JPH08339901A - Chip-type electronic component - Google Patents

Abstract

PURPOSE: To facilitate the control of precision in the direction of the thickness of a component with the protection stability by protective coating maintained in a high degree and to solve the problem of sucking errors by a vacuum chuck by making the surface of the protecting coating smoother. CONSTITUTION: In a chip type resistor having electrode films 2, which are formed at both-end parts in one direction on a substrate 1 having a plane-view rectangle shape, and a resistor film 3, which conducts the electrode films and a resistor film 3, which conducts the electrode films and is formed so that both end parts of the substrate in the other direction retreat inside of both side edges of the substrate in the other direction, protective coating is applied on the resistor film 3. The protective coating includes a first coat layer 4, which is formed before trimming and formed so as to covet the resistor film 3 and so that both end parts of the substrate in the other direction retreat inside of both side edges of the substrate in the other direction, a second coat layer 5, which is formed so that both end parts of the substrate in the other direction extended to both side edges of the substrate in the other direction, and a third coat layer 6, which is formed on the second coat layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention dramatically enhances the protection stability of the resistance coating surface by the protective coating layer, and secures the smoothness of the coating surface to reduce adsorption mistakes during mounting operation. The present invention relates to an improved chip resistor and its manufacturing method.

[0002]

2. Description of the Related Art Various electronic parts are being replaced with chip type for the purpose of improving the mounting density on a circuit board and improving the electrical characteristics. A chip resistor as a typical one of such chip electronic components is manufactured through the following manufacturing steps.

First, electrode coatings are collectively printed on both ends of each rectangular region of a plurality of rows and a plurality of columns surrounded by the slits on the upper surface of a ceramic substrate which is fired while forming slits (slits) in a grid pattern. After that, a resistive coating of a predetermined shape is collectively printed on each rectangular unit area. By this, in each rectangular area, the electrode coatings arranged at both ends thereof,
A basic portion of each unit chip resistor is formed which is composed of a resistance coating formed so as to be electrically connected between these electrode coatings. Then, the surface of the resistance coating in each rectangular unit area is coated with undercoat glass. next,
A trimming process is performed to obtain a target resistance value by forming a trimming groove in the resistance film while measuring the resistance between the electrodes.

The trimming of the resistance coating in this type of small chip resistor is generally laser trimming in which the resistance coating is heated and evaporated by a laser beam to form a groove. This laser trimming is as described above. This is performed on a resistance film coated with undercoat glass. By doing so, the resistance coating material that is scattered by the heat from the laser is less likely to redeposit on the printed coating or on the already formed groove, so that the number of defective products is reduced, and more accurately the target resistance value and can do.

Then, the surface of the undercoat glass is coated with overcoat glass in order to protect the resistance coating exposed in the groove by the trimming. The coating with the undercoat glass and the coating with the overcoat glass are performed on each rectangular area on the substrate by batch printing in the same manner as in the formation of the electrode coating and the resistance coating. That is, low melting point lead glass or the like is used as a coating material, and the glass melted in a paste form is printed as a printing material.

In this way, the substrate that has undergone the overcoating process is divided along the slits extending in the row direction to obtain a row of bar-shaped substrate pieces, and the electrode coating is applied and baked on the side edge surface or the back surface near the side edge. After the formation, the unit chip resistors are divided along the slits extending in the row direction, and finally the electrode portions of the divided chip resistors are plated.

[0007]

By the way, since the chip type resistor as described above is strictly required to have protection stability due to its glass coat, FIG. 9 emphasizes the dimension in the thickness direction to show a cross section thereof. As shown, there are circumstances in which the thickness of the overcoat must be relatively large. Then, a relatively large amount of glass is applied at once to a relatively small area (1 mm square or less), and the surface tension after application causes the surface of the overcoat to have a convex curved surface as shown in FIG. Will be in a state.

On the other hand, when a small electronic device of this type is mounted on a substrate, the electronic device is often transported from the component stocker to the substrate by suction with a vacuum chuck as shown in FIG. However, as described above, it correctly adsorbs electronic parts whose surface is a convex curved surface,
And it is difficult to convey to the correct position on the substrate,
There is a problem that there is a high probability that mounting defects will occur.

Furthermore, the chip-type resistor as described above is required to have strict accuracy in the dimension in the thickness direction in connection with being mounted in the supply mechanism of the mounting apparatus in a laminated form. Thickness H of the overcoat formed by applying a relatively large amount of glass at once
There was also a problem that it was difficult to strictly manage.

