Abstract
The stress and displacement fields at the close vicinity of a bonding edge show approximately the following singular behaviors.
σ(γ)=K/γλ (1)
σ(γ): stress
γ: distance from singularity point
K: intensity of stress singularity
λ: order of stress singularity
Formerly we presented a new adhesive strength evaluation method using these two stress singularity parameters K and λ. In this paper, the strength estimation on resin cracking at the tab edge of LSI plastic package was attempted by using these stress singularity parameters. Crack initiation criteria using stress singularity parameters were measured on 90° notch specimens, plain specimens, fracture toughness tests and so on. Crack initiation behaviors of three types LSI plastic packages were analysed using these crack initiation criteria. These analytical results of delamination and crack initiation behaviors were compared with the heat-cycle experimental results.
From these studies it was found that the intensity of stress singularity at the tab edge increased in accordance with the increase of delamination area of tab bottom, and this delamination area depended strongly on the tab size.
