White Bronze PCB Coating Without Nickel or Palladium
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Solution Overview
Problem
Existing printed circuits for smart cards and medical devices face challenges with the use of palladium and nickel, which are expensive and pose issues in radiofrequency applications and medical settings due to magnetic properties and potential skin contact.
Innovation Solution
A process for depositing a white bronze alloy on printed circuits, which replaces palladium and nickel layers, offering improved cost-effectiveness and suitability for radiofrequency and medical applications, while maintaining electrical and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a layer of gold or silver or palladium is deposited on the contacts to obtain a gold finish or silver finish, then the color matching and corrosion resistance are improved, but the manufacturing cost increases and magnetic properties are introduced that are problematic for radiofrequency applications
Solution Approach 1:
The patent replaces expensive precious metals (gold, silver, palladium) with a cheaper bronze alloy composition. The bronze layer provides sufficient corrosion resistance and color matching without requiring the expensive materials traditionally used for these finishes, directly addressing the cost issue while maintaining protective functionality.
Solution Approach 2:
The patent modifies the alloy composition parameters by using a specific bronze formulation (copper-tin-zinc alloy with controlled ratios) instead of traditional precious metals. This parameter change allows achieving the desired color match and corrosion resistance without introducing magnetic properties, solving both the cost and radiofrequency compatibility issues.
2Strength
If nickel is deposited as an underlying layer for gold to provide structural support, then the mechanical strength is improved, but magnetic properties are introduced that are problematic for radiofrequency applications and medical applications
Solution Approach 1:
The patent removes nickel from the contact layer structure entirely, extracting the harmful magnetic component while maintaining the necessary structural support function through alternative means. The bronze alloy itself provides sufficient mechanical properties without requiring a nickel underlayer, thus eliminating the magnetic property issue for radiofrequency and medical applications.
Solution Approach 2:
The patent uses a composite bronze alloy (copper-tin-zinc) that combines the benefits of multiple metals in a single non-magnetic layer. This composite material provides both the mechanical strength traditionally requiring nickel and the corrosion resistance and color matching, all without magnetic properties that would interfere with radiofrequency or medical applications.
3Reliability
If palladium is used to obtain a silver finish, then the color matching and corrosion resistance are improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive palladium with a cheaper bronze alloy that achieves the same functional outcomes. The bronze layer provides sufficient corrosion resistance and silver-like appearance without the high material cost of palladium, directly reducing manufacturing expenses while maintaining protective and aesthetic properties.
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 bronze alloy layer provides economical and effective alternatives to palladium and nickel, enhancing the durability and performance of printed circuits in smart cards and medical devices, particularly in terms of radiofrequency compatibility and medical safety.
Implementation Method 1
at least one operation of electrolytic deposition of at least one layer of at least one second electrically conductive material on at least one area of the first sheet
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
Disclosed is a method for depositing a bronze alloy on a printed circuit (5). Said method comprises an operation of electrolytically depositing at least one layer of bronze (12) on a copper sheet (10). The bronze layer (12) comprises, after deposition, 45-65% by weight of copper, 35-45% by weight of tin and 2-11% by weight of zinc. Also disclosed is a printed circuit (5) obtained by this method.