JP2003068505A - Chip resistor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip resistor which does not care about the top or bottom of a chip component at the time of mounting, in other words, appropriate for bulk mounting. SOLUTION: The chip resistor comprises a first resistor film 15a disposed over the nearly entire length on the surface of an insulation substrate 11, a pair of second resistor films 15b disposed apart from each other on both end parts of the insulation substrate, a pair of electrodes 13 disposed on the second resistor films, a protective film 17 which covers a portion of the first resistor film which is not overlaid by the second resistor film, and plating electrodes 23 disposed at least on the pair of electrodes. The surface height of the plating electrode is higher than that of the protective film.

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 for manufacturing the same, and more particularly to a so-called bulk which is mounted on a circuit board without selecting the front and back of the chip component from a bulk cassette containing a large number of chip components. The present invention relates to a chip resistor suitable for mounting and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 7A shows a structural example of a conventional thick film chip resistor. The conventional chip resistor is provided with thick film electrodes 13, 13 at both ends of the surface of an insulating substrate 11 made of alumina or the like, and a thick film resistor 15 is arranged between the electrodes. The resistor 15 is covered and protected by a protective film 17 made of a glass insulating film and a resin insulating film. Insulating substrate 11
Plated electrodes 23, 23 are formed on the front surface electrode 13 and the back surface electrode 19 and the end surface electrodes 21 on the side end surfaces, which are both end portions of the.

In this case, the height of the protective film 17 in the central portion of the substrate is higher than the height of the plated electrode 23. In many cases, a difference in level between the plated electrode 23 on the surface of the insulating substrate 11 and the surface of the protective film 17 is about 10-30 μm.

Incidentally, the conventional chip resistors are often shipped one by one at the time of factory shipment in a so-called taping package in which the surface on which the resistors are present is fixed as the surface. And when mounting on a circuit board,
It was fixed to the circuit board in the state as it is, that is, with the surface (the protective film side) where the resistor is present as the surface by the mounting machine (mounter). In this case, as shown in FIG. 7B, the back surface side of the plated electrodes 23, 23 of the insulating substrate 11 is closely attached to the land portion 27 of the circuit board 25, and is fixed by solder reflow or the like.

However, as a mounting method, there is a so-called bulk mounting method in which a large number of chip components are randomly accommodated in a bulk cassette and the chip components are taken out one by one from the bulk cassette and mounted on a circuit board. According to this mounting method, when mounting the chip component on the circuit board, the surface mounting of the chip component is performed without selecting the front and back of the chip component.

Therefore, when the conventional chip resistor shown in FIG. 7A is bulk-mounted by the bulk mounting machine,
As shown in (b), there is a case where the chip resistor is mounted so that the front surface side (protective film side) faces the circuit board 25. However, as shown in FIG. 7C, the surface side (protective film side) of the chip resistor is the circuit board 25.
There is a probability of about 50% that the device is mounted face-down so as to face. At this time, there is a strong possibility that the chip resistor will be mounted in an inclined manner, and in the worst case, one side cannot be soldered, or as shown in FIG. 7D, a phenomenon such as chip rising occurs. There is. Further, even in the phenomenon of returning to the center of the land by itself (so-called self-alignment effect of solder), there is a problem that the protective film is eventually caught and the position is displaced.

On the other hand, so-called filletless mounting technology has been developed in order to reduce the mounting area.
This is a technique of mounting the chip component on the circuit board face down (face down), and in this case as well, the surface height of the plating electrode needs to be higher than the surface height of the protective film.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides a chip resistor which does not select the front and back of a chip component at the time of mounting, and which is compatible with so-called bulk mounting. To aim.

[0009]

In order to solve the above problems, an insulating substrate, a resistor film formed on the insulating substrate, and at least a pair of electrodes formed on the resistor film, At least the protective film covering the resistor film in a portion where the electrode is not formed, and a plating electrode formed on the electrode are provided, and the resistor film corresponds to a region where the electrode is formed. By forming the chip resistor so that the thickness of the portion is increased, the height of the surface of the plating electrode is made higher than the height of the surface of the protective film. With this configuration, even if the surface side on which the protective film is formed is mounted on the circuit board, a gap is created between the protective film and the circuit board, which facilitates mounting.

The resistor film has a first resistor film formed in a region of the insulating substrate including at least a portion between the pair of electrodes, and the first resistor film is electrically connected to the first resistor film. The second resistor film may be formed in a portion corresponding to the formed region. With this structure, it is easy to form a resistor film having a partially different film thickness. A back electrode may be arranged on the back surface of the insulating substrate, end surface electrodes may be arranged on the side end surfaces, and the plating electrode may be arranged on these electrodes. With such a configuration, it can be mounted on the circuit board without distinction between the front and back.

