Method and apparatus for performing automated circuit board solder quality inspections

摘要

A method and apparatus for measuring structural characteristics of a manufactured circuit board containing solder joints by automated real-time digital X-ray radiographic inspection techniques. A circuit board under examination is automatically positioned by a digitally controlled multi-axis positioning system between an electronic X-ray source and an electronic X-ray imaging system. X-rays, in a beam of X-rays from the X-ray source, are directed towards the circuit board. The X-rays are absorbed, scattered and transmitted through the circuit board. The X-rays transmitted through the circuit board are directed upon the X-ray imaging system. The X-ray imaging system converts the transmitted X-rays into digital images which represent the radiographic density of the portion of the circuit board under examination. The digital images are stored within a digital image processor. A computer, under program control, performs calculational measurements on the digital images so as to measure the structural characteristics of the solder joints and components on the circuit board. The calculational measurements are compared to predetermined standards corresponding to acceptable quality standards programmed into the computer. In response to the comparison, the computer provides an accept/reject decision on the circuit board in addition to providing manufacturing process control information for correction of found defects.