In the welding process of BGA solder joints,it is easy to produce bubbles and form void defects which are difficult to analysis automatically during testing.A technique solution is proposed that the solder balls are separated by OTSU algorithm,the void defects are segmented by the open and close operations and the top-hat transform of mathematical morphology.The solution can be used to achieve the seamless extraction of void defects and automatic analysis in each solder ball.The experimental results show that the proposed scheme is robust and can be applied to detection of void defects in BGA solder joints.