Palladium-Coated Wire Bonding for Corrosion-Resistant Semiconductor Joints
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Solution Overview
Problem
Conventional wire bonding techniques, such as ball bonding, can lead to reliability issues due to corrosion and alloy formation between the wire and the semiconductor chip, and are not suitable for wires with small diameters.
Innovation Solution
A semiconductor device employing wedge bonding with a wire configuration that includes a core conductor and a palladium coating, where the core is separated from the semiconductor chip and lead terminal by the palladium coating, preventing direct contact and corrosion, and allowing bonding without melting, thus enhancing reliability and applicability to both large and small diameter wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ball bonding is used to electrically couple electrodes, then bonding can be achieved, but corrosion and alloy formation occur between the wire and semiconductor chip
Solution Approach 1:
A palladium coating is applied to the wire surface as an intermediary layer between the wire core and the semiconductor chip electrodes. This palladium layer prevents direct contact between the wire material (such as copper or aluminum) and the chip materials, thereby eliminating corrosion and unwanted alloy formation while maintaining electrical conductivity.
Solution Approach 2:
The wire structure is designed as a composite material system with a core conductor (providing electrical conductivity) and a palladium coating layer (providing corrosion resistance and preventing alloy formation). This composite structure combines the advantages of different materials to achieve both electrical performance and chemical stability.
2Adaptability or versatility
If ball bonding is used for wire bonding, then bonding can be achieved, but it is not suitable for wires with small diameters
Solution Approach 1:
The invention transitions from ball bonding to wedge bonding methodology, changing the bonding process parameters. Wedge bonding uses a wedge-shaped anvil to compress and bond the wire directly without forming a ball, which allows for effective bonding of wires with smaller diameters while maintaining bonding reliability.
3Reliability
If direct contact between wire and electrode is used, then electrical coupling is achieved, but corrosion occurs
Solution Approach 1:
The palladium coating serves as a protective intermediary layer that maintains direct electrical contact between wire and electrode while preventing corrosive interactions. This thin coating layer adds minimal structural complexity while providing substantial corrosion protection.
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 wedge bonding method improves the reliability of the wire bonding process by preventing corrosion and alloy formation, while enabling bonding of wires with small diameters that are not suitable for traditional ball bonding, thus enhancing the semiconductor device's performance and durability.
Implementation Method 1
a second conductor that is provided inside the first conductor and has no contact with the first electrode and the second electrode
Implementation Method 2
wedge bonding with a wire configuration that includes a core conductor and a palladium coating, where the core is separated from the semiconductor chip and lead terminal by the palladium coating, preventing direct contact and corrosion, and allowing bonding without melting
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first electrode, a second electrode, and a wire extending between the first electrode and the second electrode. The wire includes a first conductor in contact with the first electrode and the second electrode, and a second conductor that is provided inside the first conductor and has no contact with the first electrode and the second electrode.