Dummy Pad Layout for Smaller InFO Contact Pads and Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in reducing contact pad sizes for integrated fan-out (InFO) packages, which limits redistribution layer routing capability and increases costs, while also causing reliability issues due to stress and delamination in polymer layers, especially at die-corners and package-corners.
Innovation Solution
Incorporating a dummy pad feature, such as a dummy metal ring, adjacent to the contact pad and along the under-bump metallization edge, which is not electrically coupled to the contact pad, to reduce stress and provide additional area for redistribution lines without compromising reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If contact pad sizes are reduced to increase integration density, then more components can be integrated into a given area, but redistribution layer routing capability is limited and manufacturing costs increase
Solution Approach 1:
The patent introduces dummy pad features that extend the routing area into additional spatial dimensions adjacent to the contact pad. This allows redistribution lines to route through expanded areas without increasing the contact pad footprint, effectively adding routing capacity in new spatial directions while maintaining compact contact pad sizes.
Solution Approach 2:
The dummy pad feature acts as an intermediary structure between the contact pad and the redistribution layer routing paths. It provides intermediate routing areas that facilitate signal distribution without requiring larger contact pads, thereby mediating between the constraints of small contact pad size and the needs of routing capability.
2Area of moving object
If contact pad sizes are reduced, then integration density increases, but stress and delamination occur in polymer layers especially at die-corners and package-corners
Solution Approach 1:
The patent converts the potentially harmful stress concentration that occurs at die-corners and package-corners with reduced contact pads into a beneficial structure by introducing dummy pad features. These features strategically place additional material in high-stress regions to redistribute and mitigate stress concentrations, transforming the stress problem into an opportunity for improved reliability through strategic structural reinforcement.
Solution Approach 2:
The dummy pad features are selectively positioned at critical locations such as die-corners and package-corners where stress and delamination risks are highest. This localized reinforcement approach applies quality enhancement only where needed, maintaining small overall contact pad sizes while providing targeted stress relief in vulnerable regions.
3Area of stationary object
If contact pad sizes are reduced, then package area is utilized more efficiently, but the number of routing layers needed increases manufacturing complexity
Solution Approach 1:
The dummy pad features expand the available routing area in the planar dimensions without requiring additional vertical routing layers. By creating additional routing space adjacent to contact pads, the patent enables more signals to be distributed within the same layer count, thereby reducing manufacturing complexity while maintaining efficient package area utilization.
Data Source
AI summary
A device and method of manufacture is provided that utilize a dummy pad feature adjacent contact pads. The contact pads may be contact pads in an integrated fan-out package in which a molding compound is placed along sidewalls of a die and the contact pads extend over the die and the molding compound. The contact pads are electrically coupled to the die using one or more redistribution layers. The dummy pad features are electrically isolated from the contact pads. In some embodiments, the dummy pad features partially encircle the contact pads and are located in a corner region of the molding compound, a corner region of the die, and/or an interface region between an edge of the die and the molding compound.