JP5261763B2 - Inspection method of welded part by magnetic field measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device of a welded part capable of simply inspecting the welded part of a part, and an inspection method of the welded part. <P>SOLUTION: The inspection device (1) for inspecting the welding failure of the welded part is equipped with a sample stand (25) on which the part containing the welded part is placed, a power supply (30) for applying voltage to the part, a probe (35) for measuring a magnetic field, a drive device (40) for moving the probe (35), the magnetism measuring instrument (70) connected to the probe and a control arithmetic device (50) for controlling the measurement of the magnetic field by the magnetism measuring instrument and processing the data of the magnetic field measured by the magnetism measuring instrument. The probe is moved by the drive device to measure the magnetic field at each position on the part. The control arithmetic device processes the measuring data of the magnetic field on the part to output the processing result to an output device (62). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an apparatus for inspecting a welded part by magnetic field measurement, and more particularly to an apparatus for inspecting a defect such as a welded part on the back surface of a solar cell and a method thereof.

  As a method for evaluating the quality of a welded part such as an electric circuit, there is a hot electron that detects heat generated by current application. However, this method is easily affected by the heat capacity and heat conduction of the weld and is difficult to evaluate depending on the part. Moreover, it is difficult to evaluate the welding of the invisible part.

The evaluation of the welded part of the solar cell is performed visually at the manufacturing stage. The welds are on the front and back surfaces of the solar cell. After assembling the solar cell panel, the welded portion on the front surface can be seen, but the welded portion on the back surface cannot be seen. For this reason, after assembly, the current-carrying state is generally inspected as an inspection of the welded portion.
In general, a plurality of (usually, three or more) welding locations between solar cell electrodes and wiring in a solar cell panel are provided, and even if one location is poorly welded, current flows from the other welding locations and the solar The battery function is not affected. That is, it is redundant.
However, because the welding location is redundant, even if one welding location becomes poorly welded, current flows from the other welded parts. Difficult to detect.

However, high reliability is required for solar cell panels used in outer space. In order to improve the reliability of the solar cell panel, it is desired that non-destructive inspection is performed on individual welded portions not only on the surface of the solar cell but also on the welded portion on the back surface after manufacturing.
In addition to solar cells, non-destructive inspection of individual welded portions of electric circuits is desired.

  Patent Document 1 applies oblique illumination and epi-illumination to the surface of a solar cell, picks up an image with an industrial TV camera, stores image data in a memory, and applies images with oblique illumination and epi-illumination. An inspection apparatus for comparing and determining a defect is disclosed.

  Patent Document 2 discloses a photovoltaic device characteristic inspection apparatus that irradiates a photovoltaic device with light from a light source and measures the electromotive force with a measurement terminal bar.

  These are for inspecting defects on the surface of the solar cell and not for inspecting the welded portion of the solar cell.

JP-A-3-218045 JP-A-9-186212

An object of this invention is to provide the inspection apparatus and inspection method which test | inspect a welding part nondestructively.
In particular, an object of the present invention is to provide an inspection apparatus and an inspection method for non-destructively inspecting a welding defect between the front surface and the back surface of a solar cell after manufacturing in order to improve the reliability of the solar cell panel.
It is another object of the present invention to provide an inspection device and an inspection method that can detect a welding defect in each welded portion.

The present inventor has developed a method for measuring a magnetic field generated when a current is passed through a welded portion as a method for evaluating the welded portion.
When a current is passed through an electric circuit, a magnetic field is generated. Since the current flows through the welded portion in a concentrated manner, the magnetic field is greatly different compared to other portions.
If there is a weld failure, the current of the welded portion with the poor weld is different from that of the normal welded portion, and therefore the magnetic field is also different from that of the normal welded portion.
By measuring the magnetic field of the welded portion, the quality of the welded portion including the invisible portion such as the back surface can be evaluated.

