JP2003037001A - Chip resistor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip resistor with which both the front and back sides of a chip part are not selected at the time of mounting, namely, correspondence to bulk mounting is made possible. SOLUTION: The chip resistor is provided with an insulation substrate 11, an insulation layer 31 formed on the surface of the substrate, a resistor 15 and an electrode 13 which are formed on the upper side of the insulation layer, a protective film 17 for protecting the resistor and a plating electrode 23 formed on the electrode. In the insulation layer 31, an electrode forming part 31a forming the electrode is thicker than a resistor-forming part 31b which forms the resistor.

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 is particularly suitable for so-called bulk mounting in which a chip cassette is mounted on a circuit board without selecting the front and back of the chip cassette from a bulk cassette. It relates to chip resistors.

[0002]

2. Description of the Related Art FIG. 3A shows an example of the structure 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
Front surface electrode 13 and rear surface electrode 19 arranged at both ends of
And the plating electrode 2 on each surface of the end surface electrode 16 on the side end surface.
3, 23 are formed.

In this case, the surface height of the protective film 17 in the central portion of the substrate becomes higher than the surface height of the plated electrode portion 23. In the thick film chip resistor, a step difference between the surface of the plating electrode 23 on the surface of the insulating substrate 11 and the surface of the protective film 19 is often about 30 to 50 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 of the substrate on which the resistors are present is fixed as the surface. Then, when mounting on the circuit board, it is fixed to the circuit board in the same state, that is, with the surface (the protective film side) where the resistor is present as the surface by a mounting machine (mounter). In this case, as shown in FIG. 3B, 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 the connection and fixing to the land portion 27 by solder reflow or the like is performed. Done.

However, the mounting method is so-called bulk mounting, in which a large number of chip components are randomly placed in a bulk cassette regardless of front and back, and the chip components are taken out one by one from the bulk cassette and mounted on a circuit board. Exists. 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. 3A is bulk-mounted by the bulk mounting machine,
As shown in (b), no particular problem occurs when the chip resistor is mounted so that the back surface thereof faces the circuit board 25. However, as shown in FIG. 3C, the surface side (protective film side) of the chip resistor is the circuit board 2
If it is the surface opposite to 5, the chip resistor is likely to be mounted at an inclination, and in the worst case, soldering on one side is not possible, or as shown in FIG. There is a problem that such phenomena occur. Therefore, the conventional chip resistor has a problem that it cannot support so-called bulk mounting.

[0007]

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.

[0008]

In order to solve the problems in the prior art, one aspect of the present invention is to provide an insulating substrate, an insulating layer formed on the surface of the substrate, and the insulating layer. A resistor and an electrode formed on the upper side of the layer, a protective film for protecting the resistor, and a plating electrode formed on the electrode, the thickness of the insulating layer is the electrode The chip resistor is characterized in that an electrode forming portion to be formed is thicker than a resistor forming portion to form the resistor.

Here, the thickness of the insulating layer is continuously changed between the electrode forming portion and the resistor forming portion. As a result, a step is not formed between the thick portion and the thin portion of the insulating layer, and the resistor and the electrode arranged thereon can be smoothly formed.

The method of manufacturing a chip resistor according to the present invention further comprises an insulating substrate, an insulating layer formed on the surface of the substrate, a resistor and an electrode formed on the insulating layer, and A method of manufacturing a chip resistor comprising: a protective film for protecting a resistor; and a plating electrode formed on the electrode, including at least a part of a portion of the insulating layer forming the resistor. It is characterized in that it includes a step of etching the region.

