JP3748703B2 - Trimming groove inspection method for chip resistors - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a chip resistor formed by forming one resistive film on one chip-type insulating substrate, or a multiple chip type formed by forming a plurality of resistive films on one chip-type insulating substrate. The present invention relates to a method for inspecting a trimming groove for adjusting a resistance value to be engraved in a resistor film in a resistor.
[0002]
[Prior art]
In general, as shown in FIG. 1, the above-described chip resistor 1 is formed with a resistive film 3 and a black cover coat 4 covering the resistive substrate 3 on the upper surface of a chip-type insulating substrate 2, while the insulating substrate 1 2 on both the left and right side portions of the resistor film 3 with respect to both ends of the resistance film 3 (however, the two terminal electrodes 5 are the upper electrode 5a made of conductive paste formed on the upper surface of the insulating substrate 2 and the left and right sides of the insulating substrate 2) A side electrode 5b made of a conductive paste formed on the surfaces 2a and 2b, and a metal plating layer in which a solder or tin plating layer is formed on a surface of the upper surface electrode 5a and the side electrode 5b with a nickel plating layer as a base. ) Is formed.
[0003]
In addition, as shown in FIG. 2, the multiple chip resistor 11 has a plurality of resistance films 13 and a black cover coat 14 covering the resistance film 13 on the upper surface of the chip type insulating substrate 12. A plurality of terminal electrodes 15 for both ends of each of the resistance films 13 are formed on the left and right side portions of the insulating substrate 12 (however, both terminal electrodes 15 are upper surfaces made of a conductive paste formed on the upper surface of the insulating substrate 12. The electrode 15a, the side electrode 15b made of conductive paste formed on the left and right side surfaces 12a and 12b of the insulating substrate 12, and the surface of the upper surface electrode 15a and the side electrode 15b are provided with a solder or tin plating layer with a nickel plating layer as a base. And a metal plating layer formed).
[0004]
In manufacturing the chip resistor 1, a method as described below has been conventionally employed (see Japanese Patent Laid-Open No. 56-148804).
That is, as shown in FIG. 3, first, a large number of the insulating substrates 2 are arranged side by side in the horizontal direction and integrated into a rod-shaped material substrate A1, and a plurality of the rod-shaped material substrates A1 are aligned and integrated. A thin material substrate A is prepared.
[0005]
In addition, margin portions A2 and A3 are integrally provided around the material substrate A, and the material substrate A is broken on the surface of the material substrate A for each rod-shaped material substrate A1. A plurality of vertical break grooves A4 and a plurality of horizontal break grooves A5 for breaking each rod-shaped material substrate A1 for each insulating substrate 2 are formed.
[0006]
Next, as shown in FIG. 4, an upper surface electrode 5 a made of a conductive paste is formed on a portion of each surface of the material substrate A on the insulating substrate 2, while each of the insulating substrates on the back surface of the material substrate A. A bottom electrode is formed on the portion 2.
Next, as shown in FIG. 5, a resistance film 3 is formed on the insulating substrate 2 in the surface of the material substrate A, and a transparent undercoat is formed on the resistance film 3. The resistance value becomes a predetermined resistance value by engraving an L-shaped trimming groove 3a by irradiating a laser beam while measuring the resistance value of the resistance film 3 with respect to each of the resistance films 3. Laser trimming.
[0007]
Then, a black or transparent cover coat 4 covering each resistance film 3 is formed on the portion of each insulating substrate 2 in the surface of the material substrate A as shown by a two-dot chain line in FIG.
Next, after removing the blank portions A2 and A3 in the periphery of the material substrate A, the material substrate A is broken along each vertical break groove A4 for each rod-shaped material substrate A1. After the side electrodes 5b made of conductive paste are formed on the side surfaces, that is, the left and right side surfaces 2a, 2b of each insulating substrate 2 of the rod-shaped material substrate A1, the rod-shaped material substrate A1 is placed in each lateral break groove A5. Along this, each insulating substrate 2 is broken.
