JPH04282801A - Square chip resistor and its manufacturing method - Google Patents

Abstract

PURPOSE:To simplify manufacturing steps by setting a softening point of a rear surface glass higher than a baking temperature of an upper surface glass and a baking temperature of an end face electrode in a square-shaped chip resistor having glass layers on the upper surface and the rear surface to be used as a substitute of a cylindrical square-shaped chip resistor. CONSTITUTION:Since a 96 alumina board 1 in which a length of a thickness direction is 75-110% of a length of a lateral direction, upper and rear surface electrode layers 2, 3 of both main surfaces of the board 1, a resistance layer 4 partly superposed on the layer 2, a first glass layer 6 having 550-580 deg.C of a softening temperature, a second glass layer 7 having 630-850 deg.C of a softening temperature, and an end face electrode layer 8 for connecting the layers 2, 3, are provided, setting thereof to a baking jig before baking the glass and the end face can be simplified.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular chip resistor used in high-density wiring circuits, which can be mounted by a cylindrical chip resistor batch mounting machine and which can replace a cylindrical chip resistor, and a method for manufacturing the same.

0002

[Background Art] In recent years, as the demand for lighter, thinner, and shorter electronic devices has increased, extremely small square chip resistors are increasingly being used as resistance elements in order to increase the wiring density of circuit boards. It has become. Moreover, in recent years, in order to increase the mounting speed, batch mounting, in which a large number of chip components are simultaneously mounted, has become popular.

FIG. 3 shows an example of the structure of a rectangular chip resistor mounted by a conventional bulk mounting machine for thick film type cylindrical chip resistors.

[0004] The square chip resistor mounted by the conventional cylindrical chip resistor batch mounting machine is a square plate shape whose length in the thickness direction is 80% to 120% of the length in the width direction. An insulating 96 alumina substrate 10, an upper surface electrode layer 11 formed by a pair of thick film electrodes formed on the main surface of this 96 alumina substrate 10, and a ruthenium-based electrode layer 11 formed so as to be connected to this upper surface electrode layer 11. a resistance layer 12 made of a thick film resistor;
The first glass layer 14 with a softening point of 550° C. to 580° C. covers the resistance layer, and further overlaps with the back electrode layer 17 on the back surface of the 96 alumina substrate 10 and a part of the back electrode layer 17 with a softening point of 55° C.
0°C to 580°C second glass layer 18 and top electrode layer 11
An end face electrode layer 13 overlaps a part of the electrode, and a Ni plating layer 15 and a solder plating layer 16 are formed on the exposed electrode surface by electrolytic plating to ensure solderability.

When this rectangular chip resistor is mounted all at once as described above, even if the rectangular chip resistor is mounted on the side surface of the board rather than the main surface when the components are mounted, the amount of solder to be soldered is small. (The projected area of the soldering part) does not decrease, so sufficient adhesion strength can be obtained, and it also has the advantage that it is possible to use a cylindrical tube that is less likely to clog in the conveyor tube in the bulk mounting machine. are doing.

[0006] The method for manufacturing this rectangular chip resistor has been carried out according to the flow shown in FIG.

[0007]

[Problems to be Solved by the Invention] However, since this conventional rectangular chip resistor uses glass having a similar softening point (550°C to 580°C) for the first glass layer and the second glass layer, When firing glass, as shown in Figure 4, and when firing end electrodes, as shown in Figure 5, it is necessary to place the product 52 on a jig 53 and lift it above the conveyor belt 51 of the firing furnace. As shown in FIG. 6, the structural process becomes complicated (in particular, the number of man-hours is required to set the rectangular manufactured products 52 shown in FIG. 5), resulting in an increase in production costs.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a rectangular chip resistor with a simple manufacturing process.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method in which the length in the thickness direction is 80% of the length in the width direction.
A square plate-shaped insulating sintered substrate with a length of ~120%, a pair of upper surface electrode layers formed on one main surface of this sintered substrate, and a part of this pair of upper surface electrode layers. An overlapping resistance layer, a first glass layer having a softening point of 550°C to 580°C that completely covers this resistance layer, a pair of back electrode layers on the other main surface of the sintered substrate, and a pair of back electrode layers on the other main surface of the sintered substrate. Softening point that partially overlaps is 6
It is composed of a second glass layer having a temperature of 30°C to 850°C, and a pair of end electrode layers that electrically connect the pair of upper electrode layers and the pair of back electrode layers, and the manufacturing method thereof includes a second glass layer. After firing the second glass layer, the first glass layer is fired at a temperature of 550°C to 660°C, and after firing the first glass layer, the end electrode layer is fired at a temperature of 550°C. It is characterized in that it is fired at a temperature of 660°C to 660°C.

