JP4647182B2 - Chip resistor manufacturing method and chip resistor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chip resistor manufacturing method and a chip resistor having a structure similar to a cylindrical chip resistor.
[0002]
[Prior art]
Conventionally, an example of a chip resistor is shown in FIG. 7 (see Patent Document 1). Further, there is a device as shown in FIG. 8 (see Patent Document 2).
[0003]
The chip resistor B1 shown in FIG. 7 is a cylindrical chip resistor, and has a configuration in which a conductive resistive film 95 is formed on the circumferential surface of the center portion in the longitudinal direction of a substantially columnar alumina base member 94. is doing. A pair of electrodes 96 made of a conductive film are formed on the circumferential surface and both end surfaces of both ends in the longitudinal direction of the base member 94. The pair of electrodes 96 are in contact with both ends of the resistance film 95 so as to overlap. The chip resistor B1 is manufactured by molding the base member 94, applying a predetermined paste to the surface of the base member 94, and then heating, sequentially firing the resistance film 95 and the pair of electrodes 96. The
[0004]
The chip resistor B2 shown in FIG. 8 has a configuration in which a pair of electrodes 91 separated from each other are provided on the lower surface of a metal rectangular chip-shaped resistor 90. A solder layer 92 is formed on the lower surface of each electrode 91 to improve solderability during mounting. This chip resistor B2 is manufactured by a method as shown in FIG. First, as shown in FIGS. 4A and 4B, two metal plates 90 ′ and 91 ′ are prepared as materials of the resistor 90 and the electrode 91, and then they are overlapped and joined. To do. Next, as shown in FIG. 2C, a part of the metal plate 91 ′ is cut by machining to form a gap 93. Thereafter, as shown in FIGS. 4D and 4E, a solder layer 92 ′ is formed on the lower surface of the metal plate 91 ′, and then the metal plates 90 ′ and 91 ′ are cut. Thereby, the chip resistor B2 is manufactured.
[0005]
Since these chip resistors B1 and B2 are so-called leadless types, compared to a conventional resistor having leads, the entire resistor is reduced in size by the amount of no leads, and the stray capacitance is also reduced. , Stray inductance can be reduced. Furthermore, surface mounting is possible, and mounting is facilitated.
[0006]
[Patent Document 1]
JP-A-6-290906 [Patent Document 2]
JP 2002-57009 A (FIG. 1)
[0007]
[Problems to be solved by the invention]
However, since the chip resistor B1 shown in FIG. 7 has a configuration using the resistance film 95, it is suitable as a high-resistance resistor, but is manufactured as a low-resistance resistor used for, for example, current detection. Not suitable for. This is because if the resistor has a thin film shape, its electric resistance increases. Further, according to the manufacturing method of the chip resistor B1 described above, since the resistance film 95 and the electrode 96 are formed on the surface of the chip-shaped base member 94, the manufacturing becomes very complicated and the manufacturing cost is also increased. There was an expensive defect.
[0008]
On the other hand, the chip resistor B2 shown in FIG. 8 is suitable for being manufactured as a low-resistance resistor, unlike the above-described chip resistor B1, because the resistor 90 has a chip shape and is not a film shape. . However, since the chip resistor B2 is manufactured using the two metal plates 90 ′ and 91 ′, the manufacture is not always easy, and the manufacturing cost is expensive.
[0009]
The present invention has been conceived under such circumstances, and an object thereof is to make it possible to easily and efficiently manufacture a chip resistor suitable for low resistance. .
[0010]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention takes the following technical means.
[0011]
The manufacturing method of the chip resistor provided by the first aspect of the present invention provides a wire having a cylindrical first conductive member as a core and an outer peripheral surface covered with a second conductive member. By shaving a plurality of locations spaced apart in the longitudinal direction of the second conductive member over the entire circumference , a portion covered with the second conductive member and a portion not covered with the second conductive member The step of forming alternately, and the wire is cut at a portion covered with the second conductive member, whereby the first conductive member becomes a chip-shaped resistor, and the second conductive member is Forming a plurality of chip resistors as a pair of electrodes covering the outer peripheral surfaces of both ends of the resistor, and in the step of cutting the plurality of portions of the second conductive member of the wire over the entire circumference They The resistance value between several locations to the desired target resistance is characterized cylindrical and be Rukoto of small I also cutting the first conductive member.