[0008]
Next, by subjecting a large number of the insulating substrates 2 to barrel plating, metal plating layers including a nickel plating layer as a base are formed on the surfaces of both the upper surface electrodes 5a and the both side surface electrodes 5b of each insulating substrate 2. The chip resistor 1 shown in FIG. 1 is formed.
Conventionally, in the laser trimming, as shown in FIG. 7, a laser beam is appropriately condensed to a diameter D by a lens, and this is irradiated to the resistance film 3 for an appropriate time. The resistance film in the portion is vaporized / disappeared, and then the resistance film 3 and the laser beam are relatively moved by an appropriate pitch P, and then the laser beam condensed to the diameter W0 is appropriately timed with respect to the resistance film 3 The method of adopting a method of sequentially repeating the irradiation and vaporizing / disappearing the resistive film in the irradiated portion is employed.
[0009]
[Problems to be solved by the invention]
According to this conventional laser trimming method, the irradiation of the laser beam to the resistance film 3 is intermittent such that the pitch P is appropriately spaced, so that the laser beam having the diameter W0 in the trimming groove 3a is overlapped. In the portion, a portion in which the groove width dimension in the trimming groove 3a is locally narrowed from a predetermined W0 to W1 is generated at an interval of the appropriate pitch P, and a laser beam is formed in the trimming groove 3a. By forming a left-over portion that cannot be vaporized / disappeared by irradiation of light, a portion in which the groove width dimension in the trimming groove 3a is locally narrowed from a predetermined W0 to W1 is generated.
[0010]
Thus, in the portion where the groove width dimension in the trimming groove 3a is locally narrowed to W1, an energization phenomenon occurs in the voltage applied to the resistance film 3 for measuring the resistance value during laser trimming. Therefore, the predetermined laser trimming described above is performed without any problem, and is manufactured as the chip resistor 1 shown in FIG.
[0011]
The chip resistor 1 manufactured in this way may be applied with a voltage higher than the voltage applied during the laser trimming during use. In this case, the groove in the trimming groove 3a described above may be applied. In the portion where the width dimension is locally narrowed to W1, an energization phenomenon occurs, and there is a problem that the resistance value frequently changes greatly.
[0012]
In order to prevent this problem, after the laser trimming is performed on each resistance film 3, the minimum groove width dimension W1 in the trimming groove 3a formed in each resistance film 3 is determined by the laser trimming. It is necessary to inspect whether the trimming groove 3a has a dimension that does not change the resistance value even when a voltage higher than the voltage to be applied is applied.
[0013]
In this inspection, conventionally, the surface of the resistance film 3 is photographed by a camera in a state in which the surface is irradiated with light, and the image is binarized.
However, on the bottom surface of the trimming groove 3, a soot component generated when a part of the resistance film 3 is vaporized / disappeared by the irradiation of the laser beam adheres in a thin film shape with substantially the same color as the resistance film 3. Therefore, the trimming groove 3a cannot be clearly identified on the processed image. Therefore, the accuracy of the inspection of the trimming groove 3a is remarkably low, and the chip resistor manufactured in the market is not suitable. In addition, many defective products whose resistance values greatly change during subsequent use are mixed in, and the time required for inspecting the quality of the trimming groove 3a is increased, resulting in an increase in manufacturing cost.
[0014]
Further, in the case of the multiple chip type resistor 11 shown in FIG. 2, there is a similar problem because the above-described method is applied.
According to the present invention, the trimming groove in each resistance film is good or bad, that is, the dimension in which the minimum groove width in the trimming groove does not change even when a voltage higher than the voltage applied during laser trimming is applied. It is a technical object to provide an inspection method that can quickly and accurately check whether or not it is formed.
