Underfill Channel Design for IC Package Warpage and Overflow Control
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Solution Overview
Problem
Integrated circuit packages face challenges due to thermal expansion mismatches and voids in the underfill layer, leading to warping, delamination, and inefficiencies in the underfill process, especially when assembling multiple circuit devices on a substrate.
Innovation Solution
A package carrier with a first channel is used to form a contiguous underfill fillet under multiple integrated circuit devices, utilizing capillary action and flexible dispenser placement to ensure uniform underfill distribution and prevent epoxy overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill material is dispensed between circuit devices and substrate, then voids and gaps are reduced, but epoxy overflow to the top of the circuit device die occurs
Solution Approach 1:
The patent forms a channel structure in the substrate before dispensing the underfill material. This preliminary structural preparation guides the flow of epoxy and prevents it from overflowing onto the circuit device die, while still allowing complete filling of the gap between the device and substrate.
Solution Approach 2:
The channel acts as an intermediary structure that mediates between the underfill material and the circuit device. It provides a controlled pathway for the epoxy to flow underneath the device without direct contact between the overflowing epoxy and the device top surface.
2Productivity
If multiple circuit devices are mounted on the same substrate, then productivity increases, but underfill volume imbalance and processing complications occur
Solution Approach 1:
The substrate is segmented into multiple channels, each serving a specific circuit device. This segmentation allows independent control and optimization of underfill volume for each device, eliminating the volume imbalance problems that occur when multiple devices share the same substrate without individual channels.
Solution Approach 2:
Each channel is tailored to the specific requirements of its associated circuit device, providing locally optimized underfill flow characteristics. This local quality approach ensures that each device receives the appropriate amount of underfill material regardless of the presence of other devices on the substrate.
3Ease of manufacture
If CTE mismatches exist between substrate, circuit devices, underfill layer, and mold material, then manufacturing complexity increases, but warping and delamination occur
Solution Approach 1:
The patent extracts the stress management function from the bulk underfill material and concentrates it in the channel structure. The channel geometry is specifically designed to accommodate thermal expansion differences, absorbing stress and preventing warping and delamination while simplifying the overall manufacturing process.
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 enhances manufacturing yields and reliability by reducing warpage and improving underfill consistency, allowing for faster and more efficient assembly of multiple integrated circuit devices on a substrate.
Implementation Method 1
forming a contiguous underfill fillet with the first channel and under both the first integrated circuit device and the second integrated circuit device
Data Source
AI summary
An integrated circuit package system includes: providing a package carrier; forming a first channel in the package carrier; mounting a first integrated circuit device over the package carrier and adjacent to the first channel; mounting a second integrated circuit device over the package carrier and adjacent to the first channel; and forming a contiguous underfill fillet with the first channel and under both the first integrated circuit device and the second integrated circuit device.