Under-Bump Pattern Structure for Crack-Resistant Terminal Attachment
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Solution Overview
Problem
Conventional semiconductor packages face challenges in reliability and size reduction, particularly in the attachment of outer coupling terminals due to limited contact area and susceptibility to cracking during processing.
Innovation Solution
The semiconductor package device incorporates an under-bump pattern with a protruding portion and an inclined side surface, increasing the contact area with outer coupling terminals and reducing the risk of cracking by distributing stress more effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional under-bump pattern is used with limited contact area, then the device size can be kept small, but the reliability deteriorates due to cracking susceptibility during processing
Solution Approach 1:
The under-bump pattern is divided into multiple protruding portions (first, second, third protruding portions) that extend in different directions from the body portion. This segmentation increases the total contact area with outer coupling terminals while distributing stress across multiple discrete contact points, thereby improving reliability without requiring a single large complex structure
Solution Approach 2:
The under-bump pattern transitions from a two-dimensional planar structure to a three-dimensional structure with protruding portions extending vertically and laterally. The protruding portions have varying heights and extend in multiple directions, adding dimensional complexity that increases contact area and provides stress distribution pathways in three dimensions
2Reliability
If the contact area between under-bump pattern and outer coupling terminal is increased, then reliability improves, but the manufacturing precision requirements worsen due to alignment difficulty
Solution Approach 1:
Different protruding portions are designed with different local characteristics - varying heights, different extension directions, and different contact surface areas. The first protruding portion extends in a first direction with a first height, the second in a second direction with a second height, and the third in a third direction with a third height. This local differentiation allows optimization of contact quality at each specific location while maintaining overall alignment tolerance
Solution Approach 2:
The under-bump pattern employs asymmetric design where protruding portions are not uniform in shape, size, or orientation. The body portion has a first diameter, while protruding portions have different diameters and extend asymmetrically in multiple directions. This asymmetry creates multiple alignment reference points and increases the probability of successful attachment while distributing mechanical stress non-uniformly to prevent crack propagation
3Strength
If a protruding portion with inclined side surface is used, then cracking resistance improves through stress distribution, but the device complexity increases
Solution Approach 1:
The protruding portions feature inclined side surfaces that create curved or angled transitions rather than sharp corners. The inclined surfaces provide gradual stress distribution pathways, reducing stress concentration points where cracks would initiate. The curved geometry of inclined surfaces compared to flat surfaces distributes mechanical loads more evenly across the contact area
Data Source
AI summary
A semiconductor package device may include a redistribution substrate and a semiconductor chip on a top surface of the redistribution substrate. The redistribution substrate may include an under-bump pattern, which includes including a body portion and a protruding portion extended from the body portion to form a single object, an insulating layer covering a side surface of the body portion, and an outer coupling terminal on the protruding portion. The body portion may have a first diameter in a first direction parallel to the top surface of the redistribution substrate, and the protruding portion may have a second diameter in the first direction, which is smaller than the first diameter. A top surface of the protruding portion may be parallel to the first direction, and a side surface of the protruding portion may be inclined at an angle to a top surface of the body portion.