JP2009016472A - Method of manufacturing chip type resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip type resistor which can reduce the generation of a mounting defect. <P>SOLUTION: The method of manufacturing the chip type resistor includes a step of forming a space 15 in a conductor 14, a step of forming a recessed portion 16 opening on the upper surface of the conductor 14 in the mutually facing portions with the space 15 of the conductor 14 therebetween, and a step of bonding a resistor 11 consisting of a metal plate to the conductor 14 so that both ends are connected to at least one side of the lower surface and the side wall of the recessed portion 16, wherein the depth of the recessed portion 16 is made to be larger than the thickness of the resistor 11, and a protection film 13 composed of resin is formed on at least the upper surface of the resistor 11 between the conductors 14 so that its upper surface is located lower than the upper surface of the conductor 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a chip resistor used for detecting a current value of various electronic devices.

  As shown in FIG. 5, a conventional chip resistor of this type is formed by forming a pair of electrodes 2 on both ends of a lower surface of a resistor 1 made of a metal plate by plating, and then forming a lower surface of the resistor 1. A protective film 3 made of resin is formed between the pair of electrodes 2 and on the upper surface of the resistor 1.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2007-49207 A

  In the above-described conventional chip resistor manufacturing method, when the protective film 3 made of resin is formed on the upper surface of the resistor 1, the resin flows out toward both ends of the resistor 1, and the end surface of the resistor 1 In some cases, the end surfaces of the pair of electrodes 2 may be covered with resin, thereby causing a problem of mounting failure.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method of manufacturing a chip resistor that can reduce the occurrence of mounting defects.

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

  The invention according to claim 1 of the present invention is a step of forming a space portion in the conductor and a step of forming a recess opening on the upper surface of the conductor in a portion facing each other across the space portion of the conductor. And bonding a resistor made of a metal plate to the conductor so that both ends thereof are connected to at least one of the lower surface and the side wall of the recess, and the depth of the recess is determined by the thickness of the resistor. A protective film made of a resin is formed on the at least upper surface of the resistor between the conductors so that the upper surface is located below the upper surface of the conductor. According to this manufacturing method, The depth of the recess is made larger than the thickness of the resistor, and a protective film made of resin is formed between the conductors on at least the upper surface of the resistor so that the upper surface is located below the upper surface of the conductor. Because of the resistor When the protective film made of resin is formed on the surface, the outflow of the resin can also be kept in the concave portion of the conductor, thereby preventing the resin from flowing out from the upper surface of the conductor. It does not cover the end face of the resistor or the end face of the conductor, and this provides the effect of reducing the occurrence of mounting defects.

  According to the second aspect of the present invention, in particular, the conductor is tin-plated before joining at least the conductor and the resistor. Since it is not necessary to individually perform the plating for mounting after the division, it is possible to obtain the operational effect that the productivity can be improved.

  According to the third aspect of the present invention, in particular, before joining at least the conductor and the resistor, at least the surface of the conductor in contact with the resistor may be tin, gold, silver, copper, or nickel. In this method, the conductor and the resistor are joined by heating, and according to this manufacturing method, the conductor is made of tin, gold, silver, copper, or nickel melted by heating. The effect that the resistor can be firmly bonded is obtained.

  In the invention according to claim 4 of the present invention, in particular, a sheet-like metal plate is used as a conductor, and a space portion is formed by punching through the metal plate. According to this, since a plurality of resistors can be obtained at the same time, an operational effect that productivity can be improved can be obtained.

  According to the fifth aspect of the present invention, in particular, the metal plate is formed with a notch portion that is located around the end portion of the resistor and is continuous with the space portion. Since one of the end portions can be separated from other resistors by a notch portion continuous with the space portion, an effect that trimming can be easily performed is obtained.

  As described above, in the method for manufacturing a chip resistor according to the present invention, the depth of the recess formed so as to open on the upper surface of the conductor is larger than the thickness of the resistor, and the resistor is formed between the conductors. Since the protective film made of resin is formed on at least the upper surface so that the upper surface is located below the upper surface of the conductor, the resin flows out when the protective film made of resin is formed on the upper surface of the resistor. As a result, the resin does not flow out from the upper surface of the conductor to the outside, so that the resin does not cover the end face of the resistor or the end face of the conductor. Thus, it is possible to reduce the occurrence of mounting defects.

