Double-Layer RDL Fan-Out Packaging for Higher Line Density
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Solution Overview
Problem
The existing fan-out packaging technologies face limitations in reducing the minimum line width and increasing line density due to the requirement of a substrate in the chip-last packaging method, which also increases manufacturing cycle time.
Innovation Solution
A fan-out packaging structure utilizing a fan-out substrate unit with a double-layer wiring layer and a secondary fan-out unit, where the substrate is replaced by a double-layer redistribution layer (RDL), allowing for increased line density and reduced size, and the centralized preparation method for separate units shortens manufacturing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a substrate is used as supporting structure in chip-last packaging method, then structural support is provided, but the overall size of fan-out packaging structure increases and manufacturing cycle time increases
Solution Approach 1:
The patent removes the traditional substrate from the packaging structure, extracting only the essential supporting function and replacing it with a carrier board that provides minimal support while allowing direct fan-out of signal lines, thereby eliminating the size and time penalties associated with full substrate usage
Solution Approach 2:
The patent transitions from planar substrate-based packaging to a multi-layer stacked architecture where signal lines fan out in three dimensions through multiple wiring layers, allowing compact vertical integration while maintaining structural integrity without requiring a large substrate
2Strength
If a substrate is used as supporting structure in chip-last packaging method, then structural support is provided, but manufacturing cycle time increases
Solution Approach 1:
The patent divides the packaging structure into separate functional modules (carrier board, wiring layers, encapsulation layers, solder bump arrays) that can be manufactured independently and assembled through standardized processes, reducing manufacturing cycle time while maintaining structural support through the carrier board
3Ease of manufacture
If traditional packaging structure is used, then manufacturing process is simpler, but line density and minimum line width are limited
Solution Approach 1:
The patent employs multiple wiring layers stacked in the vertical dimension, allowing signal lines to fan out through three-dimensional routing rather than being constrained to a single planar layer, thereby achieving higher line density and smaller minimum line widths while using standardized manufacturing processes for each layer
4Quantity of substance
If substrate is replaced by double-layer RDL, then line density increases and size decreases, but structural complexity increases
Solution Approach 1:
The patent segments the complex multi-layer structure into standardized modular units (carrier board, first and second wiring layers, encapsulation layers, solder bump arrays) that can be manufactured and assembled using established processes, reducing the practical complexity despite the increased line density achieved through the double-layer RDL configuration
Data Source
AI summary
A fan-out packaging structure and a method for manufacturing the same are provided. The structure comprises: a fan-out substrate unit, and a secondary fan-out unit; an effective electrical connection between a second top surface of the fan-out substrate unit and a third bottom surface of the secondary fan-out unit is formed through a second solder array, and the fan-out substrate unit comprises a first wiring layer and a second wiring layer connected by conductive posts. By having a fan-out substrate unit with a double-layer wiring layer as the substrate of the fan-out wiring layer, the present disclosure reduces the achievable minimum line width, thereby increasing the achievable line density of the fan-out package. Meanwhile, replacing the traditional substrate with the double-layer wiring layer, and preparing the fan-out substrate unit and the secondary fan-out unit separately and then combining the two, shortens the time required to prepare the whole structure.