#1928 / Electroless Plating for Flexible Circuits

Electroless plating is a popular method in manufacturing printed circuits or flexible circuits. The Electroless Plating concept is not new and is used to protect conductors against oxidation. However, it is not the default process for printed circuit manufacturing. Many of circuit manufacturers do not have in- house plating capabilities and rely on plating shops for surface finishing.
Over the last decade there has been remarkable progress with electroless plating. Nowadays, material supplies have many new chemicals available for the plating process, especially for surface treatments. Chemical suppliers are confident that circuit manufacturers can secure metallizing on plastic substrates without making a large investment.
I participated in R&D projects during the 90’s where we tried to produce flexible copper laminates without adhesive layers. Manufacturers employed different processes such as casting and sputtering to generate new laminates. The combination of electroless plating and electrical plating was considered a candidate because it called for very little investment. Unfortunately, the chemical plating processes could not provide a secure enough bond strength between the base film and copper conductors and was not worth pursuing.
New plating chemicals are available to use with the plating process and provide a reliable bond strength with flexible laminates. However, plating shops do not follow the recipe line by line, and create their own process conditions by adding supplemental treatments to increase the cost performance. Usually, the chemical costs are significant
Material suppliers have an advantage from electroless plating – they can experiment with new laminates using base materials other than polyimide films or PET films at a significantly lower cost. The plating process could be available for other materials such as rubber sheets, cloths and papers.
Let’s not forget the biggest advantage with electroless plating is the metallization of the non-conductive surface of plastic materials. This could be the key process from the semi-additive process to generate ultra-fine traces in high density flexible circuits. The process is very simple – just dip flexible items in the plating bathes few minutes – that’s it!
In my opinion, the electroless plating is the key to build high density flexible circuits, but it is not easy to create stable plating conditions. Experiments in trial and errors activities are necessary to create these conditions. You could consider the process condition and handling as intellectual property owned by the manufacturer.
If you are interested in learning more about electroless plating, feel free to contact DKN Research with any questions or comments.

Dominique K. Numakura, dnumakura@dknresearch.com
DKN Research, www.dknresearch.com

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