1 aspect of this invention is an apparatus which test | inspects the welding defect of a welding part,
A sample stage on which a part including a weld is placed;
A power source for applying a current to the component;
A probe for detecting a magnetic field generated from the component;
A drive for moving the probe;
A magnetometer connected to the probe and measuring magnetism detected by the probe;
A control arithmetic unit that controls movement of the probe and processes magnetic field data measured by the magnetometer;
And an output device that displays data processed by the control arithmetic device.
Thereby, the defect of a welding part can be determined easily.

The component may be a solar cell.
Thereby, not only when the welding part of a solar cell is visible from the surface but also when it is not visible, the welding part of a solar cell can be determined easily.
In addition, there are multiple welded parts, and even if one welded part is poorly welded, even if the welded part is redundant so that current flows from other welded parts, defects in individual welded parts of the solar cell can be simplified. Can be determined.

The driving device moves the probe at a certain distance in the vertical and horizontal directions, measures magnetic field data of each part of the component,
It is preferable that the output device can display a magnetic field distribution from magnetic field data of each part of the component.
Thereby, the magnetic field data of a plurality of parts can be automatically measured, and the welding failure can be easily determined by the magnetic field distribution.

Preferably, the control arithmetic device includes a power on / off unit that turns on and off a current applied to the power source, and obtains magnetic field data by applying a current from a difference between when the power is on and when the power is off.
Thereby, only the magnetic field by flowing an electric current through components can be measured except the influence of an external magnetic field.
In addition, by energizing only during magnetic field measurement, it is possible to prevent the components from being heated by energization.

It is preferable that the control arithmetic device can determine the welding failure of the component by comparing the magnetic field of the welded portion with a predetermined value.
Thereby, the determination of poor welding can be performed automatically.

Another aspect of the present invention is a method of inspecting a solar cell weld,
Preparing a probe and a magnetometer for measuring the magnetic field generated from the solar cell,
Apply current to the solar cell,
The probe moves the probe vertically and horizontally at a certain distance, detects the magnetic field generated from the solar cell by the probe,
Measure the magnetic field detected by the probe with the magnetometer,
A control arithmetic unit controls movement of the probe by the driving device, processes magnetic field data measured by the magnetometer,
An output device displaying magnetic field data processed by the control arithmetic device;
It is a welding part inspection method of a solar cell provided with.

The driving device moves the probe at a certain distance in the vertical and horizontal directions, measures the magnetic field of each part of the component,
It is preferable that the output device displays a magnetic field distribution from magnetic field data of the magnetic field of each part of the component.

The distribution of the magnetic field on the solar cell is examined, and if at least one magnetic field data exceeds a reference value, it can be determined that there is a welding defect.
Thereby, a welding defect can be determined easily.

The drive device moves the probe to each weld and measures the magnetic field of each weld, and the control arithmetic device compares magnetic field data of a plurality of welds with a reference value, and at least one place of the If the magnetic field data of the weld exceeds the reference value, it can be determined that there is a welding failure.
Since only the welded portion can be measured and a welding failure can be determined, there are fewer measurement points.

Among the magnetic field data of the plurality of welds, it can be determined that a weld that exceeds the reference value is good, and a weld that does not exceed the reference value is poor weld.
If there are multiple welds and the welding is redundant so that current flows from other welds even if one weld is poorly welded, if there are poor welds, the current concentrates on the good weld To do. Therefore, the welded portion that does not exceed the reference value has less current concentration, and can be determined as a welding failure.

The control arithmetic device compares the magnetic field data of a plurality of welds of one solar cell, and if the difference between the maximum and minimum magnetic field data is greater than or equal to a reference value, it can be determined that there is a welding failure.
When the energization states of the plurality of welds are different, it is possible to easily detect defective welding.

According to the present invention, it is possible to easily inspect for defective welding of electrical components.
It is possible to easily inspect the surface of the solar cell and the poor welding of the part where the back surface is not visible.
Even if there is a plurality of welds and one weld is poorly welded or redundant so that current flows from other welds, it is possible to detect a weld failure at each weld location, The reliability of the location can be improved.

