Abstract: In order to improve the precision of BGA(ball grid array) solder joint inspection,a BGA solder joint inspection algorithm is proposed based on 3D X-ray and Fisher criterion.BGA solder image segmentation is implemented according to the Fisher criterion to obtain the accurate image,and the features such as area feature,continual area feature,position feature,circle feature and hole feature of BGA solder joint defects are extracted.Then the BGA solder joint inspection algorithm based on Fisher criterion is presented.Experimental results show that the short circuit,shift,lacking solder,void and broken circuit defect can be inspected by the proposed algorithm.The proposed algorithm has high precision and can meet the requirement of application.