JPH04214601A - Rectangular chip resistor for function correction use and manufacture thereof - Google Patents

Abstract

PURPOSE:To make possible a high-accuracy correction of the resistance value of a resistor even if the resistance value is greatly corrected and to prevent a disconnection from being generated in the resistor even if an overcorrection of the resistance value is further made in the chip resistor for function correction use, which corrects the operation of a circuit by correcting the resistance value by a laser after being mounted on the circuit. CONSTITUTION:A resistance element has an insulative sintered substrate 1, a pair of upper surface electrode layers 2 on the surface of this substrate 1, a first resistance layer 4, which overlaps with each one part of these layers 2 and is corrected its function after the element is mounted on a circuit, a pair of rear electrode layers 3 on the rear of the substrate 1, a second resistance layer 5, which overlaps with each one part these layers 3, and a pair of edge face electrode layers 8 which connect electrically the layers 2 with the layers 3. As the layer 5, which is used as the by-pass of a current, is provided on the rear part of the substrate 1 in addition to the layer 4 which is corrected its function, the resistance value of the element is not rapidly increased even if the dimension of a correction of the resistance value is increased. As a result, a high-accuracy correction of the resistance value becomes possible and even if an overcorrection of the resistance value is further made, a disconnection is not generated in the resistance element.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a rectangular chip resistor for functional modification, which is used in high-density wiring circuits, and which modifies the circuit operation by modifying the resistance value by laser trimming after being mounted on the circuit, and its manufacturing method. It is related to.

0002

[Prior Art] In recent years, with the increasing demand for electronic devices to be lighter, thinner, and smaller, very small resistors are increasingly being used as resistance elements in order to increase the wiring density of circuit boards. It's here. Furthermore, the recent increase in density has extended to chip volumes, and rectangular chip resistors for function modification are increasingly being used as replacements for chip volumes.

An example of the structure of a conventional thick film type rectangular chip resistor for function modification is shown in FIG.

The conventional rectangular chip resistor for function modification is 96
A top electrode layer 11 made of a pair of thick film electrodes formed on an alumina substrate 10, a resistance layer 12 made of a ruthenium-based thick film resistor formed to be connected to this top electrode layer 11, and a glass layer covering the resistance layer. 14 and an end electrode layer 13 that overlaps a part of the upper electrode layer, 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. There is.

[0005]

[Problems to be Solved by the Invention] However, in this rectangular chip resistor for function modification, the function is modified by performing laser trimming on the resistance layer 12 after circuit mounting, but the relationship between trimming dimensions and resistance value at this time is generally as follows. It can be expressed as 5.

[0006] When the trimming size increases and the remaining width of the resistor decreases, the resistance value increases rapidly and eventually leads to wire breakage. For this reason, when the target resistance value is relatively high, trimming accuracy may deteriorate or
Alternatively, there is a problem that the resistor may be disconnected.

[0007] The present invention solves these problems all at once, and enables highly accurate trimming even when the trimming dimension becomes large, and also prevents disconnection of the resistor even if over-correction is performed by trimming. The purpose of the present invention is to provide a rectangular chip resistor for function modification that does not cause any changes in function.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a rectangular plate-shaped insulating sintered substrate, a pair of upper electrode layers on the surface of the sintered substrate, and a pair of upper electrode layers on the surface of the sintered substrate. a first resistance layer that overlaps a part of the top electrode layer and whose function is modified after circuit mounting; a pair of back electrode layers on the back surface of the sintered substrate;
It has a second resistance layer that partially overlaps the pair of back electrode layers, and a pair of end electrode layers that electrically connect the pair of upper electrode layers and the pair of back electrode layers.

[0009]

[Function] According to the present invention, in addition to the first resistive layer that performs trimming, the second resistive layer that serves as a current bypass is provided on the back surface, so even if the trimming dimension of the first resistive layer becomes large, the resistance is not so great. The value does not increase, and even if the target resistance value is relatively high, highly accurate trimming is possible, and even if overcorrection is performed by trimming, the resistance element will not break.