(First embodiment)
Embodiments of the present invention will be described below. FIG. 1 is a schematic perspective view of a solar cell welded portion inspection apparatus 1 according to a first embodiment of the present invention. The solar cell welded portion inspection apparatus 1 includes a sample stage 25 on which the solar cell panel 10 is placed, a power source 30 for applying a current to the solar cell panel 10, and a magnetic field generated in the solar cell panel 10. (Magnetic field measurement) A probe 35, a magnetic measuring device (Gauss meter) 70 for measuring a magnetic field detected by the probe, and a driving device 40 for moving the probe 35 are provided. In addition, a control arithmetic device 50, an input device 61, and an output device 62 are provided.

  The sample table 25 is formed with a recess in which the solar cell panel 10 is fitted. In FIG. 1, the solar cell panel 10 is shown to be composed of 3 × 5 15 solar cells 11, but the solar cell panel 10 may be composed of other numbers of solar cells 11. In this specification, the solar cell 11 refers to a single solar cell, and the solar cell panel 10 refers to a solar cell 11 that is electrically connected and bonded.

FIG. 2 is a perspective view of a probe 35 for detecting a magnetic field.
The probe 35 has an elongated extension 36 (length L, thickness T) having a rectangular cross section, and has a hall element 37 (length A, width W) at the tip of the extension 36. A magnetic field can be detected by the Hall element 37.
The probe 35 is connected to the magnetometer 70 by a cable 38, and the magnetic field detected by the probe 35 can be measured by the magnetometer 70.

  Returning to FIG. 1, the probe 35 is coupled to the drive device 40. The drive device 40 includes a first member 40a, a second member 40b, a third member 40c, and a fourth member 40d. In response to an instruction from the control arithmetic unit 50, the second member 40b can move on the first member 40a in the y direction in FIG. 1, and the third member 40c can move on the second member 40b in the x direction. The fourth member 40d can move in the z direction along the third member 40c. As a result, the driving device 40 can move the probe 35 in the xy plane parallel to the surface of the solar cell panel 10, and also moves the probe 35 in the z-axis direction, The distance of can be adjusted.

The driving device 40 measures the magnetic field while moving the probe 35 on the solar cell 11 at a constant height (for example, 5 mm) and at a constant interval (for example, 5 mm), and calculates the distribution (mapping) of the magnetic field in the XY plane. Can be measured.
Such a mapping can be created for each solar cell 11 constituting the solar cell panel 10. Alternatively, the mapping can be created for the entire solar cell panel 10 rather than for each solar cell 11 separately.
The control arithmetic device 50, the input device 61, and the output device 62 will be described later with reference to the block diagram of FIG.

(Solar cell)
Next, the connection of the electrodes of the solar cell 11 constituting the solar cell panel 10 for inspecting defects by the solar cell inspection device 1 of the present invention will be described. The solar cell 11 may be any type of solar cell such as GaAs or Si.
3A is a top view of the solar cell 11, and FIG. 3B is a bottom view.
Referring to FIG. 3A, the upper electrode 21 is formed in a stripe shape on the surface of the solar cell 11. Each upper electrode 21 is connected to a current collecting electrode 22. The collecting electrode 22 is connected to the surface electrodes 23a, b, c, and one end portions of the upper electrode wires 26a, b, c in FIG. 3A are welded to the surface electrodes 23a, b, c, respectively. A plurality of (three in this embodiment) surface electrodes 23a, b, c are provided for redundancy.
In FIG. 3 (A), the surface electrodes 23a, b, c are arranged in the outer shape of the solar cell 11, but the surface electrodes 23a, b, c are projected upward in FIG. 26a, b, c may be easily welded.

