Package-on-Package Pillar Dam Structure for Alignment Reliability
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Solution Overview
Problem
Current package-on-package semiconductor packages face challenges in achieving structural reliability and preventing electrical short-circuits due to misalignment and oxidation of conductive pillars during interposer mounting, which affects the connectivity and durability of the semiconductor package.
Innovation Solution
The implementation of a dam structure with a solder resist material and interposer connecting pillars that surround the semiconductor chip, along with a molding member to fill the dam structure, ensures proper alignment and protection of conductive pillars, reducing the risk of short-circuits and enhancing structural reliability by preventing oxidation and excessive pressing during interposer mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive pillars are exposed during interposer mounting, then electrical connectivity can be established, but oxidation occurs and structural reliability deteriorates
Solution Approach 1:
The dam structure is formed in advance to cover and protect the conductive pillars before the interposer mounting process begins. This preliminary protective action prevents oxidation from occurring during subsequent manufacturing steps, allowing the conductive pillars to remain exposed only when actually needed for electrical connection.
Solution Approach 2:
The dam structure is selectively removed or opened at specific locations to expose the conductive pillars only where interposer connections are required. This extraction approach maintains protection for unused conductive pillars while enabling necessary electrical connectivity, resolving the contradiction between protection and connectivity.
2Ease of manufacture
If interposer is mounted directly on package substrate, then manufacturing process is simplified, but misalignment occurs causing electrical short-circuits
Solution Approach 1:
The dam structure serves as an intermediary element between the package substrate and the interposer. It provides a defined interface that guides and constrains the interposer positioning, ensuring precise alignment while maintaining manufacturing simplicity. The dam structure acts as a physical reference that facilitates accurate placement without requiring complex alignment procedures.
3Reliability
If conductive pillars are left exposed, then electrical connection is enabled, but excessive pressing occurs during interposer mounting
Solution Approach 1:
The dam structure is formed in advance to provide mechanical support and pressure distribution around the conductive pillars before interposer mounting. This preliminary structural preparation prevents excessive localized pressing on the conductive pillars during assembly, protecting their structural integrity while maintaining electrical connectivity.
Data Source
AI summary
A lower semiconductor package of a package-on-package type semiconductor package includes: a package substrate; a semiconductor chip mounted on the package substrate; a chip connecting terminal disposed between the semiconductor chip and the package substrate and configured to connect the semiconductor chip to the package substrate; conductive pillars arranged on the package substrate to at least partially surround the semiconductor chip; and a dam structure configured to cover the conductive pillars on the package substrate and having a first opening at least partially surrounding the semiconductor chip.