JP6627080B2 - Manufacturing method of chip resistor and chip resistor - Google Patents

Description

  The present invention relates to a method of manufacturing a chip resistor using a metal plate used for various electronic devices as a resistor, and a chip resistor.

  In a conventional method of manufacturing a chip resistor of this type, a pair of electrodes is formed by printing and baking a paste containing a metal on a resistor made of a metal.

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

JP 2011-96814 A

  In the above-described conventional method of manufacturing a chip resistor, it is difficult to print one pair of electrodes 2 to increase the thickness of the pair of electrodes 2 for the purpose of improving solderability or the like. Was.

  When printing is performed a plurality of times, the adhesion between the layers is reduced, and the layer directly in contact with the resistor is less likely to shrink than the other layers. There is a problem in that a large amount is added to the layer directly in contact with the resistor, and as a result, the electrode is cracked or a part of the electrode is peeled off, which may result in poor electrode formation. Was.

  An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a chip resistor capable of suppressing defective electrode formation.

  In order to achieve the above object, the present invention forms a pair of electrodes by printing and baking a paste containing a metal, and furthermore, the pair of electrodes has their opposing surfaces separated from the resistor. After forming and firing a first electrode layer having an inclined surface whose width decreases in the direction, a second electrode layer is formed so as to cover the first electrode layer and the inclined surface. Is provided.

  Since the second electrode layer is formed so as to cover the inclined surface of the first electrode layer, the adhesion density between the first electrode layer and the second electrode layer is improved, and further the first electrode layer is formed. Since the baking is performed once after the formation, the stress due to the shrinkage that is applied to the portion of the pair of electrodes directly in contact with the resistor is reduced, thereby causing the pair of electrodes to crack or partially Since it is hard to be peeled off, an excellent effect that formation failure of a pair of electrodes can be suppressed can be achieved.

FIG. 2 is a side view of the chip resistor according to the embodiment of the present invention. Top view and side view showing the manufacturing method of the chip resistor Top view and side view showing the manufacturing method of the chip resistor Top view and side view showing the manufacturing method of the chip resistor Top view and side view showing the manufacturing method of the chip resistor Side view of another example of the same chip resistor

  FIG. 1 is a side 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 is formed on a resistor 1 made of a metal such as CuNi, NiCr, and CuMn, and at both ends of one surface (upper surface) of the resistor 1. A pair of electrodes 2 made of Cu, a protective film 3 formed between the pair of electrodes 2 on the one surface of the resistor 1, and a plating layer 3a formed so as to cover the pair of electrodes 2 Have. In addition, the surface of the pair of electrodes 2 facing the surface formed on the resistor 1 is mounted on a mounting substrate (not shown).

  The pair of electrodes 2 is formed by printing a paste containing a metal, and the width thereof decreases toward the mounting substrate.

  Here, the direction in contact with the mounting substrate is referred to as “upper” for convenience, and the dimension parallel to the direction in which current flows between the pair of electrodes 2 is referred to as “width”.

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

  First, as shown in FIGS. 2 (a) and 2 (b), a sheet-shaped resistor 1a made of a metal made of CuNi, NiCr, CuMn or the like is prepared in a plate shape, and a predetermined interval is provided on the surface of the sheet-shaped resistor 1a. Then, a paste containing Cu as a main component is printed in a plurality of strips and dried to form the first layer 2a. 2A and 2B, a side surface (cross section) of one chip resistor when a portion sandwiched between lines AA, which is a center line of the plurality of first layers 2a, becomes an individual piece. ). After division into individual pieces, the sheet-shaped resistor 1 a becomes the resistor 1.

  The first layer 2a is continuously formed from one side surface to the other side surface of the sheet-shaped resistor 1a, and the periphery of the paste is thinned by surface tension, and as a result, the direction away from the sheet-shaped resistor 1a. (Towards the top surface) the width decreases.

  Here, FIG. 2A is a top view, and FIG. 2B is a side view of FIG.

  Next, as shown in FIGS. 3A and 3B, a paste containing Cu as a main component is printed and dried to form a second layer 2b so as to overlap the upper surface of each first layer 2a. I do. The second layer 2b is narrower than the first layer 2a. The second layer 2b also becomes thinner at the periphery of the paste due to surface tension, and becomes narrower toward the upper surface (as the distance from the sheet-shaped resistor 1a increases).

