JP3282424B2 - Method of manufacturing rectangular thin film chip resistor - Google Patents

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 rectangular thin-film chip resistor generally used for an electronic circuit.

[0002]

2. Description of the Related Art In recent years, with the downsizing of electronic devices, there has been an increasing demand for smaller electronic components to be mounted in order to increase the mounting density of circuit boards. Along with the miniaturization of square chip resistors, the demand for square thin film chip resistors having high accuracy (resistance tolerance, resistance temperature characteristics) and excellent current noise characteristics is increasing.

FIG. 3 shows the structure of a conventional rectangular thin film chip resistor.
4 is a cross-sectional view, and a manufacturing method thereof is shown in the process chart of FIG.

Referring to FIG. 3, a conventional rectangular thin film chip resistor includes a pair of thin film upper electrode layers 12 made of Au formed at the ends on the surface of a square 96% alumina substrate 11 and the ends on the back surface. A pair of formed thin film back electrode layers 13 also made of Au, a thin film resistor layer 14 made of a Ni—Cr alloy, which covers the pair of thin film top electrode layers 12 and is formed between the thin film top electrode layers 12; This thin film resistor layer 14
And a pair of epoxy resin protective film layers 15 that completely cover the thin film resistor layers 14 exposed on the pair of thin film upper electrode layers 12 and partially overlap both ends of the resin protective film layers 15. The conductive resin upper electrode layer 16 and the conductive resin upper electrode layer 16 and the thin film rear electrode layer 13 are connected by 96%
It comprises a pair of thin-film end face electrode layers 17 formed on both ends of the alumina substrate 11, respectively, and an electrode plating layer 18 of nickel and solder formed on exposed electrode portions.

Next, the manufacturing process of a conventional rectangular thin film chip resistor will be described with reference to FIG. First, an insulating substrate 11 made of 96% alumina is prepared. Next, after an electrode paste composed of a metal organic material containing Au as a main component is screen-printed and dried on the front and back surfaces of the 96% alumina substrate 11,
In order to remove only the organic components of the metal organic electrode paste and bake only the metal components onto the alumina substrate 11, the paste is fired by a belt-type continuous firing furnace, and the thin film upper electrode layer 12 is fired.
Then, a step of forming the thin film back electrode layer 13 is performed.

[0006] Next, Ni-
A photolithography process (a resist coating / drying process) for performing a sputtering process for forming a thin film resistor layer 14 of Cr or the like and forming the thin film resistor layer in a predetermined resistance pattern 14a
(Exposure, development, etching, resist stripping) to form a stable film of the resistance pattern 14a.
A heat treatment process is performed in a 0 ° C. atmosphere.

After that, a resistance value correcting step is performed by laser trimming to correct the resistance value of the resistance pattern to a predetermined value.

Next, the resistance value corrected resistance pattern 14b
Is formed, a step of forming a resin protective film layer 15 of a thermosetting resin is performed. Next, a thermosetting conductive resin is used to cover the resistance-corrected resistance pattern 14b that is not covered by the resin protective film layer 15 on the thin film upper electrode layer 12 and to overlap both ends of the resin protective film layer 15. The step of forming the conductive resin upper surface electrode layer 16 is performed.

Next, an end face electrode forming step of forming a thin film end face electrode layer 17 is performed by using sputtering on the end face of the insulating substrate 11.

[0010] Finally, an electrode plating step of forming an electrode plating layer 18 on the exposed electrode portion to ensure reliability at the time of soldering was performed to form a rectangular thin film chip resistor.

[0011]

However, in the conventional method of manufacturing a thin film chip resistor, the material of the back electrode is limited because the resistor is formed after the back electrode is formed. That is, in the etching performed in the photolithography process step of forming the resistor pattern, the substrate is immersed in an etching solution (strongly acidic). A back electrode layer is formed by patterning a Nichrome thin film electrode by a photolithography process after forming a sputter. For this reason, when gold is used, the equipment cost is not expensive, but the material cost is high, and when copper or nichrome is used, the equipment cost and man-hours are high, and it is difficult to reduce the manufacturing cost. There were challenges.

An object of the present invention is to provide an inexpensive rectangular thin film chip resistor in order to solve the above problems.

