JP3690556B2 - Resistance measuring method and apparatus - Google Patents

Description

[0001]
[Technical field belonging to the invention]
The present invention relates to a resistance measurement method及BiSo location, in particular, with measuring the cross-sectional shape of the printed onto a substrate such as glass conductive paste (coating), based on the measured film shape, expressed after baking The present invention relates to a method and an apparatus for predicting a resistance value of a resistance wire.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a plate glass with a resistance wire in which a plurality of conductor paste wires are printed in parallel on the surface of the plate glass and then heated and baked to form a resistance wire has been used as an anti-fogging glass for automobiles. By supplying power to the resistance wire, each resistance wire generates heat, and fogging due to water vapor or the like on the surface of the plate glass is removed. However, due to the quality of the product, the error of the parallel resistance of each resistance wire must be within a predetermined allowable range. If the resistance value is too large, the amount of heat generated is small and the time for removing the fog is prolonged. On the other hand, if the resistance value is too small, a load corresponding to the power source of the automobile is applied and other electric systems are disturbed. It is. That is, if the resistance value is measured and it is out of the specification range, the product is excluded as out of specification.
[0003]
[Problems to be solved by the invention]
However, conventionally, the conductive wire in the conductive paste is not sintered unless the conductive paste is baked on the plate glass, so the resistance value of the resistance wire does not appear, and therefore the resistance value cannot be measured. . In addition, the resistance value could not be corrected because the conductive paste was baked on the plate glass after baking. Therefore, as a result of measuring the resistance value after baking, if the resistance value is out of the allowable range, it is rejected as a defective product, and the resistance value cannot be corrected, resulting in a significant decrease in the yield of non-defective products.
[0004]
In order to measure the resistance value after printing and before baking, X-rays are irradiated to measure the amount of silver as conductive particles in the conductor paste, and the generated secondary X-ray dose and silver amount are measured. A method is proposed in which a silver amount is calculated using a standard curve and a resistance value is calculated using a silver and resistance curve (Japanese Patent Publication No. 63-36460). .
[0005]
However, in the method proposed in this publication, the element that determines the resistance value of the conductor paste is not only the amount of silver, but also a constituent component of the conductor paste, glass component (glass frit) and metal resinate (resin) In addition, various additives such as viscosity adjustment and the degree of sintering of silver particles determine the resistance value in relation to each other, so even if the resistance value is calculated only from the amount of silver, the accuracy is not sufficient There was no problem.
[0006]
The present invention has been made in view of such circumstances, and enables nondestructive measurement of the shape of a film such as a conductive paste formed on a substrate such as a plate glass, based on the measured film shape. , and to provide a resistance measurement method及beauty resistance measuring device which can accurately obtain the resistance value of the resistor filament expressed after baking.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention (invention according to claim 1) is a method for obtaining a resistance value of a resistance wire formed by heating and baking a conductive paste printed on a substrate, After the conductor paste is printed thereon, before the heating and baking process, the surface of the conductor paste is scanned by the non-contact displacement detecting means, and the conductor paste detected by the non-contact displacement detecting means by the scanning Based on the amount of displacement between the non-contact type displacement detecting means and the relative amount of movement of the non-contact type displacement detecting means with respect to the substrate in the scanning direction, the first arithmetic processing is performed, and the cross-sectional shape of the conductor paste is determined. Measuring, performing a second calculation process based on the obtained cross-sectional area shape, calculating a cross-sectional area of the conductor paste, and performing a third calculation process based on the obtained cross-sectional area, heating, Appears after baking It is characterized by calculating the resistance value of the resistor striatum.
