JP3402035B2 - How to modify the resistance value of a chip resistor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance value of a chip resistor for correcting a chip resistor used for various electronic devices to a predetermined resistance value at high speed and with high accuracy. It relates to the correction method. 2. Description of the Related Art In recent years, with the increasing precision of various electronic devices,
A chip resistor mounted inside is also required to have high accuracy, and therefore, a method of correcting the resistance value of the chip resistor is also required to have higher accuracy. A conventional method of correcting the resistance value of a chip resistor will be described below with reference to the drawings. FIG. 8 is a block diagram of a trimming correction control unit for correcting a resistance value of a conventional chip resistor. In FIG. 8, reference numeral 1 denotes a ceramic substrate having a plurality of resistors and electrodes formed on an upper surface thereof. Are provided. Reference numeral 2 denotes a reflecting mirror for irradiating a laser beam 17 to the resistor of the ceramic substrate 1. Reference numeral 3 denotes a lens for adjusting the focus of the laser beam 17 to the resistor on the ceramic substrate 1. Reference numerals 4 and 5 denote X-axis and Y-axis galvanometers, which can move the laser beam 17 to an arbitrary resistor position on the ceramic substrate 1.
Reference numeral 6 denotes a laser control unit for controlling the oscillation operation of the laser light 17, and the laser device 7 is constituted by the above-mentioned reflecting mirror 2 and the laser control unit 6. [0004] Reference numeral 13 denotes a resistance value measuring circuit for measuring the resistance value of an arbitrary resistor on the ceramic substrate 1. Reference numeral 12 denotes an initial resistance value measuring unit that measures the initial resistance value before correcting the resistance value by using the circuit of the resistance value measurement circuit 13. Reference numeral 10 denotes a turn point determining means of one resistor for changing the trimming correction direction of the resistor for correcting the resistance value, and using the initial resistance value measured by the initial resistance value measuring means 12 to change the turning point of the correction direction. (Hereinafter referred to as a turn point resistance value). 11 is a resistance value comparing means for comparing the current resistance value with the turn point resistance value and the final resistance value, and compares the current resistance value with the turn point resistance value.
If they match, the operation of changing the progress of the laser beam 17, that is, the correction direction is performed. The current resistance value and the final target resistance value are compared, and if they match, the laser beam 17 is stopped, and the operations of the X-axis galvanometer 4 and the Y-axis galvanometer 5 are stopped. Numeral 15 denotes a galvanometer position control means, which controls the X-axis galvanometer 4 and the Y-axis galvanometer 5, and can irradiate the laser beam 17 to an arbitrary resistor position on the ceramic substrate 1. The X-axis and Y-axis referred to here are shown in FIG.
In the plan view of the resistor trimming correction operation shown in FIG. 5, the coordinate from the correction start point 29 to the turn point 24 is the X axis, and the coordinate from the turn point 24 to the 90 degree direction and toward the correction end point 25 is the Y axis. A method for correcting the resistance value of the resistor of the chip resistor in the trimming correction control unit for correcting the resistance value of the resistor configured as described above will be described. First,
As shown in FIG. 2, there are a plurality of chip resistors on the ceramic substrate 1 each including a resistor 21 and an electrode 22. One of the chip resistors is measured by an initial resistance value measuring means 12 using a resistance value measuring circuit 13. From the initial resistance value R0, which is the resistance value before correcting the resistance value to the specified value, and the final target resistance value Rm, which is the specified resistance value which is finally obtained by correcting the resistance value,
The turn point resistance value Rt is calculated as follows. [0007] At this time, K1 and K2 are coefficients used for calculating the turn point resistance value (K1 and K2 are hereinafter referred to as turn point calculation coefficients). The turn point calculation coefficients K1 and K2 are values set under various conditions prior to production. The turn point resistance value Rt and the final target resistance value Rm are set in the resistance value comparison means 11 between the current resistance value, the turn point and the final target resistance value, and trimming correction of one resistor, that is, correction of the resistance value is performed. Start. When the resistor is cut by the laser beam 17 and the resistance value reaches the turn point resistance value Rt, the trajectory of the laser beam 17 is changed by 90 degrees by the galvano position control means 15 and the laser output control means 16 into an L-shape. Bend. At this time, the locus of the laser beam 17 on the resistor has reached the turn point 24 in FIG. When the resistance value reaches the final target resistance value Rm, the irradiation of the laser beam 17 and the operations of the X-axis and Y-axis galvanometers 4 and 5 are stopped. At this time, the trajectory of the laser beam 17 on the resistor corresponds to the correction end point 25 in FIG.