[0013]

According to the present invention, there is provided a method of manufacturing a rectangular thin film chip resistor, comprising: forming a pair of thin film upper electrode layers on a main surface of a rectangular insulating substrate; Forming a thin film resistor layer between the pair of thin film upper electrode layers and between the thin film upper electrode layers on the main surface of the insulating substrate, and a resin protective film layer completely covering the thin film resistor layer. Forming, forming a pair of conductive resin upper electrode layers covering the pair of thin film upper electrode layers and partially overlapping both ends of the resin protective film layer, and forming a pair of conductors on a back surface of the insulating substrate. A step of forming a resin back electrode layer; a step of forming a pair of thin film end electrode layers at both ends of the insulating substrate so as to be connected to the conductor resin top electrode layer and the conductor resin back electrode layer; Resin top electrode layer Forming an electrode plating layer so as to cover the conductive resin back electrode layer and the thin film end face electrode layer, wherein the conductive resin back electrode layer is formed after forming the thin film resistor layer. It is assumed that.

[0014]

According to the present invention, in order to form the back surface electrode after the formation of the resistor, the back surface electrode is immersed in an etching solution (strongly acidic) in the etching process performed in the photolithography process step of forming the resistor pattern. Because there is nothing
The back electrode material is not limited. Therefore, since the back electrode can be formed by a conventional screen printing method using a commonly used conductive resin silver paste, material costs, man-hours and equipment costs can be reduced, and an inexpensive rectangular thin film can be formed. A chip resistor can be realized.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a rectangular thin film chip resistor according to an embodiment of the present invention;

FIG. 1 is a sectional view of a rectangular thin film chip resistor according to one embodiment of the present invention, and FIG. 2 is a process chart showing a method of manufacturing the same.

First, the structure of a product will be described with reference to FIG.
In FIG. 1, a pair of thin film upper electrode layers 2 made of Au formed on the surface of a square 96% alumina substrate 1 and a pair of conductive resin back electrodes made of a thick film conductive resin containing silver as a conductive component formed on the back surface. Layer 3 and a Ni-C layer that covers the pair of thin film upper electrode layers 2 and is formed between the thin film upper electrode layers 2.
a thin film resistor layer 4 made of an r alloy, an epoxy-based resin protective film layer 5 that completely covers the thin film resistor layer 4, and a thin film resistor layer 4 that is exposed on a pair of thin film upper electrode layers 2 and is covered with a resin. A pair of conductive resin upper electrode layers 6 formed so as to partially overlap both ends of the film layer 5, and both ends of the 96% alumina substrate 1 so as to connect the conductive resin upper electrode layer 6 and the conductive resin back electrode layer 3. A pair of thin-film end face electrode layers 7 formed respectively
And an electrode plating layer 8 of nickel and solder formed on the exposed electrode layer among the above electrode layers.

Next, the manufacturing method will be described with reference to FIG. First, a step A of preparing a 96% alumina substrate 1 having excellent heat resistance and insulation properties is performed. Next, after an electrode paste composed of a metal organic material containing Au as a main component is screen-printed and dried on the surface of the 96% alumina substrate 1, the organic components are skipped to bake only the metal components on the 96% alumina substrate 1. The step B of forming the thin film upper surface electrode layer 2 is performed by baking at a temperature of 850 ° C. with a profile of a peak time of 6 minutes and an IN-OUT time of 45 minutes in a belt-type continuous firing furnace.

Next, Ni-Cr is placed on a 96% alumina substrate 1.
And a photolithography process D (resist coating / drying, exposure, development, etching, resist peeling) for forming the thin film resistor layer 4 into a predetermined resistance pattern 4a through the sputtering process C for forming the thin film resistor layer 4 of FIG. In order to make the resistance pattern 4a a stable film, a heat treatment step E in a temperature atmosphere of 350 to 400 ° C. is performed.

Thereafter, a resistance value correcting step F by laser trimming is performed to correct the resistance value of the resistance pattern 4a to a predetermined value.

Next, a resin paste is screen-printed to protect the resistance-corrected resistance pattern 4b.
Step G of forming a resin protective film layer 5 by thermosetting with a profile of 00 ° C. for 30 minutes is performed.

Next, it is not covered with the resin protective film layer 5,
Resistance pattern 4 with corrected resistance on thin film upper electrode layer 2
(b) is screen-printed with a conductive resin paste containing silver as a conductive metal material so as to cover part of both ends of the resin protective film layer 5 and thermally cured at a profile of 200 ° C. for 30 minutes. Step H of forming the resin upper electrode layer 6 is performed.

