Taking advantage of the synergy effect between UV-lithography and electroforming technologies, we are able to produce precise microparts.
UV-lithography meets the demand for high precision features and the feasibility for high industrial throughput as well. This additive technology involves the structuring of photoresist on top of a silicon wafer in the first place. By a subsequent electroforming step the resist cavities are filled with metal. In the last step, the silicon wafer and resist material are dissolved and the resulting, freestanding microparts are obtained.
The advantages of this technology have been demonstrated with a stable and robust process chain over 20 years, mainly for the watch industry. As soon as their engineers have recognized the design freedom of the parts, a big breakthrough regarding aesthetical and mechanical aspects has been reached. The whole process is very fast and first Microparts can be delivered after five weeks at a reasonable price.
Form & Dimension:
- Design freedom of the parts
- Small form and position tolerances = High precision
- Sidewall angle 89 - 90°
- Multifunction in one part (e.g. spring properties combined with gear elements)
- No tool shape influence
- Low surface roughness of sidewalls (Ra compared to conventional machining (μEDM, laser cutting, etching, punching, micro-milling)
- Different surface qualities on one side available (lapped, ground, polished)
- Material selection to customer needs
- Material combinations level by level (e.g. different CTE values, different wear resistances)
- No segregations
- Solderability (soft Ni and NiP12)
FEATURE SIZES & TOLERANCES
The UV-lithography produces a structured resist material. The subsequent electroforming step is producing an exact copy of that negative form, including shape and position tolerances. So the precision of the UV-lithography is the limiting factor in the whole process chain, leading to the following dimensional properties / limitations for the microparts:
- The maximum material thickness is 800 μm. Several layers can be applied and independently structured. So it is possible to create 3D-features.
- The resolution is defined by the form factor, which is the ratio between feature height and width. The value of it is approximately ten.
- The tolerances related to the part size are 3 μm for mm-sized-parts and 5 μm for cm-sized-parts.
Nickel is the most common electroforming material. It can be delivered in a broad range of mechanical properties. The achievable hardness is between 350 and 600 HV0.05. The harder the electroformed parts are, the lower the ductility will be. The value is 15% for the soft Nickel and it goes down to 0.1% for the hardest parts.
It is a nickel alloy containing app. 12% by mass phosphorous. The special characteristic of the parts is their amorphous state and hence, the parts are non-magnetic. The hardness as deposited is 550 HV0.05, which can be adjusted up to 1000 HV0.05 by means of heat treatment. But the hardness increase goes along with a crystallization process, making the material again magnetic.
Nickel-Cobalt-alloys are commonly used for electroforming of micro- and nanostructured mold inserts in the injection molding technology ( plastic parts). The Cobalt-content is up to 35% by mass and the achieved hardness is 550 HV0.05.
Copper is widely used as electroforming material in MEMS technologies, where high thermal conductivity of the material or low electrical resistivity is needed. It is used for microcoils (sensor technology) and for heat exchangers (cooling devices for laser diodes).
Is a precious metal, which comes along by a naturally given high corrosion resistance. Due to the low hardness values, it cannot be used as construction material. Therefore, the main field of application is the production of X-Ray absorbers.
Other materials and alloys (e.g. NiFe, Microform-Nickel-Iron Alloy, Microform-Chrome) can be delivered upon request.
Possible applications for the microparts can be found in different sectors, reaching from single parts to whole microsystems:
Sensor / electronic devices
- Planar microcoils
- Micro heat exchangers
- Micro reed switches
- Fork contacts
- Spring contacts
- HF-connectors planar/coax
- Watch parts
- Toothed racks
- Spinning nozzles
- E.g. masking in semiconductor industries
- Dot metallization
Please do not hesitate to contact us with your specific problem! – It will be a pleasure for us to give you technical advice and to finally solve your problem.
Steiger Galvanotechnique SA
Route de Pra de Plan 18
Tel. +41 (0)21 948 24 24
Fax +41 (0)21 948 24 20
Samuel Estoppey, Management
Jean-Claude Puippe, Head of R&D
Christian Benkel, R&D-Engineer Electroform Technics