Semiconductor Substrate With Corner Openings For Underfill Delamination
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Solution Overview
Problem
Flip-chip semiconductor packages face delamination issues at the corners of the chip due to insufficient underfill material and thermal stress, exacerbated by the mismatch in thermal expansion coefficients between the chip and substrate, and existing solutions either require additional processes or struggle with controlling resin flow, leading to unsatisfactory bonding and resin flashes.
Innovation Solution
A substrate structure with a solder mask layer featuring outwardly extended openings at the chip mounting area corners allows for effective filling of underfill material into these openings, providing enhanced protection against thermal stress and preventing delamination without additional fabrication processes, while eliminating issues related to resin control and bonding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fillet is applied around underfill material to improve protection, then corner protection is enhanced, but additional fabrication process steps and cost increase
Solution Approach 1:
The patent merges the underfill material function with the corner protection function into a single integrated structure. The underfill material itself is configured to extend and cover corner positions, eliminating the need for a separate fillet structure. This combines multiple protective functions into one material application step.
Solution Approach 2:
The patent uses preliminary action by pre-forming protrusions on the substrate before underfilling. These protrusions guide the underfill material to automatically cover corner areas during the single underfilling process, achieving enhanced corner protection without requiring subsequent fillet application steps.
2Reliability
If sealing resin is applied at chip mounting area corners to flow and fill gap, then corner coverage is improved, but resin flow control is difficult causing insufficient or excessive filling
Solution Approach 1:
The patent implements preliminary action by pre-forming protrusions at specific positions on the substrate before applying underfill material. These protrusions act as barriers and guides that control the flow and distribution of underfill material, ensuring it reaches corner areas without overflowing. This pre-structured guidance eliminates the trial-and-error nature of relying solely on resin flow control.
Solution Approach 2:
The protrusions serve as intermediary structures that mediate between the underfill material application and the final desired coverage pattern. They physically guide and constrain the underfill flow to achieve precise corner coverage without requiring complex control of resin viscosity or flow characteristics.
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 ensures reliable protection against thermal stress-induced delamination at the chip corners, improves bonding quality, and eliminates resin-related issues, enhancing the overall reliability and performance of the semiconductor package without requiring additional fabrication steps or equipment.
Implementation Method 1
By this type of underfiling technology, a sealing resin 32 is applied at the four corners of a chip mounting area on a substrate 31, and then a chip 30 is mounted and electrically connected to the chip mounting area of the substrate 31, allowing the sealing resin 32 applied on the corners of the chip mounting area to slowly flow towards the center of the chip mounting area and fill a gap between the chip 30 and the substrate 31 by capillary action.
Implementation Method 2
Flip-chip semiconductor package is formed by mounting and electrically connecting an active surface of at least one chip to a surface of a substrate via a plurality of solder bumps
Data Source
AI summary
A semiconductor package and a substrate structure thereof are provided. A solder mask layer applied on the substrate structure is formed with outwardly extended openings corresponding to corner portions of a chip mounting area of the substrate structure. When a flip-chip semiconductor chip is mounted on the chip mounting area and an underfilling process is performed, an underfill material can fill a gap between the flip-chip semiconductor chip and the substrate structure, and effectively fill the outwardly extended openings of the solder mask layer corresponding to the corner portions of the chip mounting area so as to provide sufficient protection for corners of the flip-chip semiconductor chip and prevent delamination at the corners of the flip-chip semiconductor chip during a subsequent thermal cycle.