0010

Embodiments (Embodiment 1) Hereinafter, a rectangular chip resistor for function modification according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing this embodiment. Figure 1
In this example, the rectangular chip resistor for function modification is as follows:
A square plate-shaped insulating sintered 96 alumina substrate 1, a pair of upper electrode layers 2 of a silver-based thick film formed on the front surface of the 96 alumina substrate 1, and a pair of upper electrode layers 2 formed on the back surface of the 96 alumina substrate. a back electrode layer 3; a first resistance layer 4 made of a ruthenium-based thick film overlapping a part of the top electrode layer 2; and a second resistance layer 5 made of a ruthenium-based thick film overlapped with a part of the back electrode layer 3; a first glass layer 6 that completely covers the first resistance layer 4; and a first glass layer 6 that completely covers the first resistance layer 4;
It is composed of a second glass layer 7 that completely covers the resistance layer 5, and an end electrode layer 8 made of a silver-based thick film that partially overlaps the upper electrode layer 2 and the back electrode layer 3. Note that the exposed electrode surface is coated with a Ni plating layer 9a and a Sn plating layer to improve solderability.
- The Pb plating layer 9b is applied by electrolytic plating.

Next, the manufacturing method of this embodiment shown in FIG. 1 will be explained. First, 96 has excellent heat resistance and insulation properties.
An alumina substrate 1 is received. In order to divide the alumina substrate 1 into strips and individual pieces, grooves for dividing the alumina substrate 1 (molded with a mold when forming a green sheet) are formed. Next, a thick film silver paste is screen printed and dried on the surface of the 96 alumina substrate 1, and a thick film silver paste is further screen printed and dried on the back surface of the 96 alumina substrate 1, and 850 C. and a peak time of 6 minutes and an IN-OUT time of 45 minutes to form the top electrode layer 2 and the back electrode layer 3 at the same time. Next, a thick film resistor paste mainly composed of RuO2 is screen printed and dried so as to overlap a part of the top electrode layer 2, and then a thick film resistor paste mainly composed of RuO2 is applied so as to overlap a part of the back electrode layer 3. A thick film resistor paste of
Peak time 6 minutes, IN-OUT time 45 minutes at 50℃ temperature
The first resistive layer 4 and the second resistive layer 5 are simultaneously formed by firing according to a minute profile. (At this time, in this example, the first resistance layer 4 was set to have a lower sheet resistance value than the second resistance layer 5.) Next, the resistance values of the second resistance layer 5 between the back electrode layers 3 are made equal. Therefore, a part of the second resistance layer 5 is destroyed by laser light to correct the resistance value (L cut,
100mm/sec, 12KHz, 5W). continue,
A lead borosilicate glass paste (black) is screen printed and dried so as to completely cover the second resistance layer 4, and a lead borosilicate glass paste (black) is then applied to completely cover the first resistance layer 5. The first glass layer 6 and the second glass layer 7 were screen printed (translucent green) and fired in a belt-type continuous firing furnace at a temperature of 590°C with a firing profile of 6 minutes peak time and 50 minutes IN-OUT.
are formed at the same time. Next, as a preparatory step for forming the end electrodes, the alumina substrate 1 is divided into strips to expose the end electrodes, thereby obtaining strip-shaped alumina substrates. Then, a thick film silver paste is applied to the side surface of the strip-shaped alumina substrate by a roller so as to partially overlap the top electrode layer 2 and the back electrode layer 3, and is heated at a temperature of 600° C. by a belt-type continuous firing furnace. , peak time 6 minutes, I
The end face electrode layer 8 is formed by firing according to the firing profile of N-OUT 45 minutes. Next, as a preparatory step for electrode plating, a secondary substrate division is performed in which the rectangular alumina substrate on which the end face electrode layer 8 has already been formed is divided into individual pieces to obtain individual piece-shaped alumina substrates. 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 reliability of soldering, a Ni plating layer 9a is applied by electrolytic plating. Then, a Sn--Pb plating layer 9b is formed.

[0013] If the first resistance layer 4 and the second resistance layer 5 are fired separately, there arises a disadvantage that the resistance value of the resistance layer fired first changes greatly. Therefore, a method is adopted in which the first resistance layer 4 and the second resistance layer 5 are formed simultaneously.

[0014] Through the above steps, a rectangular chip resistor for functional modification according to the first embodiment of the present invention was manufactured as a prototype.

(Embodiment 2) Next, another embodiment of the present invention will be explained. In this example,
The structure is such that the sheet resistance value of the second resistance layer 5 is set higher than that of the first resistance layer 4, and the other structure and manufacturing method are the same as in the first embodiment.

