MECHANICAL RELIABILITY ANALYSIS OF CCGA SOLDER JOINTS
Author: Arvhd Sinha Company: IBM Corporation Date Published: 4/28/1997
Surface Mount International
Abstract: The density of components in electronic assemblies is increasing. Atone time there was sufficient separation by design to prevent interaction damage between adjacent components on system backplanes. In high-end AS/400 computers, the electrical design requires that large compliant pin connectors be located directly adjacent to 1089-leaded ceramic column grid array (CCGA) modules which are soldered to the backplane. Because high forces are required to insert connectors into backplanes (approx. 68-78 newtons per each of the connector’s 720 pins), CCGA interconnect columns are susceptible to mechanical damage. The concern over the susceptibility of CCGA interconnect columns to mechanical damage, or fatigue, led to an investigation of the mechanical operations which can place the highest stress on the CCGA solder columns: Assembly of compliant pin connectors into the backplane and plugging of a daughter card into the backplane. This paper describes the techniques used to determine deformation of solder columns on CCGA modules during both backplane and system assembly operations.