JPH03215901A - Square plate type chip resistor - Google Patents

Abstract

PURPOSE:To make it possible to reduce the recesses and projections on the surface of glass, and to achieve highly precise mounting by a method wherein a thick ruthenium film resistance layer, which is overlapped on a part of the upper surface electrode layers on a thick silver film, and a precoat glass layer, having the length less than the space between the upper surface electrodes to be formed on the resistance layer, are provided. CONSTITUTION:The title chip resistor is composed of a 96-alumina substrate 1, the upper electrode layers 2 and 2, and the edge-face electrode layer 3 of thick silver film electrode, a resistance layer 4 of thick ruthenium film, a precoat glass layer 5 covering the length less than the space between the two upper electrode layers 2 and 2 on the above-mentioned resistance layer 4, a first glass layer 6, a marking glass layer 7, and a second glass layer 8. The recesses and protrusions on the surface of glass can be made small and high mounting preciseness can be achieved by forming a glass layer 5, on the recessed part of the resistance layer, of almost the same height as the protuberance of the part, where the upper electrode layer 2 and the resistance layer 4, generating on the end part of the glass surface in the conventional square plate type chip resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a square plate type chip resistor that is mainly mounted on a high-density wiring circuit by an automatic mounting machine.

Conventional technology In recent years, as the demand for lighter, thinner, and smaller electronic devices has increased, very small square plate-type chip resistors are often used as resistance elements to increase wiring density on circuit boards. It's starting to look like this.

Moreover, in order to mount this square plate type chip resistor on a printed circuit board at high speed, it is almost always mounted using an automatic mounting machine. For this reason, there is an increasing demand for improving the mounting quality of square plate type chip resistors.

The structure of a conventional square plate type chip resistor is shown in FIG.

Conventional square plate type chip resistors are made of 96 alumina substrate 1],
A top electrode layer 12 and an end electrode layer 13 made of silver-based thick film electrodes,
A resistance layer 14 made of a ruthenium-based thick film resistor and a resistance layer 14
5, a first glass layer 16, a stamping glass layer 17, and a second glass layer 8. Note that, in order to improve solderability, a Ni plating layer 19 and a Sn-Pb plating layer 20 are applied to the exposed electrode surface by electrolytic plating.

Problems to be Solved by the Invention However, in the conventional square plate type chip resistor, the upper surface electrode layer 12
Since it is formed by overlapping a part of the resistance layer 14,
A bulge occurs in the overlapping area, and this bulge affects the surface of the crow. In this case, the edge of the glass surface is raised due to the overlap of the upper electrode layer 12 and the resistance layer 14, and an unevenness of about 10 to 20 μm is generated on the glass surface.

When trying to mount a square plate type chip resistor with an uneven surface on a board, etc. using an automatic mounting machine, the square plate type chip resistor should be sucked up with the suction pins of the automatic mounting machine. When the square plate chip resistor is rotated, the suction pin and the square plate chip resistor often rotate due to the unevenness of the surface of the glass, as shown in Figure 4. There was a problem that it could not be mounted accurately on the Brin I board because it was sometimes mounted at an angle. In FIG. 4, reference numeral 21 designates the wire 1/substrate, 22 a conductor cage, and 23 a square plate type chip resistor.

The present invention solves these problems and provides a square plate type chip resistor that has a glass surface with reduced unevenness and achieves high mounting accuracy.

Means for Solving the Problems The square plate type chip resistor of the present invention includes an insulating ceramic substrate, a top electrode layer of a thick silver film on the ceramic substrate, and a part of the two-sided electrode layer. an overlapping ruthenium-based thick film resistance layer, a first glass layer having a length equal to or less than the upper surface electrode spacing of the resistance layer-1-, a stamped glass layer on the first glass layer, and the first glass layer. The second glass layer completely covers the sealing glass layer, and the end electrode layer is a silver-based thick film that partially overlaps the upper electrode layer.

Function The square plate type chip resistor of the present invention replaces the bulge at the overlapping part of the two-sided electrode layer and the resistance layer, which occurs at the end of the glass surface in the conventional square plate type chip resistor, by replacing it with the hollow part on the resistance layer. The present invention provides a square plate type chip resistor that achieves high mounting accuracy by reducing the unevenness of the glass surface by forming a glass layer to the same height as the bulge.

Embodiments Hereinafter, embodiments of the present invention will be explained using FIGS. 1 and 2.

FIGS. 1 and 2 are cross-sectional views showing embodiments of the present invention.

First, in FIG. 1, the square plate type chip resistor of the present invention includes a 96 alumina substrate 1, a top electrode layer 2 and an end electrode layer 3 made of silver-based thick film electrodes, and a resistor made of a ruthenium-based thick film resistor. It consists of a layer 4, a bricot 1 glass layer 5 covering a length equal to or less than the upper electrode layer spacing on the resistance layer 4, a first glass layer 6, a stamping glass layer 7, and a second glass layer 8. There is.

In addition, in order to improve solderability on the exposed electrode surface,
The Ni plating layer 9 and the Sn--Pb plating layer 10 are formed by electrolytic plating.

