JPH0372602A - Manufacture of square sheet type thin film chip resistor - Google Patents

Abstract

PURPOSE:To manufacture a title square sheet type thin film chip resistor with strong electrodes during soldering process as well as excellent in thermal resistance and insulation resistance by a method wherein the film resistor is printed with a resistor material comprising a metallic organic matter to be baked and then glass-coat layer are used as protective coat. CONSTITUTION:A thermal resistant and insulation resistant alumina substrate 1 wherein grooves 2 for separating the substrate 1 into strip type and piece type chips are cut is screen-printed with a paste and then baked so that under coated glass layers 3, surface electrode layers 4 partly overlapping with the layers 3, resistor layers 5 comprising metallic organic paste so as to partly overlapping with the surface electrodes 4 on the said glass layers 3 as well as overcoat layers 6 may be respectively formed. Next, after destructing the resistor layers 5 only by laser beams to correct the resistance value, the substrate 1 is divided into strip type chips and after coating the sides with a thick film silver paste to partly overlap on the surface electrode layers 5 and baking the same to form an end electrode layer 8, the substrate 1' is further divided into piece type substrate 1'' finally to form Ni, Si-Pb plated layers 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a rectangular plate type thin film chip resistor.

Conventional technology In recent years, there has been a growing demand for electronic equipment to become lighter, thinner, and smaller.
In order to increase the mounting density of resistance elements on circuit boards, square plate type chip resistors, which are small and can be surface mounted, are increasingly being used as resistance elements on circuit boards. In addition, in recent years, parts have become more accurate and have lower noise, and the demand for rectangular plate type chip resistors is increasing from the thick film type or 31.-7 to the thin film type with high precision and low noise.

An example of a conventional manufacturing method for a small square plate type thin film chip resistor (cited from Susumu Kogyo Co., Ltd.'s DATABOOK) is shown in FIG.

First, the conventional manufacturing process consists of a high-purity alumina substrate. Start with step A of inserting the heat-resistant insulating substrate 21 into the substrate receiver, and then proceed to the next step.

After a sputtering process B in which a thin film resistor 22 made of Ni-0r or the like is formed on the insulating substrate 21, an etching process C is performed in which the thin film resistor 22 is shaped into a resistance pattern 23.
In order to make the resistor pattern 23 a stable film, an atmospheric heat treatment process is performed at a temperature of 360° C. to 400° C. in nitrogen or the like. Thereafter, in order to correct the resistance value of the resistance pattern to a predetermined value, a resistance value correction step E is performed in which a trimming groove 24 is formed in the resistance pattern by a laser trimming method or the like. Furthermore, in order to protect the resistor pattern 23, a protective coat forming step F is performed in which a thermosetting resin film 25 is formed.

Next, as a preparation step for dividing the insulating substrate 21 and forming the end electrode layer 26, a scribing step G is performed to form grooves 27 for dividing the insulating substrate 21, and a strip-shaped substrate 21' A second substrate dividing step H is performed to divide the strip substrate 21 into two, and an end electrode forming step is performed to form an end electrode layer 26 on the end surface of the strip-shaped substrate 21 using sputtering or the like. Then, as a preparation process for applying a plating layer 27 to the exposed resistance pattern and the end electrode surface, the strip-shaped substrate 2
1' into individual pieces of substrates 21''
Electrode plating process K is performed to form an electrode plating layer 27 in order to prevent the exposed resistor pattern and the end surface electrode layer from being eaten away by time, and to ensure the reliability of soldering.
The square plate type thin film chip resistor is completed.

Problems to be Solved by the Invention However, the rectangular plate type thin film chip resistor produced by this process had the following problems.

(1) Since the resistive film is formed by sputtering, continuous processing is difficult and many sputtering devices are required for mass production. The cost will be twice as high.

@) Since the resistive film is heat treated at 360°C to 400°C, a glass protective coat, which requires heat treatment at about 500°C or higher, cannot be used, so a resin protective coat must be used. Therefore, their heat resistance is inferior to that of thick-film chip resistors.

(3) The split-grooved 9-board substrate, which is often used in thick-film square chip resistors, is difficult to form a thin film due to the presence of unique ridges in the board between the split grooves, making it difficult to form a thin film. In the square plate type thin film chip resistor, grooves for dividing are formed by laser scribing on a substrate with few ridges and no dividing grooves. However, laser scribing does not only detract from the aesthetic appearance of chip resistors, but also tends to cause microcracks in the substrate due to the thermal shock of the laser, which can lead to insulation deterioration.