[0012]
In a preferred embodiment of the present invention, a dumet wire is used as the wire.
[0013]
According to the present invention, a chip resistor having a structure in which outer peripheral surfaces of both end portions of a chip-like resistor are covered with a pair of electrodes is manufactured. This chip resistor is suitable for manufacturing as a low-resistance chip resistor because the resistor is chip-shaped. In addition, as the above-mentioned wire rod, it is possible to use a jumet wire that is used as various lead wires or used for glass sealing, etc., but various types of dumet wires are commercially available. Has been. Therefore, the wire can be easily prepared by purchasing the jumet wire. According to the present invention, after preparing the wire rod, the chip resistor can be manufactured by performing an operation of cutting a part of the wire rod and an operation of cutting the wire rod. Since both operations are relatively easy, it is possible to increase the productivity of the chip resistor and reduce the manufacturing cost. Of course, since a large number of chip resistors can be obtained from the above-mentioned wire rods, the reduction of the manufacturing cost is further promoted. Further, in order to efficiently adjust the resistance value in the manufacturing stage of the chip resistor, it is not necessary to perform trimming for adjusting the resistance value of the chip resistor after the chip resistor is manufactured. As a result, the cost of the chip resistor can be further reduced.
[0014]
In preferable embodiment of this invention, before cut | disconnecting the said wire, it further has the process of covering the part which is not coat | covered with the said 2nd conductive member of the said 1st conductive member with an insulating member. According to such a configuration, it is possible to manufacture a chip resistor having a structure in which a portion of the outer peripheral surface of the resistor that is not covered by the pair of electrodes is covered by the insulating member.
[0015]
In a preferred embodiment of the present invention, as the wire, a wire having a solder layer formed around the second conductive member is used, and the process of cutting the second conductive member is a process of cutting the solder layer. With. According to such a configuration, since the solder layer is laminated on the pair of electrodes, it is possible to efficiently manufacture a chip resistor having good solderability at the time of mounting.
[0016]
In a preferred embodiment of the present invention, the method further includes a step of forming solder layers on both end faces of the resistor of the chip resistor and around the electrode after cutting the wire. According to such a configuration, it is possible to manufacture a chip resistor in which a solder layer is laminated on a pair of electrodes and on both end faces of a resistor.
[0018]
The chip resistor provided by the second aspect of the present invention comprises a chip- like member made of a conductive member having a cylindrical first conductive member as a core and a wire covered with the second conductive member around the first conductive member. A resistor, a pair of electrodes covering the outer peripheral surface of both ends of the resistor, an insulating layer covering the outer peripheral surface between the pair of electrodes of the resistor, and both ends of the resistor and the periphery of the electrode A solder layer to be coated, wherein the outer diameter of the intermediate portion in the axial length direction of the first conductive member is smaller than the outer diameter of both end portions in the axial length direction.
[0019]
According to such a configuration, the resistor has a chip shape and is suitable for manufacturing as a low-resistance chip resistor. Moreover, the chip resistor having the above-described configuration can be easily and appropriately manufactured by using the manufacturing method provided by the first aspect of the present invention, and the manufacturing cost can be reduced.
[0020]
Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be specifically described with reference to the drawings.
[0022]
FIG. 1 shows an embodiment of a chip resistor according to the present invention. The chip resistor A1 of this embodiment has an external form similar to a cylindrical chip resistor, and includes a resistor 1, a pair of electrodes 2, a pair of solder layers 3, and an insulating layer 4.
