Precious-Metal PCB Manufacturing for Biocompatible Medical Devices
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Solution Overview
Problem
Existing printed circuit boards (PCBs) face challenges in achieving high biocompatibility, excellent electrical performance, and cost-effective production without using copper or nickel layers, particularly in medical applications, as current methods are time-consuming, require specialized equipment, and involve aggressive chemicals that are not suitable for industrial scale.
Innovation Solution
A method involving a first conductive layer of gold or silver, followed by a second conductive layer of platinum, rhodium, or iridium, using electroplating and etching processes to create PCBs without copper or nickel, utilizing common manufacturing techniques for scalability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper layers are used for electrical contacts in PCBs, then electrical conductivity is improved, but biocompatibility deteriorates due to chemical instability and oxidation in aqueous environments
Solution Approach 1:
The patent employs composite material structures where copper traces are covered by biocompatible metal layers (platinum, rhodium, or iridium). This creates a composite system that combines the high electrical conductivity of copper with the biocompatibility and oxidation resistance of precious metals, resolving the contradiction between electrical performance and biocompatibility in medical applications
2Reliability
If nickel layers are added to protect copper contacts, then solderability and oxidation resistance are improved, but biocompatibility deteriorates due to nickel toxicity concerns
Solution Approach 1:
The patent replaces the nickel protection layer with thin layers of platinum, rhodium, or iridium that serve the same protective function (oxidation resistance and solderability) without the biocompatibility issues. These precious metal layers act as permanent protective coatings that eliminate the need for nickel while maintaining reliability and biocompatibility simultaneously
3Object-affected harmful factors
If electroless plating with primer resin layer is used to deposit platinum, then biocompatibility is improved, but device complexity and production cost increase due to specialized equipment and multiple steps
Solution Approach 1:
The patent extracts and eliminates the complex electroless plating process with primer resin layers from the manufacturing workflow. Instead, it employs direct electroplating or screen printing methods to deposit conductive materials followed by precious metal plating, significantly simplifying the manufacturing process while maintaining biocompatibility and reducing equipment requirements
4Manufacturing precision
If sputter deposition is used to deposit metal layers, then trace fineness is improved, but manufacturing time and production efficiency deteriorate
Solution Approach 1:
The patent replaces the mechanical sputter deposition process with electroplating or screen printing techniques. These alternative methods achieve comparable or sufficient trace fineness for medical device applications while dramatically reducing manufacturing time and increasing production efficiency, as they operate at higher speeds and require less complex equipment
5Manufacturing precision
If aggressive etching chemicals are used to pattern platinum, then manufacturing precision is improved, but loss of substance increases due to material waste and environmental concerns
Solution Approach 1:
The patent converts the potential harm of aggressive etching into a benefit by using the same chemicals that etch copper to selectively remove copper while leaving the precious metal pattern intact. This approach achieves high patterning precision while minimizing precious metal waste, as the etching process is self-limiting and the precious metals serve as both the pattern definition and the final functional layer
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 method enables the production of biocompatible PCBs with high electrical conductivity and low resistivity, suitable for medical devices, using standard equipment and processes, with potential for large-scale production and recovery of precious metals.
Implementation Method 1
c) electroplating a second conductive layer over and in contact with the first conductive layer
Implementation Method 2
e) etching the first conductive layer to remove the same except at the part on which the second conductive layer was formed
Implementation Method 3
use of a conductive layer comprising platinum and/or rhodium as a resist for chemical or electrochemical etching
Data Source
Figure 1A~1E
Figure 2A~2C
AI summary
Described is a method of manufacturing a printed circuit board (PCB), comprising the following steps in the given order: a) providing a first conductive layer over and in contact with a substrate, b) providing a plating resist film on a part of the surface of the first conductive layer in a prescribed pattern, c) electroplating a second conductive layer over and in contact with the first conductive layer on the part of the surface of the first conductive layer not covered by the plating resist film, d) removing the plating resist film to expose a part of the first conductive layer not covered by the second conductive layer, and e) etching the first conductive layer to remove the same except at the part on which the second conductive layer was formed; wherein the first conductive layer comprises Au and/or Ag, and the second conductive layer comprises Pt, Rh and/or Ir, or wherein the first conductive layer comprises Ag, and the second conductive layer comprises Au, Pt, Rh and/or Ir. In addition, the use of a conductive layer comprising Au, Pt, Rh and/or Ir as a resist for chemical or electrochemical etching in the manufacture of a PCB is described. Furthermore, a PCB manufactured by the aforementioned method and a medical device comprising said PCB are described.