PURPOSE: To enable inspection of a printer state of solder paste with high precision and in a short time by a method wherein a laser beam passed through a reference mask is applied onto a printed circuit board and the quantity of light reflected therefrom is detected.
CONSTITUTION: A laser beam scanning device 2 applies a laser beam for main scanning onto a printed circuit board 10 through a reference mask 3. Besides, the printed circuit board 10 and the reference mask 3 are moved synchronously by a board-mask moving device 1 and subjected to sub-scanning. As the result, the laser beam scans the whole surfaces of the printed circuit board 10 and the reference mask 3 sequentially. On the occasion, the light intensity of the beam applied onto the printed circuit board becomes high when the beam passes through the part of high transmittance of the reference mask 3, and it lowers when the beam passes through the part of low transmittance thereof. The laser beam is reflected on the board 10 and sensed by a light-sensing device 5. Subsequently, a change in the intensity of the light sensed by the light-sensing device 5 is detected in a determining means and thereby the quality of a printed state of solder paste 10a of the board, which is an object of inspection, can be determined.
KAKIMORI NOBUAKI
YAMAMOTO YUICHI