Then, a first electrode layer 4a including the first layer 2a and the second layer 2b is formed. Since the width of the second layer 2b is smaller than that of the first layer 2a, the surfaces of the first electrode layers 4a in which the band-shaped first electrode layers 4a face each other are separated from the resistor 1. It has a substantially trapezoidal shape with an inclined surface 5 whose width decreases toward the direction. Also in the chip resistor in the form of an individual piece, the first electrode layer 4 a has an inclined surface 5 whose width decreases in a direction away from the resistor 1. The inclined surface 5 is a curved or linear shape, which is an obliquely inclined end surface of the first layer 2a and the second layer 2b. That is, the inclined surface 5 is not perpendicular to the upper surface of the resistor 1 (sheet-like resistor 1a).

  Here, FIG. 3A is a top view, and FIG. 3B is a side view of FIG.

  Next, baking is performed at 800 ° C. to 980 ° C. in a nitrogen atmosphere.

  Next, as shown in FIGS. 3C and 3D, a paste containing Cu as a main component is printed and dried so as to cover the upper surfaces of the respective first electrode layers 4a (second layers 2b). , A third layer 2c is formed. The third layer 2c has substantially the same width as the second layer 2b, and the third layer 2c also has a substantially trapezoidal shape in which the periphery of the paste becomes thinner due to surface tension and becomes narrower toward the upper surface. The paste flows on the inclined surface 5 of the first electrode layer 4a, and the third layer 2c also covers the inclined surface 5 of the first electrode layer 4a. In the drawing, only the inclined surface 5 of the second layer 2b is covered, but the inclined surface 5 of the first layer 2a may be covered.

  Here, FIG. 3C is a top view, and FIG. 3D is a side view of FIG. 3C.

  Next, as shown in FIGS. 4A and 4B, a paste containing Cu as a main component is printed and dried to cover the upper surface of each third layer 2c to form a fourth layer 2d. I do. The fourth layer 2d has substantially the same width as the second and third layers 2b and 2c. The fourth layer 2d also has a substantially trapezoidal shape in which the periphery of the paste becomes thinner due to surface tension and becomes narrower toward the upper surface.

  Here, FIG. 4A is a top view, and FIG. 4B is a side view of FIG.

  Next, baking is performed at 800 ° C. to 980 ° C. in a nitrogen atmosphere. The third layer 2c and the fourth layer 2d form a substantially trapezoidal second electrode layer 4b. The first electrode layer 4a and the second electrode layer 4b form the strip-shaped electrode 2.

  Although the second electrode layer 4b has two layers, it may have three or more layers. The first to fourth layers 2a to 2d have substantially the same thickness.

  Next, as shown in FIGS. 4C and 4D, a protective film 3 made of an epoxy resin is formed between the strip-shaped electrodes 2.

  Next, after forming the plating layer 3a, as shown in FIGS. 5 (a) and 5 (b), vertical and horizontal dividing grooves 6 are formed and divided into individual pieces, and as shown in FIG. To obtain a chip resistor.

  Here, FIG. 4C is a top view, and FIG. 4D is a side view of FIG. 4C. FIG. 5A is a top view, and FIG. 5B is a side view of FIG.

  For simplicity of description, FIGS. 2 to 5 show portions in which individual chip resistors are formed in a sheet shape in two vertical rows and two horizontal rows. Further, the resistance value may be appropriately adjusted.

  In the method for manufacturing a resistor according to one embodiment of the present invention, the second electrode layer 4b is formed so as to cover the inclined surface 5 of the first electrode layer 4a. Since the adhesion density with the second electrode layer 4b is improved, and the first electrode layer 4a is formed and then baked once, the first electrode 2 in direct contact with the resistor 1 of the pair of electrodes 2 is formed. The stress caused by the shrinkage of the layer 2a is reduced, thereby making it difficult for the pair of electrodes 2 to be cracked or to be partially peeled off. Therefore, the effect of suppressing the formation failure of the pair of electrodes 2 is obtained. It is something that can be done.

  That is, by forming the first electrode layer 4a with the first layer 2a having a large width and the second layer 2b having a small width, the first electrode layer 4a has an inclined surface 5 having an inclined surface 5 which is obliquely inclined. The paste of the third layer 2c flows on the inclined surface 5 by covering the first electrode layer 4a with the third layer 2c having the same width as the second layer 2b. Since the third layer 2c covers the inclined surface 5 and the upper surface of the first electrode layer 4a, the contact area between them becomes large, and the third layer 2c and the first electrode layer 4a (the second layer 2b) And the adhesion to the film are improved.

