness direction of the resistor 11.

  The chip resistor and the manufacturing method thereof according to the present invention have an effect that the resistance value can be easily lowered, and are small and low resistance metal used particularly for detecting the current value of various electronic devices. It is useful when applied to a chip resistor composed of a plate.

DESCRIPTION OF SYMBOLS 11 Resistor 12 Pair of electrodes 13 Plating layer 14 Protective film 15 Trimming groove 16 Recess

Claims (2)

Preparing a sheet-like resistor made of metal, forming a plurality of recesses in a strip shape at regular intervals on the sheet-like resistor, filling a metal paste inside the recesses, and firing to form a plurality of strip electrodes Cutting the sheet-like resistor formed with the strip electrodes in a direction intersecting with the plurality of strip electrodes and substantially parallel to the plurality of strip electrodes where the plurality of strip electrodes are formed. And a step of dividing the sheet-like resistor into individual pieces. The method for manufacturing a chip resistor according to claim 1 , wherein the concave portion has an inclined portion that extends toward the opening.

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