According to the above chip resistor of the present invention,
A thin portion and a thick portion of the insulating layer are provided on the surface of the insulating substrate, and the resistor and its protective film are arranged on the thin portion. Therefore, the surface height of the electrode arranged in the thick portion and the plating electrode arranged thereon can be higher than the surface height of the resistor arranged in the thin portion and the protective film arranged thereon. it can. Accordingly, even when the chip resistor is mounted face down (the protective film side faces the circuit board), a gap (standoff) between the chip resistor and the circuit board at the time of mounting can be secured on the protective film surface.
Therefore, it is possible to mount the chip resistor on the circuit board with a probability of 100% even if the mounting is performed using a mounting machine that supports bulk mounting.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a chip resistor according to the present invention will be described below in detail 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. In the drawings, the same or corresponding parts will be denoted by the same reference numerals for the description.

This chip resistor has an insulating layer 3 made of a material different from that of the substrate 11 on the surface of an insulating substrate 11 such as alumina.
1 is arranged, and the insulating layer 31 (insulating layer) has a thick portion 31a and a thin portion 31b. The insulator layer 31 is a glass layer in this embodiment, but other insulators can be used. Insulator layer 3
In No. 1, a thick portion 31a and a thin portion 31b are formed by etching. This thick part 31a
And the thin portion 31b are smoothly and continuously formed.

The thin portion 31b of the insulating layer is a resistor forming portion where the resistor 15 is arranged, and the thick portion 31a of the insulating layer is an electrode forming portion where the electrode 13 is arranged. Here, a thick film resistor such as ruthenium oxide is used as the resistor 15, but a thin film resistor such as nichrome may be used. The electrode 31 is preferably formed by applying a thick film paste of silver or silver palladium by screen printing and firing, but a metal such as copper may be used. In this embodiment, the same thick-film electrode 19 of silver or silver-palladium as the front surface is also arranged on the back surface of the substrate 11. Further, on the end face of the substrate 11, an end face electrode 16 formed by sputtering or vacuum deposition of a thin film metal such as nichrome is arranged.

On the resistor 15 is formed a first cover for covering it.
Protective film 17 including protective film 17a and second protective film 17b
Are arranged. The first protective film 17a is preferably formed of, for example, a glass layer, and the second protective film 17b is preferably formed of, for example, a resin layer. The protective film 17 may be formed of one layer instead of being formed of two layers as described above. On the electrodes 31, 16 and 19, a plating electrode 23 composed of a nickel plating layer 23a and a tin or solder plating layer 23b is arranged.

In the chip resistor having the above structure,
The height from the surface of the substrate 11 to the surface of the plating electrode 23 is higher than the height from the surface of the substrate 11 to the surface of the protective film 17.
Therefore, even when mounting is performed using a mounting machine compatible with so-called bulk mounting so that the protective film side is the surface facing the circuit board, a gap is generated between the surface of the protective film 17 and the substrate 11. Therefore, it is possible to prevent the above-described chip rising and the like and configure a chip resistor suitable for a mounting machine compatible with bulk mounting.

It is to be noted that an insulating layer having a smooth surface is used, and a resistor 15 and an electrode 13 are respectively deposited on the thin film by sputtering or the like, and are formed into a predetermined pattern by lithography to form a thick film technique. It is possible to manufacture a chip resistor that can obtain a highly accurate resistance value with a low TCR, which is difficult with. Also in such a resistor, since the insulator layer 31 includes the thick portion 31a and the thin portion 31b, the surface height of the plating electrode 23 is equal to that of the protective film 17.
Since it is higher than the surface height of, it can be used in a so-called mounting machine for bulk mounting. The surface of the plating electrode is preferably higher than the surface of the protective film, but the height may be the same.

Next, a method of manufacturing the chip resistor of the present invention will be described with reference to FIG. First, FIG.
As shown in (a), an insulating substrate 11 made of alumina or the like is prepared. Although one chip area is shown in the illustrated example, a multi-piece substrate for manufacturing a large number of chip resistors at once is used in practice. The insulating layer 31 is formed by applying a glass paste on the entire surface of the substrate 11 and then firing it.

