JP2015105947A - Defect inspection machine, defect inspection apparatus, and defect inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a quick inspection of cracking, chipping, hair cracking or the like present in a solar battery cell in a noncontact state in which a lift-off distance is set to not less than 2 mm and not more than 30 mm for the solar battery cell including a conductive layer.SOLUTION: Provided is a method and an apparatus for inspecting a crack, a chip, a hair crack or the like present in a solar battery cell in a noncontact state in which a lift-off distance is not less than 2 mm, by extracting a signal component necessary for inspection by performing processing for forming an excitation coil and a sensor coil for applying a magnetic field to the solar battery cell on a conductive layer of a multilayer insulating substrate, and cancelling an excitation induction voltage and external noise mixed into the sensor coil by differential synthesis.

Description

  The present invention is a solar cell in which at least a semiconductor layer such as silicon and a conductor layer such as aluminum are laminated, and defects such as cracks, chips and hair cracks inherent in a solar cell module in which a large number of solar cells are arranged. The present invention relates to an apparatus and a method for simply inspecting defects at a high speed in a non-contact state.

Silicon type solar cells are known as a method of utilizing solar energy. In order to make such photovoltaic power generation widely available on a commercial basis, it is necessary to reduce the power generation cost. There is also an urgent need to reduce the price of solar cells that make up the battery.
For example, in a solar cell element in which the semiconductor layer is made of polycrystalline silicon, further reduction in thickness is being attempted in order to reduce the material cost.

  However, since a semiconductor layer such as silicon is hard and brittle, the semiconductor layer is not cracked or chipped in the slicing process for thinning, the subsequent surface treatment process, the production process such as the electrode formation process, or the handling. Such defects may occur. When these defects occur in the production process, productivity is hindered, and when mixed into a product, there is a problem that power generation performance is lowered.

  Defects such as cracks and chips are often caused by the growth of fine hair cracks called hair cracks. Therefore, if it can be detected and removed at the stage of fine hair cracks, it is possible to minimize productivity degradation and decrease in power generation performance that occurs after the installation of the solar cell module, and to realize stable power generation in the long term.

  Conventionally, visual inspection during the production process has been performed as a simple detection method for cracks, hair cracks, etc., but there are large individual differences among inspectors, hair cracks and harmless scratches, or polycrystalline sun. In the case of a battery cell, there is a problem that it cannot be distinguished from a grain boundary pattern that is a boundary between crystals.

  The gazette disclosed in Patent Document 1 is arranged so as to be opposed to a solar cell element in which a semiconductor layer and a conductor layer are laminated, and to induce an eddy current by applying an alternating magnetic field to the solar cell element. A probe coil that detects eddy current and outputs it as an eddy current signal, a signal processing unit that separates the eddy current signal output from the probe coil into two signal components that are 90 ° out of phase with each other, and a signal processing unit. In addition, there has been proposed a method and an apparatus for detecting a hair crack in a solar cell element that includes a detection unit that detects a hair crack generated in the solar cell element based on a change in amplitude of any one of the signal components.

  The gazette disclosed in Patent Document 2 is a probe for eddy current flaw detection, characterized in that its coil is a printed coil, and an exciting coil and a detection coil are laminated, and a large number of printed coils are predetermined. There have been proposed eddy current flaw detection probes arranged in an array.

JP 2006-319303 A JP-A-9-33488

  However, in the method of Patent Document 1, since the probe coil for detecting eddy current and the excitation coil are the same probe coil, in the non-contact inspection, the excitation component that interferes with the probe coil is more necessary for defect detection. There is a disadvantage that it is several thousand times to several tens of thousands times larger than the eddy current signal, and it is extremely difficult to separate signal components necessary for the inspection. Therefore, in the inspection with a lift-off of 5 mm or more, the hair of the solar cell element Crack detection has not been realized. Further, since the apparatus is composed of only one probe coil, it is necessary to scan the subject over a wide range, and there is a problem that hair crack detection of solar cell elements cannot be performed at high speed.

  Patent Document 2 shows FIG. 10 in which printed coils 26 are arranged in a staggered manner in the vertical direction of the scanning direction for the purpose of eliminating the measurement blind spot in the scanning measurement. However, when the probe coils for detecting eddy currents are in a staggered arrangement, the distance between the print coil 26 and the excitation coil is different, so that the excitation induced voltage component becomes non-uniform, making it difficult to completely cancel the excitation induced voltage component, and the detection performance. There is a problem of lowering. This problem becomes a fatal defect particularly in an open magnetic path probe with a lift-off of several millimeters.