Referring to FIG. 3B, a p-side electrode 20 is formed on the entire back surface of the solar cell 11. In addition, a plurality of backside electrodes 24a, b, and c (three in this embodiment) are provided at one end, and the p-side electrode 20 is connected to the backside electrodes 24a, b, and c. The other end portions of the lower electrode wires 26a, b, c in FIG. 3B are welded to the back electrodes 24a, b, c, respectively. A plurality of (three in the present embodiment) back electrodes 24a, b, c are provided for redundancy.
In FIG. 3 (B), the back electrodes 24a, b, c are arranged in the outer shape of the solar cell 11, but the back electrodes 24a, b, c are projected downward in FIG. 26a, b, c may be easily welded.

  In the present embodiment, the front surface electrodes 23a, b, c and the back surface electrodes 24a, b, c are provided with three each and are redundant, so the front surface electrodes 23a, b, c or the back surface electrodes 24a, b , c and the electrode wires 26a, b, c are welded poorly, and even if no current flows, current flows through the other two electrode wires 26a, b, c.

  In FIGS. 3A and 3B, the front electrodes 23a, b, c and the back electrodes 24a, b, c are connected by electrode lines 26a, b, c, respectively. Instead of the electrode wires 26a, b, c, the electrode wires 26a to 26c are used as one metal foil, and the front electrodes 23a, b, c and the back electrodes 24a, b, c are connected by one metal foil. You may make it do. This makes it more redundant.

The solar cell panel 10 is usually composed of a plurality of solar cells 11. In one example, as shown in FIG. 4, five solar cells 11 are connected in series, and the five solar cells 11 are connected in parallel in three rows and arranged on the substrate 12. That is, the solar cell panel 10 is composed of 5 × 3 = 15 solar cells 11. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG.
As shown in FIG. 4, the surface electrodes 23a, b, c of the solar cell 11 at the upper end of the solar cell panel 10 are welded to one electrode bar 27a, and one end of the connection line 28 is soldered to the electrode bar 27a. And is connected to a power source 30 by a connection line 28. The back electrodes 24a, b, c of the solar cell 11 at the lower end of the solar cell panel 10 are welded to one electrode bar 27b, and the electrode bar 27b is connected to the power source 30 by a connection line 28.
The connection between the surface electrodes 23a, b, c and the power source 30 and the connection between the back electrodes 24a, b, c and the power source 30 are not limited to the structures shown in FIGS. The power source 30 may be connected to the front surface electrodes 23a, b, c and the back surface electrodes 24a, b, c.

  In the example shown in FIG. 4, five solar cells 11 in series are connected in parallel in three rows. The five solar cells 11 at the center can be turned upside down, and five solar cells 11 in series can be connected in series in three rows, and fifteen solar cells 11 can be connected in series.

(Block Diagram)
FIG. 6 is a schematic perspective view of the solar cell inspection device 1 according to the embodiment of the present invention, and shows a control arithmetic device 50, an input device 61, and an output device 62 in a block diagram. The sample stage 25, the power source 30, the probe 35, the driving device 40, and the magnetometer 70 have been described above with reference to FIG.
The control arithmetic device 50 includes a drive control unit 51 that controls the drive device 40 and a power source on / off unit 53 that controls on / off of the power source 30.

The drive control unit 51 controls the movement of the drive device 40. The drive device 40 can move the probe 35 in the xy plane parallel to the surface of the solar cell panel 10 according to an instruction from the drive control unit 51, and can move the probe 35 and the solar cell panel in the z-axis direction. The distance with 10 can be adjusted.
The magnetic field can be measured by moving the probe 35 on the surface of the solar cell panel 10 at regular intervals. Or the position of each welding part is memorize | stored previously, and a magnetic field can be measured only by the position of each welding part.
The power on / off unit 53 turns the power source 30 on and off. The power on / off unit 53 synchronizes with the magnetic field measurement by the probe 35 to measure the magnetic field with the power source 30 turned off, measure the magnetic field with the power source 30 turned on, and measure the magnetic field due to the current flowing from the difference between the two be able to.
As a result, a minute magnetic field caused by passing a current through the component can be measured without the influence of an external magnetic field.
In addition, heating the solar cell 11 due to energization can be prevented by energizing only during magnetic field measurement.