Has been reached. In the same manner as the above-described method of repairing one resistor, all the remaining resistors on the ceramic substrate 1 are trimmed and then replaced with the next ceramic substrate 1. The resistance value of the chip resistor on the ceramic substrate 1 is corrected by repeating this series of operations for one lot. However, in the conventional method, when the turn point resistance value Rt is calculated by using the relational expression (Equation 1), the turn point calculation coefficients K1 and K2 use fixed values in one lot. For the resistors in the same lot where the material of the resistors and the printing and firing conditions are constant, the secondary correction distance YL shown in FIG. 2 can be corrected with a fixed length. The phenomenon that the secondary correction distance YL is significantly different due to a change in conditions due to a change in lots, such as a difference in the initial resistance value before addition, a shift in the irradiation start position of the laser beam 17, a size of the resistor, and the like. appear. In general, in the correction of the resistance value of the chip resistor by the laser beam 17 (hereinafter referred to as laser trimming correction), the characteristics of the cutting length (hereinafter referred to as "cut amount") and the resistance value by the laser beam 17 are shown in FIG. It has the characteristics shown in the cut amount-resistance value change characteristic curve shown. The horizontal axis in FIG. 5 is the cut amount when the resistor width W in FIG. 2 is 100%, and the vertical axis is the initial resistance value R before correction.
This is a multiple of the resistance value when 0 is set to 1.0. The curve 71 indicates the characteristic when the correction direction is not changed so as not to bend into an L shape, and the curves 72 and 73 respectively indicate the primary correction distance X.
L indicates the characteristic of the secondary correction distance YL and the resistance value when the position of 60% and 50% of the resistor width W is set as the turn point 24, and accordingly, the curves 71, 72, and 73
Are approximate equations (Equation 2), (Equation 3), and (Equation 4), respectively. Here, R is the resistance value on the vertical axis in FIG. 5, and L is the cutting amount on the horizontal axis in FIG. ## EQU2 ## [0013] [0014] From the characteristic curve of FIG. 5, the secondary correction distance Y
It can be seen that the shorter L is, the larger the resistance change rate per unit cut amount (Equation 5) is. Here, dr is a small change in the resistance value, and d1 is a small change in the cut amount. [Equation 5] When the resistance is 1.8 times the initial resistance R0, the values of (Equation 5) in the curves 72 and 73 are 1.44 and 0.73, respectively, and the curve 72 is better. It can be seen that the numerical value is large and the slope of the curve is large. From this,
It can be seen that the shorter the secondary correction distance YL, the larger the amount of change in resistance value for one pulse of laser light, and the greater the variation in resistance value after laser trimming correction. A microcrack occurs at the correction end point 25 in FIG. 2, and the change in the resistance value due to the microcrack is larger in the curve 72 as in the case of the change in the resistance value with respect to the one-pulse laser beam. You can see that. Further, a curve 7 in the characteristic curve diagram of FIG.
4 shows a characteristic obtained by first-order differentiation of the curve 73 in FIG.
In FIG. 2, since the resistor 21 is substantially square, the correction start point 29 is located at a position near 20% of the resistor width W from the electrode 22, so that the secondary correction distance YL is 30 times the resistor width W.
% Is the center of the resistor in the Y-axis direction.
Corresponds to a cut amount of 80%. From these, 2
The next correction distance YL is the cutting depth 8 past the center point of the resistor.
From the 0% point, it can be seen that the value of the resistance value change rate per unit cut amount shown in (Equation 5) is very small, and the change rate of the resistance value is also small. That is, it is understood that the secondary correction distance YL needs to be long enough to pass the center of the resistor. However, according to the above-described conventional resistance value correction method, the turn point calculation coefficients K1 and K used when determining the turn point resistance value Rt are determined.
