Although a lot of interface crack problems were previously treated, few solutions are available under arbitrary material combinations. This paper deals with periodic interface cracks in a bonded infinite plate and a central interface in a bonded infinite plate. Then, the effects of material combination and relative crack length on the stress intensity factors are discussed. A useful method to calculate the stress intensity factor of interface crack is presented with focusing on the stress at the crack tip calculated by the finite element method. For periodic interface cracks, it is found that the stress intensity factors are controlled by the bimaterial parameter ε alone and increase with increasing ε and relative crack length. For a central interface crack, the relationship between the dimensionless stress intensity factors FI
and relative crack length a/W
are obtained under arbitrary material combinations. It is found that FI
has the maximum value when α = 0.2, β = 0.3 and minimum value when α = 1.0, β = 0 independent of a/W
. On the other hand, FII
has the maximum value when α = 0.1, β = 0 and minimum value when α = 0.2, β = 0.3.