JPH02262071A - Conduction inspecting method - Google Patents

Abstract

PURPOSE:To make it possible to inspect the state of conduction by forming an electrochromic layer on a surface, and recognizing the coloring degrees of the surface of a material before and after electrochemical reaction occurs in the electrochromic layer. CONSTITUTION:The solution of an electrochromic (EC) material wherein poly- substituted acetylene and the like are uniformly dispersed and dissolved is attached on the surface of a material 1 to be inspected. A voltage is applied between a conducting part 1a of the material 1 and a counter electrode 3 and a symmetric electrode 5 which are immersed in electrolyte solution 2 with a potentiostat 4 and the like. Thus, the conducting part 1a on the surface of the material which undergoes electrochemical action is discolored. An insulating part 1b other than the conducting part 1a is under the non-discolored state. The difference in colors can be recognized with the naked eyes. The minute parts can be recognized by the observation through a microscope. Therefore, the conducting state can be inspected based on the degrees of discoloration.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for testing the surface of a material having at least a conductive portion, such as inspecting a defective portion of a conductive material or testing the conductivity of an electric circuit.

(Prior art) For continuity testing of circuit boards, etc., Japanese Patent Application Laid-Open No. 62-524
As shown in Japanese Patent No. 73, a method is adopted in which a large number of metal terminals are brought into direct contact with grid points of a circuit pattern formed on a circuit board, and the electrical resistance between the contact points is measured.

(Problems to be Solved by the Invention) Automatic devices using conventional continuity testing methods are commercially available, but because the form of the material to be tested, such as the size of the circuit board and the structure of the circuit barrel, is specified, There is a drawback that it is difficult to conduct continuity tests on circuit patterns having different shapes.

Furthermore, in the above method, since the metal terminal is brought into direct contact with the surface of the material to be inspected, there is a risk that defects such as scratches may be generated on the surface of the material to be inspected. Furthermore, since there is a limit to the measurement interval depending on the thickness of the metal terminal, there is a drawback in that even the highest performance equipment can only perform continuity tests at intervals of about 0.1 mm.

The present invention is intended to solve the above-mentioned conventional drawbacks, and its purpose is not to be restricted by the surface form of the material to be inspected, and moreover, it can be used not only for flat materials but also for materials having arbitrary irregularities and curved surfaces. It is an object of the present invention to provide an electrical conductivity inspection method that can perform high-performance inspection of materials without causing surface defects.

(Means for Solving the Problems) The continuity testing method of the present invention includes the steps of forming an electrochromic (hereinafter abbreviated as EC) layer on the surface of a material having a conductive part, and forming a conductive part on the EC layer. and a step of causing the electrode to function as a working electrode, thereby achieving the above object.

Among the EC layers formed on the surface of the material to be inspected, the EC layer on the conductive part is electrochemically oxidized or reduced and changes color due to the conductive part functioning as a working electrode of the EC layer. On the other hand, the EC layer formed on parts other than the conductive part does not undergo discoloration because it is not subjected to electrochemical reaction by the working electrode. Therefore, by identifying the degree of discoloration of the material surface before and after the EC layer causes an electrochemical reaction,
The conductivity state on the material surface can be inspected.

In the continuity testing method of the present invention, first, EC is applied to the surface of the material to be tested.
EC materials are laminated to form layers.

Examples of the EC material include reduced metal oxides such as tungsten oxide and vanadium oxide, dye compounds such as Prussian blue metal phthalocyanine, and conjugated compounds such as polythiophene and polyphenylacetylene.

The method of laminating the EC materials is not particularly limited, but the method differs depending on the EC material used. For example, in the case of an inorganic material such as tungsten oxide, physical methods such as vapor deposition or sputtering can be used. In addition, sol-gel method, LB model method, etc. can be used as needed. More conveniently, an IEC material that can be dissolved or uniformly dispersed in a liquid such as an organic solvent or water,
Preferably, it is applied as a solution to the surface of the material to be inspected by coating or dipping. Such EC materials include polysubstituted acetylenes, such as JP-A-63-9
Poly(0-trimethylsilylphenylacetylene) shown in Publication No. 2619, or (o-trifluoromethylphenylacetylene), poly(0-methylphenylacetylene), poly(butylphenylacetylene), poly(2,6-dimethyl 4 -t-butylphenylacetylene). Also, overseas polymer research, 32
．． 24. (1986), the structure is not particularly limited as long as it is a soluble material such as poly(N-vinylcarbazole).