(4) Since the end electrodes are processed by sputtering, the adhesion strength of the electrodes is weaker than the strength of the end electrodes of conventional thick film chip resistors in which thick film silver electrodes are coated and fired. On the other hand, for conventional square plate type thin film resistors, a method of coating and firing a thick film end face electrode fired at a low temperature so as to overlap the thin film resistor as the end face electrode has been considered. However, this could not be realized due to the problem that the thin film resistor would be eaten away during firing of the thick film end face electrode.

The present invention solves these problems all at once; it is inexpensive, has good heat resistance due to the use of glass coating,
The present invention provides a rectangular plate type thin film chip resistor with excellent substrate insulation and strong electrode strength when soldered.

Means for Solving the Problems In order to solve the above problems, the method for manufacturing a rectangular thin film chip resistor of the present invention includes the steps of: forming an undercoat glass to smooth the surface of a heat-resistant insulating substrate; forming a top electrode overlapping a part of the undercoat glass; and forming a thin film resistor by printing a resistance material made of a metal-organic material on the undercoat glass so as to overlap a part of the top electrode. a step of forming an overcoat glass to cover and protect the resistor, a step of modifying the resistance value to match the characteristics of the resistor, and preparation for forming an end electrode. A primary board dividing process, an end face electrode forming process for forming electrodes on the end faces of the divided boards, a secondary board dividing process, which is a preparation process for electrode plating, and prevention of electrode erosion by soldering. Soldering includes an electrode plating process to ensure reliability.

action As a result, the following effects can be obtained.

(1) Thin film resistance films can be continuously formed using a printing machine and a belt-type continuous firing furnace without using sputtering equipment, reducing manufacturing costs and producing square plates as cheap as thick film square plate chip resistors. type thin film chip resistors can be provided.

(2) Since the thin film resistor is formed by printing a resistance material made of organic metal, a glass coat can be used as a protective coat, and it has improved heat resistance compared to the conventional square plate type thin film chip resistor. I can figure it out.

(3) The undercoat glass absorbs the ridges 9 of the substrate between the dividing grooves, which are peculiar to divided grooved substrates, and makes the surface smooth. Therefore, it is not necessary to form dividing grooves by performing laser scribing on a smooth substrate without ridges as in the conventional method, and thus the insulation properties of the substrate are improved.

(4) Since the thin film resistor is printed and fired after firing the thick film electrode on the top surface, the thin film resistor will not be eaten by the top electrode during firing of the end face electrode, and the thick film end face electrode can be strongly formed by firing. Therefore, the strength of the end face electrode can be made equal to that of conventional thick film chip resistors.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a process diagram showing an embodiment of the method for manufacturing a rectangular plate type thin film chip resistor of the present invention, FIG. 2 is a cross-sectional view of a product manufactured by the process of FIG. 1, and FIG. FIG. 4 is an explanatory diagram showing the heat resistance of a square plate type thin film chip resistor, and FIG. 4 is an explanatory diagram showing the tensile strength of the end face electrode of the square plate type thin film chip resistor of the present invention. FIG. 3 is an explanatory diagram showing a change in resistance value due to a moisture resistance load test when a gold-based thin film conductive material is used for the top electrode.

An embodiment of the present invention will be described with reference to FIG. As expected, Step A was performed to insert a heat-resistant button and a 96 alumina substrate 1 with excellent insulation. In order to divide the alumina substrate 1 into strips, buttons, and individual pieces, grooves 2 for dividing are formed (molded with a mold when forming a green sheet).