The present invention solves the above-mentioned conventional problems, and while maintaining a high degree of protection stability by the protective coating, it is easy to control the accuracy in the thickness direction of the component, and the surface of the protective coating is It is an object of the present invention to provide a chip-type resistor having a structure that can be made smoother and can solve the problem of a suction error due to a vacuum chuck, and a method for manufacturing the same.

[0011]

In order to solve the above problems, the present invention takes the following technical means.

That is, the chip-type resistor according to the present invention is such that an electrode coating film formed on both ends in one direction of the substrate is rectangular on a substrate, and the electrode coating films are electrically connected to each other, and In a chip-type resistor having a resistance coating formed so that both ends in the direction of the substrate are retracted inward from both side edges of the substrate in the other direction, a protective coating is applied on the resistance coating. ,
A first coat layer formed before trimming, which covers the resistance film and is formed so that both ends of the substrate in the other direction of the substrate are retracted inward from both side edges of the substrate in the other direction, and the first coat layer formed after trimming, and the substrate A second coat layer formed so that both ends in the other direction extend to both edges of the substrate in the other direction, and a third coat layer formed on the second coat layer.
It is characterized by including a coat layer of.

In the above description, one direction of the substrate means
In a rectangular substrate, the two sides are opposed to each other, and the other direction of the substrate is a direction in which the remaining two sides are opposed to each other.

[0014]

According to the present invention, the coat layer formed after trimming in the conventional chip type electronic component of this type is divided into the second coat layer and the third coat layer. Therefore, it is possible to finally form a protective coating having a sufficient thickness while forming each of the second coat layer and the third coat layer in a thin shape, and to achieve high protection stability by this protective coating.

In this way, the second coat layer and the third coat layer can be formed thinly, so that the surface of each coat layer does not become a convex curved surface at the time of application, and The surface of the protective coating does not have a convex curved surface unlike the conventional example in which it was necessary to form a relatively thick coating layer at once, but the surface has a smooth surface. Therefore, the suction by the vacuum chuck is correctly performed, and the probability of mounting failure as in the conventional case is significantly reduced.

Since each coating layer can be made thin, the influence of surface tension during coating is small, and therefore,
The thickness of each coat layer can be accurately controlled.
This leads to a remarkable improvement in accuracy of the thickness dimension of the final electronic component.

Further, the resistance film is formed such that both ends of the substrate in the other direction of the substrate are retracted inward from both side edges of the substrate in the other direction, and the first coat layer covers the resistance film and the other side of the substrate. Both end portions in the direction of the substrate are formed so as to be retracted inward from both side edges of the substrate in the other direction, and the second coat layer is formed so that both end portions in the other direction of the substrate extend to both side edges of the substrate in the other direction. Therefore, the second coat layer can be formed without strict positioning, and moreover, the resistor coat and the entire first coat layer thereabove can be surely covered with the second coat layer. This also makes it possible to maintain a high degree of protection stability by the protective coating.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. In the embodiment, the present invention is applied to a chip type resistor. The chip resistor is manufactured by the following procedure, and the structure of the present invention is adopted in the protective coating forming step which is an intermediate step.

First, as shown in FIGS. 6 and 1, a ceramic substrate having a lattice-shaped split groove formed on the surface thereof, which is composed of a plurality of horizontal slits 1a at equal intervals and a plurality of vertical slits 1b at equal intervals. 1, each of the slits 1a ...
In the rectangular unit areas A ... Enclosed by b ... As shown in FIG. 1, the electrode coatings 2 ... And the resistance coatings 3 ... As a result, the basic shape of the unit chip resistor C including the pair of electrode coatings 2 and 2 and the resistance coating 3 electrically connected between them is collectively formed in a plurality of rows and a plurality of columns on a single ceramic substrate. The Rukoto. The electrode coating 2 and the resistance coating 3 are formed by printing a paste-like electrode material and a resistance material on a ceramic substrate in a predetermined shape by printing, and then firing and solidifying.

On the ceramic substrate thus obtained, first, as shown in FIG. 2, an undercoat layer 4 which is a first coat layer is formed. The undercoat layer 4 is applied and formed in an independent rectangular shape in plan view that covers the resistive coatings 3 in plan view. This undercoat layer 4
The formation of is similar to the formation of the electrode coating and the resistance coating,
It is performed by a printing method. That is, a material obtained by melting a low-melting glass in a paste form or the like is collectively applied to each area A by a printing method, and is baked and solidified.

With the undercoat layer 4 thus formed, a measuring probe is applied to each electrode coating 2 to measure a resistance value, and a groove (not shown) is formed in the resistive coating 3 by laser light to obtain a desired resistance. Laser trimming is performed to obtain a resistance value.

Then, as shown in FIG.
A medium coat layer 5, which is a second coat layer, is formed on the undercoat layer 4. In this example, this is formed in a strip shape continuous in the column direction with respect to the unit chip resistor group arranged in the column direction (vertical direction in each drawing).
Of course, the width of the band is set to a size that can sufficiently cover the undercoat layer 4. As a result, in each unit chip resistor C, the medium coat layer 5 is formed so as to fill the space between the upper and lower edges of FIG. In addition,
The method for forming the medium coat layer 5 is also the same as above.

Subsequently, as shown in FIG. 4, an overcoat layer 6 ... As a third coat layer is formed on the medium coat layer 5. In this example, each of the overcoat layers 6 ...
Independent rectangular plan view shape of the size that covers the. As a result of forming the rectangular overcoat layer 6 on the medium coat layer 5 formed in the strip shape in the column direction as described above, as a result of looking at each unit chip resistor, the overcoat is formed at the edge in the column direction. The medium coat layer 5 is exposed from below the layer 6 to the side edge of the chip.

After the protective coating has been formed by the above-mentioned steps of forming the coating layers, the ceramic substrate 1 is divided along the vertical slits 1b ... The electrode coating is applied and baked on the back surface near the edge surface or the side edge surface to form the electrode portion 7. And
Finally, the substrate rod-shaped pieces are separated by the lateral slits 1a ... And divided into the substrate pieces 1c for each unit area A ..., to obtain the chip resistors C divided for each unit chip as shown in FIG. . The electrode portion 7 is usually plated with solder.

The chip-type electronic device of the present invention obtained through the above-described steps has a protective coating on the resistance coating 3 as is apparent from the sectional views shown in FIGS. 7 and 8 in which the dimension in the thickness direction is emphasized. Has a three-layer structure including an undercoat layer 4, a medium coat layer 5, and an overcoat layer 6. Therefore, even if a relatively thick total coating thickness is required to obtain high stability of the protective coating, each coating layer can be formed thinly, and therefore, it becomes easy to control the thickness of the protective coating as a whole. The dimensional accuracy in the thickness direction is dramatically improved compared to the conventional method, and a large amount of molten glass is applied at one time to obtain a predetermined thickness. Is eliminated, and the coating surface can be made smooth. As a result, it is possible to achieve a chip-type electronic device with few suction errors due to a vacuum chuck, good dimensional accuracy, and a highly reliable protective coating.

Moreover, in the present invention, since the medium coat layer 5 is formed in a strip shape in the column direction, it is possible to surely cover the underlying resistance coatings 3 ... And the undercoat layer 4, so that This also contributes to the improvement of protection stability by the protective coating. Further, the positioning of the medium coat layer in the printing column direction is rough and the printing efficiency is improved, and when the overcoat layer 5 is formed into an independent rectangular shape in each chip by viscous glass etc. Even if an external matter hits the side edge to cause a chip in the medium coat layer 5, the chip does not progress into the region of the overcoat layer 5, and the effect that the reliability of the protective coat is still maintained can be expected. .

[Brief description of drawings]

FIG. 1 is a partial plan view of a ceramic substrate at the time when the formation of an electrode coating and a resistance coating is completed.

FIG. 2 is an enlarged partial plan view of the ceramic substrate at the time when the formation of the undercoat layer (first coat layer) is completed.

FIG. 3 is a medium coat layer (second coat layer).
FIG. 3 is an enlarged partial plan view of the ceramic substrate at the time when the formation of the is finished.

FIG. 4 is an enlarged partial plan view of the ceramic substrate at the time when the formation of the overcoat layer (third coat layer) is completed.

FIG. 5 is a plan view of a completed chip resistor.

FIG. 6 is a plan view of the ceramic substrate itself.

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG.

8 is an enlarged cross-sectional view taken along line VIII-VIII of FIG.

FIG. 9 is an enlarged cross-sectional view showing a conventional example.

FIG. 10 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Ceramic Substrate 2 Electrode Substrate 3 Resistive Film 4 (First Coat Layer) Undercoat Layer 5 (Second Coat Layer) Medium Coat Layer 6 (Third Coat Layer) Overcoat Layer

Claims (1)

[Claims] 1. An electrode coating formed on both ends in one direction of the substrate having a rectangular shape in plan view and electrical continuity between these electrode coatings, and both ends in the other direction of the substrate are opposite side edges of the substrate in the other direction. In a chip-type resistor including a resistance film formed so as to be retracted inward, a protective coating is applied on the resistance film, and the protective coating is formed before trimming and A first coat layer that covers the coating and is formed so that both ends of the substrate in the other direction of the substrate are retracted inward from both side edges of the other direction of the substrate; A second coat layer formed to extend to both side edges and the second coat layer.
A chip-type resistor including a third coat layer formed on the coat layer of 1.