[0008]
Furthermore, in order to provide an apparatus that embodies the above-described method invention, the present invention (invention according to claim 5 ) provides a resistance value of a resistance wire formed by heating and baking a conductive paste printed on a substrate. A non-contact displacement detecting means for detecting a distance to the surface of the conductor paste before the heating and baking process, and the non-contact displacement detecting means is moved relative to the substrate in the scanning direction. A displacement means between the conductive paste obtained by scanning the surface of the conductor paste with the non-contact type displacement detecting means by the moving means, and the substrate. A first arithmetic processing means for obtaining a cross-sectional shape of the conductor paste based on a relative movement amount of the non-contact displacement detecting means in the scanning direction, and a cross-sectional shape obtained by the first arithmetic processing means. And a second calculation processing means for calculating the cross-sectional area of the conductor paste, and a third calculation means for calculating the resistance value of the resistance wire appearing after the heating and baking process based on the cross-sectional area obtained by the second calculation processing means. And an arithmetic processing means .
[0009]
According to the present invention, the shape of the film formed on the substrate can be measured nondestructively. Moreover, the cross-sectional area of the film can be calculated by performing the second calculation process based on the film shape obtained by the measurement of the film shape .
[0011]
That is, according to the present invention, it becomes possible to measure the shape and cross-sectional area of the printed film, which was difficult with the conventional technique, and the resistance value of the resistance filament that appears after the heating and baking process is accurately determined from the measurement result. Can be predicted well.
In addition, the shape of each of the plurality of conductor paste lines printed on the substrate is measured, the cross-sectional area is calculated, and the parallel resistance value when a plurality of conductor paste lines are connected in parallel is calculated from these measurement results. It is also possible to calculate.
[0012]
In realizing the present invention, it is desirable that non-contact, high resolution, small measurement spot diameter, and any displacement of a scatterer / transparent body can be measured as non-contact displacement detection means. At present, it is preferable to employ a laser displacement meter as a means having all of the above.
Further, in the present invention, in particular, when a silver paste containing silver as a main component is printed on the surface of glass, and the resistance filament is formed by heating and baking, the resistance value of the resistance filament is set before baking. It is effective for the usage mode to grasp.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Will be described in detail preferred embodiments of resistance measurement method及BiSo location according to the present invention with reference to the accompanying drawings.
Figure 1 is a block diagram of a resistance measurement device to which the present invention is applied. The resistance measurement apparatus is mainly stage 10, column 12 and 14, the shaft 16, the laser displacement meter 18, the motor 20 and 22, a motor driver (drive circuit) 24, an analog / digital signal conversion board (hereinafter, A / Abbreviated as D conversion board) 26 and a computer 28. In addition, although the so-called portal type (double column type) apparatus form is shown in the same figure, the form of an apparatus is not restricted to this.
[0014]
In the figure, reference numeral 30 denotes a glass substrate as an object to be measured, and a conductor paste (for example, silver paste) 32 (hereinafter referred to as a conductor paste wire) 32 is formed on the glass substrate 30 by screen printing. Yes. A glass plate with a resistance wire in which a plurality of silver paste wires having silver as conductive particles are printed in parallel on the surface of the glass substrate 30 and then heated and baked to form a resistance wire is, for example, an automotive rear window glass Used as.
[0015]
The stage 10 and the columns 12 and 14 are provided on a bed (not shown), and a shaft 16 is rotatably supported between the columns 12 and 14 via a bearing (not shown). The shaft 16 is constituted by a ball screw shaft whose peripheral surface is threaded, and the shaft 16 is rotated by a motor (X-axis drive motor) 20.
A movable body 34 is connected to the shaft 16 through a nut member (not shown) so as to be movable in the left-right direction (X-axis direction) in the figure. Further, two guides (guide shafts) 36 and 38 are provided between the columns 12 and 14 in parallel with the shaft 16, and the movable body 34 is slidably supported by these guides 36 and 38.
[0016]
The laser displacement meter 18 is provided below the movable body 34 and detects the displacement of the glass substrate 30 and the silver paste wire 32 placed on the stage 10. Although a specific configuration of the laser displacement meter 18 is not described in detail in this specification, for example, the object is irradiated with laser light, and the focal position is controlled so that the reflecting surface is focused on the basis of the control amount. A laser displacement type laser displacement meter that measures the distance (displacement) to the surface position of the object is adopted.
