To reduce pre-bond and post-bond test time of three dimensional IP(Intellectual Property)cores,this paper proposes a test wrapper optimization technique. The proposed technique maps scan elements to a plane,and BFD algorithm is employed to allocate scan elements to each wrapper chain to reduce post-bond test time. Secondly,AL(Allocate Layer)algorithm is presented to allocate scan elements to each circuit layer to balance pre-bond wrapper chains,which can effectively reduce pre-bond test time and the number ...