JPH09129406A - Electronic component and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the occurrence of a cobwebbing phenomenon and to improve an electrode in mechanical strength so as to enhance an electronic component in reliability by a method wherein the edge face electrode is formed of material composed of nickel, carbon, and resin. SOLUTION: An edge face electrode 15 is provided on the edge face of a board 11 so as to be electrically connected to an upper surface electrode layer 12. The edge face electrode 15 is formed through such a manner that a mixed powder of nickel with knurls and carbon and thermosetting polymer are mixed into conductive paste, the conductive paste is applied onto a roller, and the applied conducive paste is transferred and cured. At this point, the paste material is of thixotropy index 5 to 8. A nickel plating layer 16 is provided covering the edge face electrode 15, and a solder plating layer 17 is provided so as to cover the nickel plating layer 17. By this setup, an edge electrode stable in shape is formed, whereby an electronic component high in reliability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, as the demand for lighter, thinner, shorter, and smaller electronic devices has increased, chip-type electronic components have been widely used as electronic components in order to increase the wiring density of circuit boards. . In addition, the demand for precision chip resistors with improved resistance precision is also increasing.

Hereinafter, an example of a chip type resistor as a conventional electronic component will be shown and described with reference to the drawings. FIG. 7 is a perspective view of a conventional chip resistor, and FIG. 8 is a sectional view taken along line AA of FIG.

In the figure, 1 is a substrate made of 96 alumina. Reference numeral 2 is an upper surface electrode layer provided on a side portion of the upper surface of the substrate 1. Reference numeral 3 is a resistance layer formed by a ruthenium-based thick film resistor provided on the upper surface of the substrate 1 so as to be electrically connected to the upper electrode layer 2. Reference numeral 4 is a protective layer made of resin provided so as to cover at least the resistance layer 3. Reference numeral 5 denotes an end face electrode made of a silver resin provided on the end face of the substrate 1 so as to be electrically connected to the upper surface electrode layer 2. Reference numerals 6 and 7 are nickel plating layers and solder plating layers provided so as to cover the end surface electrodes 5 in order to secure solderability, and constitute a conventional chip-type resistor.

[0005]

The use of silver-based resin for the end face electrodes of electronic parts such as the conventional chip resistors has the following problems.

(1) As the silver powder, flaky silver powder (atypical silver powder, which is processed to be crushed and crushed, has been subjected to an anti-agglomeration treatment on the powder surface. The interfacial strength between the resin electrode and the resin electrode is weak, and the resin electrode has a small anchoring force such as a spherical shape. Since the strength of itself (cohesive fracture strength) is weak, the electrode strength becomes weaker than that of the conventional thick film firing electrode (fired at 600 ° C.).

(2) The silver powder content has an upper limit in order to secure the strength of the electrode with a resin binder, and the silver powder particle size has a lower limit in order to reduce the resistance value. Thixotropic index (hereinafter, E type viscometer 3 ° R
14 cones (viscosity value at 1 rpm divided by viscosity value at 10 rpm) is low (about 2-3), roller 9
When applied to the end surface electrode of the chip resistor by the above method, the paste 10 was likely to cause the stringing 10a phenomenon as shown in FIG. 9, and the applied shape was unstable.

The present invention provides a resin electrode having a strength equal to or higher than that of a conventional thick film electrode, etc., to reduce the occurrence of a stringing phenomenon, and to provide an electronic component having high electrode strength and excellent reliability at a low cost. The purpose is.

[0009]

In order to solve this problem, the present invention is that the end face electrode contains at least nickel, carbon and resin.

As a result, an electrode having high electrode strength and excellent reliability can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is an electronic component having a substrate and an end face electrode on the end face of the substrate, wherein the end face electrode contains at least nickel, carbon and resin. It will be.

According to a second aspect of the present invention, a substrate, an upper surface electrode layer provided on a side portion of an upper surface of the substrate, a resistor layer electrically connected to the upper surface electrode layer, and the substrate are provided. An end surface electrode is electrically connected to the upper surface electrode layer on the end surface, and the end surface electrode contains at least nickel, carbon, and a resin.

[0013] The invention according to claim 3 is the invention according to claim 1 or 2.
The carbon contained in the end face electrode of the described invention has a chain structure.