  The present invention has been made in view of the problem of lowering detection performance due to interference or non-uniformity of excitation induced voltage components due to adjacent excitation coils as described above. The excitation coil and the detection coil are formed on a laminated insulating substrate. However, as a feature thereof, an excitation coil is arranged on the outer periphery and two or more sensor coils are formed at equal distances from the excitation coil so that an excitation magnetic field from the excitation coil affects the sensor coil. Make the effect as equivalent as possible.

  Next, by taking the difference between the outputs of the two sensor coils, the external noise and the excitation induced voltage component are canceled out, and the eddy current information component necessary for detecting cracks, chips, hair cracks, etc. that have occurred in the solar cells. Effectively extract. The extracted eddy current information component is separated by the defect detection circuit as defect information, so that it is possible to detect cracks, chips, cracks, chips, hair cracks, etc. inherent in solar cells even when the lift-off is 6 mm or more. And

  According to the defect inspection machine according to claim 1, the exciting coil 2 for applying a magnetic field to the solar cell 30 in which the semiconductor layer and the conductor layer are laminated, and the sensor for detecting the eddy current induced in the solar cell 30. A sensor unit 5 formed integrally with a coil, and a defect detection circuit 6 for determining cracks, chips, hair cracks, etc. generated in the solar battery cell 30 based on eddy current information detected by the sensor coil 3. Based on the detected eddy current information, it is possible to detect defects such as cracks, chips and hair cracks inherent in the solar battery cell 30.

  According to the defect inspection machine of claim 2, when scanning and measuring the solar battery cell 30, the exciting coil 2 has a long-axis plane figure having a sufficiently long parallel portion, and the sensor coil 3 is It consists of a plurality of sensor coils arranged along the long axis inside the sensor coil, and the adjacent coil units have the same shape with the same area on both sides of the long axis and are mutually in relation to the long axis. By using a sensor coil structure formed of a figure that is not line-symmetric with respect to an orthogonal axis, inspection that eliminates the blind spot of measurement in scanning measurement is possible.

  According to the defect inspection machine of the third aspect, the sensor structure in which the exciting coil 2 and the sensor coil 3 are respectively formed on the number of conductor layers of the laminated insulating substrate and connected by the via-hole conductor 24 to increase the number of turns of the coil. As a result, even in the case of a multi-channel inspection apparatus in which a large number of sensor coil patterns of the sensor unit are added, the sensor coil 3 of the sensor unit 5 and the dimensional accuracy of 0.1 mm or less, which is the manufacturing accuracy of the laminated insulating substrate Since the excitation coil 2 can be formed, the excitation induction voltage from the excitation coil 2 can be canceled by taking the difference between adjacent sensor output signals, and only the eddy current signal necessary for inspection can be efficiently extracted and detected. It is possible to improve.

  Further, since the sensor unit 5 is a laminated insulating substrate sensor in which the sensor coil 3 and the excitation coil 2 are provided, the structure of the sensor unit 5 is simplified, and the sensor unit 5 is highly accurate, small, light, inexpensive, and short. It has an excellent effect that it can be produced in a large amount in time.

  According to the defect inspection machine of the fourth aspect of the present invention, the excitation coil 2 and the sensor coil 3 are not formed on the surface layer portion of the sensor portion 5 so that the sensor portion is prevented from being soiled.

  According to the defect inspection machine of claim 5, the sensor unit 60 is made of a flexible insulating substrate, for example, a polyimide insulating substrate, etc. in order to enable inspection of cracks, chips, cracks, etc. of the inspection target having a curved surface. The structure to be formed and attached to the surface of the inspection object 70 enables inspection of the inspection object having a curved surface.

  According to the defect inspection apparatus of the sixth aspect, the sensor unit assembly 7 arranged corresponding to the width of the solar cell module 100 and a plurality of defect detection processing units 10 corresponding to the number of the sensor units 5. Are sequentially processed by the sequential processing unit 11 to enable the defect inspection of the solar cell module 100 in the width direction inspection.

  According to the defect inspection method of claim 7, the solar cell to be inspected by the sensor unit 5 or the sensor unit assembly 7 using the defect inspection machine according to claim 1 or the defect inspection device of claim 6. A solar cell defect inspection method in which a distance of 2 mm or more and 30 mm or less from the surface of the module 100 is arranged in parallel, and the distance is relatively moved in a direction perpendicular to the long axis direction while maintaining the distance from the solar cell module 100. I will provide a. Further, the high-speed inspection of the solar cell module can be realized by relatively moving the position with respect to the solar cell module 100 while sequentially switching the outputs of the defect detection processing unit 10 by the sequential processing unit 11.

