JP2002231502A - Fillet-less chip resistor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fillet-less chip resistor high in moisture resistance and mass productivity and to provide its manufacturing method. SOLUTION: The fillet-less chip resistor is composed of a tantalum nitride thin film resistor 21 arranged on the top surface of an angular insulating board 12, thin film electrodes 22 of copper arranged on each side of the resistor 21, a protective film 23 which covers the major part of the resistor 21 and is formed of an inorganic material, and plating electrodes 24 formed on the thin film electrodes 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip resistor and a method of manufacturing the same, and more particularly, to a land of a printed wiring board.
The present invention relates to a so-called filletless type chip resistor that can be mounted by soldering only an electrode portion provided on an upper surface of a chip resistor without using a solder fillet.

[0002]

2. Description of the Related Art Conventionally, chip resistors have conventionally been provided with plated electrodes on the upper surface, end surface, and lower surface of both ends in the longitudinal direction of an insulating substrate, and these electrodes are soldered to the lands of the printed wiring board. It was fixed and implemented. That is, as shown in FIG. 3 (a), the connection and fixation by the solder mainly consist of the so-called solder fillet 16 in which the electrode 13 provided on the end face of the substrate 12 of the chip resistor 11 and the land 15 of the printed wiring board 14 are connected. I was connected.

However, with the reduction in the size and weight of various electronic devices that use chip resistors, the mounting density of chip resistors is also required to be improved. Therefore, as shown in FIG. 3B, there is a demand in the market for a chip resistor mounting method that does not use a solder fillet so that the area occupied by solder can be reduced as much as possible. As shown in FIG. 3B, this chip resistor is mounted by soldering an electrode 17 provided on the upper surface of the substrate to a land 15 of a printed wiring board 14 by a face-down method.
The so-called filletless type chip resistors which can be connected by the mounting method 9 are required from the market.

However, in such a filletless type chip resistor, the thickness of the electrodes 17 provided at both ends of the insulating substrate 12 is larger than the thickness of the resistor and the protective film 18 for protecting the resistor. There is a need. Otherwise, the adhesion will be impaired when the chip resistor is mounted on the printed wiring board.

In a conventional chip resistor, for example, a protective film having a thickness of, for example, 40 μm is used to secure moisture resistance.
A thick resin film is used, and the total thickness of the resistor and the protection film is generally larger than the thickness of the electrode portion on which the solder plating is performed. In order to increase the thickness of the electrode portion, it is necessary to increase the thickness of the plating electrode or the thickness of the base electrode. If an attempt is made to increase the thickness of the base electrode, the base electrode is formed so as to straddle an adjacent substrate region in the manufacturing stage, so that problems such as difficulty in breaking when dividing the substrate occur. Further, even if an attempt is made to increase the thickness of a plating electrode such as solder plating, peeling or the like occurs, and this film thickness has a certain limit.

In the conventional structure of a thin-film chip resistor using nichrome or the like, if face-down mounting as shown in FIG. There is a problem that the body easily breaks due to electrolytic corrosion. For this reason, when a filletless type chip resistor manufactured by face-down mounting is manufactured using a thin film technology, there is a problem that it is difficult to manufacture the chip resistor because electric corrosion is easily broken.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a filletless type chip resistor having good moisture resistance and mass productivity and a method of manufacturing the same. I do.

[0008]

A chip resistor according to the present invention comprises a resistor made of a tantalum nitride thin film disposed on an upper surface of a rectangular insulating substrate, and a thin film made of copper disposed at both ends of the resistor. An electrode, a protective film made of an inorganic material covering a main part of the resistor, and a plating electrode formed on the thin film electrode.

Further, according to the method of manufacturing a chip resistor of the present invention, a resistor made of a tantalum nitride thin film is arranged on an upper surface of a rectangular insulating substrate, and copper thin film electrodes are arranged on both ends of the resistor. The resistor is coated with a thin film made of an inorganic insulating material except for both ends including the copper thin film electrode, and a plating electrode is formed on the exposed thin film electrode.

According to the present invention, as the resistor, tantalum nitride (Ta) of about 500-5000 ° is used.
N) By using a thin film and using a silicon oxide film (SiO ₂ ) or a silicon nitride film (SiN) as a protective film for protecting the resistor, the thickness can be made about 1-10 μm. Therefore, the total thickness of the resistor and the protective film is about 10 μm or less, and can be relatively thin. And a resistor made of a tantalum nitride thin film;
Sufficient moisture resistance can be obtained by the combination of the inorganic insulating films, and electric corrosion breakage due to solder flux or the like can be prevented. On the other hand, since the electrode portion has a copper thin film electrode provided on a tantalum nitride thin film as a base electrode and a plated electrode provided by applying nickel plating and solder plating thereon, The thickness of this plating electrode is 10-2
The thickness is about 0 μm, which is sufficiently larger than the total thickness of the resistor and the protective film. Therefore, such a structure can provide a structure suitable for a filletless type chip resistor.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a filletless chip resistor according to an embodiment of the present invention. As shown in the top view of FIG. 1A and the sectional view of FIG.
A resistor 21 made of a tantalum nitride (TaN) thin film is disposed on the upper surface of a square insulating substrate 12 such as alumina.
Here, the thickness of the tantalum nitride film is, for example, 500-5000.
About Å. Copper (Cu) is provided on the upper surface of both ends of the resistor 21.
Is disposed.

The copper thin-film electrode is formed, for example, by sputtering and has a thickness of about 1 μm. The main part of the resistor 21 is a protective film 23 made of an inorganic material.
Coated with Here, the protective film 23 is a silicon oxide film (SiO ₂ ) or a silicon nitride film (SiN)
And the like, and its thickness is about 1-10 μm. Further, plating electrodes 24 are disposed on the copper thin film electrodes 22 at both ends in the longitudinal direction of the substrate 12. The plating electrode 24 includes a nickel plating layer having a thickness of about 5 to 10 μm and a solder plating layer having a thickness of about 5 to 10 μm.

