JP3679594B2 - Crack inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting cracks generated in a laminate used for a solar cell module, a printed wiring board, and the like, and particularly to a method for inspecting minute cracks that cannot be detected unless observed at a high magnification.
[0002]
[Prior art]
Highly integrated printed wiring boards require fine circuit formation and require small through-hole processing. If the processing conditions for forming the through hole are poor, cracks may occur around the through hole. Since this crack impairs the reliability of the printed wiring board, it is necessary to confirm the presence or absence of the crack. Conventionally, the following crack observation method has been proposed.
[0003]
The method for observing cracks described in Japanese Patent Laid-Open No. 5-18910 is to irradiate the fluorescent material with ultraviolet rays, visible rays, X-rays, α rays, β rays, etc. after infiltrating the fluorescent agent into the cracks. This is a method of observing fluorescence obtained by exciting a fluorescent agent.
[0004]
Japanese Patent Application Laid-Open No. 6-11461 describes a method for inspecting cracks on the surface of a flat steel wire manufactured by wire drawing or rolling. The inspection method is a method in which oil is applied to the surface of a flat steel wire, and then a blueing process is performed at 250 ° C. to 450 ° C., and a crack is observed by a color change appearing on the surface of the flat steel wire.
[0005]
Furthermore, Japanese Patent Laid-Open No. 5-281149 proposes a crack detection device that can be accurately detected by automatic control. In this method, a light beam is scanned to detect a crack generated on the wafer, and a crack on the wafer is detected from a shift in the imaging position of the reflected light.
[0006]
In addition, a method for detecting a crack inside a material nondestructively by an ultrasonic microscope, a method for detecting a sound wave generated by crack formation by an acoustic mission, and the like have been reported.
[0007]
Conventionally, using the crack observation method and the detection method as described above, examination of processing conditions in which a crack does not occur and inspection for the presence or absence of a crack in a manufacturing process have been performed.
[0008]
[Problems to be solved by the invention]
The roof material integrated solar cell module has a structure in which a semiconductor substrate is sealed with a resin on a reinforcing material, and the reinforcing material is processed to have a roof material function. Accordingly, the semiconductor substrate is processed in the same manner when the roof material is processed, and cracks may occur in the processed portion of the semiconductor substrate depending on the conditions. If cracks occur in the semiconductor substrate, the reliability of the solar cell module may be impaired. Therefore, in the development of the solar cell module, processing conditions that do not cause cracks have been studied, but the conventional crack observation method and detection method as described above have the following problems.
[0009]
For example, in the method described in JP-A-5-18910, in order to infiltrate the fluorescent agent into the crack, the sample is immersed in a fluorescent solution, and (1) the pressure is reduced to remove the crack. It is stated that it is preferable to combine at least two of the following methods: 2) pressurization, 3) ultrasonic vibration, or 4) heating the sample and then immersing the sample in a fluorescent solution. That is, it is difficult to allow the fluorescent solution to penetrate into the crack, and the above-described operation is required, and the process is complicated.
[0010]
Further, in order to immerse in the fluorescent solution, the sample is limited to a certain size, and in the case of a large sample such as a solar cell module, it is necessary to cut out a small piece for inspection. However, there is a possibility that a new crack may be generated due to stress such as vibration, pressure, and strain at the time of cutting out the small piece, and there is a problem that the crack in the manufacturing process cannot be accurately grasped.
[0011]
Further, the method described in JP-A-6-11461 applies oil to cracks and treats them at a high temperature of 250 ° C. to 450 ° C. In some cases, cracks may occur, and in the case of a material having a low glass transition temperature, the material dissolves, so that the method cannot be used depending on the material.
[0012]
In addition, a detection method using reflection of a light beam, a detection method using an ultrasonic microscope, a detection method using acoustic emission, and the like cannot be easily used because the apparatus is large and special.
[0013]
An object of the present invention is to provide a crack detection method that solves the above problems. Specifically, there is no need for special equipment or high-temperature treatment, and it is a method that can detect cracks in a simple process, in particular, a method that can detect cracks accurately for large laminates such as solar cell modules. It is to provide.