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

  FIG. 1 is an exploded perspective 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 formed of a metal plate, and a trimming groove for adjusting a resistance value formed at a predetermined position of the resistor 11. 11a, a pair of electrodes 12 formed in an L shape so as to continuously contact from the lower surface groove portion to the end surface of the resistor 11, and a protective film 13 formed on the lower surface and the upper surface 11b of the resistor 11, respectively. It is equipped with.

  Further, the upper surface 11b of the resistor 11 is lower than the uppermost surfaces 12a of the pair of electrodes 12, and a portion of the upper surface 11b of the resistor 11 located between the pair of electrodes 12 protruding upward from the upper surface 11b. A protective film 13 made of resin is formed. The protective film 13 needs to be formed at least only on the upper surface 11 b of the resistor 11, but, for example, a portion located between the pair of electrodes 12 on the lower surface of the resistor 11 and the resistor 11. You may form also on both sides | surfaces.

  In the above configuration, the resistor 11 is made of a metal plate made of nichrome, copper nickel, manganin or the like, and has a length of 0.4 to 15 mm, a width of 0.15 to 10 mm, and a thickness of 50 to 1000 μm. ing. In addition, a trimming groove 11 a for adjusting a resistance value is provided in the central portion of the resistor 11 from one side surface to the other side surface of the resistor 11. The trimming grooves 11a may not be formed depending on a desired resistance value, or a plurality of trimming grooves 11a may be formed.

  The pair of electrodes 12 is separate from the resistor 11 and is made of a metal such as copper having a conductivity lower than that of the resistor 11. The length of the pair of electrodes 12 is the length of the resistor 11. 1/10 to 1/3. Further, the pair of electrodes 12 is configured in an L shape so as to be in contact from the lower surface end to the end surface of the resistor 11. Further, the width of the pair of electrodes 12 is wider than the width of the resistor 11, and the uppermost surfaces 12a of the pair of electrodes 12 located on the end surfaces of the resistor 11 are higher than the upper surface 11b of the resistor 11. In this arrangement, a part of the pair of electrodes 12 protrudes upward from the upper surface 11 b of the resistor 11.

  The pair of electrodes 12 are tin-plated so that the chip resistor is mounted on the substrate. In addition, you may form nickel plating, copper plating, and gold plating between this tin plating and a pair of electrodes 12 as needed.

  The protective film 13 is made of an insulating material such as an epoxy resin or a polyimide resin, and is between the pair of electrodes 12 on the lower surface of the resistor 11, between the protruding pair of electrodes 12 on the upper surface 11 b of the resistor 11, and the resistor 11. It is formed on the side surface.

  Next, a method for manufacturing a chip resistor according to an embodiment of the present invention will be described with reference to FIGS. 2 (a) to 2 (f) and FIGS. 3 (a) to 3 (c).

  First, a large sheet-like metal plate made of copper is prepared as the conductor 14 that is the material of the electrode 12. This metal plate corresponds to the plurality of electrodes 12.

  Next, as shown in FIG. 2A, the metal plate is punched, pressed, or the like, thereby forming a plurality of space portions 15 penetrating the metal plate (conductor 14). In FIG. 2, only two space portions 15 are shown for ease of explanation.

  Further, the conductor 14 may be one in which two metal bands are arranged at regular intervals so that a space 15 is formed between them. However, as in the embodiment of the present invention, a metal plate is used. When is used, a plurality of chip resistors can be obtained at the same time, which can improve productivity and is preferable. Thereafter, tin plating is formed on the entire surface of the conductor 14. The tin plating may be performed after the concave portion 16 is formed in the conductor 14.