The control arithmetic device 50 includes a data processing unit 56 that processes the magnetic field data measured by the magnetometer 70, a data comparison unit 57, a defect determination unit 58, and a storage unit 59.
The data processing unit 56 performs necessary processing on the measured magnetic field data, and can process the distribution of the magnetic field data so that the distribution of the magnetic field data can be displayed using the magnetic field data measured at regular intervals in the x and y directions. The measured magnetic field data is stored in the storage unit 59. The stored magnetic field data can be displayed on the display of the output device 62. The display can be, for example, a two-dimensional or three-dimensional mapping image.
Or the magnetic field data of only the location which hits a welding part can also be measured.

The data comparison unit 57 can create the difference data of the magnetic field data of the solar cell 11 by taking the difference of the magnetic field data of the two solar cells.
The data comparison unit 57 can take the difference between the magnetic field data of the welded portion of the solar cell 11 to be inspected and the magnetic field data of the welded portion of the reference non-defective solar cell.
Further, it is possible to take the difference in the magnetic field data at the measurement points corresponding to the welded portions of the plurality of solar cells 11 arranged on the same panel. Further, it is possible to take the difference in the magnetic field data of the welded part before and after the predetermined reliability test of one solar cell 11.
Alternatively, it is possible to check whether there is a point indicating particularly abnormal magnetic field data from the mapping result of the entire surface of one solar cell 11.

By the control arithmetic device 50, the defect determination unit 58 can also determine the welding failure based on the magnetic field data of the solar cell 11. For example, when the magnetic field data at the measurement point corresponding to the welded portion is greater than or equal to a certain reference value (or less), it can be determined that there is a welding failure. The defect determination unit 58 outputs a determination result of good or bad.
The storage unit 59 stores measured magnetic field data, expressions for processing the magnetic field data, arithmetic expressions such as an expression for determining poor welding, and the like.

The input device 61 is a known input device such as a keyboard, and is used to input data such as the size and area of the panel and the position of the welded portion.
The output device 62 is a known display device such as a display, and can display the magnetic field data of the solar cell 11, the distribution (mapping) of the magnetic field data, the defect determination result, and the like. The output device 62 may include a printing device such as a printer, and in this case, the result can be printed out.

(flowchart)
FIG. 7 is a flowchart showing a solar cell panel inspection method using the solar cell inspection apparatus 1 according to the embodiment of the present invention. In the solar cell panel inspection method, the solar cell panel 10 is placed on the sample stage 25 in step S01.
In step S02, the height of the probe 35 is adjusted to a certain distance (for example, 5 mm) on the solar cell panel 10.
In step S03, the probe 35 is moved onto the solar cell 11, and the position at which the magnetic field on the solar cell 11 is measured (for example, at intervals of 5 mm in the X and Y directions) is stored in the storage unit 59. When measuring a plurality of solar cells 11, for each solar cell 11, the position at which the magnetic field is measured is stored.
If the position for measuring the magnetic field for each type of solar cell panel is stored in the storage unit 59 in advance, the position for measuring the magnetic field can be automatically set by inputting the type of the solar cell panel.

In step S04, in order to measure the magnetic field of the solar cell 11, the probe 35 is moved to the position above the solar cell 11 obtained in step S03. In step S05-1, the power source 30 is turned off by the power on / off device 52, and the magnetic field is measured while moving on the solar cell 11 by a certain distance. In step S05-2, the power source 30 is turned on by the power on / off device 52, a voltage is applied to the solar cell, and the magnetic field is measured while moving on the solar cell 11 by a certain distance. By taking the difference between when the power supply 30 is off and when it is on, the influence of the surrounding magnetic field can be eliminated. The order of measurement when the sensor is off and when the sensor is on may be preceded by the time when the sensor is on and after the sensor when it is off.
In step S06, the magnetic field data of each measured measurement point is processed and stored in the storage unit 59.