[0014]
[Means for Solving the Problems]
First aspect of the present invention, a crack generated in the laminate, after processing actualized, a observation to torque rack inspection method,
The laminate has at least two different layers on the substrate;
In the above-described revealing treatment, a lower layer on the substrate side of the laminate is dissolved, but a solution not dissolved in the upper layer is infiltrated from the crack, the lower layer is dissolved to form a cavity, and the upper layer on the cavity is recessed. It is a process for revealing cracks by rolling.
The second aspect of the present invention is a crack inspection method for observing a crack generated in a laminate after the revealing treatment,
The laminate has at least two different layers on the substrate, and the upper layer is an amorphous silicon layer.
The third aspect of the present invention is a crack inspection method for observing a crack generated in a laminate after the revealing treatment,
The laminate has at least two different layers on the substrate, and the lower layer on the substrate side is a metal oxide layer.
[0015]
In the present invention, since the cracks are observed after being exposed, the fine cracks can be confirmed even at a low magnification, and even if it is necessary to cut out small pieces for performing detailed observation, the cutting work is performed. Therefore, it is possible to accurately grasp the crack generated in the manufacturing process.
[0016]
And with the actualized process in the present invention, lysates how using a dissolution treatment using the upper layer of the laminate does not dissolve, the solution which dissolves the lower layer is permeated from the crack, by dissolving the lower layer By forming the hollow portion, the crack is easily observed as a black belt larger than the actual size by a method in which the upper layer on the hollow portion is depressed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the above-described dissolution treatment is preferable as the revealing treatment. Hereinafter, the present invention will be described by taking as an example a process that becomes apparent by dissolution treatment.
[0018]
FIG. 1 is a diagram schematically showing a cross-section of the laminate after the cracks generated in the laminate are revealed by a dissolution treatment. In the figure, (a) is a top view and (b) is a cross-sectional view taken along the line AA ′. In the figure, 101 is a crack, 102 is a black belt, 103 is a substrate, 104 is a lower layer, 105 is an upper layer, and 106 is a cavity. In the present embodiment, the case where the crack 101 occurs in the upper layer 105 is shown, but the crack may extend into the lower layer 104.
[0019]
In this embodiment, the upper layer 105 is not dissolved, and a solution for dissolving the lower layer 104 is dropped on the surface of the laminate, that is, the upper layer 105, left for a predetermined time, washed with water, and dried. The dissolving solution penetrates into the crack 101 and dissolves the lower layer 104 around the crack 101. As a result, a cavity 106 is formed in the lower layer 104, the upper layer 105 is depressed, and a black belt 102 is formed around the crack 101. The black belt 102 enables the crack 101 to be observed at a low magnification.
[0020]
The crack 101 detected in the inspection method of the present invention is a crack, a defect, or the like of the material, and the size thereof is not particularly limited. However, the manifestation process according to the present invention for a crack with a width of several hundreds to several thousand squares. The effect is great.
[0021]
The laminate that is the subject of the inspection method of the present invention is not particularly limited, but a photovoltaic element that is a constituent member of a plurality of types of layers laminated on a substrate, for example, a printed board or a solar cell module. In the present invention, the present invention is preferably applied. These laminates usually have a plurality of functional layers such as electrode layers and semiconductor layers on a substrate.
[0022]
The substrate 103 of the laminate according to the present invention serves as a reinforcing material for the laminate, and various functional layers are formed on the substrate. In some cases, the substrate itself is conductive and acts as an electrode layer. Specifically, stainless steel, copper, iron, aluminum, polyimide, polyethylene terephthalate, or the like is used.
[0023]
In the present invention, the upper layer 105 of the stacked body is a layer in the stacked body where cracks to be detected by the present invention are present, and is often a semiconductor layer. The reason is that the reliability of the laminated body such as a printed circuit board or a photovoltaic element is mostly caused by cracks in the semiconductor layer, and the diode characteristics change, causing short circuit or migration. . Specifically, it is an amorphous silicon layer, a single crystal silicon layer, a thin-film polycrystalline silicon layer, etc., and these semiconductors are generally difficult to dissolve, and thus are most suitable for the dissolution process which is a preferred form of the revealing process of the present invention. is there.
[0024]
Further, the upper layer 105 according to the present invention may not be a surface layer. When another functional layer is present on the upper layer 105 in FIG. 1, the functional layer is peeled off or dissolved for use in the dissolution treatment. The upper layer 105 may be exposed by dissolving and removing with a liquid.
