JP3766555B2 - Chip resistor structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a chip-type resistor in which at least one resistive film, terminal electrodes for both ends thereof, and a cover coat covering the resistive film are formed on the surface of an insulating substrate configured in a chip form. Concerning structure.
[0002]
[Prior art]
In a conventional chip resistor, for example, as described in Japanese Patent Application Laid-Open No. 60-27104, a cover coat covering a resistance film formed on the surface of a chip type insulating substrate is provided on both ends of the resistance film. The chip-type resistor is connected to a printed circuit board or the like because it protrudes considerably from the surface of the terminal electrode and the step between the surface of the cover coat and the surface of both terminal electrodes is considerably large. When soldering the chip-type resistor with the resistance film side facing the printed circuit board, one side often floats from the printed circuit board and cannot be reliably soldered.
[0003]
Therefore, Japanese Patent Application Laid-Open No. 4-102302 as a prior art does not eliminate a step between the auxiliary electrode and the cover coat by forming auxiliary electrodes on the surfaces of both terminal electrodes with respect to both ends of the resistance film. , It is proposed to reduce the size and prevent the lifting of one side as described above.
[0004]
[Problems to be solved by the invention]
However, those of this prior art, by a surface definitive auxiliary electrodes formed for both terminal electrodes, which is constituted so as not to exceed the surface of the cover coat, this chip resistor, When the chip-type resistor is placed with the resistance film side facing the printed circuit board, the cover coat surface comes into contact with the printed circuit board. When soldering in a state, the chip resistor cannot be automatically positioned at a predetermined soldering position with respect to the chip resistor by using the surface tension of the molten solder. The question that self-alignment due to the surface tension of the molten solder cannot be used to correctly position and solder the resistor at the soldering point There was.
[0005]
An object of the present invention is to provide a chip-type resistor that solves this problem and can reliably use self-alignment due to the surface tension of molten solder during soldering.
[0006]
[Means for Solving the Problems]
In order to achieve this technical problem, the present invention
“On the surface of the chip-type insulating substrate, a resistive film, terminal electrodes for both ends thereof, a black cover coat covering the resistive film, and an auxiliary electrode on the surface of both terminal electrodes are formed. In the chip resistor consisting of
The width dimension in the direction perpendicular to the longitudinal direction of the resistive film in the cover coat and both auxiliary electrodes is aligned to be narrower than the width dimension in the insulating substrate , and one end portion on the cover coat side of both auxiliary electrodes is arranged. , the surface of the covercoat, or one end of the two auxiliary electrodes overlap so as to protrude from the surface of the covercoat, or both ends of the cover coat, the lower side of the two auxiliary electrodes, the subsidiary electrode Of the cover coat so that one end of the cover coat protrudes from the surface of the cover coat, while the width dimension of the cover coat where the two auxiliary electrodes overlap is larger than the width dimension of the cover coat where the two auxiliary electrodes do not overlap. Narrow . "
It was made the composition called.
[0007]
[Operation and effect of the invention]
With this configuration, one end of both auxiliary electrodes formed with respect to both terminal electrodes protrudes from the surface of the cover coat, so that the chip resistor is connected to the printed circuit board or the like. When the chip-type resistor is placed with the resistance film side facing the printed circuit board, the one end of the auxiliary electrode that protrudes from the surface of the cover coat is first on the printed circuit board. It is possible to reliably prevent the cover coat from coming into contact with the printed circuit board side. In other words, the cover coat can be lifted from the printed circuit board or the like.
[0008]
Therefore, solder paste is applied to the upper surface of the electrode pad on the upper surface of the printed circuit board, and then the chip resistor is applied to the upper surface of the printed circuit board and the like, and both auxiliary electrodes in the chip resistor are both electrode pads. After the solder paste is melted after being placed in contact with the chip resistor, the chip resistor is properly soldered to both electrode pads on the printed circuit board by self-alignment by the surface tension of the molten solder. After being automatically shifted to the position, it is soldered at this correct position.
[0009]
Therefore, according to the present invention, when soldering with a chip-type resistor facing down on a printed circuit board or the like, it is automatically positioned correctly at a predetermined soldering position by self-alignment by the surface tension of the molten solder. Therefore, the number of steps required for mounting on a printed circuit board or the like can be greatly reduced.
In addition, as described above, the present invention is configured such that the width dimension of the cover coat where the two auxiliary electrodes overlap is narrower than the width dimension of the portion where the two auxiliary electrodes do not overlap. Thus, when the cover coat and both auxiliary electrodes are formed with the width dimension being narrower than the width dimension of the insulating substrate, if both of them are relatively displaced in the width direction, The chip part can be prevented from protruding from both or one side of both auxiliary electrodes, and the black cover coat can be maintained in a substantially complete rectangular shape in the plan view of the chip resistor. in automatically mounted on a substrate or the like, in the case of recognizing the shape of the cover coat is black of the chip type resistor with a camera, the chip resistor to the camera It has the effect of improving the reliability of recognizing I.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
In this figure, reference numeral 1 denotes an insulating substrate configured in a chip shape.