  When the position of the welded portion of the solar cell 11 is known, the magnetic field distribution only on the position corresponding to the welded portion may be measured instead of measuring the magnetic field distribution on the entire solar cell 11. . This reduces the number of measurement points and shortens the measurement time.

In step S07, it is determined whether or not the measurement of all the solar cells 11 placed on the sample stage 25 has been completed. If measurement of all the solar cells 11 has not been completed, the process returns to step S04 for measurement of the next solar cell, and the probe 35 is moved onto the next solar cell 11 to measure the magnetic field of the solar cell 11. Continue.
In the present embodiment, the magnetic field is measured for each solar cell 11, but the magnetic field distribution on all the solar cells 11 constituting the solar cell panel 10 is collected instead of measuring each one. May be measured.

  Furthermore, when implementing the reliability test of a solar cell, after implementing a predetermined reliability test, according to steps S04-S07 of the flowchart of FIG. 7, the solar cell panel is inspected again, and before and after the reliability test. Compare measured data. The reliability test includes a vibration test, an acoustic test, a thermal shock test, a thermal vacuum test, and the like. Before and after these reliability tests, the magnetic field of the solar cell 11 is measured, and if there is a difference in the magnetic field data before and after the reliability test, the reliability test results in a defect in the weld of the solar cell 11. I understand that.

The inspection of the solar cell panel is finished, and then the measured data is processed. In step S08, the magnetic field data can be compared.
When the control arithmetic device 50 performs the determination up to the defect, the magnetic field data is output to the defect determination unit 58. In step S09, the welding failure is determined based on the magnetic field data. The determination result can be displayed on the output device 62.

In steps S08 and S09, for example, the following comparison and determination can be performed.
(1) Check the distribution of the magnetic field in one solar cell, check if there is a point that shows abnormal magnetic data in particular, and if there is magnetic data above (or below) the reference value, determine that there is a welding defect To do.
(2) If the magnetic field data of the weld is above a certain reference value (or below), it is determined that there is a welding defect.
(3) The magnetic field data of a plurality of welds of the solar cell are compared, and if the difference is greater than or equal to a predetermined value, it is determined that there is a welding failure.

(4) The magnetic field data of the welded part of the solar cell to be tested is compared with the magnetic field data of the welded part of the reference solar cell. If the difference is equal to or greater than a predetermined value, it is determined that there is a welding defect.
(5) The magnetic field data of the welded part of the solar cell to be tested is compared with the magnetic field data of the welded part of the other solar cell in the same panel.
(6) Compare the magnetic field data of the welded part before and after the reliability test for the solar cell to be tested.

(Example)
The magnetic field data of the welded part of the solar cell was measured. The front electrodes 23a, b, and c are all welded, but among the three back electrodes 24a, b, and c, some solar cells are welded but the others are not welded. Compared. In the solar cell 10a, only one surface electrode is welded. In the solar cell 10b, only two surface electrodes are welded. In the solar cell 10c, all three surface electrodes are welded.

FIG. 8A is a top view of a solar cell 10a according to an embodiment of the present invention. In FIG. 8A, the n-side electrode 21 and the current collecting electrode 22 are not shown. In the solar cell 10a, the surface electrodes 23a, b, and c are all welded (indicated by ◯). Of the back electrodes 24a, b, c, only the back electrode 24c is welded (indicated by a circle), and the back electrodes 24a, b are not welded (indicated by a cross).
The solar cell 10a was placed on the sample stage 25 on the XY plane, and a voltage of 1A was applied by applying a voltage to the solar cell 10a. The probe 35 was set to 5 mm on the surface of the solar cell 10a, and the magnetic field on the solar cell 10a was measured at intervals of 5 mm in the X and Y directions.