Since 2 is a fixed constant in one lot, the secondary correction distance YL can be averaged for a small variation in the initial resistance value R0 of each resistor in one lot. A large difference in the initial resistance value R0 between lots due to the material of the resistor, printing firing conditions, and the like exceeds the adjustment range of the secondary correction distance YL. Further, since the resistance value changes depending on where the laser beam 17 performs trimming correction on the resistor, even if a product having the same final target resistance value Rm is trimmed and corrected, the lot number may be reduced. If the difference is too large, the secondary correction distance YL may be too short or too long, and a lot of variations in the resistance value may occur, causing a problem that the yield of products requiring high precision is poor. The present invention solves the above-mentioned conventional problems. A highly accurate chip resistor capable of reducing the variation in resistance value after trimming correction even when the variation in conditions due to the difference between lots is large. It is an object of the present invention to provide a method for correcting the resistance of a vessel. In order to solve this problem, a method of correcting a resistance value of a chip resistor according to the present invention is provided by a distance measuring means for measuring a secondary correction distance, and a measuring method for the distance measuring means. And a turn point determining means for changing a turn point at which the correction direction changes from the average distance to an L-shape. It is. Thus, the secondary correction distance is measured during the production of each lot, and the length is automatically corrected to the set constant length, whereby the resistance value can be corrected with high accuracy. it can. According to the first aspect of the present invention, when the resistor is trimmed and corrected into an L-shape to correct the resistance value, the correction direction of the L-shaped corner point is changed. The secondary correction distance, which is the distance from the turn point to the correction end point, is measured, the average secondary correction distance of the measured plurality of resistors is sequentially obtained, and the next correction is performed based on the average distance obtained thereby. The turning point of the resistor is changed, and it has the effect that feedback control is possible, the correction distance is averaged, and the variation can be absorbed. FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. Since the block diagram of the embodiment of the present invention shown in FIG. 1 has basically the same configuration as the block diagram of FIG. 8 of the conventional example, the same components or elements are given the same numbers or symbols. Detailed description is omitted. FIG. 1 is a block diagram showing a method of correcting the resistance value of a chip resistor according to the first embodiment. In FIG. 1, reference numeral 15 denotes a galvano position control means which controls the X-axis and Y-axis galvanometers 4 and 5 in arbitrary directions. The controller holds the current position data of the X-axis and Y-axis galvanometers 4 and 5. Reference numeral 11 denotes a resistance value comparing means which compares the current resistance value with the turn point resistance value Rt or the current resistance value with the final target resistance value Rm, and outputs a coincidence signal if they coincide with each other. Numeral 14 denotes a distance measuring means, which is an X-axis and Y-axis galvanometer 4 held by a galvanometer position control means 15.
Then, the secondary correction distance YL is measured from the current position data of (5) and (5). Reference numeral 8 denotes an average distance calculating unit that accumulates the secondary correction distances YL of the plurality of resistors measured by the distance measuring unit 14 and calculates the average value. Reference numeral 9 denotes a coefficient determining means for calculating a turn point of one resistor.
1, K2 is calculated. The average distance calculating means 8, the turn point calculating coefficient determining means 9, the turn point determining means 10 for one resistor, the initial resistance value measuring means 12, and the distance measuring means 14 execute software processing according to a predetermined control program. This is performed by a microcomputer (not shown). 1 is a ceramic substrate,
2 is a reflecting mirror, 3 is a lens, 6 is a laser control unit,
Reference numeral 7 denotes a laser device, and reference numeral 17 denotes a laser beam, which is the same as in the conventional example. FIGS. 3 and 4 are flow charts for explaining the operation of the first embodiment of the method for correcting the resistance value of the chip resistor in the above-described configuration, and FIGS. 6 and the characteristic curve diagram of FIG. Prior to production, a plurality of resistors 21 and electrodes 2
A plurality of ceramic substrates 1 formed by printing and firing 2 are prepared, and the ceramic substrates 1 are set one by one in a trimming correction machine (not shown), and the resistance value is corrected for each resistor. To go. First, in step 31 of the operation flowchart shown in FIG. 3, an initial resistance value R0 of the resistor on the ceramic substrate 1 before correction is measured by the resistance value measuring circuit 13. The turn-point resistance value Rt is calculated in the next step 32 by using the initial resistance value R0, the final target resistance value Rm of the final required value and the turn-point calculation coefficients K1 and K2 set prior to the production. I do. The turn point resistance value Rt and the final target resistance value Rm are set in the resistance value comparison means 11. In step 33, the resistor is moved while irradiating the resistor 17 with the laser beam 17 while comparing the resistance of the resistor to be trimmed and corrected by the resistance comparator 11 with the turn point resistance Rt. When the resistance value of the resistor reaches the turn point 24, the resistance value comparing means 11 notifies the galvano position control means 15 and the laser output control means 16 that the turn point resistance value Rt has been reached and notifies the laser beam 1
7 is changed to the L-shape by changing the traveling direction. When the resistance value reaches the final target resistance value Rm, the resistance value comparison means 11 instructs the galvano position control means 15 and the laser output control means 16 to move.
