Researchers at the Karlsruhe Institute of Technology, Germany, have created a three-piece 3D puzzle, with each piece less than 1 mm in size, which, they say, may be put together to make the smallest puzzle in the world. To create it, the researchers used a new process to manufacture the microstructures by casting molds at the Institute’s synchrotron source.

Series production, combined with microscale precision, is used to produce tiny components for watches, engines, or medical products. The researchers say that their process could be used to create large series of the smallest parts using injection molding with very high accuracy.

The LIGA process, which consists of lithography, electrodeposition, and molding, can be used to produce microstructures from various metals, ceramics, or plastics. The process, developed in the 1980s in Karlsruhe, has been modified as the LIGA2.X process to allow for inexpensive series production of plastic microparts of less than 0.5 cubic millimeters in volume.

While a substrate plate linking all molded parts had previously been required for demolding, the new process works without this layer, allowing for direct and separate injection molding of microparts.

The injection molding tools applied in LIGA2.X consist of three plates to demold the parts from the molds and four LIGA molds that can be installed in a tool plate and exchanged. By moving the first and second molding plate away from each other, the part is released from the LIGA mold. With the help of the third plate, the gate is removed properly. To produce the microstructured LIGA molds with the help of X-ray deep-etch lithography, the scientists used a synchrotron source on campus.