Underfill Dispensing Using Funnels for Void-Free Distribution
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Solution Overview
Problem
The challenge in underfilling an array of laminates on a substrate lies in preventing voids and ensuring uniform distribution of underfill material, as existing methods often result in trapped air and uneven deposition due to the mismatch in thermal expansion coefficients and the small gaps between components, leading to potential delamination and thermal mechanical stress.
Innovation Solution
The use of multiple funnels positioned across the substrate to locally deliver and control the underfill material, ensuring it reaches the target gap without overflowing or escaping between components, with a dispensing system that navigates between funnels to deposit the material in a parallel and precise manner, preventing voids and optimizing the underfill's properties for structural support and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If underfill material is dispensed directly onto the substrate without funnels, then the dispensing process is simple, but voids form and uniform distribution is poor
Solution Approach 1:
The patent introduces funnels as intermediary structures positioned between the dispenser nozzle and the substrate. These funnels receive underfill material and guide it into the gap between laminates, ensuring uniform distribution and preventing void formation while maintaining a relatively simple overall system architecture
Solution Approach 2:
The dispensing system is segmented into multiple funnels distributed across the substrate surface. Each funnel independently manages underfill delivery to its local region, enabling parallel processing and improving uniformity without requiring a single complex dispensing mechanism
2Productivity
If underfill material is dispensed quickly to increase productivity, then manufacturing speed improves, but voids and trapped air increase
Solution Approach 1:
The funnels are pre-positioned and prepared before underfill dispensing begins. This preliminary arrangement allows rapid dispensing into the funnels without compromising quality, as the funnels are already in place to guide the material flow and prevent void formation
Solution Approach 2:
The funnels act as intermediary reservoirs that decouple the high-speed dispensing process from the slower capillary flow into the laminate gap. This mediation allows rapid material delivery while ensuring complete, void-free infiltration through controlled flow paths
3Manufacturing precision
If underfill material is dispensed in large amounts to ensure complete coverage, then coverage improves, but material overflow and waste increase
Solution Approach 1:
Each funnel is designed with specific dimensions and positioning tailored to its local requirements. The funnel size, shape, and location are optimized to deliver the precise amount of underfill needed for complete coverage of the underlying laminate gap, preventing both deficiency and excess
Solution Approach 2:
The system uses controlled excessive action by dispensing slightly more material than theoretically needed into each funnel, but the funnel geometry and capillary forces ensure that only the required amount enters the gap, with excess material naturally contained or removed without causing waste
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 method achieves a void-free, uniformly distributed underfill layer that provides structural support and minimizes thermal mechanical stress, enhancing the reliability of solder connections and protecting the BEOL chip structure by optimizing the underfill's glass transition temperature and adhesion properties.
Implementation Method 1
The underfill material is drawn into the gap between the laminate and substrate through capillary action, ensuring complete and uniform filling without voids
Implementation Method 2
The cured underfill layer provides structural support and adhesion to the solder interconnects and BEOL chip structure, preventing delamination and mechanical damage
Data Source
AI summary
Arrays of objects on a substrate having void-free underfill as well as methods and systems of forming the same include forming a void-free layer of underfill material between a substrate and an array of multiple objects positioned on the substrate. The void-free layer of underfill material is cured to form a protective cured underfill layer that provides structural support to connections between the objects and the substrate.