  Next, as shown in FIG. 2B, the recesses 16 opened on the upper surface of the conductor 14 are formed by performing cutting, pressing, or the like on portions facing each other across the space 15 of the conductor 14. Form. The sectional view taken along the line AA in FIG. 2B is as shown in FIG. 4, and as shown in FIG. The thickness a of the part facing through the part 15 is thinner than the thickness b of the other part.

  Next, as shown in FIG. 2C, a plurality of plate-like resistors 11 are formed by cutting the strip-like metal plate 17 made of nichrome, copper nickel, manganin or the like. In this case, the width of the resistor 11 is made smaller than the width of the recess 16. Further, the length of the resistor 11 is made substantially the same as the distance l between the most distant portions of the recess 16 in FIG. 4 and the thickness thereof is made smaller than the depth h of the recess 16.

  Next, as shown in FIG. 2D, the resistor 11 is bridged between the conductors 14 so that both end portions 11 c and 11 d of the resistor 11 are fitted in the recess 16. At this time, both ends 11c and 11d of the resistor 11 are in contact with the lower surface 16a of the recess 16 and the side wall 16b of the recess 16 facing each other. In FIG. 2, one resistor 11 is formed in one space 15, but a plurality of resistors 11 may be provided.

  Next, both ends 11c and 11d of the resistor 11 and the conductor 14 are joined. The joining of the resistor 11 and the conductor 14 is performed by a method in which the resistor 11 and the conductor 14 are heated, for example, laser welding, ultrasonic welding, electric welding or the like. At this time, since the tin plating formed on the entire surface around the conductor 14 is temporarily melted by heating, the resistor 11 and the conductor 14 can be joined also by this tin, thereby firmly connecting the two. be able to. In the case where the resistor 11 and the conductor 14 are firmly joined, silver plating, gold plating, copper plating, or nickel plating may be formed on the conductor 14 instead of tin plating. is there. Laser welding is advantageous in terms of productivity over other methods because it does not use any special jig. Furthermore, the joining position of the resistor 11 and the conductor 14 may be either the lower surface 16a of the recess 16 or the side wall 16b.

  Next, as shown in FIG. 2 (e), of the both ends 11c and 11d of the resistor 11 joined to the conductor 14, the conductor 14 is punched and positioned around one end 11c. By performing press working or the like, the notch 18 that is continuous with the space 15 is formed. That is, the periphery of the other end portion 11d of the resistor 11 other than the portion where the resistor 11 and the conductor 14 are joined is in a state without the conductor 14.

  Next, as shown in FIG. 2 (f), by performing laser irradiation or pressing while measuring the resistance value, the trimming groove 11a from one side surface to the other side surface at a predetermined position of the resistor 11 is performed. To adjust the resistance value.

  At this time, as described above, the periphery of the one end 11d of the resistor 11 other than the portion where the resistor 11 and the conductor 14 are joined is in a state where the conductor 14 is not present. The one end portion of the other resistor corresponding to the one end portion 11c of the resistor 11 is separated by the notch portion 18, whereby the probe for measuring the resistance value is connected to the both end portions 11c, When it is brought into contact with 11d, an accurate resistance value can be measured without being influenced by other resistors, so that trimming can be easily performed. That is, when there is no notch 18 and is not separated from other resistors, the resistor 11 is connected in parallel with the other resistors. Even if the resistance value is measured by contacting both end portions 11c and 11d of 11, the accurate resistance value cannot be measured.

  Next, as shown in FIG. 3A, by cutting the conductor 14 around one end portion 11d of the resistor 11, a chip-shaped chip resistor is obtained. At this time, the conductor 14 becomes a pair of electrodes 12 of a piece-shaped chip resistor. The trimming described above may be performed after being divided into individual pieces.

  Next, as shown in FIG. 3B, a film 19 made of an insulating material such as an epoxy resin or a polyimide resin is bonded to the upper surface 11 b and the lower surface of the plurality of resistors 11. At this time, the film 19 is formed between a portion located between the pair of electrodes 12 on the lower surface of the resistor 11 and a pair of electrodes 12 protruding above the upper surface 11b of the upper surface 11b of the resistor 11.