0010

[Operation] According to the present invention, first, the softening point is 630°C to 85°C.
The second glass layer at 0°C is fired at a temperature of 700°C to 950°C, and then the second glass layer is heated to a temperature of 550°C to 620°C below the softening point of the second glass layer in contact with the conveyor belt.
The first glass layer can be fired at a temperature of .degree. Further, after firing the first glass layer, the end electrode layer can be fired at a temperature of 550°C to 660°C, which is lower than the softening point of the second glass layer. As described above, when firing the glass and firing the end electrode layer, it is no longer necessary to lift the manufactured product from the conveyor belt of the firing furnace during firing, thereby simplifying the manufacturing process of the rectangular chip resistor.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rectangular chip resistor and a method of manufacturing the same according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a rectangular chip resistor according to an embodiment of the present invention. In FIG. 1, the rectangular chip resistor of this embodiment includes an insulating 96 alumina substrate 1, a pair of upper surface electrode layers 2 of a silver-based thick film on one main surface of the 96 alumina substrate 1, and the 96 alumina substrate 1. A back electrode layer 3 on the other main surface of the alumina substrate, a ruthenium-based thick film resistance layer 4 partially overlapping the top electrode layer 2, and a softening point of 560±5° C. that completely covers the resistance layer 4. a second glass layer 7 with a softening point of 680±5° C. that overlaps with a portion of the back electrode layer 3; and a silver layer that overlaps with a portion of the top electrode layer 2 and the back electrode layer 3. The end face electrode layer 8 is made of a thick film. Note that, in order to improve solderability, a Ni plating layer 9 and a Sn--Pb plating layer 10 are applied to the exposed electrode surface by electrolytic plating.

Next, a method of manufacturing the rectangular chip resistor of this embodiment shown in FIG. 1 will be explained with reference to FIG. First, a 96 alumina substrate 1 having excellent heat resistance and insulation properties is received. In order to divide the 96 alumina substrate 1 into strips and individual pieces, grooves for dividing (molded with a mold when forming a green sheet) are formed. (The thickness of the board is 0.
635 mm, the grooves for division are 1.5 mm and 0.
They are formed at a pitch of 8 mm. ) Next, a thick film silver paste was screen printed on the surface of the 96 alumina substrate 1.
After drying, a thick film silver paste was screen-printed and dried on the back side of the 96 alumina substrate 1, and then heated in a belt-type continuous firing furnace at a temperature of 850°C for a peak time of 6 minutes, IN-
Baking is performed according to a profile with an OUT time of 45 minutes to form the top electrode layer 2 and the back electrode layer 3 at the same time. Next, a lead borosilicate glass paste (white) is screen printed and dried so as to overlap a part of the back electrode layer 3, and then used in a belt-type continuous firing furnace (so that the top electrode layer 2 is in contact with the conveyor belt). The second glass layer 7 is formed by firing at a temperature of 850° C. according to a firing profile of 6 minutes peak time and 50 minutes IN-OUT. Next, a thick film resistor paste mainly composed of RuO2 is screen printed and dried so as to overlap a part of the upper electrode layer 2, and is heated to 850 mm in a belt-type continuous firing furnace (so that it floats from the conveyor belt).
The resistive layer 4 is formed by firing at a temperature of .degree. C. according to a profile of a peak time of 6 minutes and an IN-OUT time of 45 minutes. Next, in order to equalize the resistance value of the resistance layer 4 between the upper electrode layers 2, a part of the resistance layer 4 is destroyed by laser light to correct the resistance value (L cut, 100 mm/sec, 12k
Hz, 5W). Subsequently, a lead borosilicate glass paste (black color) is screen printed and dried so as to completely cover the resistance layer 4, and then transferred to a belt-type continuous firing furnace (with the second glass layer 7 in contact with the conveyor belt). by 59
The first glass layer 6 is formed by firing at a temperature of 0° C. according to a firing profile of 6 minutes peak time and 50 minutes IN-OUT. Next, as a preparatory step for forming the end electrodes, the alumina substrate 1 is divided into strips (divided on the 1.5 mm pitch side) to expose the end electrodes, thereby obtaining strip-shaped alumina substrates. On the side surface of the strip-shaped alumina substrate,
A thick film silver paste is applied with a roller so as to partially overlap the top electrode layer 2 and the back electrode layer 3, and is heated in a belt-type continuous firing furnace (with the second glass layer 7 in contact with the conveyor belt) for 600 minutes. The end electrode layer 8 is formed by firing at a temperature of 0.degree. C. according to a firing profile of 6 minutes for peak time and 45 minutes for IN-OUT. Next, as a preparation step for electrode plating, the strip-shaped alumina substrate on which the end surface electrode layer 8 has been formed is divided into individual pieces (divided on the 0.8 mm pitch side).
Then, a piece-like alumina substrate was obtained. Finally, in order to prevent the exposed top electrode layer 2, back electrode layer 3, and end electrode layer 8 from being eaten away during soldering and to ensure soldering reliability, a Ni plating layer 9 is applied by electrolytic plating. Then, a Sn--Pb plating layer 10 is formed.

