JPH04254302A - Rectangular chip resistor for function correction and its trimming method - Google Patents

Abstract

PURPOSE:To obtain a rectangular chip resistor for function correction capable of correction of the resistance value, even when trimming is performed beyond the target resistance value, for a chip resistor for function correction which corrects circuit operation by correcting the resistance value with a laser, after the resistor is mounted on a circuit board. CONSTITUTION:The title resistor has two or more pairs of electrode layers 1, 2, 3. When a target resistance value is exceeded by trimming, trimming can be again performed, by electrically connecting in order the above two or more pairs of electrode layers 1, 2, 3, and decreasing once the resistance value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a rectangular chip resistor for function modification, which is used in a high-density wiring circuit, and which modifies the circuit operation by modifying the resistance value by laser trimming after being mounted on the circuit, and a method for trimming the same. 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. 4(a).

The conventional rectangular chip resistor for function modification is 96
A top electrode layer 21 made of a pair of thick film electrodes formed on an alumina substrate 20, a resistance layer 22 made of a ruthenium-based thick film resistor formed to be connected to the top electrode layer 21, and a glass layer covering the resistance layer. 24 and an end electrode layer 23 that overlaps a part of the upper electrode layer 21, and a Ni plating layer 25 and a solder plating layer 26 are formed on the exposed electrode surface by electrolytic plating to ensure solderability. ing.

[0005]

This rectangular chip resistor for functional modification is laser trimmed after circuit mounting, and the relationship between trimming dimensions and resistance value can generally be expressed as shown in FIG. 4(b).

[0006] As the trimming dimension increases and the remaining width of the resistor decreases, the resistance value increases rapidly and eventually leads to wire breakage. At this time, if the target resistance value is exceeded, the resistance value cannot be lowered by trimming, so if you want to correct it again, you will need to replace the rectangular chip resistor for function correction mounted on the printed circuit board. The problem was that it was difficult to handle compared to semi-fixed volumes.

The present invention solves this problem. Even if the target resistance value is exceeded, the rectangular chip resistor for function modification is not removed from the printed circuit board, the resistance value is lowered, and the laser is re-injected. An object of the present invention is to provide a rectangular chip resistor for function modification that allows trimming.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a rectangular plate-shaped insulating sintered substrate, and two opposing surfaces on at least one surface of the sintered substrate. In a resistor having a pair or more of electrode parts and a resistance layer electrically connected to all of the electrode parts, trimming is started from the resistance layer side between the electrodes at the end connected to the circuit, and the trimming is performed as a target. If the resistance value is exceeded, the electrode part on the side where trimming was started and the adjacent electrode part are electrically connected, the resistance value between the electrodes once connected to the circuit is lowered, and then trimming is performed again. It is something to do.

[0009]

[Operation] According to the present invention, when the target resistance value is exceeded, the electrode part on the side where trimming is started and the adjacent electrode part are electrically connected, and the resistance value between the electrodes once connected to the circuit is Since it is possible to lower the resistance value and then perform re-trimming, even if the target resistance value is exceeded, the resistance value can be adjusted and laser trimming can be performed again without removing the rectangular chip resistor for function modification from the printed circuit board. It is possible to provide a rectangular chip resistor for functional modification that makes it possible to perform the following functions.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rectangular chip resistor for functional modification according to an embodiment of the present invention will be described below with reference to FIGS. 1(a) and 1(b).

FIG. 1(a) is a perspective view of an embodiment of the present invention seen from the front, and FIG. 1(b) is a perspective view of the same embodiment seen from the back.

