Stackable Multi-Chip Package With Offset Face-to-Face Configuration
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Solution Overview
Problem
The electronic industry faces challenges in creating smaller, more reliable, and cost-effective integrated circuit packages that provide improved thermal performance, structural integrity, and electromagnetic interference (EMI) mitigation, while managing heat dissipation and warpage issues in stackable multi-chip packages.
Innovation Solution
A stackable multi-chip package system is designed with staggered dual land rows and an offset face-to-face configuration of integrated circuit dice, incorporating external interconnects with through holes and an encapsulation that includes a paddle for thermal dissipation and structural support, along with mold interlock features for enhanced rigidity and EMI shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If package stacks are made by stacking packages that have already passed the necessary tests, then the yields and reliability of these package stacks are higher, but the package stacks are thicker
Solution Approach 1:
The package is divided into multiple subassemblies, each containing an integrated circuit die and external interconnect. These subassemblies are stacked and molded together to form a complete package, allowing individual testing at the subassembly level while achieving a thinner overall package structure
Solution Approach 2:
The invention transitions from horizontal stacking of complete packages to vertical stacking of package subassemblies with offset face-to-face configuration. This dimensional reorganization allows for interlocking molding that reduces overall package thickness while maintaining structural integrity and reliability
2Reliability
If stacking features are added to provide structural and electrical integrity, then the structural and electrical uniformity is improved, but the manufacturing becomes difficult to control with incompatible materials
Solution Approach 1:
The external interconnect is designed to serve multiple functions simultaneously: providing structural support, establishing electrical connections, and enabling mechanical interlocking between stacked subassemblies. This multi-functionality eliminates the need for separate stacking features and their associated material compatibility issues
Solution Approach 2:
The invention merges the stacking feature functionality into the external interconnect structure itself. The staggered dual land row configuration of the external interconnect provides both electrical connection and mechanical stacking alignment, simplifying manufacturing by reducing the number of separate components and material types
3Adaptability or versatility
If more circuitry is packed into the integrated circuits, then the functionality is increased, but more heat is generated degrading the performance and reliability
Solution Approach 1:
The invention moves from two-dimensional heat dissipation to three-dimensional thermal management by stacking multiple subassemblies vertically. This allows heat to be distributed across multiple external interconnects and dissipated through multiple surfaces, improving thermal performance while maintaining high functionality
Solution Approach 2:
The package is segmented into multiple subassemblies, each generating heat that can be independently managed. The external interconnect structure provides multiple thermal pathways for heat dissipation, preventing heat accumulation and maintaining reliability in high-functionality configurations
4Length of stationary object
If the package height is reduced to achieve smaller form factor, then the size is decreased, but the structural integrity and warpage control become more difficult
Solution Approach 1:
The invention uses asymmetric offset face-to-face configuration of the stacked subassemblies. This asymmetric arrangement creates interlocking geometry that enhances structural rigidity and prevents warpage, allowing for reduced package height without compromising strength
Solution Approach 2:
The external interconnects are designed with predetermined staggered configurations that pre-establish mechanical interlocking and alignment features. This preliminary structural design ensures warpage control and structural integrity are built into the package architecture before final assembly, enabling thinner profiles
Data Source
AI summary
A stackable multi-chip package system is provided including forming a first external interconnect having a first through hole and a second external interconnect having a second through hole, forming a first package subassembly having the first external interconnect and a first integrated circuit die, forming a second package subassembly having the second external interconnect and a second integrated circuit die, mounting the second package subassembly over the first package subassembly, and molding the first package subassembly and the second package subassembly.