[0023]
The resistor 1 has a substantially cylindrical chip shape, and the material thereof is, for example, an Fe—Ni alloy. The pair of electrodes 2 is made of, for example, copper having higher conductivity than the resistor 1, and is formed so as to cover the entire circumference of each outer peripheral surface of both ends in the axial length direction of the resistor 1. The outer diameter d1 of the intermediate portion in the axial direction in which each electrode 2 of the resistor 1 is not formed is slightly smaller than the outer diameter d2 at both ends in the axial direction, as will be described later. This is because the resistor 1 is cut for adjusting the resistance value of the resistor 1 in the manufacturing stage or for facilitating the adjustment of the resistance value.
[0024]
Each solder layer 3 is formed so as to cover the entire outer peripheral surface of each electrode 2. The insulating layer 4 is, for example, an epoxy resin-based resin film, and covers the entire region between the pair of electrodes 2 on the outer peripheral surface of the resistor 1. The outer diameter of each electrode 2 is made larger than the outer diameter of the insulating layer 4.
[0025]
Next, an example of a manufacturing method of the chip resistor A1 described above will be described with reference to FIGS.
[0026]
First, a jumet line Da as shown in FIGS. 2 (a) and 2 (b) is prepared. This dumet wire Da has the first conductive member 1A as a core, the periphery thereof is covered with a second conductive member 2A, and the periphery of the second conductive member 2A is further covered with a solder layer 3A. It is. The first conductive member 1A is a resistor 1 as will be described later, and is, for example, an Fe—Ni alloy. The second conductive member 2A is the electrode 2, and is, for example, copper.
[0027]
Preparation of the jumet line Da having such a configuration is easy. That is, various types of dumet wires have been developed and are commercially available for use in lead wires for electronic parts or glass sealing. As shown in FIGS. 3 (a) and 3 (b), for the Dumet wire D having a structure in which the first conductive member 1A made of Fe-Ni alloy is covered with the second conductive member 2A made of copper. At least commercially available. Therefore, by purchasing the dumet line D and then providing the solder layer 3A on the dumet line D, the dumet line Da shown in FIG. 2 can be prepared. Since the solder layer 3A may be formed by, for example, a plating process, the operation of producing the dumet line Da based on the dumet line D is easy. Of course, if the jumet line Da itself is on the market, it may be prepared by purchasing it. In contrast to this, it goes without saying that the manufacturer of the chip resistor A1 itself may manufacture the jumet line Da from scratch.
[0028]
After preparing the dumet line Da, the following processing is performed on the dumet line Da. First, as shown in FIG. 4A, a plurality of points n1 of the solder layer 3A and the second conductive member 2A are cut by, for example, machining. Of course, the solder layer 3A and the second conductive member 2A may be cut by means other than this (for example, electric discharge machining or etching using an etching solution). The plurality of cutting points n1 have the same or substantially the same width, and the cutting points n1 are arranged at an equal pitch in the longitudinal direction of the jumet line Da. Further, the cutting depth dimension s1 at each cutting point n1 is slightly larger than the total dimension s2 of the thicknesses of the solder layer 3A and the second conductive member 2A, and the outer periphery of the first conductive member 1A is also set. Cut a small amount. As a result, the solder layer 3A and the second conductive member 2A can be prevented from unreasonably remaining on the outer peripheral surface of the first conductive member 1A at each cutting point n1. According to such a cutting process, the convex step portions n2 in which the solder layer 3A having a certain width and the second conductive member 2A are laminated are arranged at equal intervals on the outer peripheral surface of the first conductive member 1A. Will be formed.
[0029]
The above-described cutting process is performed so that the resistance value R becomes a desired target value while measuring the resistance value R between the adjacent convex step portions n2. The resistance value R can be easily measured by, for example, bringing a resistance value measuring probe (not shown) into contact with each convex step n2. Since the resistance value R changes as the cutting amount of the first conductive member 1A increases, the resistance value R can be appropriately set to a desired target value by adjusting the cutting amount. Of course, when adjusting the resistance value, a trimming groove as found in a general cylindrical chip resistor may be formed on the outer periphery of the first conductive member 1A. However, in this embodiment, the resistance value can be adjusted only by adjusting the cutting amount without forming such a trimming groove.