[0017]
Reference numeral 40 in the figure denotes a line detection sensor, which is arranged in a predetermined positional relationship with the laser displacement meter 18. Both the filament detection sensor 40 and the laser displacement meter 18 can be moved in the vertical direction (Z-axis direction) in the figure by a motor (Z-axis drive motor) 22.
The motors 20 and 22 are driven via a motor driver 24, and the rotation of the motors 20 and 22 is controlled by a computer 28.
[0018]
The glass substrate 30 on the stage is placed so that the conductor paste wire 32 is orthogonal to the moving direction (X-axis direction) of the movable body 34, and rotating the motor 20 moves the laser displacement meter 18 in the X-axis direction ( The measurement position in the width direction of the conductor paste line 32 can be changed (scanned) by moving in the scanning direction.
Further, by rotating the Z-axis drive motor 22, the laser displacement meter 18 and the linear detection sensor 40 move in the Z-axis direction (height direction), and can deal with glass substrates having various thicknesses. .
[0019]
In this example, the laser displacement meter 18 is moved in the scanning direction by the X-axis drive motor 20, but the object to be measured (glass substrate 30) and the displacement detection means (laser displacement meter 18) move relatively. Scanning may be performed, and the laser displacement meter 18 may be fixed and the glass substrate 30 side may be moved.
An analog signal such as a voltage output from the laser displacement meter 18 or the line detection sensor 40 is converted into a digital numerical value by the A / D conversion board 26 and input to the computer 28. The computer 28 has a display 42 as a display device and a keyboard 44 as an input device. The computer 28 controls the driving of the motors 20 and 22 and receives various signals input from the laser displacement meter 18 and the like. Processing, calculation, measurement result display, data recording, etc.
[0020]
Next, a description will be given of the principle of shape measurement by configured resistance measurement apparatus as described above.
The laser displacement meter 18 measures the displacement between the object to be measured and the displacement meter at a constant period, and outputs an analog signal such as a voltage corresponding to the amount of displacement. By scanning the laser displacement meter 18 or the measurement target at a constant speed, a detection signal (analog signal) such as a voltage corresponding to the surface shape of the object to be measured is output from the laser displacement meter 18.
[0021]
Since an analog signal such as a voltage cannot be directly calculated or stored as data in the computer 28, the analog signal is converted into a digital signal using the A / D conversion board 26. Then, the converted digital signal is input to the computer 28, where it is processed and stored as data. As described above, the waveform of the signal obtained by scanning the measurement object and via the A / D conversion board 26 indicates the cross-sectional shape of the measurement object.
[0022]
FIG. 2 shows an example of a digital signal waveform obtained by scanning a conductor paste wire 32 (corresponding to a film). FIG. 3 shows a known contact surface shape of the same measurement object for comparison. The measurement result measured using the measuring device is shown. As shown in both figures, this apparatus can measure the film shape in the same manner as the contact-type apparatus while being non-contact-type.
[0023]
Furthermore, from the cross-sectional shape data of the film obtained through the above-described steps, the cross-sectional area of the film, the film thickness, and the resistance value developed after firing can be calculated by the computer 28.
That is, from the scanning speed v (mm / s) and the A / D conversion sampling frequency ν (Hz), the width w (mm) (see FIG. 3) between the digital signals of the film cross-sectional shape is expressed by the following equation (1). Calculated.
[0024]
[Expression 1]
w = v / ν (1)
If the digital signal value of each displacement difference is Xi (i = 1, 2,..., N), the cross-sectional area S of the film can be approximated by the following equation (2) (trapezoidal approximation).
[0025]
[Expression 2]
S = 1/2 * (X1 + Xn) * w + (X2 + ... + Xn-1) * w-1 / 2 * (X1 + Xn) * (n-1) * w (2)
Next, the principle of measuring the resistance value will be described.
The apparatus according to the present embodiment can measure the film shape either before or after the conductor paste wire 32 is baked. For the resistance measurement, the conductor paste wire 32 is used as a glass substrate. The film shape is obtained before baking to 30, and the expression resistance value after baking is predicted.
