JPH07183108A - Manufacture of chip resistor - Google Patents

Abstract

PURPOSE:To reduce the generation of the continuity failure between resin side surface electrode layers and to increase the reliablity of a chip resistor by a method wherein both side parts of a ceramic substrate provided with notch parts on both side surfaces thereof are respectively dipped in a metal resin conductive paste and the resin side surface electrode layers are formed. CONSTITUTION:Vertical and lateral grooves for breaking and through holes 11c' are first provided in a ceramic substrate 11. Then, a metal grease conductive paste is printed and calcined on the surface of the substrate 11 independently in every angle unit region, which is arranged in the vertical direction, lying across both sides of the vertical grooves and in such a way as to cover a part of each through hole 11c' and surface electrode layers 12 are provided. Moreover, with rear electrode layers 13 formed at positions which oppose to the layers 12 holding the substrate 11 between the layers 12 and 13, on the rear of the substrate 11, a resistor layer 14 is provided lying across the layers 12 adjacent to each other in the lateral direction. The resistance value of the layer 14 is adjusted and a protective layer 15 is formed. Thereby, the generation of the continuity failure between the surface and rear electrode layers is reduced and the reliability of a chip resistor is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a chip resistor, and more particularly, to a method of manufacturing a chip resistor in which a resin-based electrode layer is formed on a side surface of a ceramic substrate.

[0002]

2. Description of the Related Art A general structure of a conventional chip resistor is shown in FIG. Surface electrode layers 2 are formed on both ends of the surface of the ceramic substrate 1, and a resistor layer 3 is formed between the surface electrode layers 2.
Is formed, and the resistor layer 3 has a trimming groove 4 formed by adjusting the resistance value and is covered with a protective layer 5. On the other hand, a back surface electrode layer 6 is formed on both sides of the back surface of the ceramic substrate 1, and a side surface electrode layer 7 connecting the back surface electrode layer 6 and the front surface electrode layer 2 is formed. These electrode layers 2, 6 and 7 are covered with a plated layer 8.

Conventionally, in the manufacture of the above chip resistor, a plurality of vertical and horizontal grooves are provided in a lattice pattern on the surface of an unfired ceramic sheet and then fired, as shown in FIG.
A ceramic substrate 1 having vertical and horizontal grooves 1a and 1b on its surface is obtained, and the vertical and horizontal grooves 1a and 1b on the surface of the ceramic substrate 1 are obtained.
As shown in FIG. 8, the surface electrode layer 2 and the resistor layer 3 are formed in each of the unit areas A divided by, and the surface electrode layer 2 is sandwiched on the back surface of the ceramic substrate 1 with the ceramic substrate 1 interposed therebetween. A back electrode layer 6 is formed at a position facing the resistance layer 3, the resistance layer 3 is trimmed to adjust the resistance value, and then a protection layer 5 covering the resistance layer 3 is formed. Next, as shown in FIG. Then, the ceramic substrate 1 is broken into a plurality of rod-shaped pieces 1'by breaking along the vertical grooves 1a, and as shown in FIG. 5, on both longitudinal side surfaces 1'a, 1'b of the rod-shaped pieces 1 '. The side electrode layer 7 is formed, and then the rod-shaped piece 1'is broken along the lateral groove 1b to obtain a chip shape.

Generally, as a method of forming the side surface electrode layer 7 on both longitudinal side surfaces 1'a, 1'b of the rod-shaped piece 1 ', a metal glaze system in which metal particles such as silver and palladium are mixed in a glass paste. A method of printing and firing a conductive paste to form a glass-based electrode layer is adopted. However, since the protective layer 5 and the side surface electrode layer 7 are formed after the resistance value of the resistor layer 3 is adjusted, when the protective layer 5 and the side surface electrode layer 7 are provided by high temperature firing, the resistor layer 3 is formed.
There is a problem that the resistance value of the resistor layer 3 is slightly deviated from the adjusted value due to changes in the oxidation state of the metal components therein. This problem has become one of the problems to be solved in the chip resistor as the precision of electronic parts has been required more and more recently. Therefore, in order to cope with the present situation, recently, the side electrode layer 7 is printed and cured with a metal resin conductive paste in which a thermosetting resin such as an epoxy resin is mixed with metal particles such as silver and palladium. By forming the resin-based electrode layer at a relatively low temperature, the deviation of the resistance value can be reduced as much as possible.