[0025]
The lower layer 104 according to the present invention is a layer that can be dissolved by a dissolution process. When the upper layer 105 is a semiconductor layer, the lower layer 104 is often an electrode layer, and is formed of, for example, a metal or a metal oxide. Is done. Metals and metal oxides are easier to dissolve than semiconductors, and the solution can be easily selected. Specifically, it is aluminum, zinc oxide, indium oxide, etc. In particular, since zinc oxide dissolves in both acid and alkali, it is suitable for revealing by the dissolution treatment according to the present invention.
[0026]
The solution used for the dissolution treatment according to the present invention dissolves the lower layer 104 and does not dissolve the upper layer 105. For the laminate in which the lower layer 104 is a metal or metal oxide and the upper layer 105 is a semiconductor as described above, an acidic aqueous solution such as dilute nitric acid is preferably used. Other examples include dilute hydrochloric acid and phenolic acid. Moreover, not only acidic aqueous solution but alkaline aqueous solution, an organic solvent, etc. are used. Specifically, for example, sodium hydroxide, dichloromethane or the like is used, but dilute nitric acid with less harmfulness is particularly preferable.
[0027]
According to the present invention, since the crack 101 is exposed, even if the cutting operation is performed after the revealing processing, the crack 101 can be easily distinguished from the crack generated in the cutting operation. Therefore, first, a manifestation process is performed, and only the presence or absence of the crack 101 is confirmed with a loupe or the like. Only when the crack has occurred, the region is cut out and closely observed with an electron microscope or the like, and the width and length of the crack. By measuring this, it is possible to accurately grasp the cracks generated in the manufacturing process.
[0028]
In the clarification process according to the present invention, since cracks are observed larger than actual, it can be detected at a low magnification of, for example, about 130 times, and the occurrence distribution of cracks can be observed with a wide field of view.
[0029]
【Example】
FIG. 2 is a perspective view of a roof material integrated solar cell module which is an inspection object in the embodiment of the present invention. In the module, an amorphous silicon semiconductor substrate is sealed with a laminate as a photovoltaic element on a galvanium steel plate which is a reinforcing plate 201. In the figure, 202 is a resin-sealed element. The semiconductor substrate is laminated in a flat state, and then formed into a form as shown in FIG. 2 by roller former processing and press processing. By this processing, the photovoltaic element 202 is subjected to tensile stress and compression stress, and cracks are likely to occur in a portion where the tensile force is large, for example, the peak portion 203. Therefore, it is necessary to observe the crack in order to investigate the generation of the crack.
[0030]
FIG. 3 is a schematic cross-sectional view of a small sample of a mountain portion cut out from the module of FIG. On the reinforcing plate 201, the photovoltaic element 304 is sealed with a resin 307. The photovoltaic element 304 is coated with acrylic silicon as the protective film 305 in order to prevent damage in the manufacturing process. Further, a fluorine film is laminated as the insulating layer 306 which also serves as the antifouling layer on the front surface side, a polyester terephthalate film is laminated as the insulating layer 303 on the back surface side, and ethylene vinyl acetate is laminated as the filling layers 302a to 302c for bonding them.
[0031]
A small sample is cut out from the module of FIG. 2 and is about 10 mm square. The cutting method is to cut a large size with a band saw and then cut to a predetermined size with a precision grindstone.
[0032]
FIG. 4 is a schematic cross-sectional view of the state where the surface of the small sample is peeled off and the surface of the photovoltaic element 304 is exposed, and shows details of the photovoltaic element 304 in an enlarged manner. In the photovoltaic element 304 of this embodiment, an aluminum layer as the light reflecting layer 403, a zinc oxide layer as the light diffusing layer 404, an amorphous silicon layer as the photovoltaic layer 405, and a transparent electrode layer 406 are formed on a stainless steel substrate 402. Indium oxide layers are sequentially formed, a plurality of cracks 407 are present, the depth extends to the light diffusion layer 404, and the width is about 100 mm.
[0033]
The insulating layer 306 and the filling layer 302c on the surface side were simply peeled off with radio pliers, and the protective film 305 was peeled off using a commercially available coating film peeling agent.
