A detection method detects cracks with small thickness and solder voids with small volume in a solder ball. The method immerses a washed solder ball into a high absorption material solution for a first predetermined time period. The immersed solder ball is then dried in a vacuum chamber at a fixed temperature for a second predetermined time period. Materials of the high absorption material solution of the solder ball are removed by a low absorption material solution. An X-ray machine then detects the cracks and the solder voids in the solder ball.