FIG. 8B is a diagram representing the magnetic field data for each measurement point on the solar cell 10a in three dimensions. The unit of the magnetic field is micro Tessler (μT). The strength of the magnetic field is indicated by the position in the Z-axis direction for each measurement point in the X and Y planes, and the hatching interval is also changed.
FIG. 8C is a two-dimensional representation of the strength of the magnetic field in the X and Y planes of FIG. 8B with different hatching intervals. The portions indicated by reference numerals 23a, 23b, and 23c are welded portions on the surface, which have the same level of magnetic field, and it can be seen that the currents are concentrated to the same level.
A portion indicated by reference numeral 24c is a welded portion on the back surface. The part of 24c has a magnetic field about 30 μT lower than the other parts. Since there is only one 24c weld on the back, it can be seen that the magnetic field is particularly low compared to the other parts, and the current is concentrated.

FIG. 9A represents a solar cell 10b according to an embodiment of the present invention. In the solar cell 10b, the surface electrodes 23a, b, and c are all welded. Of the back electrodes 24a, b, c, the back electrodes 24a and 24c are welded, and the back electrode 24b is not welded.
FIG. 9B is a diagram representing the magnetic field data for each measurement point on the solar cell 10b in three dimensions, and FIG. 10C is a diagram representing in two dimensions. The portions indicated by reference numerals 23a, 23b, and 23c are welded portions on the surface, which have the same level of magnetic field, and it can be seen that the currents are concentrated to the same level.
It can be seen that the portions indicated by reference numerals 24a and 24c are the welded portions on the back surface, and the welded portions on the back surface have a lower magnetic field than the other portions. The portion of the back electrode 24b that is not welded has the same magnetic field as the surroundings.

FIG. 10A represents a solar cell 10c according to an embodiment of the present invention. In the solar cell 10c, the surface electrodes 23a, b, c are all welded. The back electrodes 24a, b, c are all welded.
FIG. 10B is a diagram representing the magnetic field data for each measurement point on the solar cell 10c in three dimensions, and FIG. 10C is a diagram representing in two dimensions. The portions indicated by reference numerals 23a, 23b, and 23c are welded portions on the surface, which have the same level of magnetic field, and it can be seen that the currents are concentrated to the same level.
It can be seen that the portions indicated by reference numerals 24a, 24b, and 24c are the welded portions on the back surface, and the magnetic field at the three welded portions on the back surface is lower than that of the other portions.

In FIG. 8, since the welding location on the back surface is only one location of 24c, the current is particularly concentrated at the welding location.
In FIG. 9, since there are two welding locations 24a and 24c on the back side, the current concentration at the welding location is less than that in FIG.
In FIG. 10, since there are three welding locations 24a, 24b, and 24c on the back surface, substantially the same current flows through the three locations, and the concentration of current at the welding location is less than that in FIG.

In this way, by measuring the magnetic field, it is possible to detect a portion where current is concentrated. At the welded location, the current concentrates and the magnetic field is significantly different from the surroundings. In areas that are not welded, the current does not concentrate, so the magnetic field does not decrease.
When there is a poorly welded portion, the current is concentrated at a welded portion that is not defectively welded, and the current at the welded portion is particularly different from the surroundings.

According to the present invention, it is possible to easily evaluate the welded portion of the electric circuit board.
In particular, regardless of whether or not the welded portion can be visually checked, it is possible to easily inspect the solar cell for poor welding. Therefore, the reliability of the solar cell can be improved.
It can be applied to other tests that can be evaluated by the distribution of the magnetic field.

