Fan-Out Package Corner Opening Reduces Cracking
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Solution Overview
Problem
The increasing miniaturization of semiconductor dies and the need for more integrated functions pose challenges in packaging, particularly due to limited I/O pad density and the risk of solder bridges, which affect yield and reliability.
Innovation Solution
The development of an integrated fan-out package process that includes forming Redistribution Lines (RDLs), metal posts, and molding material to redistribute I/O pads to a larger area, allowing for increased pad density and using adjusted solder region dimensions to reduce stress and improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch of I/O pads is decreased to increase pad density, then the number of I/O pads that can be packed increases, but solder bridges may occur reducing reliability
Solution Approach 1:
The patent transitions from conventional fan-in packaging where I/O pads are limited to the die surface area to fan-out packaging where the package substrate area is larger than the die area. This dimensional expansion allows I/O pads to be redistributed to a greater area, increasing the number of pads without decreasing pitch and avoiding solder bridges
2Ease of manufacture
If fan-in packaging is used to maintain simple structure, then manufacturing is easier, but the number of I/O pads is limited due to die area constraints
Solution Approach 1:
The invention uses fan-out packaging where the package substrate area exceeds the die area, enabling I/O pad redistribution to a larger area. This allows increased pad quantity while maintaining manageable manufacturing complexity through established fan-out processes
Solution Approach 2:
The packaging process is divided into distinct stages: die preparation, RDL formation on package substrate, die attachment, and bump formation. This segmentation allows complex high-density packaging to be achieved through manageable sequential steps
3Area of moving object
If die size is reduced for miniaturization, then device size decreases, but packaging becomes more difficult affecting yield
Solution Approach 1:
By using fan-out packaging where the package substrate is larger than the miniaturized die, the invention provides ample area for I/O pad redistribution and solder ball placement. This resolves the packaging difficulty associated with small die sizes while maintaining high yield through relaxed process tolerances
4Quantity of substance
If solder ball size is reduced to fit more balls on die surface, then pad density increases, but solder bridges may occur
Solution Approach 1:
The patent redistributes I/O pads and solder balls from the limited die surface to the larger package substrate area. This allows the use of larger solder balls with adequate spacing, increasing the number of solder balls without reducing size and avoiding solder bridges
Data Source
AI summary
A package includes a device die, a molding material molding the device die therein, and a surface dielectric layer at a surface of the package. A corner opening is in the surface dielectric layer. The corner opening is adjacent to a corner of the package. An inner opening is in the surface dielectric layer. The inner opening is farther away from the corner of the package than the corner opening. The corner opening has a first lateral dimension greater than a second lateral dimension of the inner opening.