[0005]

However, when the resin-based side electrode layer is used as described above, the resin-based side electrode layer has poorer adhesion to the ceramic substrate than the glass-based side electrode layer and peels off. There is a problem that it is easy. That is, according to the above-mentioned conventional method, the ceramic substrate 1 on which the surface electrode layer 2, the resistor layer 3 and the protective layer 5 are formed is provided with the vertical groove 1a.
When the resin-based side electrode layer 7 is formed on both side surfaces 1'a, 1'b in the longitudinal direction of the obtained rod-shaped piece 1 ', the side surface layers 1'in the longitudinal direction of the rod-shaped piece 1'are broken. a, 1'b
Is composed of a side wall portion of the vertical groove 1a and a fractured portion that is actually divided. The side wall portion has a relatively large surface because the firing proceeds while contacting with the outside air during firing of the unfired ceramic sheet. On the other hand, the fractured portion is a mirror surface due to the characteristics of the ceramic when it is broken, and the resinous side surfaces are formed on both side surfaces 1'a, 1'b in the longitudinal direction of the rod-shaped piece 1 '. When the electrode layer 7 is formed, there is a problem that the side surface electrode layer 7 has a low adhesive force particularly at the fractured portion, which is a mirror surface, and the side surface electrode layer 7 is peeled off, which causes poor conduction. .

The present invention provides a chip resistor having resin-based side electrode layers formed on both sides of a ceramic substrate,
An object of the present invention is to provide a highly reliable chip resistor by reducing the occurrence of conduction failure due to the peeling of the side surface electrode layer.

[0007]

In order to achieve the above object, the present invention provides notches on both side surfaces of a ceramic substrate and dips each side portion of the ceramic substrate in a metal resin conductive paste. Then, the resin-based side electrode layer was formed. That is, the present invention relates to the following method. Along with providing a plurality of vertical grooves and lateral grooves on the surface of the unfired ceramic sheet, providing a plurality of through holes along the vertical groove, the unfired ceramic sheet is fired, a plurality of breaking vertical grooves and lateral grooves, And a step of forming a ceramic substrate having a plurality of through-holes, and the ceramic substrate is divided into unit regions corresponding to one chip resistor by the vertical grooves and the horizontal grooves, and is arranged in the vertical direction on the surface of the ceramic substrate. Independently for each unit area, straddling both ends of the vertical groove, and forming a glass-based surface electrode layer by printing a metal glaze-based conductive paste so as to cover at least a part of the through hole, and then in the lateral direction. A step of forming a resistor layer across the surface electrodes adjacent to each other, a step of breaking the ceramic substrate along the vertical groove into a rod-shaped piece, and a step of forming a rod-shaped piece along the longitudinal direction of the rod-shaped piece. A step of forming a resin side electrode layer by applying a metal resin conductive paste on each of the surfaces by dipping, and a step of breaking the rod-shaped pieces along the lateral grooves to form individual chip resistors. A method of manufacturing a chip resistor, comprising:

[0008]

According to the present invention, the ceramic substrate has a plurality of vertical grooves and horizontal grooves on its surface, and also has through holes extending along the vertical grooves. On the surface of this ceramic substrate, 1 is formed by each vertical groove and horizontal groove.
The metal glaze system is divided into unit regions corresponding to individual chip resistors, is independent for each unit region arranged in the vertical direction, extends over both ends of the vertical groove, and covers at least a part of the through hole. When the glass-based surface electrode layer is formed by printing the conductive paste, the glass-based surface electrode layer is formed in a part or all of the through hole.