[0026]
Before explaining the principle of resistance measurement in this apparatus, the relationship between the shape of the conductor paste wire and the resistance value of the resistance wire appearing after firing will be briefly explained.
When the pattern of the conductor paste printed on the glass substrate 30 is a uniform line having a length L, the following equation (3) is established between the printed cross-sectional area S and the resistance value R after firing according to Ohm's law. The relationship is established.
[0027]
[Equation 3]
R = ρL / S (3)
However, ρ is a specific resistance value (or resistivity) of a substance.
Even if the specific resistance of the conductor paste (silver paste) is unknown, the product of R and S can be obtained by measuring the cross-sectional area S of the filament after printing the conductor paste and the appearance resistance value R after firing for at least one sample. Which is equal to the product of the resistivity ρ and the length L. Therefore, even if both ρ and L are unknown, by using the above formula (3) based on the product value of ρ and L, the conductor paste film cross-sectional area on each substrate is subsequently measured. The pattern resistance value after firing on each substrate can be predicted.
[0028]
It is also possible to calculate the value of ρ × L by checking the specific resistance ρ of the conductor paste in advance and measuring the length L of the filament.
Actually, a pattern in which a plurality of strands are connected in parallel is formed on an anti-fogging glass for automobiles. When measuring a pattern in which t strips (elements) are connected in parallel, the sum ΣSt of the cross-sectional areas S1, S2,... St for each conductor paste line before baking calculated based on the pattern scanning (Integrated cross-sectional area) is calculated, and the product R × ΣSt of this ΣSt and the parallel resistance value R of the filaments developed after firing is calculated. If R × ΣSt is obtained at least once in the initial stage of production of an anti-fog glass for automobiles, the resistance value R ′ after firing of the glass from the integrated sectional area ΣS′t before baking of a glass substrate being produced is It can be predicted by (4).
[0029]
[Expression 4]
R ′ = (R × ΣSt) / ΣS′t (4)
That is, before firing the pattern of the conductor paste printed on the glass substrate 30, at least one scan of each conductor paste line 32 is detected by the above-described apparatus, and the sectional shape of each conductor paste line 32 is detected, and the sectional area is calculated. calculate. And the integrated cross-sectional area of a pattern is calculated | required and the resistance value which appears after baking is estimated using said Formula (4).
[0030]
In the case where the width of one strand is not uniform, a portion having a uniform width in the strand may be represented at one place, and the cross-sectional area variation of that portion may be measured. In addition, when the wire width can be considered to be uniform, only the film thickness of the conductor paste wire may be simply measured to predict the developed resistance after firing.
The measurement results (cross-sectional shape, cross-sectional area, and resistance value) obtained by the above-described measurement can be output via the display 42 or the like.
[0031]
4 and 5, the film thickness of the conductive paste (film) on the glass substrate 30 is actually measured using the apparatus of FIG. 1, the film cross-sectional shape is calculated, and the resistance value after firing is predicted. The graph of the measured data and the resistance value (actual measurement) actually fired are shown.
FIG. 4 shows a measurement result of screen printing of a low resistance silver paste having a specific resistance of about 3.0 μΩ · cm on a glass substrate 30 using a # 250 mesh Tetron screen (emulsion thickness 10 μm). Was measured by printing a high-resistance silver paste having a specific resistance value of about 8.0 μΩ · cm under the same conditions.
[0032]
As shown in these figures, according to this apparatus, the post-baking resistance value can be accurately predicted with a measurement error of 2% or less.
[0033]
【The invention's effect】
According to the resistance measuring method及BiSo location according to the present invention, between the obtained film and the non-contact type displacement detecting means obtained by scanning the surface of the film formed on the substrate in a non-contact type displacement detecting means Since the film shape is obtained by calculating the displacement amount and the relative movement amount of the non-contact displacement detecting means by such scanning, the shape of the target film can be measured nondestructively. Can do. Further, the cross-sectional area of the film can be calculated by further performing a calculation process based on the data of the film shape obtained by the method for measuring the film shape.