[0015]
[Means for Solving the Problems]
In order to achieve this technical problem, the inspection method of the present invention is:
“After performing laser trimming on the resistive film formed on the surface of the ceramic insulating substrate, the back surface of the insulating substrate is irradiated with the light from the light source collected by the lens. The portion including the trimming groove in the resistance film is photographed from the surface side of the insulating substrate by photographing means, and the minimum groove width dimension in the trimming groove is measured from an image obtained by processing the photographed image.
Is.
[0016]
[Operation and effect of the invention]
A ceramic thin plate is mainly used for the insulating substrate used for chip resistors. Since this ceramic thin plate is slightly transparent to light, a resistive film is formed on the surface. By condensing and irradiating the light from the light source with the lens to the back surface of the insulating substrate, the portion of the surface of the insulating substrate where the resistance film is formed blocks light transmission, and the resistance The part where the film is not formed transmits light, and the part in the trimming groove engraved in the resistive film also has a defect when the resistive film is vaporized and disappeared by laser beam irradiation. The light is transmitted only by the thin components.
[0017]
In other words, the light condensed and irradiated by the lens on the back surface of the insulating substrate is transmitted to the surface side only in the portion where the resistance film is not formed, and in the portion where the resistance film is formed. When the insulating substrate is viewed from the surface side because it does not transmit to the surface side, the part where the resistance film is formed and the other part, that is, the part where the resistance film is not formed There is a big contrast difference between them.
[0018]
Therefore, a part including the trimming groove in the resistance film on the surface of the insulating substrate is photographed by photographing means from the surface side of the insulating substrate, and this photographed image is subjected to image processing such as binarization processing. Since the shape of the trimming groove in the resistive film appears clearly in the processed image, the minimum groove width dimension in the trimming groove can be accurately and quickly measured from this processed image. .
[0019]
Therefore, according to the present invention, due to the high accuracy of inspecting the quality of the trimming groove, defective products whose resistance value greatly changes in subsequent use are mixed in the manufactured chip resistors. On the other hand, since the time required for the inspection can be shortened, manufacturing can be reduced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
In the following, an embodiment of the present invention will be described with reference to FIGS.
In this figure, reference numeral B denotes an XY table configured to reciprocate in the direction of the X axis and the direction of the Y axis perpendicular thereto, and on the upper surface of the XY table B, as shown in FIG. On the other hand, the material substrate A after the process of engraving the trimming groove 3a by laser trimming is placed on the resistance film 3 of each insulating substrate 2 while the material substrate A is placed above the XY table B. A television camera C for photographing the upper surface of the substrate A is provided, and a monitor television D is connected to the television camera C.
[0021]
The XY table B is provided with a through hole for exposing the lower surface of the material substrate A placed on the upper surface of the XY table B. A light source E such as a lamp and the light source are provided below the XY table B. A lens F is provided for condensing the light from E into a strong light and irradiating a portion of the lower surface of the material substrate A directly below the television camera C.
[0022]
Reference numeral G denotes a controller for the XY table B and the television camera C, reference numeral H denotes a program controller for the controller G, and reference numeral J denotes a computer for all of them.
The controller G, the program controller H, and the computer J operate on the XY table B and the television camera C, as described below, with respect to the portion directly below the television camera C on the lower surface of the material substrate A. The light from the light source E is condensed and irradiated by the lens F, and in this state, the trimming groove 3a is included in the resistance film 3 in the insulating substrate 2 located immediately below the television camera C. A portion is photographed and the minimum groove width dimension W1 in the trimming groove 3a is calculated from a processed image obtained by binarizing the photographed image, whereby the quality of the trimming groove 3a, that is, in the trimming groove 3a is calculated. A dimension in which the resistance value does not change even when a voltage having a minimum groove width W1 higher than a voltage applied during laser trimming is applied. Whether the inspection has been formed is performed for each of the insulating substrate 2 in the material substrate A.
