Segmented Redistribution Pad Layout for PID Crack Suppression
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Solution Overview
Problem
The existing fan-out type semiconductor packages face issues due to physical stress caused by thermal expansion differences between the redistribution pad and the photoimageable dielectric, leading to cracks in the dielectric and subsequent damage to the redistribution pad.
Innovation Solution
Incorporating segmenting grooves in the redistribution pad, which reduces the pad's area and alleviates physical stress on the photoimageable dielectric, thereby preventing crack generation and propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the redistribution pad is made large to provide sufficient electrical connection area, then the electrical connectivity is improved, but the physical stress on the photoimageable dielectric increases causing cracks
Solution Approach 1:
The redistribution pad is divided into multiple segments by introducing segmenting grooves that extend from the outer surface toward the central portion along the radial direction. This segmentation reduces the continuous area of the pad while maintaining electrical connectivity through conductive structures at the grooves, thereby reducing thermal stress on the photoimageable dielectric while preserving electrical functionality.
2Object-affected harmful factors
If the redistribution pad area is reduced to alleviate thermal stress, then crack formation is suppressed, but the electrical connection capability deteriorates
Solution Approach 1:
Conductive structures are introduced as intermediary elements at the segmenting grooves to maintain electrical connectivity between the segmented pad portions. These conductive structures act as mediators that restore the electrical path interrupted by the grooves, ensuring that the segmented pad maintains adequate electrical connection capability while benefiting from reduced thermal stress.
3Object-affected harmful factors
If segmenting grooves are introduced to reduce pad area and stress, then crack suppression is achieved, but the manufacturing complexity increases
Solution Approach 1:
The segmenting grooves and conductive structures are formed as integral parts of the redistribution layer during the same manufacturing process steps, rather than as separate post-processing operations. The grooves are formed by patterning the metal layer, and conductive structures are deposited simultaneously or in sequence, eliminating the need for additional machining or assembly steps and thus not increasing manufacturing complexity.
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
The implementation of segmenting grooves in the redistribution pad effectively suppresses crack formation in the photoimageable dielectric, enhancing the reliability of semiconductor packages by mitigating thermal expansion-induced stress.
Implementation Method 1
the redistribution pad and the PID may have different thermal expansion coefficients (TEC). Thus, physical stress may be applied to the PID disposed over the redistribution pad
Data Source
AI summary
A package substrate may include an insulation substrate, at least one redistribution layer (RDL) and a redistribution pad. The RDL may be included in the insulation substrate. The redistribution pad may extend from the RDL. The redistribution pad may include at least one segmenting groove in a radial direction of the redistribution pad. Thus, the at least one segmenting groove in the radial direction of the redistribution pad may reduce an area of the redistribution pad. Therefore, application of physical stress to a PID disposed over the redistribution pad may be suppressed, and thus generation of cracks in the PID may be reduced. Further, spreading of the cracks toward the redistribution pad from the PID may also be suppressed, and thus reliability the semiconductor package may be improved.