Package-on-Package Substrate Structure for Crack-Resistant Interconnects
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Solution Overview
Problem
Current semiconductor packages face challenges in achieving a thin and light design while incorporating multiple functions, particularly in package-on-package configurations, where the integration of upper and lower semiconductor packages requires effective electrical and physical connections without compromising structural reliability and heat dissipation.
Innovation Solution
The semiconductor package design incorporates a first package substrate with a dam structure, posts, and an underfill layer, where the posts electrically connect the substrates and physically support the upper package, while the underfill layer surrounds the posts and the dam structure to prevent cracking and enhance structural reliability, and includes a recessed groove in the second package substrate for improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If package-on-package configuration is used to increase storage capacity and functionality, then device functionality is improved, but structural reliability deteriorates due to cracking risks at connection portions
Solution Approach 1:
The patent applies beforehand cushioning by introducing a dam structure and underfill layer that preemptively absorb and distribute thermal stress and mechanical loads before cracking can occur. The dam structure surrounds the connection portion between upper and lower semiconductor packages, creating a protective barrier that cushions against stress concentration. The underfill layer fills the gap between packages, providing prior cushioning against thermal expansion differences and mechanical shocks, thereby preventing cracking before it happens.
Solution Approach 2:
The patent employs composite materials by combining the dam structure made of stress-resistant material with the underfill layer having specific mechanical properties. This composite approach creates a multi-material system where each material contributes its unique properties: the dam structure provides structural support and stress distribution, while the underfill layer provides shock absorption and thermal management. This composite construction enhances overall structural reliability without compromising the package-on-package functionality.
2Reliability
If posts are added to electrically connect substrates and support upper package, then electrical connectivity is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the posts to perform multiple functions simultaneously. The posts serve both as electrical connection elements (conducting signals and power between substrates) and as mechanical support structures (holding the upper package in position and distributing mechanical loads). This multi-functional design eliminates the need for separate electrical interconnects and mechanical supports, thereby improving electrical connectivity without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the electrical interconnection function and mechanical support function into a single integrated structure (the posts). By combining these two previously separate functions into one element, the patent reduces the total number of components needed. The posts are strategically positioned to simultaneously establish electrical pathways and provide structural support, thereby achieving improved electrical connectivity while minimizing the increase in device complexity through functional integration.
3Reliability
If underfill layer surrounds posts and extends to dam structure, then cracking suppression is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-forming the dam structure before applying the underfill layer. The dam structure is created as a guide and boundary that defines the exact region where the underfill layer should be applied. This preliminary structuring eliminates the need for high-precision direct application of the underfill layer, as the dam structure serves as a physical template that automatically guides the underfill material to the correct position and extent, thereby improving cracking suppression while reducing manufacturing precision requirements.
Solution Approach 2:
The patent uses the dam structure as an intermediary element that mediates between the manufacturing process and the final underfill layer configuration. The dam structure acts as a mediator that translates manufacturing capabilities into the desired underfill layer pattern. By introducing this intermediary structure, the patent allows for easier application of the underfill layer with lower precision requirements, while still achieving the goal of surrounding the posts and extending to the dam structure for optimal cracking suppression.
Data Source
AI summary
A semiconductor package includes a first package substrate, a dam structure on a top surface of the first package substrate and extending and surrounding a region of the first package substrate, a semiconductor chip on the top surface of the first package substrate, a plurality of posts on the top surface of the first package substrate and surrounding the semiconductor chip, and an underfill layer between the semiconductor chip and the first package substrate and surrounding a lower portion of each of the posts, wherein the posts are in the region of the top surface of the first package substrate surrounded by the dam structure.