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.

Micro-drilling

Micro drilling is basically the same as conventional drilling. Not only the size of the tool is smaller, but the method also stands for a precise rotation and a special drilling cycle. Therefore the surface of the hole is very smooth. The revolution speed used in micro drilling is much higher than in conventional drilling.

Lithography

Photolithography (also called optical lithography) is a process used in microfabrication to selectively remove parts of a thin film (or the bulk of a substrate). It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical (photoresist) on the substrate. A series of chemical treatments then engraves the exposure pattern into the material underneath the photoresist.

Wire bonding

Wire bonding is the primary method of making interconnections between a microchip, such as an integrated circuit, and a printed circuit board. Wire bonding can also be used to connect an integrated circuit to other electronics or to connect from one printed circuit board to another. Wire diameters start at 15 µm and can be up to several hundred micrometres for high-powered applications. There are two main classes of wire bonding:
  • Ball bonding
  • Wedge bonding
In either type of wire bonding, the wire is attached at both ends using some combination of heat, pressure, and ultrasonic energy to make a weld.

from the wikipedia article on wire bonding

Plasma bonding

For plasma bonding, plasma activation has to be done first with the intent to alter or improve adhesion properties of surfaces prior to coating, etc. Weakly ionised oxygen plasma is used and several processes take place. Plasma removes surface layers with the lowest molecular weight, at the same time it oxidises the uppermost atomic layer of the polymer. Oxygen radicals (and UV radiation, if present) help break up bonds and promote the three dimensional cross bonding of molecules. Oxidation of the polymer is responsible for the increase in polar groups which is directly related to the adhesion properties of the polymer surface. After having exposed the substrates to the oxygen plasma they are pressed together and then heated to a temperature slightly below the glass transition temperature. This establishes a durable bond between the two substrates.

Thermal bonding

Thermal bonding exploits the fact that thermoplastic polymers become soft at elevated temperatures close to the glass transition temperature. Therefore the substrates to be bonded are heated and then pressed together. As the polymer is soft, bindings between the two layers establish and make sure that the bonding lasts after cooling down the substrate. Care must be taken to choose the right temperature to bond the substrate without damaging the microstructure.

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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