FIG. 1 is a diagram showing a basic configuration of defect detection according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of the structure of the sensor unit of the present apparatus. FIG. 3 is a diagram illustrating an example in which the sensor unit of the present apparatus is formed of a double-sided substrate. FIG. 4 is a view showing an example in which the sensor unit of the present apparatus is formed of a laminated insulating substrate. FIG. 5 is a diagram illustrating an example of a cross section of a laminated insulating substrate which is a sensor unit of the present apparatus. FIG. 6 is a diagram showing a configuration for detecting a solar cell module by this apparatus. FIG. 7 is a diagram in which the sensor unit of the present apparatus is formed on a flexible insulating substrate. FIG. 8 is a diagram illustrating the output of the sensor coil and the waveform of the difference signal. FIG. 9 is a diagram showing waveforms obtained by separating and extracting the output of the sensor coil and eddy current information. FIG. 10 is a diagram showing the printed coils 26 in a staggered arrangement.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 includes a defect detection circuit 6 and a defect detection processing unit 10 connected to the sensor unit 5, and an alternating magnetic field is applied to the solar cell 30 as an inspection object by the sensor unit 5 to induce the solar cell 30. The structural example which test | inspects the crack of the photovoltaic cell 30, a crack, a hair crack, etc. based on the eddy current signal information to show is shown.

  First, when a sine wave is applied from the excitation drive circuit 1 to the excitation coil 2, an alternating magnetic field from the excitation coil 2 toward the solar battery cell 30 is generated. An eddy current flows through the conductor layer of the solar battery cell 30 by the action of the alternating magnetic field. The eddy current flowing in the solar battery cell 30 is detected by the sensor coil 3-1 to the sensor coil 3-n. The output of the sensor coil is a voltage of a counter electromotive force corresponding to the eddy current induced in the solar battery cell 30. In addition, the excitation induction voltage directly induced from the excitation coil 2 and the superposed signal are synthesized with the external noise component.

  Therefore, as shown in FIG. 2, by taking the difference from the outputs of the sensor first coil 3-1 and the sensor second coil 3-2, the excitation induction voltage and the external noise component included in the superimposed signal are canceled and reduced. Thus, the eddy current information component VSg necessary for detecting cracks, chips, hair cracks and the like shown in FIG. 9 is effectively extracted. The extracted eddy current information component VSg is subjected to discrimination processing by the defect detection circuit 6. Here, the defect detection circuit 6 receives the difference between the outputs of the sensor first coil 3-1 and the sensor second coil 3-2, the outputs of the sensor third coil 3-3 and the sensor fourth coil 3-4. A signal useful for detecting cracks, chippings, hair cracks, etc., which are in opposite phases of both signals, may be extracted by taking the difference from the difference signal twice.

け、割れや欠け、ヘアクラック等を高速、簡便に高速検査することが可能となる。Further, the distance between the surface of the sensor unit 5 and the solar battery cell 30 is relatively moved while maintaining a constant distance.

It is possible to perform high-speed and simple high-speed inspection of cracks, chips, hair cracks, and the like.

  FIG. 2 shows a diagram in which the excitation coil 2 and the sensor coil 3 of the sensor unit 5 of the present invention are formed. By forming the structure from the sensor first coil 3-1 to the sensor n-th coil 3-n on the inner periphery of the exciting coil 2, the entire sensor section can be obtained with a dimensional accuracy of 50 μm or less, which is the manufacturing accuracy of the insulating substrate. Since components can be formed, it is easy to accurately cancel adjacent excitation induced voltages, and the detection sensitivity can be dramatically improved by effectively extracting eddy current signals necessary for inspection.

  FIG. 3 shows an example in which the sensor unit of the present apparatus is formed of a double-sided substrate. The exciting coil may be formed so as to surround a coil having a long-axis plane figure having a sufficiently long parallel portion or two or more sensor coils 3 as shown in FIG.

  FIG. 4 shows a diagram in which the sensor unit 5 according to the present invention is formed of a laminated insulating substrate. The sensor unit 5 using the laminated insulating substrate has various functions such as excitation magnetic field adjustment, excitation induction voltage equalization, increase in the number of turns of the sensor coil, detection dead angle elimination, sensor unit protection and contamination prevention, and counterfeit prevention functions. Each function of the sensor unit 5 will be described with reference to FIG.

