Flip Chip Cavity Package Molded Leadframe Moisture Resistance
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Solution Overview
Problem
Current semiconductor packages face challenges in miniaturization due to insufficient lead count and reliability issues at high bump counts, and are susceptible to moisture-induced failures known as the 'popcorn' effect, which limits their use in applications requiring high reliability and structural robustness.
Innovation Solution
A process involving the formation of a molded leadframe strip with flip chip semiconductor devices and conductive masses, encapsulated in a mold compound to create a cavity, allowing for electrical interconnection and enhanced protection from moisture, while also enabling flexible routing of I/O through a second leadframe coupled with a soft metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If package size is reduced to match die size (CSP), then package size is improved, but lead count and reliability deteriorate
Solution Approach 1:
The patent introduces a cavity dimension within the package structure, creating a three-dimensional architecture rather than a flat two-dimensional layout. The cavity is formed by recessing the leadframe and filling with mold compound, allowing the die to be mounted in a recessed area. This vertical dimensionality enables increased lead count and improved reliability while maintaining the compact CSP footprint.
2Quantity of substance
If bump count is increased to support high I/O, then I/O count is improved, but reliability deteriorates due to moisture-induced failures
Solution Approach 1:
The patent converts the potential harm of moisture ingress into a beneficial protective structure. The cavity is filled with mold compound that encapsulates the die and conductive masses, creating a hermetic seal that prevents moisture from reaching sensitive components. This mold compound filling transforms the cavity from a potential weakness into a protective barrier against moisture-induced failures.
Solution Approach 2:
The patent employs composite material construction by combining the leadframe (metal), die (semiconductor), conductive masses (solder), and mold compound (polymer) into a unified package structure. The mold compound acts as both structural support and moisture barrier, while the cavity architecture allows these materials to work together synergistically to protect high I/O count connections from environmental damage.
3Volume of moving object
If package size is reduced, then miniaturization is improved, but structural robustness deteriorates
Solution Approach 1:
The patent implements a nested structure where the die is mounted within a recessed cavity of the leadframe, and the cavity is subsequently filled with mold compound. This nested architecture - leadframe containing cavity containing die and mold compound - creates a robust compact structure that maintains structural integrity while minimizing overall package size. The nested design distributes mechanical stresses throughout multiple layers and materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the creation of robust semiconductor packages with increased lead count and reliability, resistant to moisture-induced failures, and allows for flexible I/O routing, addressing the limitations of existing technologies in miniaturization and reliability.
Implementation Method 1
The molded leadframe strip, the at least one flip chip semiconductor device, and the conductive masses are at least partially encased in a second mold compound
Implementation Method 2
conductive masses attached thereon to effectuate electrical contact between the at least one flip chip semiconductor device and the corresponding molded leadframe
Data Source
AI summary
A process for forming a semiconductor package. The process comprises forming a first leadframe strip mounted upon an adhesive tape. The first leadframe strip is at least partially encased in a first mold compound thereby forming a molded leadframe strip. At least one flip chip semiconductor device is mounted on the molded leadframe strip. The semiconductor device has conductive masses attached thereon to effectuate electrical contact between the semiconductor device and the molded leadframe. The conductive masses can be substantially spherical or cylindrical. Liquid encapsulant is dispensed on the semiconductor device to encapsulate the flip chip semiconductor device. A cavity is formed between the semiconductor device and the molded leadframe. The molded leadframe strip, the semiconductor device, and the conductive masses are at least partially encased in a second mold compound. The second mold compound can be molded so that a surface of the flip chip semiconductor device that is not attached to the molded leadframe is substantially exposed or molded to produce a globular form on the flip chip semiconductor device. The molded leadframe strip is singulated to form discrete semiconductor packages.