Electronic Package Recesses for Solder Strain Reduction
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Solution Overview
Problem
Electronic packages face reliability issues due to solder cracking caused by thermal expansion mismatches, leading to reduced reliability of solder joints under thermo-mechanical stress, particularly in power semiconductor devices.
Innovation Solution
The electronic package design incorporates recesses in the solidified molding compound at the perimeter of the mounting portion, exposing additional lead surface area, which reduces solder strain accumulation and enhances reliability by allowing for a larger solder covering area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead is fully encapsulated by molding compound, then the electronic component is well protected, but the solder joint reliability deteriorates due to strain accumulation
Solution Approach 1:
The patent extracts a portion of the molding compound from the encapsulation structure by creating recesses at the mounting portion of the lead. This exposes the lead surface that would otherwise be fully covered, allowing solder to directly contact the lead and form a larger solder joint area. The extracted molding compound volume creates space for improved solder attachment while maintaining protection in other areas.
Solution Approach 2:
The patent introduces a dimensional change by creating recesses that expose the lead surface in a new spatial configuration. Instead of a flat encapsulated surface, the recesses create a three-dimensional structure with exposed lead portions at the mounting area, increasing the effective surface area for solder attachment and reducing strain concentration points.
2Reliability
If the solder covering area is increased, then the resistance to solder crack is improved, but the molding compound encapsulation is reduced
Solution Approach 1:
The patent selectively removes molding compound material from specific regions (creating recesses) where solder attachment is needed, while maintaining full encapsulation in other areas. This extraction creates additional surface area for solder coverage without requiring a complete reduction of molding compound, thus improving crack resistance while preserving protective encapsulation.
Solution Approach 2:
The patent applies different quality characteristics to different regions of the encapsulation structure. The mounting portion area has reduced molding compound coverage to maximize solder attachment area and reduce strain, while other portions maintain full encapsulation for protection. This local differentiation optimizes both solder joint reliability and component protection.
Data Source
AI summary
An electronic package and method for manufacturing is provided. The package includes an electronic component having a terminal, a solidified molding compound encapsulating the electronic component, a lead including an inner and a mounting portion. The molding compound includes a first recess at or near a perimeter of a bottom surface of the mounting portion, exposing a portion of a bottom surface of the inner portion arranged near the mounting portion, and/or a second recess at the perimeter of the bottom surface of the mounting portion, the second recess exposing a portion of a side surface of the mounting portion extending between the top and the bottom surface of the mounting portion. The package provides more exposed lead space for a larger solder covering area using the first and/or second recess. Thus, solder strain accumulation is reduced or mitigated, and reliability of the electronic package can be enhanced.