JPH07147203A - Chip resistor and its manufacture - Google Patents

Abstract

PURPOSE:To increase soldering strength, reduce soldering part area, improve packaging density, realize high quality, and facilitate manufacturing. CONSTITUTION:Metal glaze based first electrodes 6 which are directly in contact with a resistor 3 are formed on both end parts of the surface of an insulative beard 2. Second metal glaze based electrodes 7 are formed on the rear of the board as the opposite side of the first electrodes 6, so as to protrude from the rear of the board. Third electrodes 8 which cover directly both end surfaces of the board 2 and are in contact with the first and the second electrodes 6, 7 are formed. The third electrodes 8 covere a part of the second electrodes 7 with a specific thickness, from the end surface sides of the board 2. The second electrodes 7 and the third electrodes 8 are formed step-wise, from the central part of the rear of the board 2 toward the end surface sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip resistor in which a resistor is provided on the surface of a chip-shaped insulating substrate and electrodes are formed at both ends of the substrate, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, the structure of the electrodes of a chip resistor has been formed by applying a so-called metal glaze paste containing Ag-Pt or the like as a component using glass as a binder and firing it. Further, as disclosed in Japanese Patent Laid-Open No. 61-210601, there is also one in which electrodes are formed on the back surface of the substrate and the electrodes on the front and back sides are contained in a conductive paste and cured by heating to form the electrodes.

[0003]

In the above-mentioned conventional technique, when the chip resistor is soldered to the circuit board, the solder joined to the electrode on the back surface of the chip resistor spreads around the back electrode. In some cases, the solder was unnecessarily spread, or the solder came into contact with other electrodes or circuit patterns in some cases. Moreover, if the solder is widely adhered around the back surface electrode, it hinders the improvement of the mounting density of the circuit board, and due to the warp of the circuit board or the like later, a part of the soldered part that has spread becomes a back surface electrode of the chip resistor. Alternatively, it may come off from the land of the circuit board.

Further, heat treatment at a relatively high temperature such as metal glaze paste or glass coating is performed in the process of the chip resistor, which has a bad influence on the deterioration of the resistor or the like and other parts to be formed.

The present invention has been made in view of the above problems of the prior art, and has a high soldering strength, a small area of a soldering portion, a high mounting density on a circuit board, and high quality. It is an object of the present invention to provide a chip resistor which can be easily manufactured and a manufacturing method thereof.

[0006]

According to the present invention, a metal glaze type first electrode directly connected to a resistor is provided at both ends of a substrate surface of an insulator, and the first electrode separates the substrate. On the opposite side of the substrate, a metal glaze type second electrode is also provided so as to project from the substrate backside, and a third electrode that directly covers both end faces of the substrate and is in contact with the first and second electrodes is provided. The third electrode covers a part of the second electrode from the end surface side of the substrate with a predetermined thickness, and the second electrode and the third electrode from the central portion side of the back surface of the substrate toward the end surface side.
It is a chip resistor in which electrodes are formed so as to project in a stepwise manner.

The resistor is covered with a glass coat and a resin coat, and the first, second and third electrodes exposed to the outside are all covered with Ni plating and solder plating.

Further, according to the present invention, metal glaze-based first electrodes are respectively formed on both ends of each chip portion on the surface of a large-sized substrate of an insulator in which a large number of dividing grooves are formed. Form a metal glaze type second electrode on the opposite side of the substrate across the substrate so as to project from the substrate back side, and form a resistor between each of the first electrodes. A glass coat is applied, the substrate is divided along the dividing groove, both end faces of the divided substrate are directly covered to contact the first and second electrodes, and part of the second electrode is attached to the substrate end face side. A method of manufacturing a chip resistor, in which a third electrode covering a predetermined thickness is formed from the substrate, and the second electrode and the third electrode are formed so as to protrude stepwise from the central portion side of the back surface of the substrate toward the end surface side. Is.

Further, all of the first, second, and third electrodes exposed to the outside are covered with Ni plating and solder plating, and trimming for adjusting the resistance value of the resistor is performed as individual chip resistors after the solder plating. This is done after it is formed.

Further, during the heat treatment in each of the above steps,
When heat treating different materials in the previous process and the subsequent process,
The heat treatment temperature of the subsequent process is lower than the heat treatment temperature of the previous process.