The invention according to claim 4 is the invention according to claim 1 or 2.
The nickel contained in the end face electrode of the described invention has a structure having a plurality of protrusions.

According to a fifth aspect of the present invention, in a method of manufacturing an electronic component in which an end face electrode is provided on an end face of a substrate, the end face electrode is a paste material containing uniform nickel, carbon and resin formed on a roller. It is formed by transferring and applying.

According to a sixth aspect of the present invention, the paste material according to the fifth aspect has a thixotropic index of 5 to 8.

Hereinafter, embodiments of the present invention will be described with reference to the drawings by taking a chip resistor as an example of electronic components as an example.

(Embodiment 1) FIG. 1 is a perspective view of a chip resistor according to an embodiment of the present invention, and FIG.
It is -B sectional drawing. In the figure, 11 is a substrate made of 96 alumina. Reference numeral 12 is an upper surface electrode layer provided on the side surface of the upper surface of the substrate 11 by a thick silver film. Reference numeral 13 is a resistance layer provided by a ruthenium-based thick film on the upper surface of the substrate 11 so as to be electrically connected to the upper electrode layer 12. 1
Reference numeral 4 is a protective layer provided with an epoxy resin so as to cover at least the resistance layer 13. Reference numeral 15 denotes an end surface electrode provided on the end surface of the substrate 11 so as to be electrically connected to the upper surface electrode layer 12, and at least one of the nickel and carbon mixed powders 15a, 15 has a plurality of wart-shaped protrusions.
The conductive paste prepared by mixing b and a thermosetting polymer as a binder is applied and cured. Reference numeral 16 denotes a nickel plating layer provided so as to cover the end surface electrode 15, 17
Is a solder plating layer provided so as to cover the nickel plating layer 16.

A method of manufacturing the chip resistor according to the embodiment of the present invention configured as above will be described below.

First, the substrate 11 made of 96 alumina, which is excellent in heat resistance and insulation, is received. In order to divide the substrate 11 into strips and individual pieces, grooves for division (molding at the time of a green sheet) are formed in advance.

Next, a thick film silver paste was screen-printed and dried on the side portion of the upper surface of the substrate, and a belt type continuous firing furnace was used at a temperature of 850 ° C. for a peak time of 6 minutes, IN-OUT4.
The top electrode layer 12 is formed by firing with a profile of 5 minutes.

Next, a thick film resistor paste containing ruthenium oxide as a main component is screen-printed on the upper surface of the substrate 11 so as to be electrically connected to the upper electrode layer 12, and the temperature is set to 850 ° C. in a belt type continuous firing furnace. Peak time 6 minutes, IN-
The resistance layer 13 is formed by firing according to the profile of the OUT time of 45 minutes.

Next, in order to make the resistance values of the resistance layer 13 between the upper electrode layers 12 uniform, the resistance layer 13 is irradiated with laser light.
Part of is cut off to correct the resistance value (L cut, 30 mm / sec,
12 KHz, 5 W).

Next, an epoxy resin paste is screen-printed so as to cover at least the resistance layer 13 and cured by a belt type continuous curing oven at a temperature of 200 ° C. with a curing profile of a peak time of 30 minutes and an IN-OUT of 50 minutes. Then, the protective layer 14 is formed.

Next, as a preparatory step for forming the end face electrode 15, the substrate is divided into strips to expose the end face portion forming the end face electrode 15.

Next, the strip-shaped substrate is fixed using an uneven holding jig so that the end face electrode forming surface becomes horizontal.

Next, a grain size of about 2 to 20 μm having a plurality of wart-like projections so as to cover at least the upper surface electrode layer 12 is provided.
m nickel powder 15a and chain structure particle size of about 0.04 μm
The resin electrode paste prepared by kneading the mixed powder of the carbon powder 15b and the resol-based phenolic resin with butyl carbitol as a solvent by a three-roll mill is uniformly formed in advance with a film thickness of about 70 μm on the stainless steel roller, While rotating, the uneven strip-holding jig is moved to apply the paste on the roller to the side surface of the strip-shaped alumina substrate to apply it, and the belt type continuous far-infrared curing furnace sets a peak time of 160 ° C.-30 minutes, IN- A heat treatment was performed according to a temperature profile of 40 minutes OUT to form the end face electrode 15 having a side surface thickness of about 30 to 40 μm.

