JP3353037B2 - Chip resistor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating ceramic
Chip with surface mounting electrodes formed on the edge of the substrate
Related to resistors . 2. Description of the Related Art Conventionally, for example, an electrode structure of a chip resistor for surface mounting is made of Ag-Pt using glass as a binder.
It was formed by applying and firing a so-called metal glaze paste containing such components. As disclosed in Japanese Patent Application Laid-Open No. 61-268001, this electrode manufacturing method divides a large substrate into strips, each electrode end face is exposed on a side face, and a number of chips are arranged in a line. Then, a conductive paint is applied to the end face, and thereafter, the chip is divided into individual chip components. [0003] For THE INVENTION It is an object of the prior art described above, electrodes are printed only on the end face of the chip substrate, were those mechanical strength weak. [0004] The present invention has been made in view of the above problems, high mechanical strength of the electrode, there is also resistance to high temperatures, to provide terminal electrodes of a connection failure hardly occurs chip resistor The purpose is to: According to the present invention, a pair of first electrodes are formed on the surface of an insulating ceramic substrate, and the pair of first electrodes are sandwiched between the pair of first electrodes on the back surface of the substrate. A pair of second electrodes are formed at opposing positions, and the pair of first electrodes is formed.
A resistor is formed between the electrodes, and partially overlaps the pair of first electrodes and the pair of second electrodes to form a pair of the second electrodes.
Between the pair of side edges of the substrate so as to form a step between
This is a chip resistor in which a pair of third electrodes made of a conductive paint is formed, and an exposed portion of the first electrode, an exposed portion of the second electrode, and an outer surface of the third electrode are covered with a plating layer. In addition, a protective film such as a glass coat is formed on the surface of the resistor, and the outer surface of the protective coating at a portion where the resistor and the electrode are connected has a protective coating of another portion on the resistor. It is located at a position protruding outward from the outer surface. The second electrode and the third electrode protrude in a stepwise manner from the center of the back surface of the substrate toward the end surface. Further, the first and second electrodes can be formed of a metal glaze-based electrode material, and the third electrode can be formed of an Ag-resin-based conductive paint. , 3 electrodes can be covered with Ni plating and solder plating. An embodiment of the present invention will be described below with reference to the drawings. Chip <br/> resistor of this embodiment, as shown in FIG. 1, the chip resistor 1
And a convex resistor 3 on the surface of the ceramic substrate 2.
Are formed by printing, and electrodes 4 are provided at both ends.
The resistor 3 is provided with ruthenium oxide to a thickness of about 10 μ,
A trimming groove 5 is formed upward from the bottom of the convex shape by laser or sand blast, and the resistance value is trimmed. The electrode 4 of the chip resistor 1 is connected to the resistor 3
A first electrode 6 having both ends directly connected to each other,
A second electrode 7 is formed so as to protrude from the back surface side of the substrate 2 so as to face the electrode 6 with the substrate 2 interposed therebetween. The first and second electrodes 6 and 7 are made of Ag-Pd, Ag-Pt. Etc. are formed by printing a metal glaze paste. In addition, the first,
End surface 2a and side surface 2b of substrate 2 between second electrodes 6 and 7
Third, a paste of an Ag-resin-based conductive paint in which Ag is mixed into xylene or epoxyphenol resin is used.
An electrode 8 is provided. The third electrode 8 is provided so as to partially cover the first and second electrodes 6 and 7 from the end face side of the substrate 2 with a predetermined thickness, thereby achieving conduction between the two. Thus, the second electrode 7 and the third electrode 8 are formed so as to protrude in a stepwise manner from the central portion of the back surface of the substrate 2 toward the end surface. Then, the first, second,
Ni plating 9 and solder plating 10 are sequentially applied to cover the entire third electrodes 6, 7 and 8, and the shape of the electrode 4 on the back surface side of the substrate 2 after the solder plating 10 is applied also changes to the back surface of the substrate 2. Is formed so as to protrude stepwise from the central portion side toward the end surface side. The surface of the resistor 3 is protected by a glass coat 11 and a resin coat 12 as a protective coating. The glass coat 11 and the resin coat 12 on the surface of the resistor 3 are connected portions 12 a where the resistor 3 overlaps and is connected to the first electrode 6. It is located at a position protruding outward from the outer surface. Next, a method of manufacturing the chip resistor according to this embodiment will be described with reference to FIGS. First, as shown in FIG. 3A, a plurality of rows of metal glaze pastes serving as the first electrodes 6 are arranged at predetermined intervals across slits 14 which are division grooves of a ceramic plate 13 which is a large substrate to be divided. Print and bake at a temperature near 900 ° C. Further, similarly, the second electrode 7 is formed on the back surface of the ceramic plate 13 at a position facing the first electrode 6.
Next, as shown in FIG. 3B, a large number of resistors 3 are printed and formed in a matrix on the ceramic plate 13 between the first electrodes 6, and fired at a temperature of 850 ° C. on average. And FIG.
As shown in (C), a glass coat 1 is formed on the surface of the resistor 3.
And firing at an average temperature of 650 ° C. Thereafter, the ceramic plate 13 is divided individually along slits 14 provided vertically and horizontally for each chip resistor 1, and as shown in FIG. A third electrode 8 of a conductive paint is applied to a thickness of about 20 μ and cured at a temperature of about 200 ° C. Then, as shown in FIGS. 3E and 3F, Ni plating 9 and solder plating 10 are sequentially applied to cover the first, second, and third electrodes 6, 7, and 8 exposed to the outside. [0010] Finally, the resistor 3 of each chip resistor is trimmed to adjust the resistance value. Also, a resin coat 12 such as an epoxy resin is applied to the surface of the resistor 3 and cured at a temperature of about 200 ° C. The trimming may be performed in the state shown in FIG. 3 (C).
