Palladium-Gold Bonding Copper Wire for Peel-Resistant Plating
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Solution Overview
Problem
Existing bonding wires face issues of low coverage rate and poor chemical resistance after welding, leading to potential peeling and corrosion, which affect their reliability and service life in applications like semiconductor packaging.
Innovation Solution
An electroplating process for a copper wire that involves multiple layers of palladium and gold, using specific plating solutions containing tetraamminepalladium acetate, 4-sulfamoylbenzoic acid, 6-azauracil, and other compounds to ensure uniform deposition and strong adhesion, preventing peeling and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding wire is plated with a precious metal layer to improve chemical resistance and oxidation resistance, then the chemical stability is improved, but the coverage rate of the plated layer becomes insufficient and peeling occurs after welding
Solution Approach 1:
The patent divides the plated layer into multiple segments: a copper core wire, a palladium plating layer, and a gold plating layer. This multi-layer segmentation allows each layer to perform its specific function - the palladium layer provides base corrosion resistance and adhesion, while the gold layer provides superior chemical resistance and solderability, collectively achieving high coverage rate and prevented peeling
Solution Approach 2:
The patent uses composite material structure by combining copper core with palladium and gold plating layers. The copper core provides electrical conductivity and mechanical strength, while the palladium and gold layers provide chemical resistance and oxidation resistance. This composite structure achieves both high coverage rate and excellent chemical stability
2Loss of substance
If the plated layer is made thinner to reduce cost, then the manufacturing cost is reduced, but the chemical resistance after welding deteriorates
Solution Approach 1:
The patent applies local quality by using different materials with different thicknesses at different locations of the bonding wire. The palladium layer is applied as a thin base layer for adhesion and corrosion resistance, while the gold layer is applied as a thinner outer layer for chemical resistance and solderability. This localized material distribution achieves cost reduction while maintaining chemical resistance after welding
Solution Approach 2:
The patent changes the parameters of the plating process by controlling the thickness, composition, and microstructure of each layer. By optimizing the plating parameters such as current density, plating time, and solution composition, the patent achieves thin but dense layers that provide sufficient chemical resistance while minimizing precious metal usage and cost
3Reliability
If the plated layer is made denser to improve adhesion and prevent peeling, then the reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent uses the palladium layer as an intermediary between the copper core and the gold layer. The palladium layer serves as a transition layer that provides excellent adhesion to the copper core and a suitable surface for gold plating. This intermediary layer simplifies the overall process by ensuring strong bonding between layers without requiring complex surface treatment or additional adhesion promoters
Solution Approach 2:
The patent applies preliminary action by first plating the palladium layer on the copper core before applying the gold layer. The palladium layer is deposited under optimized conditions to create a dense, adherent base layer that prepares the surface for subsequent gold plating. This preliminary plating action ensures strong adhesion and prevents peeling while maintaining a relatively simple two-step electroplating process
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 process results in a bonding wire with high coverage rate, improved chemical resistance, and enhanced reliability, maintaining conductivity and thermal performance even after deformation or welding, thus extending the service life and reducing oxidation and corrosion risks.
Implementation Method 1
electroplating a first palladium layer on a surface of a copper wire with a first palladium plating solution, electroplating a second gold layer with a first gold plating solution
Implementation Method 2
palladium of the tetraamminepalladium acetate in the first palladium plating solution is connected with two acetic acid groups, which can be complexed with a sulfonamide group and a carboxyl group
Data Source
AI summary
The present application relates to the technical field of electroplating, and particularly to a bonding copper wire plated with palladium and gold and an electroplating process thereof. The electroplating process includes: electroplating a first palladium layer on a surface of a copper wire with a first palladium plating solution, electroplating a second gold layer with a first gold plating solution to obtain a semi-finished product, electroplating a third palladium layer onto the semi-finished product with a second palladium plating solution, and electroplating a fourth gold layer with a second gold plating solution to obtain a finished product; and the first palladium plating solution comprises tetraamminepalladium acetate, 4-sulfamoylbenzoic acid and 6-azauracil.