Next, a conductive resin paste containing silver as a conductive metal material is screen-printed on a position opposite to the conductive resin upper electrode layer 6 on the back surface of the 96% alumina substrate, and is subjected to screen printing.
Step I of forming the conductor resin back surface electrode layer 3 by thermosetting with a profile of 00 ° C. for 30 minutes is performed. By forming the conductive resin back electrode layer 3 after the formation of the resin protective film layer 5 in this manner, it is possible to prevent the thin film resistor layer 4 from being stained or damaged from the conductive resin paste or the like. In the present embodiment, since the conductive resin back electrode is formed as the back electrode after the resistor is formed, the resistance to the etchant is not limited. Therefore, the material of the back electrode is not limited. In this case, the conductive resin silver paste generally used conventionally can be used, so that material cost, equipment cost and man-hour can be reduced.

Next, an end face electrode forming step J of forming a Ni—Cr thin film end face electrode layer 7 on the end face of the 96% alumina substrate 1 by sputtering is performed.

Lastly, in order to prevent electrode erosion at the time of soldering of the exposed conductive resin back electrode layer 3, conductive resin upper electrode layer 6, and thin-film end electrode layer 7, and to ensure reliability during soldering. Ni and Sn-P by electroplating
electrode plating step K for forming electrode plating layer 8 consisting of b
I do.

Through the steps described above, a square thin film chip resistor according to the present embodiment was experimentally manufactured. Comparing such a rectangular thin-film chip resistor of this example with a conventional rectangular thin-film chip resistor, the electrode strength was the same.

In this embodiment, the conductive resin electrode layer is formed of a silver-based resin material. However, the conductive resin electrode layer is not limited to the silver-based material, but may be used as an electrode material such as copper or gold. It goes without saying that the same effect can be obtained in all cases.

Further, in the present embodiment, the conductor resin back surface electrode layer is formed after the conductor resin top electrode layer, but the order of the steps may be any.

[0029]

As described above, according to the present invention, since the back electrode is formed after the resistor is formed, the material of the back electrode is not limited. Therefore, the following effects (1) and (2) can be obtained, and a rectangular thin film chip resistor can be realized at low cost.

(1) Since it can be formed by a screen printing method, equipment costs and man-hours can be reduced as compared with the photolithography method (sputtering, exposure, development, etching).

(2) Since the conductive resin silver paste which is generally used in large quantities can be used, the material cost can be reduced. In addition, since the paste is cured at about 200 ° C. after printing to form the back electrode layer, power consumption can be reduced as compared with conventional high-temperature baking (about 850 ° C.).

Conventionally, since the back electrode is formed of a thin film, when the substrate is firstly divided into pieces, chipping occurs on the back electrode near the dividing slit. By forming the conductive resin electrode layer of the above, it is possible to have a function of absorbing shock due to contact with the dividing jig at the time of primary division, prevent chipping of the back electrode, and have a highly reliable square thin film A chip resistor can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a rectangular thin film chip resistor according to one embodiment of the present invention.

FIG. 2 is a process chart showing a method for manufacturing a conformal thin film chip resistor.

FIG. 3 is a sectional view showing the structure of a conventional rectangular thin film chip resistor.

FIG. 4 is a process chart showing a method for manufacturing a conformal thin film chip resistor.

[Explanation of symbols]

 Reference Signs List 1 96% alumina substrate 2 Thin film top electrode layer 3 Conductive resin back electrode layer 4 Thin film resistor layer 5 Resin protective film layer 6 Conductive resin top electrode layer 7 Thin film end face electrode layer 8 Electrode plating layer

Claims (2)

(57) [Claims] 1. A step of forming a pair of thin film upper electrode layers on a main surface of a rectangular insulating substrate, and said thin film upper electrode on each of said pair of thin film upper electrode layers and on a main surface of said insulating substrate. Forming a thin film resistor layer between the layers, forming a resin protective film layer that completely covers the thin film resistor layer, and covering one end of the resin protective film layer while covering the pair of thin film upper electrode layers. Forming a pair of conductive resin upper surface electrode layers overlapping the portion; forming a pair of conductive resin back electrode layers on the back surface of the insulating substrate; and forming the conductive resin upper surface electrode layer and the Forming a pair of thin-film end face electrode layers so as to be connected to the conductive resin back electrode layer; and forming an electrode plating layer so as to cover the exposed conductive resin top electrode layer, the conductive resin back electrode layer, and the thin-film end electrode layer. Form And forming the conductive resin back surface electrode layer after forming the thin film resistor layer. 2. The method for manufacturing a rectangular thin film chip resistor according to claim 1, wherein after forming a resin protective film layer covering the thin film resistor layer, a conductive resin back electrode layer is formed.