SACE – Spark Assisted Chemical Engraving

SACE – Spark Assisted Chemical Engraving – is an innovative solution to machine glass substrates without material alteration, keeping transparency properties with high accuracy.

SACE technology explanation sketch

Principle / Function

Spark Assisted Chemical Engraving (SACE) is a hybrid technology, that combines chemical etching accelerated by thermal process. SACE allow to machine glass and all material that contain silicon dioxyde. This technology preserves material while machining burrs- and cracks-free without leaving any deposits on the surface. Operations with aspect ratios of up to 1:10 can be realized.

Micro-holes with a depth of millimeters can be drilled in a few seconds and channels of several hundred microns deep can be produced without difficulty. It is also possible to cut glass over a thickness of a few millimeters. All these machining methods can be realized directly, without any intermediate process. And no post processes are necessary after machining.

Our objective is to increase the fundamental knowledge about material removal process with the aim to increase repeatability and precision of machining and develop strategies to functionalize glass during machining.

The picture shows a gas film that is electrochemically formed and insulating the tool from the electrolyte. This gas film becomes visible after about 5 ms.

Sparks are visible through the gas film, as a result of the insulation, heating up the tool locally.

Gas film that is electrochemically formed and insulating the tool from the electrolyte
SACE technology diagram temperature versus KOH Etching rate

Why using this technology?

Glass micro-maching very often comes to its limits when requirements of no microcracks, no deposits and no burrs are necessary for post-processing e.g. like fusion bonding. Posalux SACE technology overcomes these issues. Our built-in patented “zero force” technology regulates vertical forces such that there is never a touch of workpiece and tool. SACE is a hybrid process, chemical and thermal, which does not influence the material structure while maching the required geometries. Various processes are possible like drilling, cutting, engraving, and structuring that are normally very difficult to machine.

Configuration of different types of holes that are possible to machine:

  • cylindrical holes
  • blind holes
  • conical holes ( TGV)

Various examples of milling and engraving:

  • free formed shapes
  • height controlled structures ( pyramid)
  • roughing or finishing
Through hole of 500 microns diameter drilled by SACE process
Blind hole of 150 microns diameter drilled by SACE process
Conical shaped hole drilled by SACE process
Free from milling of 150 microns width made by SACE
2.5D pyramid depth controlled operation by SACE process
Smooth surface cutting by SACE process

Multitool operation in order to increase productivity

Plate with milling holes matrix by SACE process
Multitools SACE in action
Multitools SACE in action with visible sparks
Multitools close look used by SACE process


Machining of SiO-based non-conductive material, e.g. glass, quartz, silicon etc. Glass is optically transparent, highly chemically inert and sterilizable. The burr and micro-crack free process makes it suitable to downstream processing e.g. fusion bonding.

Medical industry:
  • Microfluidic devices
  • Multi-layer mixer
  • Lab-On-Chip
  • Chemical (mixer chips, micro-reactor)
Electronic industry:
  • Drilling of Through Glass Vias (TGV)
  • Optical PCB
  • Micro-Electro-Mechanical-Systems (MEMS)
Watch industry:
  • Watch dial glass
  • Mechanical parts
  • Decoration
Glass substrate with micro holes drilled by SACE process
Tool for molding
Micro holes in glass substrate drilled by SACE process
Tool for molding
Micro fluid system in glass substrate machined by SACE process
Microfluid system
Watch dial in glass machined by SACE process
Watch dial
Medical device system sample in glass substrate machined by SACE process
Medical device
Thick micro fluid system in glass substrate machined by SACE process
Thick microfluid system

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