Pad cratering is a mechanically induced fracture in the resin between copper foil and outermost layer of fiberglass of a printed circuit board (PCB).
The pad remains connected to the component (usually a Ball Grid Array, BGA) and leaves a "crater" on the surface of the printed circuit board.
The ball pull test is specifically design for BGA components and has a large sensitivity to the solder alloy and joint formation.
Conventional nondestructive testing and failure analysis techniques such as visual inspection and X-Ray microscopy may not detect the issue.
Typically, pad cratering is detected or confirmed via destructive testing and failure analysis such as dye and pry, acoustic emissions,[10] cross sectioning, and Scanning Electron Microscopy.
[1][6] Relevant examples include ICT failures or products with potential for large shock events (i.e. portable electronics).
Typically, pad cratering is considered a high strain rate event with minimal creep, however there is still potential for plasticity in the solder.
More compliant solders or those with lower yield points will reduce pad cratering potential by providing additional load sharing.