On the upper surface of the insulating substrate 1, a pair of left and right upper terminal electrodes 2 and 3 and a resistance film 4 connected between them are formed. Further, on the upper surface of the insulating substrate 1, a glass covering the resistance film 4 is formed. Undercoat 5, middle coat 6 made of glass or the like covering this undercoat 5, and cover coat 7 made of black glass covering the entire middle coat 6, the resistance film 4 in each of these coats 5, 6, 7. The width dimension in the direction perpendicular to the longitudinal direction is made narrower than the width dimension in the insulating substrate 1.
[0011]
Further, a pair of left and right lower surface side electrodes 8 and 9 are provided on the lower surface of the insulating substrate 1, and further, the upper surface side terminal electrodes 2 and 3 of the insulating substrate 1 are provided on both left and right end surfaces of the insulating substrate 1; Side electrodes 10 and 11 are formed to electrically connect the lower surface side electrodes 8 and 9.
Wherein the said portions of both upper surface side terminal electrodes 2 and 3 of the upper surface of the insulating substrate 1, the auxiliary electrodes 12 and 13 covering each of the two top side terminal electrodes 2 and 3, wherein in the auxiliary electrodes 12 and 13 The resistance film 4 is formed so that the width dimension in the direction perpendicular to the longitudinal direction is aligned with the width dimension in the cover coat 7 in the direction perpendicular to the longitudinal direction of the resistance film 4. On the surfaces of the electrodes 12, 13, the upper surface side terminal electrodes 2, 3, the lower surface side electrodes 8, 9 and the both side surface electrodes 10, 11, for example, a nickel plating layer and a solder plating layer or Metal plating layers 14 and 15 made of a tin plating layer are formed.
[0012]
When the cover coat 7 and the auxiliary electrodes 12 and 13 are formed with the same width , the end portions 12a and 13a on the cover coat 7 side of the auxiliary electrodes 12 and 13 are covered with the cover coat. 7 is overlapped so that one end portions 12a and 13a of the auxiliary electrodes 12 and 13 protrude from the surface of the cover coat 7, or both end portions 7a and 7b of the cover coat 7 are overlapped with the both auxiliary electrodes. 12 and 13, one end portions 12 a and 13 a on the cover coat 7 side of the auxiliary electrodes 12 and 13 are stacked so as to protrude from the upper surface of the cover coat 7.
[0013]
With this configuration, the one end portions 12a and 13a of the auxiliary electrodes 12 and 13 protrude from the upper surface of the cover coat 7. Therefore, as shown in FIG. 16, when the chip type resistor is placed with the resistance film 4 side facing the printed circuit board 16, the cover coat of the auxiliary electrodes 12, 13 is applied to the printed circuit board 16. It is possible to reliably avoid that the one end portions 12a and 13a projecting from the upper surface of 7 are in contact with each other first and the cover coat 7 is in contact with the printed circuit board 16 side.
[0014]
Therefore, solder paste is applied to the upper surfaces of the electrode pads 16a and 16b on the upper surface of the printed circuit board 16, and then the chip resistor is applied to the upper surface of the printed circuit board 16, and both auxiliary electrodes in the chip resistor are used. 12 and 13 are placed in contact with both electrode pads 16a and 16b and then heated to melt the solder paste, so that the chip resistor melts both electrode pads 16a and 16b. After self-alignment due to the surface tension of the solder automatically shifts to the correct soldering position, the soldering is performed at this correct position.
The chip resistor having the above-described configuration is roughly manufactured in the following order.
That is, as shown in FIG. 4, a pair of left and right upper surface side terminal electrodes 2 and 3 and a resistance film 4 are formed on the upper surface of the insulating substrate 1 having a pair of left and right lower surface side electrodes 8 and 9 previously formed on the lower surface. (In addition, when forming the upper surface side terminal electrodes 2 and 3 and the resistance film 4, the upper surface side terminal electrodes 2 and 3 may be formed first and then the resistance film 4 may be formed. Then, the upper surface side terminal electrodes 2 and 3 may be formed on the film 4).
[0016]
Next, as shown in FIG. 5, after forming an undercoat 5 covering the resistance film 4, a trimming groove 17 is formed in the undercoat 5 and the resistance film 4 by laser beam irradiation or the like. Then, trimming adjustment is performed so that the resistance value of the resistance film 4 becomes a predetermined value. When this trimming adjustment is completed, a middle coat 6 covering the undercoat 5 is formed, and the trimming groove 17 is formed in the middle coat 6. Seal.
[0017]
Next, as shown in FIG. 6, a cover coat 7 made of black glass is formed so as to cover the middle coat 6, the undercoat 5 and the resistance film 4, and then, as shown in FIG. Form.
