Chip Stack Overhang Support Structure for Deflection Control
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Solution Overview
Problem
Chip stack packages face failures during fabrication due to deflections of overhanging semiconductor chips, which are prone to damage when forces are applied during processes like wire bonding, as they lack sufficient support.
Innovation Solution
Attaching a supporter to the bottom surface and sidewall of the overhang of the upper chip and the sidewall of the lower chip to provide additional support and suppress deflection, using materials with similar thermal expansion coefficients to minimize stress and enhance adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an upper semiconductor chip is stacked over a lower semiconductor chip with an overhang, then the chip stack package can include chips of different sizes or optimized layouts, but the overhanging portion is prone to deflections and failures during fabrication
Solution Approach 1:
A support structure is introduced as an intermediary element between the upper and lower chips. This support structure extends from the lower chip to the underside of the overhanging portion of the upper chip, providing mechanical reinforcement and preventing deflection during wire bonding and fabrication processes.
Solution Approach 2:
The solution adds a vertical support element that extends downward from the overhanging chip into the space between chips. This creates a three-dimensional support architecture that addresses the two-dimensional planar limitation, allowing overhangs to be stabilized without changing the chip layouts.
2Reliability
If a support structure is added to prevent overhang deflection, then overhang stability improves, but device complexity increases
Solution Approach 1:
The support structure is implemented as a thin adhesive layer or support film that can be applied conformally to the chip surfaces. This thin-film approach provides the necessary mechanical support while minimizing the added volume and visual complexity of the package structure.
Solution Approach 2:
The support structure is integrated with the existing adhesive layers used for chip stacking. By combining the support function with the bonding adhesive, the solution provides dual functionality without requiring separate discrete support components, thereby reducing overall complexity.
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 additional support structure significantly reduces deflection and damage to overhanging chips, improving the bending resistance and reliability of chip stack packages by distributing forces effectively and maintaining adhesive strength across temperature variations.
Implementation Method 1
a first supporter attached to a bottom surface of the overhang of the second chip and the sidewall of the first chip
Implementation Method 2
using materials with similar thermal expansion coefficients to minimize stress and enhance adhesive strength
Data Source
AI summary
A chip stack package includes a first chip disposed over a substrate, a second chip disposed over the first chip and having an overhang, and a first supporter attached to a bottom surface of the overhang of the second chip and a sidewall of the first chip. The overhang of the second chip protrudes from the sidewall of the first chip.