Angled RDL Routing at Die-Encapsulant Boundary
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Solution Overview
Problem
The semiconductor industry faces challenges in ensuring reliability robustness of redistribution layers (RDL) at the semiconductor-encapsulant boundary due to thermal expansion mismatch, leading to cracking issues during the transition from fan-in to fan-out areas, particularly at die corners and sides.
Innovation Solution
A specific RDL routing design is implemented within pre-defined areas at the die-encapsulant boundary, where the metallization patterns are routed at angles relative to the tensile forces to avoid parallel alignment, reducing stress and the risk of cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If RDL metallization patterns are routed parallel to the boundary at die corners and sides, then routing simplicity is improved, but stress concentration and cracking risk increase due to thermal expansion mismatch
Solution Approach 1:
The patent applies different routing strategies to different locations: in fan-out areas away from the die, RDL patterns are routed parallel to the die boundary for simplicity, while in fan-in areas near die corners and sides, RDL patterns are routed at angles (45-135 degrees) to the boundary to reduce stress concentration. This location-specific routing approach optimizes both manufacturability and reliability.
Solution Approach 2:
The patent changes the routing angle parameter of RDL patterns based on location. In high-stress fan-in areas near die corners and sides, the routing angle is changed from parallel (0 degrees) to angled (45-135 degrees) to distribute stress more evenly and prevent cracking, while maintaining parallel routing in lower-stress fan-out areas.
2Reliability
If RDL patterns are routed at angles to reduce stress, then reliability is improved, but routing complexity increases
Solution Approach 1:
The patent applies angled routing only locally in fan-in areas where stress concentration occurs near die corners and sides, rather than throughout the entire RDL structure. This localized application minimizes the increase in routing complexity while maximizing the reliability benefit where it is most needed.
Solution Approach 2:
The patent applies angled routing partially only in the critical fan-in areas near die corners and sides, rather than applying it excessively throughout all RDL patterns. This partial application reduces stress concentration where necessary while avoiding unnecessary complexity in other areas.
3Ease of manufacture
If standard RDL routing is used without considering thermal expansion mismatch, then manufacturing process is simpler, but stress concentration leads to cracking during heating
Solution Approach 1:
The patent incorporates stress-reducing routing angle adjustments during the RDL design and fabrication stages, before the thermal heating process occurs. By pre-positioning RDL patterns at optimal angles in fan-in areas, the design proactively prevents stress concentration and cracking that would occur during subsequent thermal processing.
Solution Approach 2:
The patent applies preliminary anti-action by designing RDL routing patterns that counteract the expected thermal expansion stresses before they occur. By routing patterns at angles in fan-in areas, the design creates a stress-distributing configuration that opposes and prevents the harmful cracking effect during heating.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces the normalized stress on RDL patterns by 38% to 75% when routed at angles such as 45 degrees or 90 degrees relative to tensile forces, enhancing reliability robustness and preventing cracking during heating processes.
Implementation Method 1
thermal expansion mismatch, leading to cracking issues during the transition from fan-in to fan-out areas
Data Source
AI summary
An embodiment is a structure including a first die having an active surface with a first center point, a molding compound at least laterally encapsulating the first die, and a first redistribution layer (RDL) including metallization patterns extending over the first die and the molding compound. A first portion of the metallization patterns of the first RDL extending over a first portion of a boundary of the first die to the molding compound, the first portion of the metallization patterns not extending parallel to a first line, the first line extending from the first center point of the first die to the first portion of the boundary of the first die.