  As an exciting magnetic field adjustment function, a weak current from the external connection electrode 22 is caused to flow through the exciting magnetic field adjusting coil 27 to generate a magnetic field in the opposite direction to the exciting magnetic field from the laminated insulating substrate a layer exciting coil 20 and the end of the laminated insulating substrate. The excitation induction voltages of the first sensor coil and the second sensor coil are equalized. This cancels out the excitation induced voltage unnecessary for defect inspection and increases inspection sensitivity. Further, an excitation shielding pattern 25 may be provided on the laminated insulating substrate so as to have a function of shielding the excitation induced voltage transmitted from the surface from the excitation coil to the sensor coil.

  As a function for equalizing the excitation induction voltage, the distance relationship between the excitation coil 2 and the adjacent sensor coil is formed at 50 μm or less with the aim of canceling the excitation induction voltage from 1,000 to 1 / 100,000 or less. FIG. 9 shows an image waveform in which the excitation induced voltage is canceled and the eddy current information component VSg necessary for defect inspection is emphasized. The exciting current applied to the exciting coil 2 is preferably an optimum value for the lift-off distance and the characteristics of the inspection object, and may be a sine wave of several hundred Hz to 200 MHz or a pulse wave including them.

  As a function for increasing the number of turns of the sensor coil, the sensor coil 3a is provided on the laminated insulating substrate a layer, the sensor coil 3b is provided on the laminated insulating substrate b layer, and the upper and lower coil patterns are connected in series by the via-hole conductor 24. The detection sensitivity can be increased by increasing the number of turns of the coil by the number of layers of the insulating substrate. Further, two or more sensor coils may be connected with opposite polarity on the laminated insulating substrate, and the sensor unit may have a function of canceling the excitation induced voltage and the external noise component.

  As the detection blind spot exclusion function, when the solar cell 30 is scanned and measured, the sensor unit 5 is provided with two or more sensor coils in a direction perpendicular to the scanning direction, and a line is formed with respect to the scanning direction in a method of taking a difference between the sensor coils. It is possible to detect cracks, hair cracks, etc. in all directions by eliminating the measurement blind spot in scanning measurement by using a sensor coil formed in a symmetrical figure, such as an oblique ellipse, an oblique ellipse, or a parallelogram or polygon. And As shown in FIG. 10, there is a method of eliminating the measurement blind spot by arranging the sensor coils in a staggered arrangement and taking the difference between the coils. However, in this case, the areas on both sides of the major axis are not substantially the same. Since there is a problem that the output signal greatly fluctuates due to a time difference until the sample reaches the two coils at the edge portion where the inspection sample approaches in the vertical direction, it is not suitable for high-sensitivity inspection.

  The sensor part protection and dirt prevention function function prevents the coil pattern structure from being seen from the outside while protecting the coil pattern of the sensor part by preventing the sensor coil coil and sensor coil from being formed on the surface layer part of the laminated insulating substrate. In order to prevent forgery.

  FIG. 5 is a view showing an example of a cross section in which the sensor unit of the present apparatus is a laminated insulating substrate, and is disposed on the conductor layer of the laminated insulating substrate by a via-hole conductor 24 that penetrates the insulating layer 28 from the external connection terminal 22. Connect upper and lower coil patterns or relay patterns.

  FIG. 6 shows a sensor unit 5 arranged corresponding to the width of the solar cell module 100 or the sensor unit assembly 7 arranged in parallel as a distance of 2 mm or more and 30 mm or less from the surface of the solar cell module 100 to be inspected. Output of each defect detection processing unit 10 by the sequential processing unit 11 showing a configuration example of defect inspection of a solar cell that is moved and inspected in a direction perpendicular to the long axis direction while maintaining a distance from the battery module 100. By moving the position relative to the solar cell module 100 while sequentially switching the two, it is possible to detect cracks, chips, hair cracks, and the like inherent in the solar cell module 100 in a single scan. Furthermore, the detection information may be displayed as a two-dimensional image or the like in conjunction with the relative position information between the solar cell module 100 and the sensor coil 3.

  FIG. 7 shows an example in which the sensor unit 60 is formed on a flexible polyimide insulating substrate as an application example of the present invention, and the inspection unit 70 having a curved surface is formed by attaching the sensor unit 60 to the inspection target 70. It enables defect inspection such as chipping and cracking.

  FIG. 8 is a diagram showing a waveform of a signal in which the excitation induced voltage is canceled by taking a difference from the outputs of the sensor first coil 3-1 and the sensor second coil 3-2 adjacent to each other in the sensor coil of the present invention.