[0030]
Next, as shown in FIG. 2B, the insulating layer 4 is formed in a region where the convex step n2 is not formed on the outer peripheral surface of the first conductive member 1A. The insulating layer 4 is formed, for example, by applying an epoxy resin and then curing it.
[0031]
Thereafter, the first and second conductive members 1A and 2A and the solder layer 3A are cut along the center line L in the width direction of each convex stepped portion n2. By this cutting operation, a plurality of chip resistors A1 can be obtained as shown in FIG. That is, the first conductive member 1A is cut into a plurality of substantially cylindrical chips, thereby forming each resistor 1 of the plurality of chip resistors A1. The second conductive member 2A and the solder layer 3A become the electrode 2 and the solder layer 3 of each chip resistor A1.
[0032]
According to the series of manufacturing methods described above, the chip resistor A1 shown in FIG. 1 can be manufactured appropriately and with high productivity by performing simple processing or processing on the dumet line Da. Therefore, the manufacturing cost of the chip resistor A1 is low. Further, since the resistance value is adjusted by cutting the first conductive member 1A together with the cutting of the solder layer 3A and the second conductive member 2A of the dumet wire Da, the resistance value adjustment is performed. Is reasonable. After the manufacture, it is not necessary to trim the resistor 1 for adjusting the resistance value, and this also reduces the cost of the chip resistor A1.
[0033]
Unlike the conventional cylindrical chip resistor, the chip resistor A1 of the present embodiment is suitable for having a low resistance because the resistor 1 has a columnar shape and is not simply a film. The chip resistor A1 can be manufactured with a low resistance of, for example, about 0.5 mΩ to 50 mΩ, which is optimal for current detection applications, for example. This chip resistor A1 can be surface-mounted at a desired location using a solder reflow technique, but since each electrode 2 has a larger diameter than the insulating layer 4, solder is appropriately applied to each electrode 2. Can be attached to. Further, due to the presence of the solder layer 3, the solderability to each electrode 2 is good.
[0034]
FIG. 5 shows another embodiment of the chip resistor according to the present invention. In the drawings after FIG. 5, the same or similar elements as those in the above embodiment are denoted by the same reference numerals.
[0035]
The chip resistor A2 shown in FIG. 5 has a configuration in which the solder layer 3 is different from that of the above embodiment. More specifically, in this chip resistor A2, not only the solder layer 3 is formed on the pair of electrodes 2, but also the solder layer 3 is formed on both end faces 1a of the resistor 1. Has been.
[0036]
In order to manufacture the chip resistor A2, the dumet line D shown in FIGS. 3A and 3B is used in place of the dumet line Da used in the above embodiment. The processing applied to the dumet line D is basically the same as in the above embodiment. First, as shown in FIG. 6A, a plurality of points n1 of the second conductive member 2A of the dumet line D are formed. To cut. At this time, similarly to the above-described embodiment, the outer circumference of the first conductive member 1A is slightly cut to adjust the resistance value. Next, as shown in FIG. 2B, after forming the insulating layer 4 between the second conductive members 2A divided into a plurality of regions, the center line L in the width direction of each second conductive member 2A is formed. The first and second conductive members 1A and 2A are cut along the line. As a result, a plurality of chip resistors A2 ′ are obtained as shown in FIG. Thereafter, solder plating is performed on the plurality of chip resistors A2 ′ by, for example, barrel plating. According to this solder plating process, the solder layer 3 is formed not only on the surface of the electrode 2 but also on both end faces 1a of the resistor 1, thereby obtaining a plurality of chip resistors A2 shown in FIG. .