Next, as shown in FIG. 2B, the insulating layer 3
A thick portion 31a and a thin portion 31b are formed on the substrate 1. In this case, in the area between the thick portion 31a and the thin portion 31b, in order to achieve a good connection state between the resistor 15 and the electrode 13, it is desirable to avoid a sudden change in film thickness due to a step. In the present embodiment, the insulating layer 3 is continuously formed between the thick portion 31a and the thin portion 31b.
The thickness of 1 is changed. As a result, the electrodes and resistors to be formed later can be arranged on a smooth curved surface, and a good connection between them can be formed. In order to form a continuous film thickness change in forming such a thin portion 31b of the insulating layer, isotropic wet etching is used, for example, by masking the thick portion 31a with a resist film. desirable. It is also possible to use isotropic dry etching instead of wet etching. In addition, in the example shown in FIGS. 1 and 2, the region of the insulator layer 31 to be etched and the resistor 1 are
Although the region forming 5 is substantially the same region, at least a part of the portion forming the resistor 15 is included even if the region to be etched is different from the region forming the resistor 15. If you have. That is, the region to be etched may be wider or narrower than the region in which the resistor 15 is formed. In the former case, it is necessary to provide the electrode 13 from the thick portion 31a to the region where the film thickness decreases until reaching the resistor 15. In the latter case, since the resistor 15 is formed over the thick portion 31a, the electrode 13 has the resistor 15 on the thick portion 31a.
It is necessary to form so that at least a part of them overlap. Further, in the latter case, the region to be etched is preferably substantially the central portion of the insulator layer 31, but it may be laterally biased. As described above, regardless of which region is etched, the effect of the present invention can be obtained by making it possible to secure a thicker layer thickness in the region where the electrode 13 is formed than in the region where the resistor 15 is formed. Can play. In the above example, the insulating layer 31 is provided with a thick portion and a thin portion in the insulating layer 31 by etching, but when the purpose is only to increase the height of the electrode portion, the glass in the etched portion remains. You don't have to.

Next, as shown in FIG. 2C, the resistor 1 is formed in the region including the etched thin portion 31b of the glass layer.
Place 5. The resistor 15 can be formed, for example, by applying a thick film resistor paste such as ruthenium oxide by screen printing to form a pattern and firing the pattern. Alternatively, a metal thin film may be formed by sputtering or vapor deposition without using such a thick film resistor. In this case, the thin film resistor 15 is formed by forming an opening pattern of the resistor with a photoresist film in advance, forming a metal thin film by sputtering or vapor deposition, and then removing the photoresist film by lift-off. You can

Next, as shown in FIG. 2D, the electrode 13 is formed on the thick portion 31a of the insulating layer. The electrode 13 is
It can be formed by applying a silver or silver palladium paste by screen printing and baking at a high temperature. Further, an opening pattern is provided in the photoresist film, a metal thin film is deposited by sputtering or vapor deposition, and then the photoresist film is removed by lift-off to form a metal thin film pattern, on which the electrode 13 is formed by copper plating or the like. Can also be formed. The electrode 19 is also formed on the back surface of the substrate by the same method as described above.

Next, as shown in FIG. 2E, a first protective film 17a and a second protective film 17b for covering the resistor are formed by screen printing or the like. For example, the first protective film 17
A is formed by applying a glass paste by screen printing and firing it. The second protective film 17b is formed by applying a resin paste by screen printing and heating and curing the resin paste.
After forming the first protective film 17a, the resistor 15 is trimmed by laser trimming as necessary.

Next, in the above process, a large number of substrates are collectively processed, but these are divided into individual chips by cracking or cutting. This division is first performed along the lateral direction of the chip section, and the end face electrode 16 is formed on each end face corresponding to a series of chips formed in a strip shape. The end face electrode 16 is formed by mounting a series of chips corresponding to a strip shape on an appropriate jig so that the end face is exposed, and depositing a metal thin film by vacuum vapor deposition or sputtering.