According to the above-structured chip resistor, the resistor 2
1 and the thickness of the protective film 23 are at most 1 from 1-2 μm.
On the other hand, since the plating electrode has the same electrode structure as the conventional one, its thickness is 10-20.
It becomes as large as about μm. Therefore, the total thickness of the resistor and the protective film is much smaller than that of the plated electrode, thereby forming a structure preferable as a filletless chip resistor.

Further, the resistor of the tantalum nitride film has high corrosion resistance to humidity, and good corrosion resistance can be obtained by combining this with an inorganic insulating film. Therefore, even if the filletless solder is fixed by the face-down method, no electrolytic corrosion breakage occurs due to the solder flux, and a filletless chip resistor using thin film technology can be obtained.

FIG. 1C shows a mounting state of the chip resistor. The chip resistor is mounted face-down on the printed wiring board 14 with the upper surface of the insulating substrate 12 shown in FIG. That is, the plating electrode 24 of the chip resistor 11 is connected and fixed to the land 15 of the printed wiring board 14 by a filletless method. Then, as described above, since the thickness of the protective film 23 is smaller than the thickness of the portion of the plating electrode 24, one surface of the plating electrode 24 comes into contact with the land portion 15 of the printed wiring board 14, The lower surface of the protective film 23 is the printed wiring board 14
It is located in a state of floating from the surface. According to such a connection fixing method that does not use a solder fillet, an area equivalent to a conventional solder fillet is not required, so that mounting density can be improved and stray capacitance can be reduced. Response is possible.

Next, a method of manufacturing a chip resistor according to an embodiment of the present invention will be described with reference to FIG. First, an alumina substrate on a sheet is prepared, and a resistor 21 made of a tantalum nitride thin film is arranged in a portion corresponding to each chip region as shown in FIG. The arrangement of the resistor 21 is such that a tantalum nitride film is deposited on the entire surface of the substrate by sputtering or the like, and this is etched into a predetermined pattern using a photolithography technique. Next, a thin film electrode 22 of copper (Cu) is deposited as shown in FIG. The copper thin film electrode is formed with a thickness of about 1 μm by sputtering using a metal mask technique or a photolithography technique. Next, an inorganic insulating film 23a is deposited on the entire surface of the substrate. This deposited film is formed by depositing a silicon oxide film (SiO ₂ ) or a silicon nitride film (SiN) with a thickness of about 1 to 10 μm by CVD or sputtering. Then, using a metal mask technique or a photolithography technique, processing is performed into a predetermined pattern as shown in FIG.
Thereby, the protective film pattern 23 made of the inorganic insulating film is formed. Then, as shown in FIG.
A plating electrode 24 is formed on 2. This plating electrode 24
First, nickel (Ni) plating 5
Then, a solder plating is similarly applied to a thickness of about 5 to 10 μm. Thus, a filletless type chip resistor shown in FIG. 1 is obtained.

In the above-described method for manufacturing a filletless type chip resistor, the resistor pattern is formed only on one side,
Since the electrode and the end face electrode on the lower surface of the chip, which are conventionally required, are not required, the corresponding steps are not required, the mass productivity is good, and the manufacturing cost can be reduced as compared with the related art. Further, since the back surface and the end surface electrodes are not required, it can be easily applied to a chip resistor having a fine size of, for example, about 1 mm or less.

[0018]

As described above, according to the present invention, by using a tantalum nitride film for a resistor and combining it with a protective film of an inorganic insulating film, a chip resistor which does not cause electric corrosion and disconnection by a thin film process. Is obtained. In such a chip resistor, the thickness of the resistor and the protective film can be made thinner than the thickness of a normal plated electrode, so that a structure suitable for a face-down type mounting as a filletless type chip resistor is obtained. Can be The filletless type chip resistor having such a structure has high reliability and good mass productivity, and can be mounted on a printed wiring board to improve the mounting density and improve high-frequency characteristics.

[Brief description of the drawings]

FIG. 1A is a top view of a filletless chip resistor according to an embodiment of the present invention, FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A, and FIG. FIG. 3 is a cross-sectional view showing a state where the chip resistor is mounted on a printed wiring board.

FIG. 2 is a view showing a process of manufacturing the filletless chip resistor according to the embodiment of the present invention, wherein the left column is a top view and the right column is a cross-sectional view along a longitudinal center portion thereof.

FIG. 3A is a diagram illustrating a mounting structure of a chip resistor using a fillet, and FIG. 3B is a diagram illustrating a state where a filletless type chip resistor by face-down bonding is mounted on a printed wiring board; is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Chip resistor 12 Substrate 14 Printed wiring board 15 Land portion 21 Resistor made of tantalum nitride thin film 22 Copper thin film electrode 23 Protective film of inorganic insulator 24 Plating electrode

Claims (2)

[Claims] 1. A resistor made of a tantalum nitride thin film disposed on an upper surface of a rectangular insulating substrate, a thin film electrode made of copper disposed at both ends of the resistor, and a main part of the resistor covered. A filletless chip resistor comprising a protective film made of an inorganic material and a plating electrode formed on the thin film electrode. 2. A resistor made of a tantalum nitride thin film is arranged on an upper surface of a rectangular insulating substrate, copper thin film electrodes are arranged on both ends of the resistor, and both ends including the copper thin film electrode are removed. A method for manufacturing a filletless chip resistor, comprising: depositing the resistor with a thin film made of an inorganic insulating material; and forming a plating electrode on the exposed thin film electrode.