Flip Chip Routing Method Using Longest Common Subsequence
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Solution Overview
Problem
Current routing methods for flip-chip packages, particularly those using pre-assignment routing, face inefficiencies due to high computation time and complexity, making them unsuitable for the semiconductor industry's need for speed and cost-effectiveness.
Innovation Solution
A routing method and device that sets sequences of pads based on arrangement orders and uses the longest common subsequence algorithm to establish direct and detour connections, minimizing computation time and routing length by determining the most direct connections between pad arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pre-assignment routing method is used for flip-chip package, then the corresponding relationships between driver pads and bump pads are predetermined, but the routing computation time becomes excessively long and complexity increases
Solution Approach 1:
The routing problem is segmented into two distinct stages: a first stage that determines routing paths for connections between driver pads and bump pads, and a second stage that provides detailed routing implementations. This segmentation allows the complex pre-assignment routing problem to be broken down into manageable parts, reducing overall computation time while maintaining predetermined relationship requirements.
Solution Approach 2:
The method performs preliminary determination of routing paths in the first stage before detailed routing is completed in the second stage. By establishing the overall routing paths beforehand based on predetermined corresponding relationships, the system prepares the framework early, which simplifies subsequent detailed routing work and reduces total computation time.
2Adaptability or versatility
If pre-assignment routing method is used for flip-chip package, then the routing paths must follow predetermined corresponding relationships, but the routing length increases due to detour connections
Solution Approach 1:
The method applies different routing strategies to different types of connections: direct connections are used where predetermined relationships allow for optimal paths, while detour connections are used only where necessary to satisfy predetermined corresponding relationships. This local differentiation minimizes overall routing length by avoiding unnecessary detours while maintaining required connection mappings.
Solution Approach 2:
The system uses direct connections for the majority of routing paths where predetermined relationships permit, and reserves detour connections only for specific cases where connection requirements demand them. This partial use of detour connections minimizes their negative impact on total routing length while still satisfying all predetermined corresponding relationships.
Data Source
AI summary
Disclosed herein are rouging methods and devices for a flip-chip package. The flip chip includes several outer pads and several inner pads. The routing method includes: setting an outer sequence based on the arrangement order of the outer pads; setting several inner sequences based on the connection relationships between inner pads and the outer pads; calculating the longest common subsequence of each inner sequence and the outer sequence, defining the connection relationships between the inner pads and the outer pads corresponding to the longest common subsequence as direct connections, and defining the connection relationships between the inner pads and the outer pads that do not correspond to the longest common subsequence as detour connections; establishing the routing scheme of the flip chip based on the connection relationships between the inner pads and the outer pads.