Then, the nickel plating layer 23a is formed on the electrodes 13, 16 and 19 by electrolytic plating such as barrel plating.
And by depositing the tin or solder plating layer 23b,
The plating electrode 23 is formed. This completes the chip resistor shown in FIG. Figure 1 shows the completed chip resistor.
Since the surface height of the plated electrode 23 is higher than the surface height of the protective film 17 as shown in (4), an electrode structure suitable for so-called bulk mounting can be obtained.

As described above, by forming the resistor 15 with a metal thin film on the glass layer 31, a chip resistor having a low TCR and a high resistance value accuracy can be manufactured. This is because the glass layer having a smooth surface is used as the base layer of the resistor 15 to remarkably reduce the unevenness existing on the surface of the insulating substrate 11 such as alumina, and to make the resistor pattern nonuniform and the film thickness. This is considered to be because the non-uniformity of is greatly reduced. Therefore, by manufacturing a thin film chip resistor by such a manufacturing method, it becomes possible to easily manufacture a highly accurate chip resistor with low TCR.

In the above embodiment, an example in which electrodes are provided on the front and back surfaces of the insulating substrate and the chip resistors can be mounted face-up or face-down has been described. However, electrodes are provided only on the substrate surface. The purpose of the present invention can also be applied to so-called filletless mounting, which is mounted only face down.

In addition, in the above-described embodiment, insulation
An example of using a glass layer as the object layer has been described.
A ceramic layer may be used instead of the lath layer.
And a ceramic mixed layer. This allows the substrate and
Both the adhesion to the electrodes and the shape retention of the insulating film can be secured.
It Furthermore, TiO_Two, SiN or SixNy, SiO
_TwoContaining SiOn, HfO_Two, Al_TwoO_Three, AlN, etc.
A material may be used, and the forming method includes a coating method and heating.
There are a firing method, a sputtering method, a CVD method and the like.

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]

According to the present invention, the height of the surface of the plating electrode can be made relatively higher than the height of the surface of the protective film as compared with the conventional chip resistor, and the circuit board The certainty of implementation in

[Brief description of drawings]

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

FIG. 2 is a diagram showing a manufacturing process of the chip resistor.

3A and 3B are cross-sectional views showing the overall structure of a conventional chip resistor, FIG. 3B is a protective film side mounted on the front side, and FIG. FIG. 3D is a diagram showing a state in which the chip is mounted, and a so-called chip is raised.

[Explanation of symbols]

11 Insulating substrate 13, 16, 19 electrodes 15 resistor 17a, 17b, 17 protective film 23a, 23b, 23 plated electrode 31 Insulator layer (glass layer) 31a Thick part of insulator layer 31b Thin portion of insulating layer

Claims (5)

[Claims] 1. An insulating substrate, an insulating layer formed on the surface of the substrate, a resistor and an electrode formed on the upper side of the insulating layer, and a protective film for protecting the resistor. A plating electrode formed on the electrode, wherein a thickness of the insulating layer is such that an electrode forming portion forming the electrode is thicker than a resistor forming portion forming the resistor. Chip resistor. 2. The chip resistor according to claim 1, wherein the height of the surface of the plating electrode is higher than the height of the surface of the protective film. 3. The chip resistor according to claim 1, further comprising a back surface electrode formed on the back surface side of the substrate, and a side surface electrode for electrically connecting the electrode and the back surface electrode. 4. The chip resistor according to claim 1, wherein a thickness of the insulating layer is continuously changed between the electrode forming portion and the resistor forming portion. 5. An insulating substrate, an insulating layer formed on the surface of the substrate, a resistor and an electrode formed on the upper side of the insulating layer, and a protective film for protecting the resistor. A method of manufacturing a chip resistor including a plated electrode formed on the electrode, including a step of etching a region including at least a part of a portion of the insulating layer where the resistor is formed. A method of manufacturing a chip resistor.