Reduced Layer RDL Wiring Structure for RF Die Packages
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Solution Overview
Problem
The manufacturing process for RF die packages with a 5P5M RDL structure is time-consuming and costly, leading to warpage and delamination issues due to its thickness, and the yield rate is low due to impedance matching concerns and insufficient exposure of photoresist for conductive via formation.
Innovation Solution
A wiring structure with a reduced number of layers, where the lower RDL is directly disposed on the lower circuit structure, omitting additional conductive and insulating layers, and using a same photomask and patterned photoresist for both, allowing for a more efficient manufacturing process and improved bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 5P5M RDL structure is used to achieve impedance matching, then the electrical performance is improved, but the manufacturing time increases to about 60 days and the cost increases
Solution Approach 1:
The patent extracts and removes unnecessary intermediate layers (insulating layers and conductive layers) from the traditional 5P5M structure. By directly connecting the lower RDL to the lower circuit structure and using a simplified ball pad structure, the manufacturing process is reduced from 60 days to a much shorter duration while maintaining electrical performance through direct impedance control.
Solution Approach 2:
Instead of building up multiple layers to achieve impedance matching, the patent inverts the approach by using a reduced layer structure with direct connections and controlling impedance through the geometry and material properties of the simplified structure, achieving the same electrical performance with fewer manufacturing steps.
2Reliability
If a 5P5M RDL structure with five passivation layers and five metal layers is used, then the impedance matching is achieved, but the structure thickness increases causing warpage and delamination issues
Solution Approach 1:
The patent removes excessive insulating and conductive layers from the traditional 5P5M structure, retaining only the essential ball pad structure with a reduced number of layers. This extraction of unnecessary layers directly reduces the overall structure thickness, eliminating the root cause of warpage and delamination while preserving the impedance matching function through optimized geometry and material selection.
3Adaptability or versatility
If additional conductive and insulating layers are included in the RDL structure, then the design flexibility is improved, but the manufacturing complexity and time increase
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate conductive and insulating layers, keeping only the essential ball pad structure. This simplification reduces the number of layers from five conductive and five insulating layers to a minimal structure, thereby reducing manufacturing complexity and time while maintaining design flexibility through direct geometric and material optimization of the reduced structure.
4Reliability
If a traditional multi-layer RDL structure is used, then the electrical connections are established, but the manufacturing cost is high due to the 60-day production cycle
Solution Approach 1:
The patent removes unnecessary manufacturing steps by extracting intermediate layers and simplifying the structure to an essential ball pad configuration. This reduction in layers directly shortens the production cycle from 60 days to a much shorter duration, thereby reducing manufacturing cost while maintaining reliable electrical connections through the optimized simplified structure.
Data Source
AI summary
A wiring structure includes an insulating layer and a conductive structure. The insulating layer has an upper surface and a lower surface opposite to the upper surface, and defines an opening extending through the insulating layer. The conductive structure is disposed in the opening of the insulating layer, and includes a first barrier layer and a wetting layer. The first barrier layer is disposed on a sidewall of the opening of the insulating layer, and defines a through hole extending through the first barrier layer. The wetting layer is disposed on the first barrier layer. A portion of the wetting layer is exposed from the through hole of the first barrier layer and the lower surface of the insulating layer to form a ball pad.