Since the ceramic substrate on which the glass-based surface electrode layer is formed is broken along the vertical groove as described above, a part or all of the wall surface of the cutout portion on both sides of the obtained ceramic rod-shaped piece is broken. Has a glass-based surface electrode layer formed thereon. Therefore, the area of the ceramic surface exposed on the side surface of the rod-shaped piece is reduced by the amount of the surface electrode layer formed in the cutout portion.
When both sides of this rod-shaped piece are dipped in a metal resin conductive paste to form a resin-based side electrode layer, the resin-based side electrode layer should adhere to the glass-based surface electrode layer at the notch. Therefore, the area where the resin-based side surface electrode layer and the glass-based surface electrode layer overlap with each other increases. Further, the side surface electrode layer is formed so as to substantially completely fill the recess in the cutout portion.

The glass-based surface electrode layer is superior in adhesiveness to the ceramic substrate as compared with the resin-based side electrode layer,
Further, the resin-based side surface electrode layer is more excellent in adhesion to the glass-based surface electrode layer than to the ceramic substrate. Therefore, as described above, the contact area of the resin-based side surface electrode layer with the glass-based surface electrode layer increases, while the contact area with the ceramic substrate decreases, so that the adhesion of the resin-based side surface electrode layer is improved. Can improve.

Further, the notch portion increases the coating area of the resin-based side surface electrode layer, and the layer thickness of the resin-based side surface electrode layer can be increased at the notch portion. Since the anchor effect is increased by the resulting recessed portion, the adhesion of the resin-based side electrode layer can be improved. As described above, according to the present invention, the adhesiveness of the resin-based side electrode layer can be improved, so that the problem of conduction failure due to peeling of the side electrode layer can be reduced, and a highly reliable chip resistor is provided. You can do it.

[0012]

EXAMPLES The features of the present invention will be described below in more detail by showing Examples of the present invention, but the present invention is not limited thereto. A vertical sectional view and a horizontal sectional view of an example of a chip resistor obtained by the method of the present invention are shown in FIGS. 1 (a) and (b)
Among them, reference numeral 11 is a ceramic substrate, reference numeral 11c ′ is a notch, reference numeral 12 is a front electrode layer, reference numeral 13 is a back electrode layer, reference numeral 14 is a resistor layer, reference numeral 14a is a trimming groove, and reference numeral 14a is a trimming groove. Reference numeral 15 is a protective layer, reference numeral 16 is a side electrode layer, and reference numeral 17 is a plating layer.

First, on the surface of the unfired ceramic sheet,
A plurality of vertical grooves and horizontal grooves having a depth of about half the thickness of the unsintered ceramic sheet are provided in a grid pattern, and a plurality of through holes penetrating in the thickness direction of the ceramic sheet are provided along the vertical grooves. As shown in FIG. 2, the vertical groove 11a and the horizontal groove 11b for breaking, and the through hole 1 are fired.
A ceramic substrate 11 having 1c is obtained. At this time, the through hole 11c is divided by the vertical groove 11a and the horizontal groove 11b, and is a unit area B corresponding to one chip resistor.
At least one or more are provided on the vertical grooves 11a at both ends of. The through hole 11c is not limited to a circular shape in plan view, and may have an appropriate shape such as an elliptical shape, a quadrangular shape, and an H shape.

Next, as shown in FIG. 3, the vertical groove 11a is formed.
On the surface of the ceramic substrate 11 divided into the unit regions B by the lateral grooves 11b, each of the unit regions B arranged in the vertical direction is independent, and extends over both sides of the vertical groove 11a, and at least the through hole 11c. To cover a part
For example, a so-called metal glaze-based conductive paste in which metal particles such as silver or silver / palladium are mixed in the glass paste is printed and fired to form the glass-based surface electrode layer 12.
Further, on the back surface of the ceramic substrate 11, a glass-based back electrode layer 13 is formed by printing and firing, for example, a metal glaze-based conductive paste at a position facing the front electrode layer 12 with the ceramic substrate 11 interposed therebetween. , The resistor layer 1 across the surface electrode layers 12 adjacent in the lateral direction.
4 is provided. Then, the resistance value is adjusted by trimming as necessary, and a protective layer 15 made of glass or resin is formed so as to cover the resistor layer 14.