Finally, as a preparation step for electrolytic plating, the strip-shaped substrate is disassembled into individual pieces, and the nickel plating layer 16 and the solder plating layer 17 are formed on the exposed upper surface electrode layer 12 and end surface electrode 15 on the individual piece-shaped substrate. And are formed by barrel-type electrolytic plating to manufacture a chip-type resistor.

The chip type resistor according to the embodiment of the present invention, the conventional chip type resistor (where a silver-based resin electrode is formed as a side electrode) and the one using a silver-based thick film electrode as a side electrode are used. For comparison, a flexural strength test was conducted according to JIS C-5202.

FIG. 3A shows the present embodiment.
FIG. 3B shows a conventional silver-based resin electrode, FIG. 3C shows an outline of the coating shape of the end face electrode of each chip resistor of the conventional thick film electrode, FIG. 4 shows the test results, and FIG. A comparison of viscosity characteristics is shown.

As is clear from FIG. 4, the chip-type resistor in one embodiment of the present invention has a strong electrode strength (equivalent to a silver-based thick film electrode product), and as is clear from FIG. It can be seen that it has a stable shape. This is because the viscosity characteristics of the resin electrode material are improved and the thixotropy index is increased.

In this embodiment, the end face electrode layer has a plurality of wart-shaped protrusions. Since a high-grade nickel powder is used, the resin material and the plurality of wart-shaped protrusions on the surface of the nickel powder are used. Since it has a strong anchoring force between it and (as shown in the schematic cross-sectional view in Fig. 6), conventional thick film electrodes etc. can be used at low temperature (around 200 ° C) where the electrical characteristic value between end face electrodes does not change. An end face electrode layer having a strength equal to or higher than that of can be formed. At the same time, since carbon powder having a fine chain structure with a large specific surface area is added, the resin electrode material can have a thixotropic index (5 to 8), and a side electrode having a stable shape can be formed. It is possible to provide an electronic component having excellent reliability.

In this embodiment, the resol type phenol resin is used as the binder of the end face electrode layer, but if the electroplating property is not impaired and a sufficiently low conductor resistance can be secured, it is possible to obtain a high heat resistance such as novolak or aralkyl. It is also possible to use a phenol resin, an imide resin, or an epoxy resin.

Further, although the chip type resistor has been described in the present embodiment, the present invention is not limited to this, and any device having an end face electrode may be used.

[0035]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to form an end face electrode having a stable shape and provide an electronic component having excellent reliability.

[Brief description of the drawings]

FIG. 1 is a perspective view of a chip resistor according to an embodiment of the present invention.

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

FIG. 3 is a sectional view showing the shape of the end face electrode.

FIG. 4 is a method for comparing a conventional embodiment with one embodiment of the present invention.
Explanatory drawing showing test results

FIG. 5 is a viscosity characteristic comparison diagram comparing the conventional embodiment and one embodiment of the present invention.

FIG. 6 is a schematic sectional view of the same.

FIG. 7 is a perspective view of a conventional chip resistor.

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

FIG. 9 is an explanatory diagram for explaining the stringing phenomenon.

[Explanation of symbols]

 11 96 Alumina substrate 12 Upper surface electrode layer 13 Resistance layer 14 Protective layer 15 End surface electrode 16 Nickel plating layer 17 Solder plating layer

Claims (6)

[Claims] 1. An electronic component having a substrate and an end face electrode on an end face of the substrate, wherein the end face electrode contains at least nickel, carbon and a resin. 2. A substrate, an upper surface electrode layer provided on a side portion of an upper surface of the substrate, a resistor layer electrically connected to the upper surface electrode layer, and the upper surface electrode layer on an end face of the substrate. And an end face electrode that is electrically connected to
An electronic component containing at least nickel, carbon, and a resin. 3. The electronic component according to claim 1, wherein the carbon contained in the end face electrode has a chain structure. 4. The electronic component according to claim 1, wherein the nickel contained in the end face electrode has a structure having a plurality of protrusions. 5. A method of manufacturing an electronic component comprising an end face electrode provided on an end face of a substrate, wherein the end face electrode is formed by transferring and applying a paste material containing nickel, carbon and resin formed uniformly on a roller. A method of manufacturing an electronic component to be formed. 6. The method of manufacturing an electronic component according to claim 5, wherein the paste material has a thixotropy index of 5-8.