Next, in order to smooth out the undulations and protrusions on the substrate, an undercoat glass paste was screen-printed, and it was baked in a belt-type continuous firing furnace for 15 minutes at a peak temperature of 900°C.
Step B was performed in which the undercoat glass layer 3 was formed by firing according to a profile of N-0UT for 2 hours. Next, a thick film silver paste was screen printed so as to overlap a part of the undercoat glass layer 3, and a belt-type continuous firing furnace was used to heat the film at a temperature of 600'C for a peak time of 6 minutes and lN.
Baking was performed according to a profile of -0UT45 minutes, and Step C of forming the upper surface electrode layer 4 was performed. Next, a resistance paste made of a metal-organic substance containing RuO2 as a main component was screen printed on the foot glass layer 3 so as to partially overlap the upper electrode layer 4. Then, in order to remove only the organic components of the metal-organic resistance paste and bake only the metal components onto the undercoat glass layer, a belt-type continuous firing furnace was used at a temperature of 640°C for 10 minutes at a peak time of 1N-
The process of forming the resistor layer 5 was performed by firing according to a profile with a 0UT time of 45 minutes. Furthermore, in order to protect the resistor layer 4, an overcoat glass paste is screen printed to completely cover the resistor layer 4,
Step E was performed in which the overcoat glass layer 6 was formed by firing in a belt-type continuous firing furnace at a temperature of 600'C, a peak time of 15 minutes, and a firing profile of 1N-0UT of 90 minutes. Next, in order to equalize the resistance value of the resistor layer 4 between the upper electrode layers 5, the resistor layer is Resistance value correction step F was carried out to destroy only 4. Next, attach the end electrode to 1
1 H-7 As a preparatory step for forming the alumina substrate 1, the alumina substrate 1 is divided into strips in order to expose the end electrodes.

A primary substrate dividing step G was performed to obtain strip-shaped alumina substrates 1'. Further, a thick film silver paste was applied to the side surface of the strip-shaped alumina substrate 1' by a roller so as to overlap a part of the upper surface electrode layer 5, and was heated in a belt-type continuous firing furnace at a temperature of 600° C. for a peak time of 6. min, lN-0UT45
An end face conductor paste printing and firing process R was carried out to form the end face electrode layer 8 by firing according to the firing profile of 10 minutes. Next, as a preparation step for the electrode plating step J, a secondary substrate dividing step J is performed in which the rectangular alumina substrate 1' on which the end face electrode layer 8 has already been formed is divided into individual pieces. I got it. And finally, the exposed top electrode layer 5
When soldering the end face electrode layer 8, an electrode plating process J was performed in which a plating layer 9 of Ni and 5n-Pb was formed by electrolytic plating to prevent the electrode from being eaten away and to ensure reliability of soldering.

Through the above steps, a rectangular plate type thin film chip resistor according to an embodiment of the present invention was fabricated.

The resistance value variations and resistance temperature characteristics (TGR) of the rectangular plate type thin film chip resistor according to this embodiment of the present invention.

The current noise characteristics and resistance change during a heat resistance test (450°C for 10 minutes) were compared with a conventional square plate type thin film chip resistor. As a result, it was found that the resistance value variation, TCR, and current noise characteristics were equivalent to those of the conventional square plate type thin film chip resistor. Furthermore, as shown in FIGS. 3 and 4, it can be said that the heat resistance and electrode strength are superior to conventional square plate type thin film chip resistors.

In the example, the top electrode layer 5 was formed by printing and firing a silver-based thick film conductive material, but the top electrode layer 5 was formed by printing and firing a gold-based thin film conductive material on a square plate. When a prototype thin-film chip resistor was manufactured, the resistance value hardly changed even after a long-term (10,000 hours) moisture resistance load test, as shown in FIG.

In the example, the firing temperature of the undercoat was 900°C.
The firing temperature of the metal-organic resistance paste was 13B-7640℃, the firing temperature of the top conductor was 600℃, the firing temperature of the overcoat glass paste was 600℃, and the firing temperature of the end conductor paste was 600'Q. does not limit the firing temperature.

Further, although a metal-organic resistance paste containing RuO2 as a main component was used, the metal-organic resistance paste is not limited to the metal-organic resistance paste.

! Furthermore, although a silver-based thick film electrode paste was used for the top electrode layer and the end face electrode layer, a thick film electrode paste based on a noble metal such as gold or platinum may be used instead.

In addition, as shown in FIG. 5, by using a gold-based thin film conductive material as a layer for the upper electrode, it is possible to significantly reduce the change in resistance value caused by a long-term (100 oO hours) moisture resistance load test.