Next, details of the embodiment of the present invention shown in FIG. 1 will be explained. First, a 96 alumina substrate 1 having excellent heat resistance and insulation properties is received. In order to divide the alumina substrate 1 into strips and individual pieces, grooves (molded with a mold during green sheeting) are formed for dividing the alumina substrate 1 into strips and individual pieces. next,
A thick film silver paste was screen printed on the 96 alumina substrate 1, and fired in a belt-type continuous firing furnace at a temperature of 850°C, a peak time of 6 minutes, and an IN-OUT of 45 minutes in a Pl1 file to form the top electrode layer 2. do. Next, a thick film resistive paste 1 containing Ru02 as a main component was screen-printed so as to overlap a part of the upper electrode layer 2,
The resistive layer 4 is formed by firing in a continuous firing furnace at a temperature of 8506°C according to a profile with a peak time of 6 minutes and an IN-OUT time of 45 minutes. Next, on the resistance layer 4, using a pattern with a length equal to or less than the electrode spacing of the one-sided electrode layer 2, a color space is printed using a Bell type continuous firing furnace. At a temperature of 590℃, peak time 6 minutes, IN-OUT50
The firing profile (:") is used to form the bricoat glass layer 5.Next, in order to equalize the resistance value of the resistance layer 4 between the surface electrode layer 2, the resistor layer 4 is heated using a laser beam. The resistance value is corrected by destroying layer 4 and a part of the precoated glass layer 5.Furthermore, a first glass paste is screen printed so as to completely cover the resistive layer 4 and the precoated glass R5. Dry in an infrared drying oven at 150°C for 10 minutes.
On the glass paste, a color space 1 mark was screen printed and dried in a near-infrared drying oven at 110° C. for 10 minutes. Further, on the dried first glass base 1, so as to completely cover the dried stamping glass paste,
The second glass paste is screen printed and dried in a near-infrared drying oven at 150° C. for 10 minutes. After that, Bell 1
- Firing in a type continuous firing furnace at a temperature of 590°C with a firing profile of 6 minutes peak time and 50 minutes IN-OUT to simultaneously form the first clast layer 6, the imprint crow layer 7, and the second clast layer 8. Next, as a preliminary step for forming the end electrodes, the alumina substrate 1 is divided into strips to expose the end electrodes, and primary substrate division is performed to obtain strip-shaped alumina substrates. Thick film silver paste 1 was applied by a roller to the side surface of the strip-shaped alumina substrate so as to partially overlap the upper electrode layer 2, and heated in a belt-type continuous firing furnace at a temperature of 600° C. for a peak time of 6 minutes. IN-
The electrode layer 3 is formed by firing according to the firing profile of OUT 45 minutes. Next, as a preparatory step for the electrode plating step J, secondary substrate division is performed in which the strip alumina substrate on which the end face electrode layer 3 has been formed is divided into individual pieces to obtain individual pieces of alumina substrate. Finally, in order to prevent the electrodes from being eaten away when soldering the exposed top electrode layer 2 and end electrode layer 3 and to ensure the reliability of soldering, the Ni plating layer 9 and the Snpb layer are electrolytically plated. Electrolysis is performed to form the plating layer 10.

Through the above steps, a square plate type chip resistor according to an embodiment of the present invention was prototyped.

The unevenness on the glass surface of this chip resistor was less than 5 μm, and the glass surface was flat. As a result, the mounting performance is also very excellent, and the number of diagonal mountings (Fig. 4), which occurred in the conventional product, has been improved from 6 out of 10,000 to 0 out of 10,000.

It was also confirmed that other characteristics (resistance value variation, TCR, life characteristics) were comparable to conventional products.

In addition, in the example, a precoat glass layer was formed in order to reduce variations in resistance value, but as shown in FIG. This also ensures the flatness of the glass surface.

Effect of the Invention 9 As is clear from the above explanation, the square plate type chip resistor of the present invention can provide a square plate type chip resistor that reduces the unevenness of the glass surface and enables high precision mounting. You can get excellent results.

[Brief explanation of drawings]

1 and 2 are sectional views showing the structure of a square plate chip resistor according to an embodiment of the present invention, and FIG. 3 is a sectional view showing an example of the structure of a conventional square plate chip resistor, Fourth
The figure is an explanatory diagram of a state in which a conventional square plate type chip resistor is mounted diagonally. 1...9 alumina substrate, 2...top electrode layer, 3...end surface 7, pole layer, 4...
・Resistance layer, 5...First crow layer, 6...
Imprint glass layer, 7...Second glass layer, 8-
- Ni Meggi layer 11, 9-...-S n-P b Meggi layer.

Claims (2)

[Claims] (1) An insulating ceramic substrate, a top electrode layer of a silver-based thick film on the ceramic substrate, a resistance layer of a ruthenium-based thick film overlapping a part of the top electrode layer, and a top electrode on the resistance layer. a first glass layer having a length equal to or less than the interval; a stamped glass layer on the first glass layer; a second glass layer that completely covers the first glass layer and the stamped glass layer; and one of the top electrode layers. A square plate type chip resistor characterized by comprising an end face electrode layer made of a silver-based thick film that overlaps the top part. (2) an insulating ceramic substrate, a top electrode layer of a silver-based thick film on the ceramic substrate, a resistance layer of a ruthenium-based thick film overlapping a part of the top electrode layer, and a top electrode on the resistance layer. a pre-coated glass layer having a length equal to or less than the interval; a first glass layer that completely covers the pre-coated glass and the resistive layer; a stamping glass layer on the first glass layer; and a stamping glass layer on the first glass layer. A square plate type chip resistor comprising: a second glass layer that completely covers the top electrode layer; and a silver-based thick film end electrode layer that partially overlaps the upper electrode layer.