[0034]
FIG. 5 is a schematic cross-sectional view after the small sample of FIG. 4 is subjected to the dissolution treatment according to the present invention to reveal the crack 407. In this example, 3% nitric acid was used as a solution, and the solution was dropped onto the small piece sample and allowed to stand for 3 minutes, followed by washing. By the treatment, the transparent electrode layer 406 was dissolved and removed, and the solution was infiltrated from the crack 407, and the light diffusion layer 404 and the light reflection layer 403 as lower layers were dissolved. As a result, a cavity 501 was formed around each crack 407, the photovoltaic layer 405 was depressed, and a black belt 502 was generated around the crack 407 on the surface of the photovoltaic layer 405.
[0035]
When the presence or absence of cracks in the sample and the distribution of the occurrence were observed with an electron microscope, it could be determined even at 130 times.
[0036]
In this example, in order to confirm the effect of the revealing process according to the present invention, the small piece sample was cut out and then the revealing process was performed. As described above, the manifestation process was performed before cutting out the small piece sample. By performing the treatment, it is possible to distinguish a crack that has not been revealed as a crack generated at the time of cutting out the sample.
[0037]
【The invention's effect】
According to the present invention, since fine cracks can be observed even at a low magnification, it can be observed with an electron microscope, an optical microscope, a loupe, etc. Can do. Moreover, since observation is possible at a low magnification, the observation visual field is wide and the crack generation distribution can be observed simultaneously. Furthermore, even when performing detailed observations such as the width, length, and shape of cracks, the presence or absence of cracks should be detected in advance with a magnifying glass, etc., and then the cracks detected anew can be observed with an electron microscope or the like. It can be performed.
[0038]
By carrying out the revealing treatment of the present invention by dissolution treatment, it can be preferably applied to a laminate having no heat resistance. Moreover, since the said process can be performed before cutting out a small piece, it can distinguish from the crack which generate | occur | produces in a cutting process, and can grasp | ascertain the crack which generate | occur | produced in the manufacturing process correctly.
[Brief description of the drawings]
FIG. 1 is an enlarged schematic view of a crack peripheral portion of a laminated body after a materializing process according to an embodiment of the present invention is performed.
FIG. 2 is a perspective view of a roofing material integrated solar cell module that is a crack detection target in an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of a small piece sample cut out from the module of FIG. 2;
4 is an enlarged schematic cross-sectional view of a photovoltaic element portion after the surface of the small sample shown in FIG. 3 is peeled off.
FIG. 5 is a schematic cross-sectional view showing a state after subjecting the small sample of FIG. 4 to the revealing process according to the present invention.
[Explanation of symbols]
101 Crack 102 Black belt 103 Substrate 104 Lower layer 105 Upper layer 106 Cavity 201 Reinforcement material 202 Photovoltaic element 203 Mountains 302a to 302c Filling layers 303 and 306 Insulating layer 304 Photovoltaic element 305 Protective film 307 Resin 402 Substrate 403 Light reflection Layer 404 Light diffusion layer 405 Photovoltaic layer 406 Transparent electrode layer 406 Transparent electrode layer 407 Crack 501 Cavity 502 Black belt

Claims (9)

A crack inspection method for observing a crack generated in a laminated body after revealing it,
The laminate has at least two different layers on the substrate;
In the above-described revealing treatment, a lower layer on the substrate side of the laminate is dissolved, but a solution not dissolved in the upper layer is infiltrated from the crack, the lower layer is dissolved to form a cavity, and the upper layer on the cavity is recessed. A method for inspecting cracks, characterized in that it is a process for revealing cracks when exposed . The crack inspection method according to claim 1 , wherein the lower layer is a metal oxide layer. Crack inspection method according to claim 1 or 2 said solution is an acidic aqueous solution. A crack inspection method for observing a crack generated in a laminated body after revealing it,
A crack inspection method, wherein the laminate has at least two different layers on a substrate, and the upper layer is an amorphous silicon layer. A crack inspection method for observing a crack generated in a laminated body after revealing it,
A crack inspection method, wherein the laminate has at least two different layers on a substrate, and the lower layer on the substrate side is a metal oxide layer. The crack inspection method according to claim 2 , wherein the metal oxide layer is a zinc oxide layer. Crack inspection method according to any one of claims 1～3,5,6 layer of the laminate is a semiconductor layer. The crack inspection method according to claim 7 , wherein the semiconductor layer is an amorphous silicon layer.   The crack inspection method according to any one of claims 1 to 8, wherein after the revealing process, a desired region is cut into small pieces and observed.

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