  In addition, since the first layer 2a and the second layer 2b are baked after being formed, the adhesion between the first layer 2a and the second layer 2b is good, and the third layer 2c and the fourth layer 2c are baked. Since the baking is performed after the formation of the layer 2d, the adhesion between the third layer 2c and the fourth layer 2d is also good. Therefore, even if printing is performed a plurality of times to form a pair of electrodes 2, the adhesion between the layers does not decrease.

  Furthermore, since the first layer 2a is in direct contact with the resistor 1, the shrinkage due to firing is smaller than that of the other second to fourth layers 2b to 2d, but the formation of the second layer 2b Once fired once, the stress due to shrinkage caused by firing only affects the first layer 2a to the second layer 2b, so the stress due to shrinkage applied to the first layer 2a is reduced.

  Note that if CuNi is used instead of Cu for the first layer 2a, which is the lowermost layer of the first electrode layer 4a that is in direct contact with one surface of the resistor 1, the TCR characteristics are improved.

  At this time, when the other layer (the second layer 2b) and the second electrode layer 4b (the third layer 2c and the fourth layer 2d) of the first electrode layer 4a are made of Cu, the resistance value is reduced. Can be stabilized.

  Generally, when a paste containing a solvent is printed and dried, bleeding may occur and the shape may not be stable. In the present application, before baking (dry state) the lowermost first layer 2a made of CuNi, the second layer 2b made of Cu is printed on the first layer 2a. Since the solvent of the layer 2b is absorbed by the first layer 2a, no bleeding occurs in the second layer 2b, and the shape is stabilized. The first layer 2a made of CuNi may have bleeding and unstable shape. However, since CuNi has a higher specific resistance than Cu, the first layer 2a mainly affects the resistance value. Since the second layer 2b made of Cu has no bleeding and a stable shape as described above, the distance between the pair of electrodes 2 is also stable, As a result, the resistance value can be stabilized.

  Further, as shown in FIG. 6, a metal layer 7 made of CuNi having a higher specific resistance than Cu constituting the pair of electrodes 2 may be formed on at least one entire surface of the resistor 1 in the longitudinal direction. At this time, the pair of electrodes 2 are formed on the upper surface of the metal layer 4 at both ends of the resistor 1.

  With this configuration, similar to the above description, the pair of electrodes 2 made of Cu does not cause bleeding, and the shape can be stabilized, so that the resistance value can be stabilized.

  Further, the metal layer 7 made of CuNi may be formed separately from the first to fourth layers 2a to 2d constituting the pair of electrodes 2, or the lowermost first layer 2a may be formed of CuNi. It may be provided by being formed on the entire surface of one surface of the resistor 1.

  The method of manufacturing a chip resistor and the chip resistor according to the present invention have an effect of suppressing formation failure of an electrode, and in particular, a chip resistor and the like using a metal plate as a resistor used in various electronic devices. It becomes useful by applying to.

Reference Signs List 1 resistor 2 electrode 4a first electrode layer 4b second electrode layer 5 inclined surface

Claims (5)

A method for manufacturing a chip resistor in which a pair of electrodes is formed by printing and baking paste containing metal on both ends of one surface of a resistor made of metal, wherein the pair of electrodes face each other. After forming and firing a first electrode layer having an inclined surface whose width decreases in a direction away from the resistor, the first electrode layer and the inclined surface are covered. A method for manufacturing a chip resistor provided by forming a second electrode layer. 2. The first electrode layer according to claim 1, wherein a lowermost layer of the first electrode layer directly in contact with one surface of the resistor is made of a metal having a higher specific resistance than the second electrode layer and the other first electrode layers. 3. Manufacturing method of chip resistor. 2. The method of manufacturing a chip resistor according to claim 1, wherein a metal having a higher specific resistance than a metal forming the pair of electrodes is formed on an entire surface of the resistor. 4. The method of manufacturing a chip resistor according to claim 3, wherein the pair of electrodes is made of Cu, and the metal having a higher specific resistance than the metal forming the pair of electrodes is made of CuNi. A resistor made of metal, a metal layer formed by printing and baking a paste containing a metal on the entire surface of one surface of the resistor, and a metal layer on both ends of one surface of the resistor. A chip resistor comprising: a pair of electrodes formed by printing and baking a paste containing: CuNi for the metal layer and Cu for the pair of electrodes.