In FIGS. 1(a) and 1(b), the rectangular chip resistor for functional modification of this embodiment has a 96 alumina substrate 10.
A pair of first upper surface electrode layers 1 of silver-based thick films formed to face each other on the long sides of the surface of the 96 alumina substrate 10 and provided adjacent to each other, and a pair of second upper surface electrode layers 1. 2. A pair of third upper surface electrode layers 3 and a first electrode layer formed on the back surface of the 96 alumina substrate 10 corresponding to the third upper surface electrode layer 3.
A ruthenium-based thickness that overlaps the back electrode layer 13, the second back electrode layer 14, the third back electrode layer 15, and a portion of the first top electrode layer 1, second top electrode layer 2, and third top electrode layer 3. a resistive layer 5 of the membrane and a glass layer 6 completely covering said resistive layer 5;
and the first top electrode layer 1 and the first back electrode layer 13,
It is composed of an end electrode layer 16 made of a silver-based thick film that electrically connects the second top electrode layer 2 and the second back electrode layer 14, and the third top electrode layer 2 and the third top electrode layer 15. Ru. In addition, in order to improve solderability on the exposed electrode surface,
The Ni plating layer and the Sn-Pb plating layer are applied by electrolytic plating.

Next, the manufacturing method of this embodiment will be explained. First, a 96 alumina substrate 10 having excellent heat resistance and insulation properties is received. In order to divide this alumina substrate 10 into strips and individual pieces, grooves for dividing (molded with a mold when green sheeting) are formed, and through holes for forming the end electrode layer 16 are further formed. There is. Next, a thick film silver paste for forming the first top electrode layer 1, second top electrode layer 2, and third top electrode layer 3 is screen printed and dried on the surface of the 96 alumina substrate 10, and then
A thick film silver paste for forming a first back electrode layer 13, a second back electrode layer 14, and a third back electrode layer 15 was screen printed and dried on the back surface of the 6 alumina substrate 10. At this time, since suction is applied to the through holes during each printing, the thick film silver paste for forming the end electrode layer 16 is also simultaneously printed and dried through the holes. Thereafter, the belt-type continuous firing furnace was used to bake at a temperature of 850° C. with a peak time of 6 minutes and an IN-OUT of 45 minutes to obtain the first upper electrode layer 1, the second upper electrode layer 2, the third upper electrode layer 3, The first back electrode layer 13, the second back electrode layer 14, and the third back electrode layer 15 were formed simultaneously. As a result, the first top electrode layer 1 and the first back electrode layer 13, the second top electrode layer 2 and the second back electrode layer 14, and the third top electrode layer 3 and the third back electrode layer 15 are thereby formed. End surface electrode layer 16
This will result in an electrical connection.

Next, RuO2 is deposited so as to partially overlap the first upper electrode layer 1, the second upper electrode layer 2, and the third upper electrode layer 3.
A thick film resistor paste containing as a main component was screen printed and dried, and fired in a belt-type continuous firing furnace at a temperature of 850°C with a profile of a peak time of 6 minutes and an IN-OUT time of 45 minutes to form a resistance layer 5. . Subsequently, a lead borosilicate glass paste (transparent) was screen-printed and dried so as to completely cover the resistance layer 5, and then baked in a belt-type continuous firing furnace at a temperature of 590° C. for a peak time of 6 minutes.
The glass layer 6 was formed by firing according to the firing profile of -OUT 50 minutes. Next, the 96 alumina substrate 1 was divided into strips to obtain strip-shaped alumina substrates. Next, as a preparation step for electrode plating, the rectangular alumina substrate was divided into individual pieces to obtain individual pieces of alumina substrate. Finally, in order to prevent the exposed electrode surface from being eaten away during soldering and to ensure soldering reliability, electrolytic plating is applied to the exposed electrode surface.
An i plating layer and a Sn-Pb plating layer were formed.

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

[0016] This is a top view when the rectangular chip resistor for function modification of this embodiment is mounted on a printed circuit board via the first upper electrode layer 1 and the first back electrode layer 13, and trimming and modification are actually performed. are shown in FIGS. 3(a), (b), and (c). Further, FIG. 2 shows an increase in the resistance value between the first upper surface electrode layers 1 and a decrease in the resistance value due to modification of the first, second, and third upper surface electrodes by soldering short-circuits. As shown in Figure 3(a), if you retouch after trimming, I
It can be seen that the resistance value increases due to trimming and decreases due to rework as shown in the section. Similarly, Figure 3 (
The resistance value in the situation b) was II in FIG. 2, and the resistance value in the situation in FIG. 3(c) was III in FIG.