[0014] Through the above steps, a square chip resistor according to this example was prototyped (the dimensions of the finished product were 1.6 mm in length).
mm, width was 0.8 mm, thickness was 0.74 mm, and the dimension in the thickness direction was 92.5% of the dimension in the width direction).

According to this embodiment, compared to the conventional manufacturing method, there is no need to lift the manufactured product from the conveyor belt of the firing furnace during glass firing and end face electrode firing, so the process is simplified (especially before end face electrode firing). (This eliminates the need to set strip-shaped products.)

Furthermore, the square chip resistor of this embodiment, like the square chip resistor mounted by a conventional cylindrical chip resistor batch mounting machine, requires a sufficient amount of solder even when mounted on the side of the board. The fixation strength (the limit load of the rectangular chip resistor from the direction parallel to the printed circuit board) is the same as when it is mounted on the main surface of the board (in this case, it was about 10 kg when mounted on the side). ).

Furthermore, since the rectangular chip resistor of this embodiment has a large length in the thickness direction, it can be mounted with solder in the through-hole of a printed circuit board having a land pattern, compared to the conventional flat plate-shaped chip resistor. Needless to say, they are less likely to clog and have less backlash than square chip resistors.

Furthermore, by making the shape of the square chip resistor similar to a cylinder, a cylindrical tube can be used as the transport tube in the mounting machine, which naturally has the effect that the square chip resistor is less likely to get clogged within the transport tube. It will be done.

In this example, the first glass layer is made of glass with a softening point of 560±5°C, and the second glass layer is made of glass with a softening point of 6.
Although 80±5°C glass was used, it goes without saying that any glass having the softening point described in the claims would have the same effect (however, the softening point in this example is different from that of the glass composition). The resistance performance of the square chip resistor is the best because it is the most stable.)

[0020]

Effects of the Invention As is clear from the above explanation, the rectangular chip resistor of the present invention has a softening point of 630°C to 850°C.
The second glass layer is fired at a temperature of 700°C to 950°C, and then the second glass layer is brought into contact with a conveyor belt to a temperature of 550°C to 620°C, which is below the softening point of the second glass layer. Then, the first glass layer is fired, and after firing the first glass layer, the heating temperature is 550°C or lower, which is below the softening point of the second glass layer.
By firing the end electrode layer at a temperature of 660°C, there is no need to lift the manufactured product above the conveyor belt of the firing furnace during glass firing and firing of the end electrode layer.
This has an excellent effect of simplifying the manufacturing process of the square chip resistor.

[Brief explanation of the drawing]

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

FIG. 2 is a process diagram showing a method for manufacturing a rectangular chip resistor according to an embodiment of the present invention.

[Figure 3] Cross-sectional view showing the structure of a conventional square chip resistor

[
Figure 4: Explanatory diagram of a conventional glass firing jig for square chip resistors

[Figure 5] Explanatory diagram of a jig for firing end electrodes of a conventional square chip resistor

[Figure 6] Process diagram showing an example of a conventional method for manufacturing a square chip resistor

[Explanation of symbols]

1 96 alumina substrate 2 Top electrode layer 3 Back electrode layer 4 Resistance layer 6 First glass layer 7 Second glass layer 8 End electrode layer 9 Ni plating layer 10 Sn-Pb plating layer

Claims (2)

[Claims] Claim 1: The length in the thickness direction is 80% or more of the length in the width direction.
A square plate-shaped insulating sintered substrate with a length of 120%, a pair of upper surface electrode layers formed on one main surface of this sintered substrate, and a part of the upper surface electrode layers overlapped with each other. a resistive layer and a first layer having a softening point of 550°C to 580°C that completely covers this resistive layer.
The softening point of the glass layer, the pair of back electrode layers on the other main surface of the sintered substrate, and a portion of the back electrode layer that overlaps is 63.
A prismatic chip resistor comprising a second glass layer having a temperature of 0°C to 850°C, and a pair of end electrode layers electrically connecting the pair of upper electrode layers and the pair of back electrode layers. . 2. The second glass layer is fired at a temperature of 700°C to 950°C, and after the second glass firing, the first glass layer is
The rectangular chip resistor according to claim 1, wherein the square chip resistor is fired at a temperature of 50°C to 620°C, and further, the end electrode layer is fired at a temperature of 550°C to 660°C after the first glass layer is fired. Production method.