The operation of the X-axis and Y-axis galvanometers 4 and 5 for notifying that the final target resistance value Rm has been reached and stopping the irradiation and movement of the laser beam 17 is stopped. In the next step 35, it is determined whether or not the resistance value of the corrected resistor in the step 34 is within a non-defective range of a specified value.
In step 9, the secondary correction distance YL of the resistor is not fed back. In step 36, the distance measuring means 14
Then, the secondary correction distance YL is measured from the Y coordinate of the turn point 24 of the resistor trimmed in step 34, that is, the Y coordinate value of the trimming start position and the Y coordinate value of the correction end point 25, and the process proceeds to step 37. move on. Step 3
In step 7, the secondary correction distance YL measured in step 36 is stored. Thereafter, in step 38, the number C of chips of non-defective chip resistors is counted, and the process proceeds to step 39. In step 39, it is confirmed whether or not all the resistors on the ceramic substrate 1 whose trimming is to be corrected have been corrected. If it has been completed, the process proceeds to step 40, and if not completed, the process proceeds to step 31.
Returning to the next step, trimming of another resistor is performed, and the operations from step 31 to step 39 are repeated until the correction of all resistors on the ceramic substrate 1 which is currently being trimmed is completed. In step 40, the number of ceramic substrates 1 for which trimming correction has been completed is increased by one. In step 41, the lot end condition is confirmed, and if the condition is satisfied, the flow proceeds to step 46, which is a production end operation of one lot. On the other hand, if the lot end condition is not satisfied in step 41, the process proceeds to step 42.
The secondary correction distance YL is evaluated every time a specified number of N ceramic substrates 1 are produced, and the turn point calculation coefficient K is calculated.
1, K2 is set again. The specified number N of boards for which the secondary correction distance YL is to be re-evaluated is set before production.
In step 42, it is checked whether or not the number of substrates counted in step 40 has reached N. If so, the process proceeds to step 43;
1 and the trimming of another new ceramic substrate 1 is corrected. If the number of substrates has reached N in step 42, the process proceeds to step 43, in which the average value L of the secondary correction distance YL is calculated using the secondary correction distance YL of each resistor and the number of chips C of the chip resistor (number). Calculate using 6). (Equation 6) In step 44, the number N of substrates counted in step 40 is reset to 0, and the routine proceeds to step 45. Average value L of secondary corrected distance YL obtained in step 43
Is compared with a secondary correction distance YL of, for example, (Table 1) which is a data table set prior to production, and coefficients K1 and K2 for calculating a turn point are determined. It is assumed that the turn point resistance value Rt is calculated from the coefficients K1 and K2.
1, the trimming correction operation of the resistor of the new ceramic substrate 1 is performed. [Table 1] FIG. 4 is a flowchart for explaining the detailed operation of step 45 in FIG.
The operation of determining the turn point calculation coefficients K1 and K2 from the comparison between the average value L of L and (Table 1) is shown. That is, in step 51, the average value L of the secondary correction distance YL is compared with the reference value of the secondary correction distance YL shown in rank 1 of (Table 1). Turn point calculation coefficients K1 and K2 are newly set so that K1 and K2 of rank 1 in Table 1) are used for production. Steps 52 to 56 correspond to the average value L of the secondary correction distance YL and the ranks 2, 3, 4, 5, and 6 of (Table 1).
