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May 27, 2002

3 Min Read
Tiny molds, big marketing challenge

Tool_Mimotec_Slide1.jpg

Tool_Mimotec_Slide2.jpg

Weidmann Plastics Technology AG (Rapperswil, Switzerland), found Mimotec micromolds (top) reduce the surface roughness of its molded PC microfluidic devices (bottom) when compared to wire EDM. The microchannels in this part have a 100-µm width and height.

Imagine trying to tell moldmakers that they've been making molds the wrong way. That's the tough sale facing the North American rep for a Swiss manufacturer of micromolds. His task is to convince moldmakers that the best way to make micromolds is through the addition of material, rather than its subtraction.

His name is Robin Francois. A Swiss engineer who migrated to the U.S. to pursue a degree in manufacturing engineering, Francois formed his own company to represent small to medium-sized Swiss firms. He presently spends most of his time working for Mimotec SA (Sion, Switzerland) as its North American sales manager.

Mimotec has patented a photolithographic method for making micromold cavity inserts based on technology originally developed for the semiconductor industry. But Mimotec's process uses UV light. Its UV-LIGA technique is a lower-cost alternative to the original, higher-resolution X-ray-based LIGA technology. Not only that, but it's faster. Mimotec can deliver a 1 million-cycle micromold in about five to six weeks after receipt of a CAD file (see September 1999 IMM, pp. 79-80 for an initial report on the technology).

Mimotec's process also cuts into the more popular use of wire EDM to make micromolds. Francois says the 50- to 100-µm diameter of the wire used to cut plates is a limiting factor when it comes to true miniaturization. And it's not always possible to cut certain shapes sharply because of the wire's circular profile.

More For Less
 "How Mimotec makes molds must be understood by moldmakers if they are to take full advantage of the technology," Francois says. Yet, the UV-LIGA process is not that hard to understand. First, a glass/chromium mask of the part is created from the CAD file. The mask is used to build a master, layer-by-layer, from a photosensitive epoxy through exposure to UV light. Following post-bake curing, the finished master is electroplated with metal, usually nickel or a nickel alloy. The master is scrapped and the resulting mold cavity is lapped down to the finished thickness. Mold features stand .060 inch (1.5 mm) high. Parts are precise to within +/-1.5 µm. Multicavity and multiple single-cavity molds can be created in a single process.

Even though the process is easily understood and can present benefits such as reduced surface roughness, the key to its success lies in getting micro moldmakers to understand its potential. To this end, Francois has taken his show on the road, presenting papers at technical conferences. He also has been arranging personal meetings with micro moldmakers; with micromolders of plastics, metals, and ceramics; and with OEM design engineers serving markets like medical, life sciences, and IT that are hot for micro parts.

Contact information
Swiss Agents LLC
Brighton, MA
Robin Francois
(617) 283-9917
www.mimotec.ch
[email protected]

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