A pair of electrodes are formed on the resistor film formed on the surface of the insulating substrate, and the surface shape of the resistor film is such that the thickness of the portion corresponding to the region where the electrodes are formed is increased. A method of manufacturing a chip resistor formed in, wherein the intaglio formed in a shape corresponding to the surface shape of the resistor film formed on the insulating substrate, a step of filling a resistive material, At least a step of pressing the intaglio plate against the insulating substrate to transfer the filled resistance material to form the resistor film, and a step of forming the electrode at a portion where the thickness of the resistor film is increased; A chip resistor is configured by a manufacturing method including a step of forming a protective film that covers the resistor film in a portion where the electrode is not formed. With such a manufacturing method, it is possible to form a resistor film having a partially different film thickness in one printing process.

The chip resistor may be constructed by a manufacturing method including a step of forming a back surface electrode on the back surface of the insulating substrate and a step of forming a side surface electrode on the side surface of the insulating substrate. With this manufacturing method, it is possible to manufacture a chip resistor that can be mounted on a circuit board without distinction between the front and back.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a chip resistor according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a diagram showing an overall configuration of a chip resistor according to an embodiment of the present invention.

This chip resistor has a first resistor film 15a extending over substantially the entire length of the surface of an insulating substrate 11 made of alumina or the like.
Is equipped with. The resistor film 15a is formed, for example, by applying a resistor paste of ruthenium oxide by screen printing and firing it at a high temperature.

At both ends of the first resistor film 15a, a pair of second resistor films 15b are arranged apart from each other. This second resistor film 15b also has the same thickness as this, or the height of the surface of the plating electrode 23 finally (the height of the surface of the plating electrode 23 on the surface side of the insulating substrate 11 on which the protective film 17b is formed). ) Can be appropriately selected within a range in which the height is higher than the height of the surface of the protective film 17b. Second resistor film 15
Since the region where the electrode of the resistor film is formed is thickened by b, it constitutes a raised portion for raising the electrode 13 as described later.

An electrode 13 for covering the second resistor film 15b is arranged on the second resistor film 15b. This electrode 13 is formed, for example, by applying a thick film electrode paste of silver or silver palladium by screen printing and then firing. The electrode 13 is preferably formed to have a thickness of about 10-20 μm. A portion of the first resistor film 15a which is not covered with the second resistor film 15b is covered with a first protective film 17a made of, for example, a glass layer and a second protective film 17b made of, for example, a resin layer. It is covered. The protective film 17 is formed as a whole by these protective films 17a and 17b. The glass insulating film 17a has a thickness of 15
The thickness is preferably about −20 μm, and the resin insulating film 17b is preferably formed with a thickness of about 20 μm.

The back surface of the insulating substrate 11 is similarly provided with back surface electrodes 19 and 19 formed by applying and firing a thick film electrode paste, and the end surface is provided with an end surface electrode 21 formed by metal sputtering or the like. A plating electrode 23 is formed on these electrodes 13, 19, 21. Here, the plating electrode 23 is composed of, for example, a nickel plating layer 23a and a solder or tin plating layer 23b. The nickel plating layer 23a has a thickness of 3-10 μm.
The thickness of the solder or tin plating layer 23b is preferably about 5 to 15 μm.

In the chip resistor having the above-mentioned structure, since the plating electrode 23 protruding from the surface of the protective film 17 of the chip resistor is formed, even if the chip resistor is mounted face down, Can be suppressed, so that the circuit board can be reliably mounted on the circuit board. For this reason, the surface mounting of the front and back surfaces from the bulk cassette by the bulk mounting machine without selectivity is performed, and the surface side (protective film side) of the chip resistor is mounted.
Even if it is mounted so as to face the circuit board 25 (face down), it can be fixed by soldering without any problem.

FIG. 2 shows a chip resistor according to the second embodiment of the present invention. This chip resistor has an integrally formed concave resistor film 15c having convex portions arranged apart from each other.
Is equipped with. That is, in the first embodiment, the resistor film is composed of the first resistor film 15a and the second resistor film 15b, whereas the first resistor film 15a and the second resistor film 15b are formed. The body film 15b is formed simultaneously by one printing process. Other than the difference in the structure of this resistor film,
It has the same configuration as the chip resistor of the first embodiment. Therefore, even this chip resistor can be used for so-called bulk mounting.

