Curved Pad Structure in Semiconductor Packages for Bonding Reliability
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Solution Overview
Problem
Existing semiconductor packages face challenges in maintaining reliability due to issues such as voids, cracks, and delamination at the interface between pads and insulating layers, which affect the integrity and performance of electrical connections.
Innovation Solution
A semiconductor package design featuring a pad structure with a recessed upper surface and a pad surface layer made of a different conductive material, where the edge of the lower surface is higher than the center of the upper surface, combined with a specific manufacturing process involving etching and plating to enhance the bonding between the pad and insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pad structure with flat upper surface is used, then the manufacturing process is simple, but voids, cracks, and delamination occur at the interface between pad and insulating layer
Solution Approach 1:
The upper surface of the pad is designed with a curved profile where the edge of the lower surface is positioned at a higher vertical level than the center of the upper surface. This curvature allows the insulating layer to conformally cover the pad surface, improving adhesion and preventing voids and delamination at the interface.
Solution Approach 2:
A pad surface layer made of a different conductive material is applied to the upper surface of the pad. This creates a localized region with enhanced properties for bonding to the insulating layer, while the bulk pad material maintains its original electrical and mechanical characteristics.
2Reliability
If a single-layer pad structure is used, then the manufacturing process is simple, but electrical connection reliability is insufficient
Solution Approach 1:
The pad structure is divided into multiple functional layers: the base pad layer providing electrical connection, and the pad surface layer providing enhanced bonding interface. This segmentation allows each layer to be optimized for its specific function, improving overall electrical connection reliability.
Solution Approach 2:
The pad structure uses composite material composition with the base pad made of one conductive material and the pad surface layer made of a different conductive material. This composite structure combines the advantages of different materials to achieve both good electrical conductivity and reliable bonding to the insulating layer.
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 improves the reliability of electrical connections by reducing the likelihood of voids, cracks, and delamination, enhancing the overall performance and durability of the semiconductor package.
Implementation Method 1
etching a portion of a central region of the pad
Implementation Method 2
plating the central region of the pad
Data Source
AI summary
A semiconductor package includes a first insulating layer, a second insulating layer on the first insulating layer, the second insulating layer having an opening, a pad on the first insulating layer or the second insulating layer to at least partially vertically overlap the opening, and a pad surface layer on an upper surface of the pad to at least partially vertically overlap the opening, the pad surface layer including a conductive material different from that of the pad. The upper surface of the pad is recessed to have a shape more curved than that of a lower surface of the pad.