[0023]
That is, when the light from the light source E is condensed and irradiated by the lens F onto the lower surface of the insulating substrate 2 located immediately below the television camera C behind each insulating substrate 2 in the material substrate A, Since each insulating substrate 2 in the material substrate A is made of a ceramic thin plate and has a slight light transmittance with respect to light, a portion of the surface of the insulating substrate 2 where the resistive film 3 is formed is The portion where the transmission of light is blocked and the resistance film 3 is not formed transmits light, and the portion in the trimming groove 3 a formed in the resistance film 3 also includes the resistance film 3. Since the soot component at the time of vaporizing and disappearing due to the irradiation of the laser beam is only thinly attached, the light is transmitted.
[0024]
That is, the light irradiated to the back surface of the insulating substrate 2 located directly below the TV camera C is transmitted to the front side only in the portion where the resistance film 3 is not formed, and the resistance film 3 is formed. In the portion where the insulating substrate 2 is viewed from the surface side, the portion where the resistive film 3 is formed and the other portion, that is, the resistive film is formed. A large contrast difference can be made between the non-applied part.
[0025]
Therefore, a portion including the trimming groove 3a in the resistance film 3 on the surface of the insulating substrate 2 is photographed by the television camera C, and this photographed image is subjected to image processing such as binarization processing. As shown in FIG. 10, since the shape of the trimming groove 3a in the resistive film 3 appears clearly in the image, the minimum groove width dimension d in the trimming groove 3a is accurately determined from this processed image. Whether or not the minimum groove width dimension d is formed to a dimension that does not change the resistance value even when a voltage higher than that applied during laser trimming is applied can be determined. By doing so, the quality of the trimming groove 3a can be inspected.
[0026]
In this way, when the inspection on the resistive film 3 of one insulating substrate 2 in the material substrate A is completed, the next insulating substrate 2 is sent to a position directly below the TV camera C by the movement of the XY table B, and the resistive film. 3 is inspected for all the insulating substrates 2 in the material substrate A.
In addition, by simultaneously photographing the resistance films 3 on the plurality of insulating substrates 2 with the television camera C, the inspection speed may be increased by performing the inspection on each of the plurality of insulating substrates 2. Needless to say, the present invention can also be applied to the inspection of the trimming groove 13a of each resistance film 13 in the multiple chip resistor 11 shown in FIG.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a chip resistor.
FIG. 2 is a perspective view showing multiple chip resistors.
FIG. 3 is a perspective view of a material substrate used in manufacturing the chip resistor.
FIG. 4 is a perspective view showing a state in which an upper surface electrode is formed on the upper surface of the material substrate.
FIG. 5 is a perspective view of a state in which a resistance film is formed on the upper surface of the material substrate.
FIG. 6 is a perspective view of a state in which a cover coat is formed on the upper surface of the material substrate.
7 is an enlarged view of a main part of FIG.
FIG. 8 is a perspective view showing an embodiment of the present invention.
9 is a cross-sectional view taken along the line IX-IX of FIG.
FIG. 10 is a diagram showing a processed image in the embodiment of the present invention.
[Explanation of symbols]
A Material substrate 1 Chip resistor 11 Multiple chip resistors 2, 12 Insulating substrate 3, 13 Resistive films 3a, 13a Trimming groove B XY table C TV camera D Monitor TV E Light source F Lens G Controller H Program controller J Computer W0 Groove width dimension in trimming groove W1 Minimum groove width dimension in trimming groove

Claims (1)

After performing laser trimming on the resistance film formed on the surface of the ceramic insulating substrate, the back surface of the insulating substrate is irradiated with light from a light source collected by a lens, and in this state, the insulating film is irradiated. A chip-type resistor characterized in that a portion including a trimming groove in the resistance film is photographed by photographing means from the surface side of a substrate, and a minimum groove width dimension in the trimming groove is measured from an image obtained by processing the photographed image. Method for inspection of trimming grooves in a container

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