1 is a schematic perspective view of a solar cell welded portion inspection apparatus according to a first embodiment of the present invention. The perspective view of the probe for detecting a magnetic field. (A) is a front view of a solar cell, (B) is a back view of the solar cell. The top view which shows the arrangement | sequence of a solar cell panel. FIG. 6 is a schematic sectional view taken along line 6-6 in FIG. The block diagram of a solar cell welding part inspection apparatus. The flowchart which shows the inspection method of the welding part of a solar cell. The schematic top view of the solar cell 10a with which one back surface electrode was welded. The figure which represented the magnetic field data for every measuring point on the solar cell of FIG. 8A in three dimensions. The figure which represented the magnetic field data for every measuring point on the solar cell of FIG. 8A in two dimensions. The schematic top view of the solar cell 10b with which the two back surface electrodes were welded. The figure which represented the magnetic field data for every measuring point on the solar cell of FIG. 9A in three dimensions. The figure which expressed the magnetic field data for every measuring point on the solar cell of Drawing 9A in two dimensions. The schematic top view of the solar cell 10c by which the three back surface electrodes were welded. The figure which represented the magnetic field data for every measuring point on the solar cell of FIG. 10A in three dimensions. The figure which expressed the magnetic field data for every measuring point on the solar cell of Drawing 10A in two dimensions.

Explanation of symbols

1 Solar cell weld inspection system
10 Solar panel
10a, b, c solar cell
11 Solar cell
12 Board
20 p-side electrode
21 n-side electrode
22 Current collecting electrode
23a, b, c Surface electrode
24a, b, c Back electrode
25 Sample stage
26a, b, c electrode wire
27a, b electrode bar
28 Connection line
30 Power supply
35 probes
36 Extension
37 Hall element
38 cable
40 Drive unit
50 Control arithmetic unit
51 Drive controller
53 Power ON / OFF section
56 Data processing section
57 Data comparison part
58 Defect judgment section
59 Memory
61 Input device
62 Output device

Claims (5)

A method for inspecting a solar cell weld having a plurality of welds,
Preparing a probe and a magnetometer for measuring the magnetic field generated from the solar cell,
Applying current to the solar cell;
The probe moves the probe vertically and horizontally at a certain distance, detects the magnetic field generated from the solar cell by the probe,
Measure the magnetic field detected by the probe with the magnetometer,
A control arithmetic unit controls movement of the probe by the driving device, processes magnetic field data measured by the magnetometer,
The output device displays the distribution of the magnetic field from the magnetic field data of the magnetic field of each part of the solar cell processed by the control arithmetic device,
We can detect the welding failure of each weld,
A welded part inspection method in which current is concentrated and a welded part that exceeds the reference value is good, and a welded part that does not exceed the reference value is determined to be poorly welded. A method for inspecting a solar cell weld having a plurality of welds,
Preparing a probe and a magnetometer for measuring the magnetic field generated from the solar cell,
Applying current to the solar cell;
The probe is moved to each weld by a driving device, the magnetic field generated from the solar cell is detected by the probe,
Measure the magnetic field detected by the probe with the magnetometer,
A control arithmetic unit controls movement of the probe by the driving device, processes magnetic field data measured by the magnetometer,
The output device displays the distribution of the magnetic field from the magnetic field data of each weld of the solar cell processed by the control arithmetic device,
We can detect the welding failure of each weld,
A stage where it is determined that a weld where the current is concentrated and the reference value is exceeded is good, and a weld that does not exceed the reference value is poor weld;
A method for inspecting a welded portion.   The control arithmetic device includes a power on / off unit that turns on and off a current applied to the power, and obtains magnetic field data by applying a current from a difference between when the power is on and when the power is off. The welding part inspection method as described in 2.   The control arithmetic device compares magnetic field data of a plurality of welds with a reference value, and determines that there is a welding defect when the magnetic field data of at least one of the welds exceeds the reference value. The welding part inspection method as described in 2.   The control arithmetic device compares magnetic field data of a plurality of welds of one solar cell, and determines that there is a welding defect when the difference between the maximum and minimum magnetic field data is greater than or equal to a reference value. The welded part inspection method according to 2.

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