JP2775718B2 - Chip resistor and manufacturing method thereof - Google Patents

Description

Description: 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. It relates to the manufacturing method. 2. Description of the Related Art Conventionally, the electrode structure of a chip resistor has been formed by applying and firing a so-called metal glaze paste containing Ag-Pt or the like using glass as a binder. Further, as disclosed in Japanese Patent Application Laid-Open No. 61-210601, there is also an electrode in which electrodes are formed on the back surface of a substrate, and the front and back electrodes are covered with 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 covers the periphery of the back surface electrode. In some cases, the solder spreads unnecessarily, or the solder contacts other electrodes or circuit patterns in some cases. Moreover, if the solder is widely adhered to the periphery of the back surface electrode, it will hinder the improvement of the mounting density of the circuit board. Or, it may come off the land of the circuit board. Further, in the process of the chip resistor, a heat treatment at a relatively high temperature, such as a metal glaze paste or a glass coat, is performed, which has a detrimental effect on the resistor and the like and an adverse effect on other formed portions. The present invention has been made in view of the above-mentioned conventional problems, and has a high soldering strength, a small soldering area, a high mounting density on a circuit board, and high quality. An object of the present invention is to provide a chip resistor that can be easily manufactured and a manufacturing method thereof. According to the present invention, a metal glaze-based first electrode which is directly connected to a resistor is provided at both ends of an insulator substrate surface. A metal glaze-based second electrode protruding from the rear surface of the substrate is also provided on the back surface of the opposite substrate with the substrate interposed therebetween, and the Ag-resin-based electrode covering both end surfaces of the substrate and contacting the first and second electrodes is provided. The third electrode partially covers the second electrode from the end face of the substrate with a predetermined thickness, and the third electrode is provided with the second electrode from the center of the back surface of the substrate toward both end faces. This is a chip resistor in which the third electrode is formed to protrude stepwise in two steps. The third electrode is formed in a U-shape, extends from an end surface of the substrate, directly contacts the first and second electrodes, and connects the first and second electrodes with a predetermined thickness from the end surface of the substrate. And a chip resistor in which the second electrode and the third electrode are formed so as to protrude in a stepwise manner from the center portion side to the end surface side of the back surface of the substrate. The resistor is covered with a glass coat and a resin coat, and the electrodes exposed to the outside are covered with plating. Further, according to the present invention, a metal glaze-based first electrode is formed at each end of each chip portion on the surface of an insulating substrate on which a large number of division grooves are formed to obtain a large number of chips by division. A metal glaze-based second electrode is formed on the opposite back surface of the substrate with the one electrode protruding from the back surface of the substrate, and a resistor is formed between the first electrodes; Is divided along the dividing grooves, and an Ag-resin-based conductive paint is applied to the divided both end surfaces of the substrate, and the conductive paint is formed in a U-shape and is formed on the first and second electrodes. A third electrode is formed which is in contact with and covers a part of the second electrode from the end face of the substrate with a predetermined thickness, and the second electrode and the third electrode are formed from the center of the back surface of the substrate toward the end face. A chip resistor formed by projecting three electrodes stepwise in two steps Vessels is a method of manufacturing. Further, the present invention is a method of manufacturing a chip resistor in which the conductive paint is directly applied to the end face of the substrate, and after forming the third electrode, the first, second and third electrodes exposed outside are covered with plating. Further, after the formation of the resistor, a glass coating is applied to the surface of the resistor, and trimming for adjusting the resistance value of the resistor is performed after the plating. Further, after applying a glass coat on the surface of the resistor, trimming is performed to adjust the resistance value of the resistor, a resin coat covering the resistor is formed, and then the substrate is divided into individual chip portions. This is a method for manufacturing a chip resistor. According to the chip resistor and the method of manufacturing the same of the present invention, the second and third electrodes are formed at both ends of the back surface of the substrate so as to protrude in a stepwise manner. The three electrodes come into contact with the circuit board, and the second electrode is slightly separated from the circuit board. Solder surely penetrates between the circuit board and the second electrode, and the soldering of the chip resistor is surely performed. At the same time, the soldering area is accurately restricted, and the solder is not inadvertently spread. An embodiment of the present invention will be described below with reference to the drawings. In the chip resistor 1 of this embodiment, as shown in FIG. 1, a convex resistor 3 is formed by printing on the surface of a ceramic substrate 2, and electrodes 4
Is provided. The resistor 3 is composed of about 1 part of ruthenium oxide.
It is provided with a thickness of 0 μm, and a trimming groove 5 is formed upward from the bottom of the convex shape by laser or sandblast to trim the resistance value. 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,
On the end face of the substrate 2 between the second electrodes 6 and 7, a third electrode 8 made of a paste of an 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, thereby achieving conduction between the two. Thus, the second electrode 7 and the third electrode 8 are formed so as to protrude in two steps 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. 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 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 a metal glaze paste to be the first electrode 6 are printed at predetermined intervals with 4 interposed therebetween and fired at a temperature close to 900 ° C. Further, similarly, the second electrode 7 is also connected to the ceramic plate 1.
3 is formed on the back surface 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 along the slits 14,
As shown in (D), a third electrode 8 of an Ag-resin-based conductive paint is applied to the end surface of the substrate 2 to a thickness of about 20 μm.
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 such as an epoxy resin is applied to the surface of the resistor 3 and cured at a temperature of about 200 ° C. In some cases, the trimming is performed in the state shown in FIG. 3C.
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, the solder penetrates between the second electrode 7 and the circuit board at the time of soldering, between the second electrode 7 and the circuit board. The effect is high and the fixing force to the circuit board is extremely strong. Further, since the solder is sucked below the second electrode, the distance between the electrodes can be shortened, and the chip resistor can be reduced in size and the circuit board can be mounted at a high density. Furthermore, it is also possible to pass a circuit pattern on the circuit board surface between the second electrodes,
The effect of improving the mounting density by preventing unnecessary spread of the solder is extremely large. In the manufacturing process, the temperature of the heat treatment in the subsequent step is lower than the temperature of the heat treatment in the previous step.
A high-quality chip resistor can be manufactured without adversely affecting a portion formed in a previous step by a heat treatment in a subsequent step. Furthermore, by performing the trimming after the electrode 4 is solder-plated and the individual chip resistors are formed, the influence of the resistor due to heat in each step can be removed, and a more accurate chip resistor can be obtained. Can be provided. Furthermore, the chip resistor of this embodiment is
Since the divided end face is covered with the third electrode 8 made of a conductive resin, the edge of the divided part is covered with the resin, so that the edge is hardly disconnected. 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. 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. 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, and the soldering is performed. The area is reliably limited, and the adhesion to the circuit board is extremely strong. Also, since the solder is sucked below the second electrode, the distance between the electrodes of the chip resistor and the distance between the electrodes and other electronic components on the circuit board can be shortened. This enables high-density mounting of circuit boards.

