System to inspect soldering on printed circuit boards

Citation

(1999), "System to inspect soldering on printed circuit boards", Sensor Review, Vol. 19 No. 1. https://doi.org/10.1108/sr.1999.08719aad.011

System to inspect soldering on printed circuit boards

System to inspect soldering on printed circuit boards

Keywords Electronics, Inspection, Laser

Mitsubishi Heavy Industries Ltd (MHI) has developed a system dubbed the Mitsubishi three-dimensional solder shape inspection machine, which checks soldering on printed circuit board and detects faulty soldering by using MHI's non-contact three-dimensional shape measuring system through the application of laser measuring technology. MHI has achieved ten times higher outstanding accuracy in judging faulty soldering, compared with conventional systems. The system also achieved a dramatic reduction in the time required for pre-operational arrangement to one-tenth that of normal. This system performance is the highest among those of its kind ever commercialized in Japan as well as the whole world.

By using the non-contact three-dimensional shape measuring system, that utilizes a thin laser light of 5 micron meter (µ) thickness, the system can identity the outline of the solder on the printed board. Together with a high-speed camera, the system pictures the solder outline visualized through laser reflection from the solder surface, then processes the picture at a speed of 0.016 second per frame and recognizes the shape of the solder.

The three-dimensional shape measuring system detects the shape of solder and the height of components on the board and makes quantitative evaluations based on measured data about the size and adhesion angle of the solder and component's height. By this method, accuracy in detecting soldering failure is heightened, at the same time greatly reducing misjudgement of proper soldering as defective.

In accordance with increasingly minimized electronic component size on the printed board, checking of soldering by human eyes has become very difficult. Although various automated systems to check soldering were on the market, accuracy in the measuring of solder shape was insufficient. Owing to their inadequate failure recognition rates, automated systems have not become popular.

As MHI's system applies laser light from multiple angles and uses multi-camera processing, it can recognize solder shapes more precisely. The application of laser light from a slanted angle can check soldering right at the base of J-shaped lead line. In addition, by checking the component's height and clearance between component and board, the system can judge proper soldering of ball grid array packages and chip scale packages, both of which have solder spots under components, which was impossible in conventional systems without X-ray.

By using its function to record pictures of printed circuit board and a PC to support checking, soldering checking programs can be input off-line. The system to repair failure soldering spot is also provided as a peripheral support system. As the off-line programming and easy setting of conditions for judgement greatly contribute to reducing the time for pre-operation arrangement, the system also benefits in the production of a limited quantity of varied product types.

MHI has tested the performance of the new system at the production line of highly integrated printed circuit boards, which are used for mobile phones among others, at Hiwada Electronic Co. Ltd, which belongs to the giant group of electronics manufacturers in Japan named Pioneer, and verified its outstanding accuracy in judging soldering condition, compared with conventional systems.

MHI will market the new system only in Japan for the time being, but plans to expand overseas after producing enough satisfactory achievements in Japan. In preparation for the advance to the USA and Taiwan market, MHI is looking for overseas dealers.

For further information contact Mitsubishi Heavy Industries Ltd, Public Relations and Advertising Section, 5-1 Marunouchi 2-chome, Chiyoda-ku, Tokyo 100-8315, Japan. Tel: (03) 3212 3111; Fax: (03) 3212 9860.