Micro-Fluidics Interest Group

In the column on the right you will find useful information about the manufacturing of micro-fluidic devices.

Below you will find recent posts on the 4M Association which are considered to be of interest to the Micro-fluidics Interest Group.

Sputtering

Sputtering is a physical vapor deposition (PVD) method of depositing thin films by ejecting, material from a "target," which then deposits onto a "substrate". Sputtered atoms ejected from the target have a wide energy distribution, typically up to 10's of eV's (100000 K). The sputtered ions collide with the gas atoms that act as a moderator and move diffusively, reaching the substrates or vacuum chamber wall and condensing after undergoing a random walk. The sputtering gas is often an inert gas such as argon. For efficient momentum transfer, the atomic weight of the sputtering gas should be close to the atomic weight of the target, so for sputtering light elements neon is preferable, while for heavy elements krypton or xenon are used. Reactive gases can also be used to sputter compounds. The compound can be formed on the target surface, in-flight or on the substrate depending on the process parameters. The availability of many parameters that control sputter deposition make it a complex process, but also allow experts a large degree of control over the growth and microstructure of the film.

Water jet (WJ) and sinking electrical discharge machining

A water jet cutter is a tool capable of slicing into metal or other materials using a jet of water at high velocity and pressure, or a mixture of water and an abrasive substance. The process is essentially the same as water erosion found in nature but greatly accelerated and concentrated. It is often used during fabrication or manufacture of parts for machinery and other devices. It has found applications in a diverse number of industries from mining to aerospace where it is used for operations such as cutting, shaping, carving, and reaming.

Sinker EDM sometimes is also referred to as cavity type EDM or volume EDM. Sinker EDM consists of an electrode and workpiece that are submerged in an insulating liquid such as oil or dielectric fluid. The electrode and workpiece are connected to a suitable power supply. The power supply generates an electrical potential between the two parts. As the electrode approaches the workpiece, dielectric breakdown occurs in the fluid forming an ionization channel, and a small spark jumps. The resulting heat and cavitation vaporize the base material, and to some extent, the electrode. These sparks strike one at a time in huge numbers at seemingly random locations between the electrode and the workpiece. As the base metal is eroded, and the spark gap subsequently increased, the electrode is lowered automatically by the machine so that the process can continue uninterrupted. Several hundred thousand sparks occur per second in this process, with the actual duty cycle being carefully controlled by the setup parameters. These controlling cycles are sometimes known as "on time" and "off time". The on time setting determines the length or duration of the spark. Hence, a longer on time produces a deeper cavity for that spark and all subsequent sparks for that cycle creating a rougher finish on the workpiece. The reverse is true for a shorter on time. Off time is the period of time that one spark is replaced by another. A longer off time for example, allows the flushing of dielectric fluid through a nozzle to clean out the eroded debris, thereby avoiding a short circuit. These settings are maintained in micro seconds. The typical part geometry is to cut small or odd shaped angles. Vertical, orbital, vectorial, directional, helical, conical, rotational, spin and indexing machining cycles are also used.

Laser drilling

Laser drilling is a non-cutting machining method. The energy input by Laser is locally so high that the material ionises and evaporates. This plasma leaves the substrate and leaves a hole. The biggest advantages of this technique are the contactless machining and that the temperature stays very low.

Ultrasonic drilling

Ultrasonic drilling, also known as ultrasonic impact grinding, is a machining operation in which an abrasive slurry freely flows between the workpiece and a vibrating tool. It differs from most other machining operations because very little heat is produced. The tool never contacts the workpiece and as a result the grinding pressure is rarely more than 2 pounds, which makes this operation perfect for machining extremely hard and brittle materials, such as glass, sapphire, ruby, diamond, and ceramics.

Micro-sandblasting

Micro sandblasting uses air and micro particles to create structures on a micrometric scale. With this technique it is also possible to create holes when either the substrate is very thin (foil) or the method is applied longer. The geometry of created structures is defined by masks.

4th congress on Micro and Nano Manufacturing

Micromachines - Supporting the 4M Association

MDPI - Supporting the 4M Association

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Micro-Fluidics Interest Group

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