  FIG. 9 shows the difference between the outputs of the sensor first coil 3-1, the sensor first coil, and the sensor second coil 3-2 adjacent to the sensor coil of the present invention, thereby canceling the excitation induced voltage and necessary for the inspection. It is a figure which shows the waveform which isolate | separated and extracted the eddy current information VSg.

  FIG. 10 is a diagram showing a film substrate in which the printed coils 26 of Patent Document 2 are arranged in a staggered arrangement.

  The present invention can be applied to a wide range of applications from manufacturing processes of solar cells and modules to shipping inspection, acceptance inspection before installation, and inspection at the maintenance site after installation.

  The present invention is not only used for high-speed inspection of solar cells, module cracks and chips, hair cracks, etc., but also for high-speed inspection of metal and transparent electrode thickness and electrical performance irregularities and defects, and mixing into lithium ion battery separators, etc. This includes the possibility of a wide range of applications up to high-speed inspection of metallic foreign matter.

DESCRIPTION OF SYMBOLS 1 Excitation drive circuit 2 Excitation coil 3 Sensor coil 3-1 Sensor 1st coil 3-2 Sensor 2nd coil 3-3 Sensor 3rd coil 3-4 Sensor 4th coil 3-n Sensor nth coil 4 Via-hole conductor connection pattern DESCRIPTION OF SYMBOLS 5 Sensor part 6 Defect detection circuit 7 Sensor part aggregate | assembly 10 Defect detection process part 10-n nth defect detection process part 11 Sequential process part 20 a layer excitation coil 22 External connection terminal 24 Via-hole conductor 25 Excitation shield pattern 27 Excitation magnetic field adjustment Coil 28 Insulator layer 3a-1 a layer first sensor coil 3a-2 a layer second sensor coil 3a-3 a layer second sensor coil 3a-na a layer n sensor coil 3b-1 b layer first sensor coil 3b-2 b layer second sensor coil 3b-3 b layer third sensor coil 3b-n b layer n sensor coil 3c c layer sensor coil 50 Battery cell 60 Sensor section 70 formed on flexible insulating substrate 100 Inspected object 100 with curved surface Solar cell module V1 Output waveform V2 of sensor first coil Output waveform V3 of sensor second coil V1 and V2 Difference output waveform image VSg Defect information waveform image 21 Film substrate 26 Staggered printed coil

Claims (7)

  An exciting coil disposed opposite to the solar battery cell to act on an exciting magnetic field, and an eddy current defect information detecting sensor coil disposed at a position surrounded by the exciting coil in the same plane as the exciting coil are formed on a laminated insulating substrate. A sensor unit formed on a conductor layer; and a defect detection processing unit that inspects defects of the solar battery cell based on eddy current defect information detected by the sensor coil, and includes an excitation magnetic field applied by the excitation coil. The defect inspection machine which inspects defects, such as a crack of a solar cell, a crack, and a hair crack, by the defect detection processing part based on eddy current defect information obtained by this.   The excitation coil has a long-axis plane figure having a sufficiently long parallel portion, and the sensor coil is composed of a plurality of sensor coils arranged along the long axis inside the sensor coil; 2. The adjacent sensor coil has a sensor coil formed of a figure that has substantially the same shape on both sides of the major axis and is not line-symmetric with respect to an axis orthogonal to the major axis. Defect inspection machine described in.   The said sensor part consists of an excitation coil and a sensor coil which were formed in a plurality of conductor layers of the above-mentioned laminated insulation board, and has a structure connected by a via hole conductor so that the number of turns of each sensor coil may be increased. The defect inspection machine according to claim 1.   The defect inspection machine according to claim 1, wherein a surface layer portion of the laminated insulating substrate is a layer that does not form the excitation coil and the sensor coil.   The defect inspection machine according to any one of claims 1 to 4, wherein the sensor portion is formed on a flexible insulating substrate in order to enable inspection of a crack, a chip, a crack or the like of an inspection target having a curved surface.   A plurality of sensor parts of the defect inspection machine according to claim 1, wherein a plurality of sensor parts are arranged corresponding to the width of the solar cell module, and a plurality of defect detection processes corresponding to the number of the sensor parts. And a sequential processing unit that collectively processes the plurality of defect detection processing units.   Using the defect inspection machine according to claim 1 or the defect inspection apparatus according to claim 6, the sensor unit assembly is arranged in parallel at a distance of 2 mm or more and 30 mm or less from the surface of the solar cell module to be inspected. A method for inspecting a defect of a solar cell, in which a distance from a battery module is maintained while moving relative to a direction perpendicular to the major axis direction and inspected.

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