Then, after both side electrodes 10 and 11 are formed on the insulating substrate 1, the whole is subjected to barrel plating, whereby both the auxiliary electrodes 12 and 13, both the upper surface side terminal electrodes 2, 3, and both Metal plating layers 14 and 15 are formed on the surfaces of the lower surface side electrodes 8 and 9 and the both side surface electrodes 10 and 11 to form the chip resistor shown in FIGS.
[0018]
By the way, since the cover coat 7 and the auxiliary electrodes 12 and 13 are formed by screen printing, there is a relative printing misalignment between the cover coat 7 and the auxiliary electrodes 12 and 13. On the other hand, when the chip resistor is automatically mounted on a printed circuit board or the like, the shape of the cover coat 7 which is black among the chip resistors is recognized by a camera.
[0019]
In this case, the overall shape of the cover coat 7, as shown in FIG. 10, when a rectangular shape with the same width dimension over the length, with respect to the cover coat 7, wherein the insulating substrate width dimension when both auxiliary electrodes 12 and 13 aligned in a narrow than the width has deviated printed by a dimension E in the width direction of, as shown in FIG. 11, a portion of the cover coat 7, both auxiliary electrodes 12 and 13 In the plan view of the chip resistor, the black cover coat 7 has a shape in which the protruding portions are added to both ends of the rectangle , so that a complete rectangular shape is obtained. As a result, recognition errors frequently occur in the recognition by the camera.
[0020]
In contrast, in the present invention, as shown in FIGS. 6 and 7, the cover coat 7 has a width dimension in the portion where the auxiliary electrodes 12 and 13 overlap with each other. , 13 is made to have a shape in which the four corners of the rectangle are cut obliquely so as to be narrower than the width dimension in the non-overlapping portion .
By forming in this way, when the auxiliary electrodes 12 and 13 are displaced from the cover coat 7 by a dimension E in the lateral direction as shown in FIG. , Both the auxiliary electrodes 12 and 13 can be prevented from protruding from one side, and the black cover coat 7 in the plan view of the chip-type resistor can be maintained in a substantially perfect rectangle, so that recognition by the camera is recognized. It is possible to reliably reduce the occurrence of mistakes.
[0021]
Further, the width dimension of the cover coat 7 in the portion where the auxiliary electrodes 12 and 13 overlap is made smaller than the width dimension in the portion where the auxiliary electrodes 12 and 13 do not overlap . The shape is not limited to the four corners notched obliquely, but may be a shape in which the four corners of the rectangle are notched at right angles, as shown in FIG.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view of a chip resistor according to an embodiment of the present invention.
FIG. 2 is a plan view of FIG.
FIG. 3 is a longitudinal front view showing a state in which the chip resistor is soldered to a printed board.
FIG. 4 is a plan view showing a state in which a resistive film and both terminal electrodes are formed in the chip resistor.
FIG. 5 is a plan view showing a state in which an undercoat is formed in the chip resistor.
6 is a plan view showing a state where a cover coat is formed in the chip resistor. FIG.
FIG. 7 is a plan view showing a state in which both auxiliary electrodes are formed in the chip resistor.
FIG. 8 is a plan view showing printing misalignment between a cover coat and both auxiliary electrodes in the chip resistor.
FIG. 9 is a plan view showing a modification of the cover coat in the present invention.
FIG. 10 is a plan view showing the shape of a cover coat before reaching the present invention.
FIG. 11 is a plan view showing a printing deviation between the cover coat and both auxiliary electrodes in FIG. 10;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulation board | substrate 2, 3 Terminal electrode on the upper surface side 4 Resistance film 5 Undercoat 6 Middle coat 7 Cover coat 8, 9 Terminal electrode on the lower surface side 10, 11 Side electrode 12, 13 Auxiliary electrode 14, 15 Metal plating layer 16 Printed circuit board

Claims (1)

A resistive film, terminal electrodes for both ends thereof, and a black cover coat covering the resistive film are formed on the surface of the chip-type insulating substrate, and an auxiliary electrode is formed on the surfaces of the terminal electrodes. In chip resistors,
The width dimension in the direction perpendicular to the longitudinal direction of the resistive film in the cover coat and both auxiliary electrodes is aligned to be narrower than the width dimension in the insulating substrate , and one end portion on the cover coat side of both auxiliary electrodes is arranged. , the surface of the covercoat, or one end of the two auxiliary electrodes overlap so as to protrude from the surface of the covercoat, or both ends of the cover coat, the lower side of the two auxiliary electrodes, the subsidiary electrode Of the cover coat so that one end of the cover coat protrudes from the surface of the cover coat, while the width dimension of the cover coat where the two auxiliary electrodes overlap is larger than the width dimension of the cover coat where the two auxiliary electrodes do not overlap. A chip resistor structure characterized by narrowing .

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