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, and 3F are longitudinal sectional views showing steps of manufacturing the chip resistor according to the embodiment; FIGS. [Description of References] 1 Chip resistor 2 Substrate 3 Resistor 4 Electrode 6 First electrode 7 Second electrode 8 Third electrode 9 Ni plating 10 Solder plating

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yozo Ohara               3158 Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama               Hokuriku Electric Industry Co., Ltd.

Claims (1)

(57) [Claims] A metal glaze-based first electrode that is directly connected to the resistor is provided at both ends of the substrate surface of the insulator, and the metal glaze-based first electrode is also provided on the back surface of the substrate opposite to the first electrode. A second electrode is provided so as to protrude from the back surface of the substrate, and a third electrode covering both end surfaces of the substrate and in contact with the first and second electrodes is provided. The third electrode connects the second electrode to the end surface of the substrate. A chip resistor which is partially covered with a predetermined thickness from the center of the back surface of the substrate, and wherein the second electrode and the third electrode are formed to protrude in two steps from the center to the both end surfaces. 2. The third electrode is formed in a U-shape, extends from an end surface of the substrate, directly contacts the first and second electrodes, and
The two electrodes are covered with a predetermined thickness from the end face side of the substrate, and the second electrode and the third electrode are formed so as to protrude in a stepwise manner from the center part side of the back surface of the substrate toward the end face side. 2. The chip resistor according to 1. 3. The chip resistor according to claim 1, wherein the resistor is covered with a glass coat and a resin coat, and the electrode exposed to the outside is covered with plating. 4. A large number of dividing grooves are formed, and a large number of chips are obtained by division. A metal glaze-based first electrode is formed at each end of each chip portion on the surface of the insulating substrate, and the substrate is sandwiched between the first electrodes. A metal glaze-based second electrode is formed on the opposite substrate back surface so as to protrude from the substrate back surface, a resistor is formed between the first electrodes, and the substrate is divided along the division grooves. Then, a conductive paint is applied to the divided two end surfaces of the substrate, and the conductive paint is formed in a U-shape, contacts the first and second electrodes, and a part of the second electrode is attached to the substrate. The third one covered with a predetermined thickness from the end face side
A method of manufacturing a chip resistor, comprising forming electrodes and forming the second electrode and the third electrode so as to protrude in two steps from the center to the end face of the back surface of the substrate. 5. 5. The third electrode is an Ag-resin-based conductive paint, applied directly to the end face of the substrate, and covers the first, second, and third electrodes exposed to the outside by plating after the formation of the third electrode. A manufacturing method of the chip resistor according to the above. 6. 6. The method according to claim 5, wherein after the formation of the resistor, a glass coating is applied to the surface of the resistor, and trimming for adjusting the resistance value of the resistor is performed after the plating. 7. After applying a glass coat on the surface of the resistor, trimming is performed to adjust the resistance value of the resistor, a resin coat covering the resistor is formed, and then the substrate is divided into individual chip portions. Item 6. The method for manufacturing a chip resistor according to item 4 or 5.