  Finally, as shown in FIG. 3C, the film 19 is cut so as to correspond to the individual resistors 11 to form the protective film 13 on the resistors 11. At this time, the protective film 13 is also formed on both side surfaces of the resistor 11. The protective film 13 is formed such that the upper surface thereof is located below the upper surface of the conductor 14 in the recess shown in FIG.

  In the above-described chip resistor manufacturing method according to the embodiment of the present invention, the depth of the recess 16 formed to open on the upper surface of the conductor 14 is made larger than the thickness of the resistor 11, and Since the protective film 13 made of resin is formed on at least the upper surface of the resistor 11 between the conductors 14 (electrodes 12) so that the upper surface is positioned below the upper surface of the conductor 14, the upper surface of the resistor 11 The outflow of the resin when forming the protective film 13 made of resin can also be kept in the concave portion 16 of the conductor 14, thereby preventing the resin from flowing out from the upper surface of the conductor 14. The resin does not cover the end face of the resistor 11 or the end face of the conductor 14, thereby obtaining the effect that the occurrence of mounting defects can be reduced.

  Further, as described above, by extending the electrode 12 positioned on the lower surface of the resistor 11 above the upper surface 11b of the resistor 11 at the end surface of the resistor 11, the area of the electrode 12 positioned on the end surface of the resistor is increased. Therefore, the fillet at the time of board mounting can be increased, thereby reducing mounting defects.

  In addition, since the pair of electrodes 12 are configured in an L shape so as to be in contact with the end surface from the lower end of the resistor 11, the contact area between the electrode 12 and the resistor 11 can be increased. As a result, the bonding strength between the electrode 12 and the resistor 11 can be increased.

  Further, in the above-described chip resistor manufacturing method according to the embodiment of the present invention, the electrodes 12 are not processed individually into an L shape, but are processed into an L shape continuously. Therefore, productivity does not deteriorate.

  Furthermore, since the conductor 14 is tin-plated before the conductor 14 and the resistor 11 are joined, it is not necessary to divide the conductor 14 into individual pieces and individually perform plating for mounting. Thus, productivity can be improved.

  The chip resistor manufacturing method according to the present invention has the effect of reducing the occurrence of mounting defects, and is particularly suitable for chip resistors used for detecting the current value of various electronic devices. It becomes useful by applying.

The exploded perspective view of the chip type resistor in one embodiment of the present invention (A)-(f) Top view which shows the manufacturing method of the same chip type resistor (A)-(c) Top view which shows the manufacturing method of the same chip type resistor A-A line sectional view of Drawing 2 (b). Perspective view of a conventional chip resistor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Resistor 11b Upper surface of resistor 11c, 11d Both ends of resistor 12 Pair of electrodes 13 Protective film 14 Conductor 15 Space portion 16 Recess 16a Lower surface of recess 16b Side wall of recess 18 Notch

Claims (5)

A step of forming a space in the conductor; a step of forming a recess opening in the upper surface of the conductor in a portion facing each other across the space of the conductor; and at least one of a lower surface and a side wall of the recess Bonding a resistor made of a metal plate to the conductor so that both ends thereof are connected, the depth of the recess is made larger than the thickness of the resistor, and the resistance between the conductors A method for manufacturing a chip resistor, wherein a protective film made of a resin is formed on at least an upper surface of a body so that the upper surface is located below the upper surface of the conductor. 2. The method of manufacturing a chip resistor according to claim 1, wherein at least the conductor is tin-plated before joining the conductor and the resistor. Before joining at least the conductor and the resistor, tin is plated on the surface of the conductor that is in contact with the resistor, and is made of gold, silver, copper, or nickel, and then the conductor and the resistor are joined. The manufacturing method of the chip-type resistor of Claim 1 joined by heating a body. 2. The method of manufacturing a chip resistor according to claim 1, wherein a sheet metal plate is used as the conductor, and the space is formed by punching through the metal plate. The chip resistor manufacturing method according to claim 4, wherein a notch portion is formed in the metal plate and is continuous with the space portion and is located around one end portion of the resistor.

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