Next, a method of manufacturing the chip resistor of the present invention will be described with reference to FIGS. First,
As shown in FIG. 3A, an insulating substrate 11 made of alumina or the like is used.
To prepare. The example shown shows one chip area,
In practice, a multi-piece sheet-like substrate that collectively manufactures a large number of chip resistors is used.

Next, as shown in FIG. 3B, a concave resistor film 15c is formed by transfer printing (stamping). This transfer printing, as shown in FIGS.
By using the transfer pad 33 (intaglio), the insulating substrate 1
The resistor film 15c can be easily transferred and formed on the substrate 1. That is, first, the resistor film 15 to be formed is first formed on the tip of the transfer pad 33 made of, for example, silicon rubber.
An intaglio 33c, which is a three-dimensional pattern type corresponding to the surface shape of c, is provided. Then, the transfer pad 33 is put into the resistor paste 35, and the intaglio plate 3 of the pattern type is formed.
3c is filled with a resistor paste. Next, as shown in FIG. 4B, the resistor paste is applied by pressing on the insulating substrate 11 and pulled up to form a resistor film 15c having a convex cross section with concave portions at both ends. be able to. According to such transfer printing, a resistor film having a partially different film thickness can be formed by one printing process.

As another embodiment of forming the resistor film of the present invention by screen printing, the example shown in FIG.
After forming the lower resistor film 15b across the cut portion of the insulating substrate, the upper resistor film 1 is formed over the entire insulating substrate.
5a may be formed and then cut. The examples shown in FIGS. 6A and 6B are examples in which the resistor film portions for raising the electrodes shown in FIGS. 1 and 5 have two layers (two or more layers may be used). With this configuration, the electrode can be raised to a higher height. Further, as shown in FIG. 6C, the resistor portion for raising the electrode has two layers, but the upper layer of the two-layer resistor film covers the lower layer. Has been done. Although not shown in the drawing, the first resistor film is formed so that both ends thereof are left not in the substantially entire length of the insulating substrate 11, and the second resistor is formed in the portions where the first resistor film is not formed. The resistor film may be formed. In this case, the second resistance film is formed to be thicker than at least the first resistance film. Here, the second resistor film also serves as an electrode for the first resistor film 15a that governs the resistance value, so that the resistance value is higher than that of the first resistor film 15a. You may make it low. It is preferable to use ruthenium oxide or the like as the resistor, and the resistor is fired at a temperature of about 850 ° C., for example.

Next, as shown in FIG. 3C, the electrode 13 is formed on the convex portion of the resistor film 15c (that is, the second resistor film 15b or the portion whose thickness is increased by transfer printing).
The electrode 13 is formed by forming an Ag or Ag-Pd paste pattern by screen printing and firing it at a temperature of about 850 ° C., for example. Similarly, the back electrode 19 is also formed by arranging an Ag or Ag-Pd paste pattern by screen printing and firing it. Either of the front surface side electrode 13 and the rear surface side electrode 19 may be formed first.

Next, as shown in FIG. 3 (d), a first protective layer pattern is formed on the concave portion of the resistor film 15c by screen printing and baked. The first protective layer 17a is a glass insulating layer and is preferably fired at a temperature of about 600 ° C. The resistor film 15c is subjected to laser milling as necessary to adjust the resistance value. Next, a second protective layer pattern of a resin paste is formed on the glass insulating layer 17a by screen printing and heated and cured to form a second protective layer 17b. The second protective layer 17b is an epoxy resin,
It is preferable to perform heat curing at a temperature of about 0 ° C. The first protective layer 17a and the second protective layer 17b are arranged in the concave portion formed between the pair of convex portions of the resistor film 15c.

The above processing is a batch processing of a large number of sheet-shaped substrates, but a processing for dividing into strips is next performed.
The processing may be dicing or break.
After dividing the multi-cavity sheet-shaped substrate into strips,
As shown in (e), the end face electrode 2 is formed on the exposed end face of the substrate.
1, 21 are formed. The end face electrodes 21 and 21 are Ni / Cr thin film layers deposited by, for example, sputtering.
Then, a process of dividing the chip into individual chips is performed. Either dicing or break can be used for processing. Next, as shown in FIG. 3 (f), electrolytic plating is performed to form electrodes 13, 19, 21.
The plated electrodes 23, 23 are formed on top. In order to prevent electrode breakage and improve the reliability of soldering, the Ni plating layer 23a and the Sn-Pb plating layer (Sn) are formed by electrolytic plating.
A plating layer 23b).