As for the method of laminating the EC material, the method described above is one example, and other known lamination methods may be used as long as the method allows the EC material to be laminated relatively uniformly on the surface of the material to be inspected.

It is easier to inspect the shape of the material to be inspected if it is smooth and flat; however, the inspection method of the present invention does not limit the shape (the material can be of any shape as long as it has at least a conductive part). Can be applied to surfaces.

Once the EC layer is formed on the surface of the material to be inspected, the conductive portion is then made to function as a working electrode for the EC layer.

EC materials originally have the property that their light absorption characteristics change when they are electrically or electrochemically oxidized or reduced.

In the inspection method of the present invention, a conductive portion on the surface of the material to be inspected is used as a working electrode. That is, by supplying current to the conductive part, electrochemical oxidation or reduction occurs in the EC layer stacked on the conductive part, thereby reducing the E on the conductive part.
The conductive part and the insulating part are distinguished by changing the light absorption property of the C layer and comparing it with the light absorption property of the non-discolored part of the EC layer laminated on the non-working electrode, that is, the insulating part on the surface of the material to be inspected. That's what I do.

As an electrochemical operation method for the EC layer, an EC layer, an electrolyte layer, and a counter electrode are laminated in this order on the surface of the material to be tested so as to create an IEc cell, and the conductive part of the material to be tested and the counter electrode are stacked in this order. An example of a method is to cause oxidation or reduction in the EC layer covering the conductive portion of the material to be inspected by applying a voltage during the test. More simply, as shown in FIG. 1, the material to be inspected 1 is immersed in an electrolyte solution 2, and a potentiometer is placed between the conductive part 1a of the material to be inspected 1 and the counter electrode 3 immersed in the electrolyte solution 2. One example is a method in which oxidation or reduction occurs only in the EC layer laminated on the conductive part 1a by applying a voltage with the stud 4 or the like. The voltage application method is not particularly limited, but the reference electrode 5
It is preferable to use the three-electrode method using

Water or an organic solvent can be used as the solvent for the electrolyte solution, but when the conductive portion on the surface of the material to be inspected is made of a corrosive metal, an organic solvent is preferable. Specific examples of the organic solvent include acetonitrile, propylene carbonate, methanol, and nitromethane. If a soluble EC material is used, a solvent must be used that does not dissolve the EC material. In addition, metal chlorides, protonic acids, etc. can be used as electrolyte materials, but to avoid corrosion, LiCl0n, LiBF4, LiP
F,, Et4NBF4, Et, NPF6, n-Bu4N
Non-aqueous electrolytes such as BF4 and n-BuJPF6 are suitable.

Optical identification becomes easier if the surface of the material to be inspected after electrochemical manipulation of the EC layer is washed with a solvent that does not contain an electrolyte and dried.

The EC layer subjected to electrochemical manipulation changes color in the conductive parts on the surface of the material to be inspected, and remains uncolored in the insulating parts other than the conductive parts. This color difference can be discerned with the naked eye. Furthermore, finer parts can be identified by microscopic observation. When the surface of the material to be inspected has a large area and a complex pattern such as a circuit pattern, the inspection can be easily performed by processing it with a computer. That is, if a driving part is provided in which a light source and a photodetector are paired, and the surface of the material to be inspected is flat, X,
By determining the coordinates of the drive unit on the two axes of Y, or on the three axes of x, y, and z in the case of a curved surface, and inputting the optical characteristics at any point, it is possible to determine whether or not the color changes two-dimensionally or three-dimensionally. can be identified.

In this case, if the material to be inspected is highly translucent, the material is placed between a light source and a photodetector, and the absorbance of the light transmitted through the material is measured to distinguish between discolored and undiscolored areas. can be identified. In addition, even if the material to be inspected is transparent, if the material cannot be placed between the light source and the photodetector, such as a spherical material, or if the material to be inspected is opaque, By providing a light source and a photodetector on the side and measuring optical characteristics such as absorbance or reflectance of light reflected on the surface of the material, it becomes possible to distinguish between discolored areas and non-discolored areas.

As a light source, white light, monochromatic light, laser light, etc. can be used, and by focusing the light, it is also possible to identify finer patterns. According to such an identification method, identification on the order of several μm is possible, which is incomparable to the conventional method using metal terminal contact, and by using a special laser or the like, identification on the order of 1 μm or less is also possible.

