Flux application state inspection device and flux application state inspection method

A flux application state inspection method for inspecting a transparent or translucent flux applied to an electrode of a circuit board, the flux application state inspection method comprising:

• a first irradiation process of irradiating the circuit board with first irradiation light that is ultraviolet light or visible light at a first incident angle that is not less than 0 degree and not greater than 30 degrees, wherein
• the ultraviolet light has a wavelength of not lower than 320 nm and not higher than 400 nm, and
• the visible light has a complementary color of a color of a base material portion of the circuit board;
• a second irradiation process of irradiating the circuit board with second irradiation light that is visible light having red color or green color, at second incident angle that is a larger than the first incident angle;
• a first imaging process of taking, with an imaging device disposed above the circuit board such that an optical axis of the imaging device is orthogonal to the circuit board, a first image of light radiated to the circuit board in the first irradiation process and reflected from the circuit board;
• a second imaging process of taking, with the imaging device, a second image of light radiated to the circuit board in the second irradiation process and reflected from the circuit board;
• a first specification process of specifying, based on the first image, an electrode area that indicates an existing area of the electrode in the circuit board;
• a second specification process of specifying, based on the second image, at least one of a flux application area and an electrode exposure area, wherein
• the flux application area is located in the electrode area, and the flux is applied to the flux application area, and
• the electrode exposure area is located in the electrode area, and the electrode is exposed on the electrode exposure area;
• and
• a detection process of detecting whether an application state of the flux to the electrode is defective or non-defective, based on at least one of the flux application area and the electrode exposure area that have been specified.