Solder hierarchy for lead free solder joint
US6892925B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 18, 2002 |
| Grant date | May 17, 2005 |
| Priority date | — |
| Expiry date | Feb 20, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P70/50
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A lead free solder hierarchy for use in the second level solder connection of electronic components such as joining an electronic module to a circuit board. An off-eutectic solder concentration of SnCu or SnAg is used for the module side connection. This off-eutectic solder contains sufficient intermetallics to provide the module side connection with a robust second level assembly and rework process. The off-eutectic composition provides an inter-metallic phase structure in the module side fillet during assembly. The inter-metallic phase structure eliminates problems of tilt and collapse during second level assembly and aids in rework by providing a more cohesive joint allowing removal of the columns from the board without simultaneous removal from the module.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.