[0037]
In this chip resistor A2, since the solder layer 3 is also formed on both end faces 1a of the resistor 1, soldering to the both end faces 1a of the resistor 1 when the chip resistor A2 is surface mounted. The property is also good. Therefore, a solder fillet connected to both end faces 1a of the resistor 1 is formed, which is suitable for increasing the mounting strength of the chip resistor A2.
[0038]
The present invention is not limited to the contents of the above-described embodiment. The specific configuration of each step of the chip resistor manufacturing method according to the present invention can be changed in various ways. Similarly, the specific configuration of each part of the chip resistor according to the present invention can be varied in design in various ways.
[0039]
In the present invention, although an existing jumet wire can be used for manufacturing the chip resistor, the chip resistor may be manufactured using a wire material different from the existing jumet wire. As the first conductive member of the wire, various metals such as a Cu—Mn alloy, a Ni—Cu alloy, and a Ni—Cr alloy can be used in addition to the Fe—Ni alloy. Although not very realistic, for example, the resistor of the chip resistor can be made of a non-metallic material. The specific material of each part of the chip resistor is a matter that can be selected appropriately in consideration of the balance between the size of the chip resistor and the target resistance value, the application, etc., and the specific material of the wire according to this Will also be determined. Although this invention is suitable when making a chip resistor into low resistance, the specific resistance value is not limited, either.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing an embodiment of a chip resistor according to the present invention, and FIG. 1B is a cross-sectional view taken along line II of FIG.
2A is a partial cross-sectional perspective view showing an example of a dumet wire used for manufacturing a chip resistor, and FIG. 2B is a main cross-sectional view thereof.
FIG. 3A is a partial cross-sectional perspective view showing another example of a dumet wire used for manufacturing a chip resistor, and FIG. 3B is a cross-sectional view of a main part thereof.
4 (a) to 4 (c) are cross-sectional views of relevant parts showing one embodiment of a method for manufacturing a chip resistor according to the present invention.
FIG. 5 is a cross-sectional view showing another embodiment of the chip resistor according to the present invention.
FIGS. 6A to 6D are cross-sectional views illustrating the main parts of an embodiment of a method for manufacturing a chip resistor according to the present invention. FIGS.
FIG. 7A is a perspective view showing an example of the prior art, and FIG. 7B is a cross-sectional view thereof.
FIG. 8 is a perspective view showing another example of the prior art.
9A to 9E are explanatory views showing an example of a conventional chip resistor manufacturing method.
[Explanation of symbols]
A1, A2 Chip resistors D, Da Dumet wire (wire)
1 Resistor 1A First conductive member (of wire)
2 Electrode 2A Second conductive member 3 Solder layer 3A Solder layer 4 Insulating layer

Claims (2)

Preparing a rod- shaped first conductive member as a core and a wire whose outer peripheral surface is covered with a second conductive member;
A portion of the first conductive member covered with the second conductive member and a portion not covered with the first conductive member by cutting a plurality of locations spaced in the longitudinal direction of the second conductive member over the entire circumference , Alternately forming steps,
By cutting the wire at the portion covered with the second conductive member, the first conductive member is used as a chip-shaped resistor, and the second conductive member is formed at both ends of the resistor. Producing a plurality of chip resistors as a pair of electrodes covering the outer peripheral surface,
In the step of cutting a plurality of locations of the second conductive member of the wire over the entire periphery, the resistance value between them a plurality of locations so that a desired target resistance, it also is cutting the first conductive member wherein the cylindrical and be Rukoto of small diameter, the manufacturing method of the chip resistor. A pair of chip-shaped resistors made of a conductive member having a cylindrical first conductive member as a core and a wire covered with a second conductive member, and a pair covering the outer peripheral surfaces of both ends of the resistor An insulating layer that covers an outer peripheral surface between the pair of electrodes of the resistor, and a solder layer that covers both ends of the resistor and the periphery of the electrode,
A chip resistor, wherein an outer diameter of an intermediate portion in the axial length direction of the first conductive member is smaller than an outer diameter of both end portions in the axial length direction.

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