To perform the steps shown in FIG. As a result, the trimming operation can be performed efficiently because the resistance value is trimmed without separating the ceramic plate 13 for each chip, and the resin coat 12 has an adverse effect on the resistor even during the subsequent plating operation. Nor. According to the chip resistor of this embodiment, since the third electrode 8 of the Ag-resin type is formed by printing after being divided into the individual chip resistors 1, the first, second, and seventh electrodes 7 and 7 are formed.
The third electrode 8 is formed by printing on the surface of the substrate 8 and the five surfaces of the substrate end surface 2a and the side surface 2b, and the five surfaces of the terminal electrodes are formed as the electrodes 4. Therefore, the third electrode 8
It covers the end of the substrate in a cap shape, has high mechanical strength, hardly causes cracks, and hardly causes poor connection. In particular, by forming the third electrode 8 using a conductive paint of an epoxy phenol resin, it is possible to make the third electrode 8 more durable. Although the divided substrate end surface stands on a rough surface, by covering this rough surface with the third electrode 8 made of conductive paint, the third electrode is securely attached to the substrate end surface, and the end surface electrode is more mechanically mounted. Electrical and electrical reliability. Further, the second electrode 7 functions as an independent land between the second electrode 7 and the circuit board during soldering, and the solder penetrates between the second electrode 7 and the circuit board due to surface tension during soldering. However, the soldering area is limited, the insulating effect is high, and the fixing force to the circuit board is extremely strong. Further, since the solder is sucked below the second electrode 7, it is possible to shorten the distance between electrodes, chips
This enables the miniaturization of the terminal electrode of the resistor and the high-density mounting of the circuit board. Further, it is possible to pass a circuit pattern through the surface of the circuit board between the second electrodes 7, and the effect of preventing the unnecessary spread of the solder is extremely great in improving the mounting density. Further, since the back surface of the chip resistor protrudes stepwise and is soldered to the substrate at the tip,
The positioning is accurately performed, and the measurement of the resistance value and the like can be reliably performed. Furthermore, since the third electrode 8 and the first and second electrodes 6, 7 exposed to the surface are covered with the Ni plating 9 and the solder plating 10, there is no migration of silver atoms and good solderability. It is. further,
Glass coat 11 and resin coat 1 on the surface of resistor 3
2 is a connection portion 12a where the resistor 3 is connected to the first electrode 6.
Therefore, even if the resistor 3 faces the sliding surface side, even if the resistor 3 faces the sliding surface side, it is located at a position protruding outward from the outer surfaces of the glass coat 11 and the resin coat 12 at other portions on the resistor 3. Most do not touch the sliding surface. Thus, even when the chip resistors are sequentially supplied by a parts feeder or the like, the resin coat 12 on the surface of the resistor 3 is smoothly supplied without being attracted to the guide member or the like by static electricity. Similarly, since the portion of the second electrode 7 which is the back electrode also protrudes in a stepwise manner, it is not absorbed on the sliding surface. Incidentally, the resistor of the chip resistor according to the present invention comprises:
A metal film resistor, a carbon film resistor, and the like can be appropriately selected according to the application. The components of the metal glaze paste and the Ag-resin-based conductive paste may contain other additives as appropriate, and are not limited to those of this embodiment. [0016] [Effect of the Invention] The chip resistor covers the end face of the chip resistor in the third electrode of electrically conductive coating material, to increase the strength of the third electrode, and prevent the occurrence of cracks and the like, electrical reliability The nature is high . Also, the second electrode and the third electrode
The formation of the step between them surely restricts the soldering area and makes the fixing force to the circuit board extremely strong.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an embodiment of a chip resistor according to the present invention. FIG. 2 is a sectional view taken along line AA of FIG. FIGS. 3A, 3B, 3C, 3D, 3E, 3F are longitudinal sectional views showing steps of manufacturing the chip resistor according to the embodiment; FIGS. [Description of Signs] 1 Chip resistor 2 Substrate 2a End surface 2b Side surface 3 Resistor 4 Electrode 6 First electrode 7 Second electrode 8 Third electrode 9 Ni plating 10 Solder plating 11 Glass coating 12 Resin coating

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Mitsuru Yokoyama               3158 Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama               Hokuriku Electric Industry Co., Ltd. (72) Inventor Yozo Ohara               3158 Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama               Hokuriku Electric Industry Co., Ltd.                (56) References JP-A-61-245501 (JP, A)                 JP-A-55-120101 (JP, A)                 JP-A-55-99701 (JP, A)                 JP-A-61-210601 (JP, A)                 JP-A-61-268001 (JP, A)                 JP-A-57-184202 (JP, A)                 Shokai Sho 57-119501 (JP, U)                 Shokai 59-185801 (JP, U)

Claims (1)

(57) [Claims] A pair of insulating ceramics formed on the surface of the substrate
A first electrode and the first electrode sandwiching the substrate on the back surface of the substrate;
A pair of second electrodes formed at positions facing the pair of first electrodes.
A pole, a resistor formed between the pair of first electrodes,
Partially superimposed on the pair of first electrodes and the pair of second electrodes
To form a pair of side edges formed on a pair of side edges of the substrate.
A third electrode, an exposed portion of the pair of first electrodes,
Covering the exposed portion of the second electrode and the outer surfaces of the pair of third electrodes
A chip resistor comprising a plating layer.