Originally Published EMDM September 2002
TECHNOLOGY NEWS
MICROTECHNOLOGYTooling-Free Process Benefits Production of Device Subassemblies
On the face of it, the Rapid Micro Product Development (RMPD) process created by MicroTEC GmbH (Duisburg, Germany) sounds strikingly similar to stereolithography. It is described as a tooling-free generative production technology that can build 3-D microstructures by depositing thin layers of polymer materials on top of each other. But that is where the similarity ends, according to project manager Helge Bohlmann. The capabilities of RMPD, which has been applied to the manufacture of medical products, far surpass those of rapid prototyping, he stresses.
While RMPD is certainly suitable for prototyping, more importantly it enables the tooling-free production of mass quantities of parts, says Bohlmann. "We can split the laser beam, thus allowing parts to be produced in parallel," he explains. "For some applications, we can produce up to 100,000 parts per hour."
Another differentiator is the technology's compatibility with a range of light-curable materials. "We have developed materials for use with RMPD—some on our own and some with partners—that have functional properties, not just form and fit," notes Bohlmann. RMPD-compatible materials have even been developed with qualities similar to PEEK.
MicroTEC's process also has led to advances in the surface quality of finished parts. "We are able to achieve a 1-µm resolution, and by adding postprocessing operations, we can attain nanoscale levels of roughness and near-optical quality," he says.
The technology enables a one-step process for the production of complex systems as well as their packaging. "The process can be stopped at any time—to insert a mechanical component, for example—after which you simply continue layering the material. You can generate electrical connections, if desired, and miniaturized components can be sealed onto any microstructure," says Bohlmann. He cites one recent project involving a blood-pump component to illustrate how the one-step process can improve productivity and repeatability.
"We developed the housing, inserted a die for the pressure sensor, and generated the interconnects in a single step," explains Bohlmann. "This one-step process replaced several manual assembly operations," he says, adding that it resolved handling problems with which the device manufacturer had been wrestling. MicroTEC manufactures the subassemblies in parallel on a 4-in. substrate. They are glued onto the device by the OEM.
In another recent application, the RMPD process proved to be an enabling technology for the manufacture of an electrode holder, a honeycomb-shaped device with tiny holes through which electrodes are inserted to monitor neural activity. "The tolerances were extremely tight," says Bohlmann. The holes, measuring 150 µm diam, had to be sufficiently narrow to prevent the electrodes from slipping out, but not so tight as to hamper their removal. In addition, the holes acted as precisely positioned spacers between the electrodes. "No other technology was able to achieve these results," says Bohlmann, "not even LIGA."
Norbert Sparrow
Copyright ©2002 European Medical Device Manufacturer
