Multi-Surface Bonding Pad Protrusions for Crack Resistance
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Solution Overview
Problem
The structural flexibility of materials in semiconductor chip packaging substrates leads to mechanical strain, causing deterioration and failure of interconnections between bonding pads and substrate traces, particularly exacerbated by miniaturization which reduces the thickness of conductive traces, increasing the risk of cracking or partial separation.
Innovation Solution
A bonding pad design featuring a conductive pad with a plating layer and protrusions extending parallel to the signal trace, providing multiple interface surfaces for increased contact area and stability, with a nickel-gold plating layer for protection and strength, to reduce the likelihood of cracking or separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of conductive trace is decreased to achieve miniaturization, then the size of the bonding pad is reduced, but the interconnection becomes more prone to cracking and separation
Solution Approach 1:
The patent transitions from a single-plane interface to a multi-dimensional interface by creating protrusions that extend vertically from the bonding pad. This adds a third dimension (height) to the contact interface, allowing the thin trace to be contacted at multiple elevations rather than relying solely on horizontal surface area, thereby maintaining reliability while enabling miniaturization.
Solution Approach 2:
The bonding pad interface is segmented into multiple contact points through the protrusions. Instead of a single continuous interface, the electrical connection is divided into discrete contact regions at different heights and positions, which distributes mechanical stress across multiple locations rather than concentrating it at one point, reducing the risk of complete failure.
2Reliability
If protrusions are added to increase contact area, then interconnection reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent modifies geometric parameters of the bonding pad (protrusion height, width, spacing) to optimize the balance between reliability improvement and manufacturing complexity. By carefully controlling these parameters, the design achieves enhanced mechanical coupling without creating excessively complex structures that would be difficult or costly to manufacture.
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 enhanced bonding pad design significantly reduces the occurrence of breaks and cracks between the pad and substrate trace, improving the reliability and durability of interconnections by increasing the surface area of contact and providing structural support against mechanical stress.
Implementation Method 1
plating means covering a surface of the conducting means for protecting the conducting means from corrosion and/or providing strength to the conducting means
Data Source
AI summary
A bonding pad such as for a ball grid array includes a conductive pad having a top surface and a first interface surface in contact with a signal trace of a substrate, and a plating layer having a bottom surface in direct contact with the top surface of the conductive pad. The plating layer includes one or more protrusions extending toward the signal trace in a direction generally parallel to a longitudinal axis of the signal trace. Each of the one or more protrusions includes two parallel sidewalls extending upwardly from the bottom surface of the plating layer, and a second interface surface contiguous with the bottom surface of the plating layer. The second interface surface is positioned over and in direct contact with a top surface of the signal trace. The protrusions prevent the connection to the signal trace from being compromised.