Multichip Interconnect Underfill for Stronger Micro-Joints
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Solution Overview
Problem
Current underfill processes for multi-chip interconnected structures face issues such as mechanical strength degradation due to low fracture toughness and adhesion strength of non-conductive paste, and contamination during edge dispensing, leading to micro-joint fractures and increased processing time.
Innovation Solution
An underfill layer is formed between chips and the interconnect structure, utilizing capillary action to fill gaps between chips and interconnects, reducing thermal stress and allowing for faster attachment to an organic substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-conductive paste is used for underfilling, then chips can be attached to interconnect structure, but mechanical strength is degraded due to low fracture toughness and adhesion strength
Solution Approach 1:
The patent changes the physical and chemical parameters of the underfill material by transitioning from non-conductive paste to a low-viscosity resin composition with specific molecular weight and functional groups. This parameter change enables the resin to penetrate gaps effectively while achieving superior mechanical strength and adhesion properties.
Solution Approach 2:
The patent employs a composite resin composition containing specific fillers, coupling agents, and functional additives within the resin matrix. This composite structure provides both the flowability needed for gap penetration and the mechanical strength required for robust chip attachment.
2Ease of manufacture
If edge dispensing is used for underfilling, then underfill material can be applied, but contamination occurs leading to micro-joint fractures
Solution Approach 1:
The patent utilizes capillary action to enable the resin composition to automatically penetrate and fill the gaps between chips and interconnect structure without requiring external dispensing equipment. This self-service mechanism eliminates edge dispensing operations and associated contamination risks.
Solution Approach 2:
The patent replaces the mechanical edge dispensing system with a capillary-driven fluid penetration system. This substitution eliminates the mechanical contact and potential contamination from dispensing nozzles while achieving complete gap filling.
3Ease of manufacture
If conventional underfill processes are used, then chips can be attached, but processing time is increased
Solution Approach 1:
The patent performs preliminary gap penetration by the resin composition before chip attachment, ensuring complete gap filling occurs in advance. This preliminary action eliminates the need for subsequent underfilling steps, thereby reducing overall processing time.
Solution Approach 2:
The patent maintains continuous resin flow through the gap during the attachment process, ensuring uninterrupted gap filling. This continuous action eliminates idle time between dispensing and attachment operations, improving manufacturing efficiency.
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
The solution enhances structural integrity by minimizing micro-joint fractures and reduces processing time, enabling efficient attachment of chip-interconnect-chip structures to an organic substrate.
Implementation Method 1
utilizing capillary action to fill gaps between chips and interconnects
Data Source
AI summary
An interconnected semiconductor subassembly structure includes an interconnect structure; a first semiconductor die bonded to a first portion of a top surface of the interconnect structure; a second semiconductor die bonded to a second portion of the top surface of the interconnect structure; and a resin layer located within at least a first portion of a gap between the first semiconductor die and the second semiconductor die, wherein at least one of a top surface and a bottom surface of the resin layer located within the at least first portion of the gap has a concave meniscus shape.