Empa scientists have created the next generation of watch springs. These springs are not made in the traditional manner using Nivarox wires; instead, they are deposited electrochemically into the required form thanks to the use of an aqueous saline solution. This new design produces springs that are tiny, powerful, and extremely durable.
The process starts with a silicon wafer, much like the ones found in computer chips. The wafer is coated first with a gold conductive layer. Next, light-sensitive paint is applied in a very thin layer. Scientists then project the shape of the spring onto it. The illuminated parts of the paint are carefully etched out. Finally, the metallic alloy of choice is electroplated directly onto the gold base, which acts as a conductive layer.
The technique is far from simple; a single error in temperature can wreck the entire process. The spring gets a dip in a galvanic bath mixed in with organic additives. Ultimately, scientists hope to dissolve the springs right out of a galvanic mold. To achieve this, scientists check the spring molds with a light microscope to determine if they are properly filled with metal. Next, the top of the mold must be fine-polished. This guarantees the springs have a uniform, defined thickness.
Scientists check the results using X-ray fluorescence analysis. Lastly, oxygen plasma is utilized to remove the paint. A strong alkaline solution helps to etch away the remains of the silicon wafer. The springs are deposited into a specially designed washing machine for several hours. This helps to remove any unwanted ridges or extra metal pieces. The final springs are then sent to the watch lab, where they undergo prototype production.
Although these springs could very soon be used in commercial timepieces, that is not the ultimate goal of the Empa scientists. Instead, they are focused on the details of the miniaturization process. After completion of the springs, researchers investigate the specific mechanical properties of each component. By studying the ways the parts interact and respond to different materials, researchers can more easily adjust and modify them to suit their specific needs.
Scientists hope to streamline and improve this system for creating springs. They also intend to find ways to speed up the process, so as to make it more viable for use in commercial production of small and powerful timepieces.