Next, as shown in FIG. 4, the ceramic substrate 11 on which the layers 12, 13, 14, and 15 are formed as described above is broken along the vertical grooves 11a to obtain rod-shaped pieces 11 '. . Next, as shown in FIG. 5, the longitudinal side portions 11'a and 11'b (break surface side) of the rod-shaped piece 11 'are respectively provided with, for example, silver particles, silver / palladium particles, or other metal particles, epoxy resin, or the like. The resin side electrode layer 16 is provided by immersing the resin in the metal resin conductive paste mixed with the thermosetting resin or the ultraviolet curable resin and heating or irradiating the resin to cure the resin. The method of immersing the longitudinal side portions 11'a, 11'b of the rod-shaped piece 11 'in the metal resin-based conductive paste is not particularly limited, and is described in, for example, Japanese Patent Publication No. 3-52201. It can be performed by an apparatus and method using a coating roller having a notched groove formed on the outer peripheral surface. At this time, the resin-based side surface electrode layer 16 is formed on the surface of the ceramic substrate 11,
The side surface and the back surface come into close contact with the glass-based front surface electrode layer 12 and the back surface electrode layer 13.

Then, the rod-shaped piece 11 'is attached to the lateral groove 11'.
A chip resistor is formed by breaking along b to form a chip and providing a plating layer 17, for example, a Ni plating layer and a solder plating layer so as to cover the front surface electrode layer 12, the back surface electrode layer 13 and the side surface electrode layer 16. It is said that

[Brief description of drawings]

FIG. 1A is a vertical sectional view and FIG. 1B is a horizontal sectional view showing a chip resistor obtained in an embodiment of the present invention.

FIG. 2 is a partial top view showing a ceramic substrate according to an example of the present invention.

3 is a partial top view showing a state in which a front surface electrode layer, a back surface electrode layer, a resistor layer and a protective layer are provided on the ceramic substrate of FIG.

FIG. 4 is a schematic top view illustrating a state in which the ceramic substrate of FIG. 2 is broken along a vertical groove to form a rod-shaped piece.

FIG. 5 is an enlarged top view showing a state in which side electrode layers are provided on both side portions along the longitudinal direction of the rod-shaped piece in the example of the present invention.

FIG. 6 is a vertical sectional view showing a chip resistor obtained by a conventional method.

FIG. 7 is a partial top view showing a ceramic substrate in a conventional method.

8 is a partial top view showing a state in which a front surface electrode layer, a back surface electrode layer, a resistor layer and a protective layer are provided on the ceramic substrate of FIG.

[Explanation of symbols]

 11 Ceramic Substrate 11a Vertical Groove 11b Horizontal Groove 11c Through Hole 11c 'Notch 11' Rod-like Piece 11'a, 11'b Longitudinal Side of Rod-like Piece 12 Front Electrode Layer 13 Back Electrode Layer 14 Resistor Layer 15 Protective Layer 16 Side Electrode layer B Unit area

Claims (1)

[Claims] 1. A plurality of vertical grooves and horizontal grooves are provided on the surface of an unfired ceramic sheet, and a plurality of through holes are provided along the vertical groove, and the unfired ceramic sheet is fired to obtain a plurality of breaks. A step of forming a ceramic substrate having vertical grooves, horizontal grooves, and a plurality of through holes; and a surface of the ceramic substrate partitioned by the vertical grooves and horizontal grooves into a unit area corresponding to one chip resistor, A glass-based surface electrode layer is formed by printing a metal glaze-based conductive paste so as to be independent for each unit region arranged in the vertical direction, straddle both ends of the vertical groove, and cover at least a part of the through hole. Then, a step of forming a resistor layer across the surface electrodes adjacent to each other in the lateral direction, a step of breaking the ceramic substrate along the vertical groove to form a rod-shaped piece, and a length of the rod-shaped piece A step of forming a resin-based side electrode layer by immersing each of both side portions along the hand direction in a metal resin-based conductive paste, and an individual chip resistor by breaking the rod-shaped piece along the lateral groove. A method of manufacturing a chip resistor, comprising: