JPH0770365B2 - Chip type electronic parts - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a chip type electronic component improved so that the protection stability of the resistance coating surface by the coating glass is dramatically improved and the smoothness of the coating surface is ensured to reduce the suction error during the mounting operation.

[Prior art]

Various electronic components 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, after batch-printing and forming an electrode coating 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 the ceramic substrate that is fired while forming the dividing grooves (slits) in a grid pattern, A resistive coating having a predetermined shape is collectively printed on each rectangular unit area. As a result, a basic portion of each unit chip resistor is formed in each rectangular area, the electrode coating being provided at both ends of the rectangular coating, and the 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 step 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 vaporized by laser light to form a groove, and this laser trimming is performed using the undercoat glass as described above. Is applied to the resistance film coated with. 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 by batch printing on each rectangular area on the substrate in the same manner as in the formation of the electrode coating and the resistance coating. That is,
Using low melting point lead glass etc. as coating material,
It is performed by printing a glass melted in a paste form as a printing material. In this way, the substrate which has been subjected to the overcoating process is divided along slits extending in the row direction to obtain a single-row bar-shaped substrate piece, and the electrode coating is formed on the side edge surface or the back surface near the side edge by coating and baking. After that, each unit chip resistor is divided along a slit extending in the row direction, and finally,
The electrode portion of each divided chip resistor is plated.

[Problems to be Solved by the Invention]

By the way, since the chip resistor as described above is strictly required to have protection stability due to its glass coat,
As shown in FIG. 9 by emphasizing the dimension in the thickness direction to show the cross section,
There are circumstances in which the thickness of the overcoat glass must be relatively thick. Then, a relatively small amount (1 mm square or less (a relatively large amount of glass is applied at a time to the area), and the surface tension of the overcoated glass causes the surface of the overcoated glass to move as shown in FIG. On the other hand, when mounting a small electronic device of this kind on a board, the electronic device from the component stocker to the board must be transported by a vacuum chuck as shown in Fig. 10. However, it is difficult to correctly pick up electronic components with a convex curved surface as described above and to transport them to the correct position on the board, and the probability of causing mounting defects is high. In addition, the chip-type resistors as described above are stacked in the supply mechanism of the mounting apparatus in a stacked form, and the dimension in the thickness direction has a strict accuracy. However, there is also a problem that it is difficult to strictly control the thickness H of the overcoat formed by coating a relatively large amount of glass at once as described above. The conventional problems described above have been solved, and while maintaining a high degree of protection stability due to glass coating, it is easy to control the accuracy in the thickness direction of parts, and the surface of the coated glass is made smoother by a vacuum chuck. It is an object of the present invention to provide a structure of a chip-type electronic device that can solve the problem of adsorption error.

[Means for solving the problem]

In order to solve the above problems, the present invention takes the following technical means. That is, the chip type electronic component of the present invention, on a predetermined planar substrate piece, an electrode coating formed on both ends thereof, and a resistance coating formed to conduct between the electrode coating, Furthermore, a protective coating consisting of three layers, an undercoat glass layer applied before trimming, a medium coat glass layer applied after trimming, and an overcoat glass layer formed on the upper layer, is formed on the resistance film. It is characterized by being applied.

[Action and effect]

In the present invention, the overcoat glass layer formed after trimming in the conventional chip-type electronic component of this type,
It is divided into two layers, a medium coat glass layer and an overcoat glass layer. Therefore, it is possible to finally form the protective coating having a sufficient thickness while applying the medium-coated glass and the overcoated glass in a thin state. Then, medium coated glass and over coated glass can be applied thinly,
The surface of the coated glass does not have a convex curved surface at the time of application, so that the surface of the protective coating has a convex curved surface as in the conventional example where it was necessary to apply a relatively thick coating glass at once. It 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. Then, since each coat glass layer can be made thin, the influence of the surface tension at the time of application is small, and therefore the thickness of each coat glass layer can be accurately controlled.
This leads to a remarkable improvement in accuracy of the thickness dimension of the final electronic component.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be specifically described 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 FIG. 6 and FIG. 1, a ceramic substrate 1 having a lattice-shaped split groove formed on the surface thereof, which includes a plurality of evenly-spaced horizontal slits 1a and a plurality of equally-spaced vertical slits 1b. In the rectangular unit areas A surrounded by the slits 1a, ..., 1b ..., the electrode coatings 2 ... And the resistance coatings 3 at both ends thereof are successively shown in detail in FIG. It is formed by batch printing. Thereby, the pair of electrode coatings 2,
The basic form of the unit chip resistor C including 2 and the resistance film 3 electrically connected between them is collectively formed in a plurality of rows and a plurality of columns on a single ceramic substrate. 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 glass layer 4 is formed.
The undercoat glass layer 4 is applied and formed in a rectangular shape in a plan view which covers the resistive coatings 3 in a plan view. The formation of the undercoat glass layer 4 is also carried out by a printing method similarly to the formation of the electrode coating and the resistance coating. That is, a low melting point glass melted in a paste form is collectively applied to each area A by a printing method,
And it is baked and solidified. With the undercoat glass layer 4 thus formed, a resistance is measured by applying a measuring probe to each electrode coating 2 and a groove (not shown) is formed in the resistive coating 3 by laser light to obtain a desired resistance. Laser trimming is performed. Subsequently, as shown in FIG. 3, a medium coat glass layer 5 is formed on each resistance coating 3 and the undercoat glass 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 belt is
The dimensions are sufficient to cover the undercoat glass layer 4 in the width direction. As a result, in each unit chip resistor C, the medium coat glass layer 5 is formed so as to extend between the upper and lower edges of FIG. The method of forming the medium coat glass layer 5 is also the same as above. Further subsequently, as shown in FIG. 4, overcoat glass layers 6 ... Are formed on the medium coat glass layer 5. In the present example, the rectangular plan view shape has a size that covers the undercoat glass layer 4 that is rectangular in plan view. As a result of forming the overcoat glass layer 6 having each rectangular shape on the medium coat glass layer 5 formed in the strip shape in the column direction as described above, as a result of looking at each unit chip resistor, at the edge in the column direction, Overcoat glass layer 6
The medium coat glass layer 5 is exposed from below to the side edge of the chip. Then, after the glass coating step is completed, the ceramic substrate 1 is divided along the vertical slits 1b ... to obtain a substrate rod-shaped piece (not shown), and an electrode is formed on the side edge surface or the back surface near the side edge surface. The coating film is applied and baked to form the electrode portion 7. Then, finally, the substrate rod-shaped piece is cut into the horizontal slit 1a.
Are separated by ... and divided into substrate pieces 1c for each unit area A,
A chip resistor C divided into unit chips as shown in FIG. 5 is obtained. The electrode portion 7 is usually plated with solder. In the chip-type electronic device of the present invention obtained through the above-mentioned steps, the glass coating on the resistance coating 3 is clear, as is clear from the sectional views shown in FIGS. 7 and 8 in which the dimension in the thickness direction is emphasized. The undercoat glass layer 4, the medium coat glass layer 5, and the overcoat glass layer 6 have a three-layer structure. Therefore, even if a relatively large total coating thickness is required to obtain high coating stability, each coating glass can be applied thinly, which makes it easy to control the coating thickness as a whole, especially in the thickness direction. The dimensional accuracy of is dramatically improved compared to the conventional one, and the tendency to form a convex curved surface on the surface due to the influence of surface tension unlike the conventional example where a large amount of molten glass is applied at one time to obtain a predetermined thickness The coating surface can be made smooth. As a result, there are few suction mistakes due to the vacuum chuck,
A chip-type electronic device having high dimensional accuracy and a highly reliable protective coating is achieved. Moreover, in this example, the medium coat glass layer 5
Since the strips are formed in a band shape in the column direction, the positioning in the column direction of this printing is rough and the printing efficiency is improved, and the overcoat glass layer 5 is independently formed in each chip by viscous glass. When the rectangular shape is adopted, even if an external matter hits the side edge of the chip and a chip is generated in the medium coat glass layer 5, the chip does not propagate into the area of the overcoat glass layer 5, and the reliability of the protective coat is improved. Is also maintained. The scope of the present invention is not limited to the above-described embodiments. For example, although the present invention is suitable for a chip resistor in the above embodiments, a protective glass coating is required for other chip electronic parts. The present invention can be applied to the following.

[Brief description of drawings]

FIG. 1 is a partial plan view of the ceramic substrate at the time when the formation of the electrode coating and the resistance coating is completed, and FIG. 2 is an enlarged partial plan view of the ceramic substrate at the time when the formation of the undercoat glass layer is completed. The figure is an enlarged partial plan view of the ceramic substrate at the time when the formation of the medium coat glass layer is completed,
FIG. 4 is an enlarged partial plan view of the ceramic substrate at the time when the formation of the overcoat glass layer is completed, FIG. 5 is a plan view of the finished chip resistor, and 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. 5, FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG. 5, FIG. 9 is an enlarged sectional view showing a conventional example, and FIG. It is explanatory drawing of an example. 1 ... Ceramic substrate, 2 ... Electrode substrate, 3 ... Resistive film, 4 ... Undercoat glass layer, 5 ... Medium coat glass layer, 6 ... Overcoat glass layer.

Claims (1)

[Claims] 1. A chip-type electronic component comprising a substrate piece having a predetermined planar shape and provided with electrode coatings formed at both ends thereof and a resistance coating formed so as to electrically connect between the electrode coatings. A protective coating consisting of three layers, an undercoat glass layer applied before trimming, a medium coat glass layer applied after trimming, and an overcoat glass layer applied on the upper layer, is applied on the resistance film. A chip-type electronic component characterized in that