Chip Package With Segmented Metal Pads For Pad Integrity
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Solution Overview
Problem
Conventional IC packaging techniques face challenges in forming solder bumps and wirebonds on aluminum pads without damaging the original aluminum pads due to the etching process used for the under bump metallurgy layer, leading to potential damage and inefficiencies in high-density packaging.
Innovation Solution
A chip package design featuring two types of metal pads on a semiconductor substrate, where one pad is connected to a tin-containing layer and the other to a wire or external circuit using anisotropic conductive films/pastes, allowing for different bonding methods such as tape automated bonding, wirebonding, or direct solder bonding, while maintaining pad integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an under bump metallurgy layer is formed on aluminum pads for solder bumps, then adhesion and barrier functions are improved, but the aluminum pads are damaged by hydrofluoric acid etching
Solution Approach 1:
The bonding pads are segmented into two distinct types: aluminum-based pads for wire bonding and copper-based pads for solder bump formation. This segmentation allows each pad type to be optimized for its specific function, preventing the aluminum pads from being damaged by HF etching during UBM formation while maintaining their integrity for wire bonding operations.
Solution Approach 2:
Different material compositions are applied to different regions of the semiconductor chip surface. Aluminum-based pads are used in regions requiring wire bonding, while copper-based pads are used in regions requiring solder bumps. This local quality differentiation ensures that each region has the appropriate material properties for its intended function, avoiding cross-contamination and damage.
2Speed
If high-density packaging is implemented with solder bumps, then signal transmission speed increases, but the complexity of forming multiple bonding structures on the same chip increases
Solution Approach 1:
The chip surface is divided into distinct functional zones with aluminum-based pads for wire bonding and copper-based pads for solder bumps. This segmentation simplifies the manufacturing process by allowing each bonding technology to be applied to its designated pad type without interference, reducing the overall process complexity while enabling high-density packaging.
Solution Approach 2:
The semiconductor chip is designed to support multiple bonding technologies (wire bonding and solder bump bonding) simultaneously through the use of different pad materials. This multi-functionality allows the chip to accommodate various interconnection methods, providing design flexibility and simplifying the integration of different packaging approaches.
Data Source
AI summary
A chip package includes a semiconductor substrate, a first metal pad over the semiconductor substrate, and a second metal pad over the semiconductor substrate. In a case, the first metal pad is tape automated bonded thereto, and the second metal pad is solder bonded thereto. In another case, the first metal pad is tape automated bonded thereto, and the second metal pad is wirebonded thereto. In another case, the first metal pad is solder bonded thereto, and the second metal pad is wirebonded thereto. In another case, the first metal pad is bonded to an external circuitry using an anisotropic conductive film, and the second metal pad is solder bonded thereto. In another case, the first metal pad is bonded to an external circuitry using an anisotropic conductive film, and the second metal pad is wirebonded thereto.