[0034]
In particular, if a laser displacement meter is employed as the non-contact type displacement detection means, it is possible to measure with higher accuracy.
In addition, according to the present invention, before the conductor paste printed on the substrate is heated and baked, the cross-sectional shape is measured to calculate the cross-sectional area, and is expressed after the heating and baking process based on the cross-sectional area. Since the resistance value of the resistance filament is predicted, the resistance value can be measured easily and accurately after printing the conductor paste and before baking. As a result, even when the measurement result is not within a predetermined allowable range, it is possible to correct the conductor paste printed on the product, and the yield rate of manufacturing can be remarkably improved.
[0035]
Furthermore, since the print film thickness can be controlled, it is extremely useful for quality control.
[Brief description of the drawings]
Diagram of Figure 1 the present invention applied resistance measurement device Figure 2 is a waveform chart showing an example of a digital signal waveform obtained by scanning the conductive paste line [3] Conventional contact surface Waveform diagram showing an example of the shape of a conductor paste wire measured using a shape measuring device. [FIG. 4] Predicted value of resistance value after firing and actual fired resistance value when low-resistance silver paste is printed (actual measurement) [Fig. 5] A graph showing the relationship between the predicted resistance value after firing and the actually fired resistance value (actual measurement) when printing a high-resistance silver paste [Explanation of symbols]
10 ... Stage 16 ... Shaft (moving means)
18 ... Laser displacement meter (non-contact displacement detection means)
20 ... Motor (moving means)
28: Computer (arithmetic processing means)
30 ... Glass substrate 32 ... Conductor paste wire 34 ... Movable body (moving means)
36, 38 ... guide (moving means)

Claims (6)

A method for obtaining a resistance value of a resistance wire formed by heating and baking a conductive paste printed on a substrate,
After the conductor paste is printed on the substrate, before the heating and baking process, the surface of the conductor paste is scanned with a non-contact displacement detecting means,
A displacement amount between the conductor paste and the non-contact displacement detection means detected by the non-contact displacement detection means by the scanning, and a relative movement amount of the non-contact displacement detection means in the scanning direction with respect to the substrate, The first arithmetic processing is performed based on the above, the cross-sectional shape of the conductor paste is measured,
Based on the obtained cross-sectional area shape, the second arithmetic processing is performed, the cross-sectional area of the conductor paste is calculated,
A resistance measurement method characterized by calculating a resistance value of a resistance filament that appears after a heating and baking process by performing a third calculation process based on the obtained cross-sectional area. The third in the calculation process, based on the cross-sectional area of the plurality of conductive paste lines, according to claim 1, wherein the conductive paste lines, characterized in that the parallel resistance value when it is plural parallel connections is calculated Resistance measurement method. 2. The resistance measuring method according to claim 1 , wherein a laser displacement meter is used as the non-contact type displacement detecting means. 2. The resistance measuring method according to claim 1 , wherein the conductive paste printed on the substrate is a silver paste formed on a glass substrate by a screen printing method. In an apparatus for obtaining a resistance value of a resistance wire formed by heating and baking a conductive paste printed on a substrate,
Non-contact displacement detecting means for detecting the distance to the surface of the conductor paste before heating and baking treatment;
Moving means for moving the non-contact displacement detecting means relative to the substrate in the scanning direction;
A displacement amount between the conductor paste and the non-contact displacement detection means obtained by scanning the surface of the conductor paste with the non-contact displacement detection means by the moving means, and a non-contact displacement detection with respect to the substrate First arithmetic processing means for obtaining a cross-sectional shape of the conductor paste based on a relative movement amount of the means in the scanning direction;
A second arithmetic processing means for calculating a cross-sectional area of the conductor paste based on the cross-sectional shape obtained by the first arithmetic processing means;
A third arithmetic processing means for calculating a resistance value of the resistance wire appearing after the heating and baking process based on the cross-sectional area obtained by the second arithmetic processing means;
A resistance measuring device comprising: 6. The resistance measuring apparatus according to claim 5 , wherein a laser displacement meter is used as the non-contact type displacement detecting means.

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