According to the above manufacturing process, the insulating substrate 1
The surface of the electrode 23 at both ends of 1 is raised by the convex portion of the resistor film 15c (or the second resistor film 15b), and the surface portion of the protective film 17 in the center is covered with the circuit board surface or between the lands. There is a gap (standoff) with respect to the pattern. According to such a method of manufacturing a chip resistor, a normal method of manufacturing a chip resistor can be adopted as it is, except for the step of forming the resistor film. Therefore, by using the transfer printing technique, it is possible to manufacture the chip resistor corresponding to bulk mounting without increasing the manufacturing cost without increasing the manufacturing cost and suppressing the front and back of the mounting surface.

In the above embodiment, an example has been described in which electrodes are provided on the front surface and the back surface of the insulating substrate so that the chip resistor can be mounted face-up or face-down. However, it is also applicable to so-called filletless mounting, in which electrodes are provided only on the front surface of the substrate and the mounting is performed only on the back side. That is, a chip resistor compatible with filletless mounting can be manufactured by simply omitting the formation of the back surface electrode 19 and the end surface electrode 21.

Although one embodiment of the present invention has been described so far, it goes without saying that the present invention is not limited to the above-described embodiment and may be implemented in various different forms within the scope of the technical idea thereof.

[0029]

As described above, according to the present invention, the reliability of the surface mounting on the circuit board can be increased by the electrode raised on the surface of the protective film of the chip resistor.

[Brief description of drawings]

FIG. 1 is a sectional view showing a chip resistor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a chip resistor according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the chip resistor.

4A and 4B are explanatory diagrams of transfer printing of a concave resistor film, in which FIG. 4A shows a step of attaching a resistor paste to a tip portion of a transfer pad, and FIG. 4B shows a concave resistor on an insulating substrate. The respective stages of transferring the film are shown.

FIG. 5 is a cross-sectional view showing a modified example of formation of a resistor film.

FIG. 6 is a cross-sectional view showing a modified example of formation of a second resistor film.

7A and 7B are cross-sectional views showing the overall configuration of a conventional chip resistor, FIG. 7B is mounted with the protective film side facing the front side, and FIG. 7C is the protective film side facing the circuit board. And (d) is a view showing a state in which a so-called chip is raised.

[Explanation of symbols]

11 Insulating substrate 13, 19, 21 electrodes 15 resistor 15a First resistor film 15b Second resistor film 15c Recessed resistor film integrally formed 17a, 17b, 17 protective film 23a, 23b, 23 plated electrode

Continued front page    (72) Inventor Ikatsu Sakai             14016 Nakaminowa, Minowa-cho, Kamiina-gun, Nagano Prefecture             Inside Coer Co., Ltd. F-term (reference) 5E032 BA04 BB01 CA02 CC14 CC16                 5E033 AA27 BB02 BC01 BD01 BE02                       BG02 BG03 BH02

Claims (5)

[Claims] 1. An insulating substrate, a resistor film formed on the insulating substrate, at least a pair of electrodes formed on the resistor film, and at least a portion of the resistor where the electrodes are not formed. A protective film covering the body film, and a plating electrode formed on the electrode, by forming the resistor film to increase the thickness of the portion corresponding to the region where the electrode is formed, A chip resistor, wherein the height of the surface of the plating electrode is made higher than the height of the surface of the protective film. 2. The first resistor film is formed in a region including at least a portion between the pair of electrodes of the insulating substrate.
2. The resistor film according to claim 1, and a second resistor film formed in a portion that is electrically connected to the first resistor film and corresponds to a region where the electrode is formed. The chip resistor described in. 3. A back surface electrode is arranged on the back surface of the insulating substrate, an end surface electrode is arranged on a side end surface, and the plating electrode is arranged on these electrodes. The chip resistor described in. 4. A shape in which a pair of electrodes are formed on a resistor film formed on the surface of an insulating substrate, and the surface shape of the resistor film has an increased thickness at a portion corresponding to a region where the electrodes are formed. A method of manufacturing a chip resistor formed so as to include a step of filling a resistive material into an intaglio molded into a shape corresponding to the surface shape of the resistor film formed on the insulating substrate, A step of forming the resistor film by pressing the intaglio plate onto the insulating substrate and transferring a filled resistor material; and a step of forming the electrode in a portion where the thickness of the resistor film is increased. And a step of forming a protective film covering at least a portion of the resistor film where the electrode is not formed, the method of manufacturing a chip resistor. 5. The chip resistor according to claim 4, including a step of forming a back surface electrode on the back surface of the insulating substrate, and a step of forming a side surface electrode on a side surface of the insulating substrate. Manufacturing method.