| Objectives | Background | Approach |
This project will provide PoF software and guidelines for
evaluating the durability of package interconnects for through
hole insertion components when used in printed wiring assemblies.
While great deal of research is being conducted on new packaging technologies, a large volume of electronic products still use only insertion mounted component or are a mix of through hole packaging with other components types such as surface mount or Chip scale packaging. Also in many cases assemblies using only advanced packaging components will use through hole wiring connectors for off board system interfaces. Application of the current CALCE tool for these situations results in an incomplete assessment. CALCE members who use insertion technology have noted this gap, in supporting industry needs, as an issue that hinders the acceptance of the software as a widely used CAE tool.
Insertion components are incorporated into PWA's using either Single Sided (SS), Double Sided (DS), or Double Sided Plated Through-Hole (DS-PTH) solder attachments. The reliability and durability attributes are of course dependent upon the amount of application specific stress transmitted through the structure of the attachment and the strength and fatigue resistance of the structure. While the greatest durability & reliability will be provided by the stronger DS-PTH structure, even the weaker single sided structure can provides adequate reliability for low stress applications. Unfortunately, there are no clear guidelines or easy to use assessment tools to aid engineers in selecting when to specify which structure. Without the ability to clearly and accurately quantify the durability or reliability value or need for a stronger structure, engineers are frequently directed to use the lowest cost alternative by cost driven management. This frequently results in field problems. Even this past year, the CALCE center was requested to perform failure analysis on a single side printed wiring board assembly using insertion components.
Insertion mount interconnects present a unique set of reliability challenges. They are susceptible to various types of solder joint failures and lead fatigue. For insertion interconnects in plated through holes, lead fatigue may present the more significant problem especially with larger offset and coaxial components. Presently, the calcePWA software and Web Site does not provide adequate coverage of insertion mount components. While preliminary models and information exists for analyzing these configurations, they have not been validated, documented, integrated into the CALCE CAE tool set, or organized to the point of being useful. This project will focus on closing these gaps by providing the needed models, support information and validation necessary for engineers to quickly access, comprehend, and apply the failure models and guidelines to their products.
This project will examine reliability issues related to interconnects of insertion components in PWA's, beginning with a brief review of the related literature and known models. As a central part of this project, failure model plug-ins will be developed to provide coverage of SIP, DIP, PGA, Axial, Coaxial, Connect Bodies and other insertion mount packages. A tutorial on single-sided assemblies including web based failure modeling using the developed failure model plug ins will be provided. Validation data for the individual insertion mount failure models will be collected and finite element modeling will be used to validate the stress modeling implemented by the individual failure model plug-ins. Finally, the failure model plug-ins will be added to the calcePWA software to extend its coverage of failures on printed wiring boards.