Palladium-Enriched Signal Bonding Wire for Semiconductor Corrosion Resistance
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Solution Overview
Problem
Semiconductor devices using die attach films (DAF) face corrosion issues due to chloride ions, leading to disconnection between aluminum electrode pads and gold bonding wires, which compromises the reliability of the semiconductor package.
Innovation Solution
The semiconductor device incorporates a palladium content-rich bonding wire for signal wiring, sealed with a resin composition having high ionic conductivity to prevent corrosion, while using a filler-rich resin composition for structural integrity and a palladium-free gold wire for power supply wiring to maintain redundancy and avoid increased resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gold bonding wire is used to connect to an aluminum electrode pad through a die attach film, then electrical connection is achieved, but chloride ions corrode the aluminum electrode pad causing disconnection
Solution Approach 1:
The patent changes the material parameter of the bonding wire from conventional gold to palladium-containing wire. This parameter change fundamentally alters the chemical interaction at the bonding interface, preventing chloride ion corrosion of the aluminum electrode pad while maintaining electrical connectivity and mechanical bonding strength.
Solution Approach 2:
The patent uses a small amount of palladium (0.01-5 wt%) mixed with gold to create a cost-effective solution. The palladium acts as a protective component that sacrificially prevents corrosion of the aluminum pad, extending the functional life of the connection without requiring pure palladium which would be prohibitively expensive.
2Reliability
If palladium content is increased in the bonding wire to prevent corrosion, then corrosion resistance improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the palladium concentration parameter to a specific range (0.01-5 wt%) where sufficient corrosion protection is achieved while minimizing cost. This parameter optimization balances performance requirements with economic constraints, avoiding both under-protection and excessive expense.
Solution Approach 2:
The patent applies palladium locally at the bonding interface rather than throughout the entire wire structure. The palladium-containing bonding wire creates a protective layer specifically where corrosion occurs (at the aluminum pad interface), while the bulk of the wire maintains gold's excellent electrical conductivity and ductility properties.
3Reliability
If a resin composition with high ionic conductivity is used to seal the bonding wire, then corrosion prevention improves, but structural integrity may be compromised
Solution Approach 1:
The patent employs a composite resin composition containing both inorganic filler particles and ionic conductivity-enhancing components. The filler provides mechanical strength and structural integrity, while the ionic conductivity components (such as alkali metal oxides or fluorides) create pathways for ion transport that prevent corrosive species from reaching the bonding interface.
Solution Approach 2:
The resin composition acts as an intermediary barrier between the external environment (source of chloride ions) and the bonding wire-aluminum pad interface. The high ionic conductivity of the resin allows benign ions to pass through while blocking harmful chloride ions, effectively mediating the chemical environment to protect the sensitive bonding interface.
Data Source
AI summary
According to one embodiment, a semiconductor device includes a wiring board, a controller chip that is provided on the wiring board and is sealed with a first resin composition, a nonvolatile memory chip that is provided on the first resin composition and is sealed with a second resin composition, a second bonding wire that connects a pad for electric power supply wiring of the controller chip to the wiring board and is sealed with the first resin composition, and a first bonding wire that connects a pad for signal wiring of the controller chip to the wiring board, is sealed with the first resin composition, and has a higher Pd content than that of the second bonding wire.