NCF Thermocompression Die Stack for Reliable 3D Packaging
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in achieving high reliability and efficient integration of multiple core dies while maintaining compactness and low power consumption, particularly in three-dimensionally integrated devices.
Innovation Solution
A semiconductor package design that includes a buffer die, core dies stacked with non-conductive films (NCF) and molding layers, where the NCF bonds the core dies and forms a coplanar surface with the molding layers, enabling efficient electrical connections and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple core dies are stacked vertically to achieve three-dimensional integration, then device integration and compactness are improved, but manufacturing complexity and reliability challenges increase
Solution Approach 1:
The patent divides the bonding process into two distinct stages: first bonding the buffer die to the first core die, then bonding the second core die to the first core die. This segmentation of the manufacturing process simplifies each individual bonding step while achieving the overall goal of three-dimensional integration, making the complex multi-die stacking process more manageable and reliable.
2Reliability
If non-conductive films are used for thermocompression bonding, then electrical isolation and bonding strength are improved, but process precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the thermocompression bonding process, including temperature (70-150°C), pressure (1-100 atm), and time (1 second to 1 hour). By defining these parameter ranges, the patent optimizes the bonding process to achieve strong electrical isolation and bonding strength while maintaining feasibility for manufacturing, thus balancing reliability with process precision requirements.
3Strength
If molding layers are designed to completely surround core dies, then mechanical protection is improved, but thermal dissipation and electrical access are restricted
Solution Approach 1:
The patent designs the molding layer with differentiated regions: a first molding layer that surrounds the first core die for mechanical protection, and a second molding layer that surrounds the second core die but leaves certain areas exposed. This local differentiation allows the molding layer to provide mechanical protection where needed while maintaining thermal dissipation pathways and electrical access points, thus resolving the contradiction between protection and heat management.
4Volume of moving object
If core dies are closely stacked to reduce package size, then form factor is improved, but heat accumulation and signal interference increase
Solution Approach 1:
The patent introduces non-conductive films as intermediary layers between the stacked core dies. These NCFs serve multiple functions: they provide electrical isolation to prevent signal interference between adjacent dies, facilitate thermal management by creating controlled thermal pathways, and enable mechanical bonding. This intermediary approach allows close stacking for compactness while mitigating heat accumulation and electromagnetic interference.
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 design enhances the reliability and integration of semiconductor packages by ensuring strong bonding between core dies and efficient electrical connections, while maintaining a compact form factor and low power consumption.
Implementation Method 1
a first non-conductive film (NCF) disposed between the first core die and the second core die and bonding the first core die and the second core die to each other
Data Source
AI summary
A semiconductor package includes: a buffer die; a first core die disposed on the buffer die; a second core die disposed on the first core die; a first non-conductive film (NCF) disposed between the first core die and the second core die and bonding the first core die and the second core die to each other; a first molding layer at least partially surrounding a side surface of the first core die; and a second molding layer surrounding the first NCF and the first molding layer, wherein the first core die, the second core die, and the buffer die are disposed on the second molding layer, wherein a side surface of the first molding layer and a side surface of the first NCF form a coplanar surface.