The EC layer formed on the surface of the material to be tested can be used as a protective film or a coating film if necessary even after the continuity test. If it is necessary to remove the EC layer, it is preferable to use a soluble EC material. The EC layer can be easily removed using a solvent.

(Examples) Hereinafter, the present invention will be specifically illustrated by Examples, but the present invention is not limited to these Examples.

11 On a glass substrate (50mm x 50mm x 1 plate),
Indium tin oxide (hereinafter referred to as IT) is a transparent conductive material.
(abbreviated as O) was formed into a film by sputtering. Unnecessary parts of the ITO film are removed by etching to form a conductive part 1a (ITO film) and an insulating film lb (
A material to be inspected 1 in which a glass substrate) was exposed on the surface was prepared.

Next, the conductive part 1a and the insulating part 1 of this material 1 to be inspected are
A solution prepared by dissolving 0.1 g of poly(o-trimethylsilylphenylacetylene) synthesized by the method disclosed in JP-A No. 63-92619 in 6 ml of toluene was dropped onto the exposed surface of b. The dropped solution is evenly applied using a spin coater and dried to give a coating of 0.2 to 0.58
The EC layer was n-thick.

After attaching a terminal to the conductive part 1a of the material to be inspected 1 having an EC layer formed on its surface, the material to be inspected 1 is attached as shown in FIG.
was immersed in electrolyte solution 2. LiCl04 (0.1 mol/I!) was used as the electrolyte of electrolyte solution 2, and acetonitrile was used as the solvent. A reference electrode 5 (Ag/AgC1) is connected between the counter electrode 3 and the conductive part 1a of the material 1 to be inspected.
A voltage of +1■ was applied for several seconds. After applying the voltage, the material to be tested 1 was pulled up from the electrolyte solution 2, its surface was washed with acetonitrile, and it was dried at 80° C. for 5 minutes.

The EC layer on the insulating part lb remained reddish-purple and did not change color, but on the conductive part la the EC layer was oxidized and changed to colorless and transparent. FIG. 3 shows visible absorption spectra 6 and 7 of the conductive portion 1a and the insulating portion 1b after discoloration.

1 Material to be inspected 1 was prepared by forming interdigitated electrodes shown in FIG. 4 on an ITO glass substrate similar to that in Example 1 using a photoresist film. The line width and line spacing of the comb-shaped electrodes forming the conductive portion 1a on the surface of the material to be inspected 1 are each 50 μm.
It was set as m. An EC layer made of poly(0-trimethylsilylphenylacetylene) was formed on the surface of the material to be inspected 1 in the same manner as in Example 1, and the material was electrochemically oxidized and discolored. The surface after discoloration was photographed using a microscope. The line width ratio between the comb-shaped electrode part (conductive part 1a) and the glass substrate part (insulating part 1b) is 1.05, and the discolored part (colorless) and the undiscolored part (reddish-purple) measured from the micrograph are 1.05. ) line width ratio is 1.
It was 10.

(Effects of the Invention) The continuity testing method of the present invention can be used for continuity testing of circuit boards (including detection of short-circuited parts), defective part detection of conductive materials, and the like.

The continuity testing method of the present invention is not limited to testing the continuity of flat materials, but can test arbitrary shapes such as curved surfaces, and can be applied to materials of any size from small area materials to large area materials. Furthermore, since there is no metallic contact, there is no risk of damaging the material surface. Furthermore, since it is an optical measurement, it is possible to inspect minute parts on the order of 1 μm or less, making it an extremely useful method for inspecting circuit patterns and the like.

4. Figure 1 is a schematic diagram for explaining the electrochemical operation step in the continuity testing method of the present invention, and Figure 2 (a) is a plane view of the material to be tested used in the example of the present invention. Figure 2(b) is a cross-sectional view, Figure 3 is a visible absorption spectrum diagram of the material surface after the material to be inspected has undergone electrochemical manipulation, and Figure 4 (
4(a) is a plan view of another material to be inspected, and FIG. 4(b) is a sectional view thereof.

DESCRIPTION OF SYMBOLS 1... Material to be inspected, la... Conductive part, 1b... Insulating part, 2... Electrolyte solution, 3... Opposite scratch, 4... Potentiostat, 5... Reference Electrode, 6... Visible absorption spectrum of conductive part, 7... Visible absorption spectrum of insulating part.

that's all

Claims (1)

[Claims] 1. A continuity test that includes the steps of: forming an electrochromic layer on the surface of a material having a conductive part; and making the conductive part function as a working electrode for the electrochromic layer. Method.