[0011]

According to the chip resistor and the method of manufacturing the same of the present invention, the second and third electrodes are formed in a stepwise manner on both ends of the back surface of the substrate, and when the chip resistor is mounted on the circuit board, The three electrodes contact the circuit board, the second electrode is slightly separated from the circuit board, and the solder surely invades between the circuit board and the second electrode to ensure the soldering of the chip resistor. In addition, the soldering area is accurately limited, and the solder does not spread unintentionally.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The chip resistor 1 of this embodiment is shown in FIG.
As shown in FIG. 3, a convex resistor 3 is printed on the surface of the ceramic substrate 2, and electrodes 4 are provided on both ends of the resistor 3. The resistor 3 is made of ruthenium oxide having a thickness of about 10 μm, and a trimming groove 5 is formed upward from the bottom of the convex shape by laser or sandblasting to trim the resistance value.

The electrode 4 of the chip resistor 1 is a resistor 3
The first electrode 6 whose both ends are directly connected to each other, and
The second electrode 7 is formed so as to face the electrode 6 and the substrate 2 and to project to the back surface side of the substrate 2. The first and second electrodes 6 and 7 are Ag-Pd and Ag-Pt. It is formed by printing a metal glaze paste such as. In addition, the first,
On the end surface of the substrate 2 between the second electrodes 6 and 7, a third electrode 8 made of a paste of Ag-resin-based conductive paint in which Ag is mixed in xylene or epoxyphenol resin 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, and achieves electrical continuity between them. As a result, the second electrode 7 and the third electrode 8 are formed so as to project in a stepwise manner from the central portion side of the back surface of the substrate 2 toward the end surface side.

The first, second, and
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 is also the back surface of the substrate 2. Is formed so as to project in a stepwise manner from the central portion side toward the end face side. The surface of the resistor 3 is protected by a glass coat 11 and a resin coat 12.

Next, a method of manufacturing the chip resistor of this embodiment will be described with reference to FIGS. First, as shown in FIG. 3A, a slit 1 which is a dividing groove of a ceramic plate 13 which is a large substrate to be divided.
A plurality of rows of the metal glaze paste to be the first electrodes 6 are printed at predetermined intervals with 4 sandwiched therebetween, and baked at a temperature close to 900 ° C. Further, similarly, the second electrode 7 is also connected to the ceramic plate 1
It is formed on the back surface of No. 3 at a position facing the first electrode 6. Next, as shown in FIG. 3 (B), 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), the glass coat 1 is formed on the surface of the resistor 3.
1 and baked at an average temperature of 650 ° C. After this, the ceramic plate 13 is divided along the slits 14,
As shown in (D), the third electrode 8 of Ag-resin-based conductive paint is applied to the end surface of the substrate 2 to a thickness of about 20 μ, and 2
It is cured at a temperature of about 00 ° C. And FIG. 3 (E),
As shown in (F), 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.

Finally, the resistor 3 of each chip resistor is trimmed to adjust the resistance value. Further, a resin coat 12 of epoxy resin or the like is applied to the surface of the resistor 3 and cured at a temperature near 200 ° C.

The trimming may be performed in the state shown in FIG. 3C. In this case, the resin coat 12 is then used.
Then, the steps following FIG. 3D are performed. As a result, the resistance value is trimmed without separating the ceramic plate 13 into chips, so that the trimming work can be performed efficiently, and the resin coat 12 adversely affects the resistor during the subsequent plating work. Nor.

According to the chip resistor of this embodiment, the solder penetrates between the circuit board and the second electrode 7 at the time of soldering to limit the soldering area,
In addition to having a high insulation effect, it also has an extremely strong adhesion to the circuit board. Further, since the solder is sucked below the second electrode, the distance between the electrodes can be shortened,
This enables miniaturization of chip resistors and high-density mounting of circuit boards. Further, it is possible to pass a circuit pattern on the surface of the circuit board between the second electrodes, and the effect of improving the mounting density by preventing unnecessary spread of solder is extremely large.

In the manufacturing process, the temperature of the heat treatment in the subsequent process is lower than the temperature of the heat treatment in the previous process,
It is possible to manufacture a high quality chip resistor without adversely affecting the portion formed in the previous process by the heat treatment in the subsequent process. Furthermore, by trimming after the electrodes 4 are solder-plated and the individual chip resistors are formed, it is possible to eliminate the effect of the resistor due to heat in each step, and to provide a more accurate chip resistor. Can be provided.

Further, in the chip resistor of this embodiment, since the divided end face portion is covered with the third electrode 8 made of a conductive resin, the edge of the divided portion is covered with the resin and the disconnection at this edge portion occurs. Is less likely to occur. Further, since the back surface of the chip resistor projects in a stepwise manner and is soldered to the substrate at the tip of the chip resistor, the positioning is accurately performed, and the resistance value can be measured reliably.

