Pad Cratering - The Invisible Threat to the Electronics Industry

Published:	September 6, 2012
Author:	Chris Hunrath
Abstract:	First published in the 2012 IPC APEX EXPO technical conference proceedings. Pad Cratering opens circuits. This occurs when the resin crack (fracture) migrates through a copper trace or via. This happens at assembly, in service or during handling. When com...

Ag September 10, 2012 So, how does this resilient material become an element of a fabricated board? * Does the board designer specify it to the fabricator? * Does the designer do a callout for a resilient design and the the fabricator selects the material? * Or what? KParent September 10, 2012 The resilient material (Zeta® Cap) is added in the process of building the circuit board in place of the copper foil. The Zeta Cap is a copper and c-staged polyimide that is very easy for the PCB Fabricator use as a cap layer on the outer layer of the PCB to improve the Pad Cratering resistance. The designer should specify Zeta Cap on the print. Thank you for your questions. Ag September 10, 2012 What types of materials are used a the resilient buffer layer? KParent September 10, 2012 Zeta® Cap is a copper foil coated with c-staged polyimide. The copper foil and polyimide are available in various thicknesses to meet the demands of designers for electrical and mechanical needs. davef September 11, 2012 It makes sense that making the fabricated board less rigid would reduce cratering, but how do you know that's the driver to cratering? KParent September 11, 2012 Davef, we know there are several drivers creating pad cratering in PCB Assemblies. By adding Zeta Cap to the PCB we have data from several reliable sources that have shown we can and do improve the resistance to pad cratering in the PCB assembly whether or not the pad crater is initiated by bend and flex, thermal shock or drop testing. You must be a registered user to talk back to us.