FIG. 2 shows the rise curve of the resistance value when the first resistance layer is trimmed after circuit mounting of the rectangular chip resistor for function modification of the first embodiment of the present invention, and the rise curve of the resistance value of the second embodiment is shown in FIG. FIG. 3 shows an increase curve of the resistance value when the first resistance layer is trimmed after circuit mounting of the rectangular chip resistor for functional modification. (A straight single cut was used for trimming.)
As can be seen from FIG. 2, when the first resistance layer 4 is set lower than the second resistance layer 5, it is possible to modify the function at a relatively high magnification (compared to conventional products, it is possible to modify the function slightly in the small remaining width of the resistor). (adjustable), and even if the first resistance layer 4 is open, the second
Since the resistance layer 5 (high resistance) remains, the resistance element itself will not become open.

Furthermore, as can be seen from FIG. 3, setting the first resistance layer 4 higher than the second resistance layer 5 results in relatively low magnification function correction, but fine adjustment of the resistance value (second resistance layer (near the resistance value) is possible. Furthermore, even if the first resistance layer 4 becomes open, the second resistance layer 5 (low resistance) remains, so the resistance element itself will not become open.

From this, according to the embodiment of the present invention,
It can be seen that excellent effects not found in conventional rectangular chip resistors for function modification, such as higher precision in function modification and prevention of open resistance, can be obtained.

In these examples, the first resistance layer 4 was covered with green glass and the second resistance layer 5 was covered with black glass, but this is intended to improve the reliability of the resistance element, and is not particularly necessary. However, other colors of glass may be used.

Furthermore, in these embodiments, laser trimming has been explained using a straight single cut, but it can of course also be applied to an L cut or a J cut.

Furthermore, in these embodiments, the second resistive layer 5 is trimmed, but this need not be done if the correction curve does not need to be very accurate. That is,
By also trimming the second resistance layer, a correction curve with even higher accuracy can be obtained.

Furthermore, by making the sheet resistance values of the first and second resistance layers 4 and 5 the same, it becomes possible to modify the function on either the front or back surface. You can get something that you don't mind implementing on top.

[0023]

Effects of the Invention As is clear from the above description, according to the rectangular chip resistor for function modification of the present invention, in addition to the first resistance layer that performs trimming, a second resistance layer that functions as a current bypass is provided on the back side. Therefore, even if the trimming dimension of the first resistance layer becomes large, the resistance value does not increase significantly, and even when the target resistance value is relatively high, highly accurate trimming is possible. Even if the modification is made, it is possible to achieve an excellent effect in that the resistive element will not be disconnected.

Further, in setting the resistance values of the first resistance layer and the second resistance layer, it is possible to simultaneously obtain the effect that various correction curves can be set depending on the setting method.

Furthermore, by firing the first resistive layer and the second resistive layer at the same time, there is no problem that the resistance value of the resistive layer fired first changes greatly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a rectangular chip resistor for function modification according to the first and second embodiments of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between trimming dimensions and resistance value of the rectangular chip resistor for function modification according to the first embodiment of the present invention.

[
FIG. 3 is a characteristic diagram showing the relationship between trimming dimensions and resistance value of the rectangular chip resistor for function modification according to the second embodiment of the present invention.

[Figure 4] Cross-sectional view of a conventional rectangular chip resistor for function modification

[Figure 5
]Characteristic diagram showing the relationship between trimming dimensions and resistance value of a conventional rectangular chip resistor for function modification

[Explanation of symbols]

1 96 alumina substrate 2 Top electrode layer 3 Back electrode layer 4 First resistance layer 5 Second resistance layer 6 First glass layer 7 Second glass layer 8 End electrode layer 9a Ni plating layer 9b Sn-Pb plating layer

Claims (4)

[Claims] 1. A square plate-shaped insulating sintered substrate, a pair of upper electrode layers on the surface of the sintered substrate, and a layer that partially overlaps the pair of upper electrode layers and whose function is modified after circuit mounting. a first resistance layer, a pair of back electrode layers on the back surface of the sintered substrate, a second resistance layer partially overlapping the pair of back electrode layers, and a pair of back electrode layers on the pair of top electrode layers. A rectangular chip resistor for function modification, characterized in that it has a pair of end face electrode layers electrically connected to each other. 2. The method of manufacturing a rectangular chip resistor for functional modification according to claim 1, wherein the first resistance layer and the second resistance layer are fired at the same time. 3. The rectangular chip resistor for functional modification according to claim 1, wherein the sheet resistance value of the first resistance layer is set higher than the sheet resistance value of the second resistance layer. 4. The rectangular chip resistor for functional modification according to claim 1, wherein the sheet resistance value of the first resistance layer is set lower than the sheet resistance value of the second resistance layer.