The resistor element of the chip resistor of the present invention is
A metal film resistor, a carbon film resistor, or the like can be appropriately selected according to its use. Further, the components of the metal glaze paste and the Ag-resin-based conductive paste may appropriately contain other additives, and are not limited to those of this embodiment.

[0022]

According to the chip resistor and the method of manufacturing the same of the present invention, when the chip resistor is soldered to the circuit board, the solder penetrates between the second electrode and the circuit board to ensure the soldering area. It is limited to, and the adhesion force to the circuit board is extremely strong. Further, since the solder is sucked below the second electrode, the distance between the electrodes of the chip resistor and the electrode interval with other electronic components on the circuit board can be shortened, and the chip resistor can be made smaller and smaller. It enables high-density mounting of circuit boards.

Further, in the manufacturing process, the heat treatment temperature of the subsequent process is lower than the heat treatment temperature of the previous process, so that the portion formed in the previous process is not adversely affected in the subsequent process, and is of high quality and high accuracy. A chip resistor can be provided.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a chip resistor of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 (A), (B), (C), (D), (E), and (F) are vertical cross-sectional views showing the manufacturing process of the chip resistor of this embodiment.

[Explanation of symbols]

 1 Chip Resistor 2 Substrate 3 Resistor 4 Electrode 6 First Electrode 7 Second Electrode 8 Third Electrode 9 Ni Plating 10 Solder Plating

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[Procedure amendment]

[Submission date] October 19, 1994

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yozo Ohara 3158 Shimookubo, Osawano-cho, Kamishinagawa-gun, Toyama Prefecture Hokuriku Electric Industry Co., Ltd.

Claims (6)

[Claims] 1. A metal glaze-based first electrode directly connected to a resistor is provided at both ends of a substrate surface of an insulator,
A metal glaze-based second electrode is provided on the back surface of the substrate opposite to the first electrode so as to project from the back surface of the substrate, and both end surfaces of the substrate are covered with the first and second electrodes. A contacting third electrode is provided, which is the second electrode
A chip in which a part of the electrode is covered with a predetermined thickness from the end face side of the substrate, and the second electrode and the third electrode project in a stepwise manner from the central portion side of the back face of the substrate toward the end face side. Resistor. 2. The third electrode is directly formed on the end surface of the substrate, the resistor is covered with a glass coat and a resin coat, and the first, second and third electrodes exposed to the outside are all Ni-plated and soldered. Claim 1 covered with plating
The listed chip resistor. 3. A metal glaze-based first electrode is formed on each end of each chip portion on the surface of an insulating substrate where a large number of dividing grooves are formed and a large number of chips are obtained by division. Form a metal glaze type second electrode on the opposite side of the substrate across the substrate so as to project from the substrate backside, form a resistor between each of the first electrodes, and divide the substrate into Divide along the groove, print Ag-resin-based conductive paint on the divided both end faces of the substrate, and bake it so that the Ag-resin-based conductive paint contacts the first and second electrodes. At the same time, a third electrode is formed by covering a part of the second electrode from the substrate end face side with a predetermined thickness, and the second electrode and the third electrode are formed from the center side of the substrate back face toward the end face side. A method of manufacturing a chip resistor, which is formed by projecting in a stepwise manner. 4. The third electrode is directly printed on the end face of the substrate, and after forming the third electrode, the first, second and third electrodes exposed to the outside are all covered with Ni plating and solder plating. Manufacturing method of chip resistor. 5. The method of manufacturing a chip resistor according to claim 3, wherein after forming the resistor, a glass coat is applied to the surface of the resistor, and trimming for adjusting the resistance value of the resistor is performed after the solder plating. . 6. A metal glaze-based first electrode is printed on both ends of each chip portion of a large-sized substrate surface of an insulator in which a large number of dividing grooves are formed, and each is baked at a predetermined temperature. A metal glaze-based second electrode is similarly formed on the back surface of the substrate opposite to the electrode so as to sandwich the first electrode.
A resistor is printed between the electrodes, the resistor is fired at a temperature lower than the firing temperature of the first electrode, the surface of the resistor is glass-coated, and the glass coat is heated at a temperature lower than the firing temperature of the resistor. And the substrate is divided along the dividing groove so as to cover both end faces of the divided substrate so as to contact the first and second electrodes and a part of the second electrode from the substrate end face side. Print a third electrode with a thickness of
A method of manufacturing a chip resistor in which the third electrode is thermally cured at a temperature lower than the firing temperature of the glass coat.