Innovation of the Month

New Surface "PureGold" - corrosion-resistant and biocompatible

The underlying idea
Time and again, we have been asked in the past few years if there is a surface that is resistant to strong acids but does not allow corrosion through pores or at edges. Calls for such surfaces have also been made by the field of cell research: Here, the surface must not leave the slightest traces of copper or nickel and must therefore be free of these metals.

In conventional printed circuit boards, the copper of the outer layers is usually plated with nickel and gold. However, the capillary effect means liquids can penetrate the interface with the base material, causing nickel and copper to come away.

Conventional chem. Ni/Au surface with signs of corrosion appearing



Conventional chem. Ni/Au surface
with signs of corrosion appearing

Take, as a concrete example, sensor circuit boards that are installed in the fuel cell stack and there measure the distribution of current densities and temperatures. The board therefore comes into direct contact with corrosive process fluids.


Copper corrosion on a sensor board for
fuel cells and batteries

Copper corrosion on a sensor board for fuel cells and batteries

The solution
"We leave off the copper and nickel!" This simple solution seemed unrealistic at first: All processes are based on copper-based films and it was unthinkable to use gold foils instead, for example. Since ANDUS believes (almost) anything is possible, we went ahead and tried anyway, with the early development phase showing that there are indeed ways to manufacture printed circuit boards with outer layers of pure gold.

To achieve this goal, several methods were explored, rejected, modified, tested and, finally, some of them qualified.

Simplified diagram of the new PureGold surface


Simplified diagram of the
new PureGold surface

During the development work, it turned out that there are several ways to create the new PureGold surface. Which method is suitable for which application depends largely on the layout. Long fine conductor tracks for in vivo medical engineering require different process sequences compared with sensor arrays for the chemical and food industry.

Other applications
The PureGold surface is used everywhere where conductor paths and pads must withstand corrosive environments and where the surrounding media must not be contaminated with metal ions. So, for example, nerve cells can be contacted on pure gold electrodes and investigated.

We are also happy to review your projects and see whether the new surface is suitable for use.

Get in touch!