Effects of the Invention As is clear from the above description, the present invention includes a step of printing and firing an undercoat glass to smooth the surface of a heat-resistant insulating substrate, and a step of printing and firing an undercoat glass to smooth the surface of a heat-resistant insulating substrate, and a step of printing and firing an upper surface portion that partially overlaps the undercoat glass. printing and baking a chemically stable conductive material to form an electrode; and printing a metal on the undercoat glass to form a thin film resistor overlapping a portion of the top electrode. A step of printing and firing a resistive material made of organic matter, a step of printing and firing an overcoat glass to cover and protect the resistor, a step of modifying the resistance value to match the characteristics of the resistor, and an end face. The primary substrate dividing step is a preparatory step for forming electrodes, the edge electrode printing and firing step is to form electrodes on the end surfaces of the divided substrates, and the secondary substrate dividing step is a preparatory step for electrode plating. Since the structure is such that the electrode plating process is sequentially performed to prevent the electrode from being eaten away by soldering and to ensure the reliability of the soldering process, the following effects can be obtained.

(1) Thin film resistive films can be formed continuously using a printing machine and a belt-type continuous firing furnace without using sputtering equipment, increasing productivity and making them as inexpensive as thick film rectangular chip resistors. A square plate type thin film chip resistor can be provided.

(2) The thin film resistor is made of a resistance material made of a metal organic substance.
”-/ Since it is printed and fired, a glass coat can be used as a protective coat, and heat resistance can be improved compared to conventional square plate type thin film chip resistors.

(3) In conventional thin film chip resistors, it was necessary to form dividing grooves by laser scribing on a smooth substrate without ridges, but according to the present invention, dividing grooves are formed by forming an undercoat glass layer. It can also be used on substrates with undulations and grooves, improving the insulation properties of the substrate.

(4) Since the electrodes can be strongly formed by applying and baking a thick film end face paste, the strength of the end face electrodes can be made equal to that of conventional thick film chip resistors.

(5) Furthermore, by using a gold-based thin film conductive material as a layer for the upper electrode, it is possible to significantly reduce changes in resistance value due to a long-term (10 o o o o hour) moisture resistance load test.

[Brief explanation of drawings]

1 is an explanatory diagram showing the manufacturing process of the rectangular plate type thin film chip resistor of the present invention, FIG. 2 is a sectional view of a sample manufactured by the method of manufacturing the rectangular plate type thin film chip resistor of FIG. 3
The figure is an explanatory diagram showing the heat resistance of the rectangular plate type thin film chip resistor of the present invention, Figure 4 is an explanatory diagram showing the strength of the end electrode of the rectangular plate type thin film chip resistor of the present invention, and Figure 5 is an explanatory diagram showing the top electrode. An explanatory diagram showing the change in resistance value due to a long-term (1000 hours) moisture resistance load test when a gold-based thin film conductive material is used in the process. Figure 6 shows the manufacturing process of a conventional square plate type thin film chip resistor. It is an explanatory diagram showing an example. 1...96 alumina substrate, 1. 96 alumina substrate in the form of a strip, 1"...96 alumina substrate in the form of individual pieces,
2...Groove for division, 3...Undercoat glass layer, 4...Resistor layer, 5...Top electrode layer, 6...Over Coated glass layer, 7.
mark trimming groove, 8... end face electrode layer, 9...
Electrode plating layer.

Claims (3)

[Claims] (1) a step of forming an undercoat glass to smooth the surface of the heat-resistant insulating substrate; a step of forming an upper surface electrode overlapping a part of the undercoat glass;
forming a thin film resistor by printing a resistive material made of a metal-organic substance on the undercoat glass so as to overlap a part of the upper surface electrode; and applying an overcoat glass to cover and protect the resistor. a resistance value correction step for aligning the characteristics of the resistor, a primary substrate dividing step which is a preparation step for forming end surface electrodes, and a step for forming electrodes on the end surface portions of the divided substrates. It is characterized by comprising an end face electrode forming process, a secondary board dividing process which is a preparation process for electrode plating, and an electrode plating process to prevent the electrode from being eaten away by soldering and to ensure reliability of solderability. A method for manufacturing a square plate type thin film chip resistor. (2) The method for manufacturing a rectangular plate type thin film chip resistor according to claim 1, wherein the upper surface electrode is formed by printing and firing a gold-based thin film conductive material. (3) Claim 1, characterized in that the resistance value is modified by destroying the resistor covered by the overcoat with a laser beam that passes through the overcoat glass.
A method of manufacturing the rectangular plate type thin film chip resistor described above.