As a result, this embodiment has an excellent feature that conventional rectangular chip resistors for function modification do not have, in that when the target resistance value is exceeded, the resistance value can be temporarily lowered and re-trimmed. It can be seen that it has

In the embodiment, the repair work was carried out by shorting the terminals on the components by soldering, but other means (automatic application and curing of conductive resin paste) may be used.

Further, the resistance value adjustment may be performed on a land on a printed circuit board on which a component is mounted, as long as it is electrically connected.

Furthermore, although the upper surface electrode and the back surface electrode are electrically connected in the embodiment, this is not particularly necessary in order to provide the functions of the present invention.

Furthermore, in this embodiment, three pairs of upper surface electrodes are used,
Although they are arranged horizontally, four or five pairs may be used as long as there are two or more pairs, and the arrangement does not necessarily have to be horizontal (however, the trimming dimension becomes shorter if they are arranged horizontally).

[0022]

As is clear from the above description, the rectangular chip resistor for function modification of the present invention includes a rectangular plate-shaped insulating sintered substrate, and at least one surface of the sintered substrate. In a resistor having two or more pairs of opposing electrode parts and a resistance layer electrically connected to all of the electrode parts, trimming is started from the resistance layer side between the electrodes at the end connected to the circuit. If the target resistance value is exceeded, electrically connect the electrode part on the side where trimming is started and the adjacent electrode part to lower the resistance value between the electrodes once connected to the circuit, and then perform trimming again. If the target resistance value is exceeded, the electrode part on the side where trimming was started and the adjacent electrode part are electrically connected, and once connected to the circuit. The resistance between the electrodes can be lowered and then re-trimmed. Therefore, even if the target resistance value is exceeded, the resistance value can be adjusted and laser trimming can be performed again without removing the rectangular chip resistor for function modification from the printed circuit board. It has excellent effects such as being able to provide

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing the structure of the upper surface of a rectangular chip resistor for function modification according to an embodiment of the present invention; FIG. Perspective view showing the structure of the back side

[Figure 2] An explanatory diagram showing the increase/decrease in resistance value when the rectangular chip resistor for functional modification of the same example is mounted on a printed circuit board and laser trimmed and reworked.

[Fig. 3] (a), (b), and (c) are top views showing the state when the rectangular chip resistor for functional modification of the example is mounted on a printed circuit board and laser trimmed and reworked.

[Fig. 4] (a) is a cross-sectional view showing the structure of a conventional rectangular chip resistor for function modification; (b) is an explanatory diagram showing trimming dimensions and increase in resistance value of a conventional rectangular chip resistor for function modification;

[Explanation of symbols]

1 First top electrode layer 2 Second top electrode layer 3 Third top electrode layer 5 Resistance layer 6 Glass layer 10 96 alumina substrate 13 First back electrode layer 14 Second back electrode layer 15 Third back electrode layer 16 End face electrode layer

Claims (3)

[Claims] 1. A square plate-shaped insulating sintered substrate, two or more pairs of opposing electrode sections on at least one surface of the sintered substrate, and electrically connected to all of the electrode sections. In a resistor having a resistance layer, trimming is started from the resistance layer side between the electrodes at the end connected to the circuit, and if the target resistance value is exceeded, the trimming is started from the electrode part on the side where trimming is started. A method for trimming a rectangular chip resistor for functional modification, characterized by electrically connecting adjacent electrode parts, lowering the resistance value between the electrodes once connected to a circuit, and then trimming again. 2. The method for trimming a rectangular chip resistor for functional modification according to claim 1, wherein the electrode portion on the side where trimming is started and the adjacent electrode portion are electrically connected by bridging with solder. 3. A square plate-shaped insulating sintered substrate, two or more pairs of opposing electrode portions on at least one surface of the sintered substrate, and electrically connected to all of the electrode portions. A rectangular chip resistor for function modification with a resistance layer.