To determine whether the condition is satisfied. If the condition is satisfied, each of steps 52 to 56 corresponds to steps 58 to 6
Go to 2 to calculate the respective turn point calculation coefficients K1 and K
2 is newly set and the operation is terminated. If the condition is not satisfied in step 56, the process proceeds to step 63, in which the turn point calculation coefficients K1 and K2 of rank 7 are set as new turn point calculation coefficients K1 and K2. By changing the turn point calculation coefficients K1 and K2, the characteristic of the turn point resistance value Rt with respect to the initial resistance value R0 becomes
It can be changed as shown in the initial resistance value-turn point characteristic curve diagram of FIG. Note that curves 81 to 87 correspond to ranks 1 to 7 in (Table 1). The variation of the resistance value after the trimming correction according to the present embodiment and the variation of the resistance value by the conventional resistance value correction method are shown in comparison with (Table 2). [Table 2] As is clear from Table 2, the method of correcting the resistance value of the chip resistor according to the present embodiment has an excellent effect in that the variation in the resistance value after the trimming correction is reduced. As described above, according to the present embodiment, the distance measuring means, the average distance calculating means, and the turn point determining means are set to be processed by a microcomputer or the like, so that the secondary The correction distance YL can be averaged to a certain distance, and high-precision trimming correction can be performed without adding hardware such as equipment to the conventional system configuration. Further, by using the data table for the calculation of the turn point calculation coefficients K1 and K2, the turn point coefficients K1 and K2 can be calculated at high speed. In the present embodiment, the method of implementing the turn point calculation coefficient determining means 9 is realized by comparison with a data table, but this may be performed by calculation using a dedicated function. Although the turn point determining means 10 for one resistor is calculated by (Equation 1), the calculation formula is not limited to the same as that of (Equation 1). Further, the determination may be made by referring to a data table instead of calculation. Also, the average distance calculating means 8, 1
Turn point calculation coefficient determination means 9 for one resistor
Although the turn point determining means 10, the initial resistance value measuring means 12, and the distance measuring means 14 of one resistor are implemented by software, they may be implemented by hardware, and the laser trimming correcting means may be implemented by a sandblast method. Needless to say, it's good. As described above, the present invention provides a distance measuring means,
By providing the average distance calculating means and the turn point determining means, an excellent method of correcting the resistance value of the chip resistor, which can automatically average the secondary correction distance and correct the resistor with high accuracy, is realized. The advantageous effect that it can be obtained is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a trimming correction control unit for correcting a resistance value of a chip resistor according to an embodiment of the present invention. FIG. 2 is a plan view showing a resistor trimming correction operation of the chip resistor. FIG. 3 is a flowchart illustrating an operation according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating an operation of determining a turn point calculation coefficient. FIG. 5 is a cut amount and a resistance value change illustrating the same effect. FIG. 6 is a characteristic diagram of a first-order derivative of a cutting amount and a resistance value obtained by first-order-differentiating a characteristic curve of the same cutting amount and a change in resistance value, and FIG. 7 is an initial resistance value illustrating the same effect. FIG. 8 is a block diagram of a trimming correction control unit for correcting a resistance value of a conventional chip resistor. [Description of References] 1 Ceramic substrate 2 Reflecting mirror 3 Lens 4 X-axis galvanometer Reference Signs List 5 Y-axis galvanometer 6 Laser control unit 7 Laser device 8 Average distance calculation means 9 Turn point calculation coefficient determination means 10 Turn point determination means for one resistor 11 Resistance value comparison means 12 Initial resistance value measurement means 13 Resistance value measurement circuit 14 Distance measuring means 15 Galvano position control means 16 Laser output control means 17 Laser light

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Claims (1)

(57) [Claims] [Claim 1] When trimming and correcting a resistor into an L-shape to correct a resistance value, from a turn point for changing a correction direction of an L-shaped corner to a correction end point. Is the distance of 2
A chip resistor which measures a next correction distance, sequentially calculates an average secondary correction distance of the measured plurality of resistors, and changes a turn point of a resistor to be corrected next from the average distance obtained by this. How to correct the resistance value.