Ion beam machining

Ion beam machining is generally a surface finishing process in which the material removal takes place by sputtering of ions.
It is also called the etching process. This is a different process from electric discharge, electron beam, laser beam and plasma arc machining. 

Working Principle :

This process is very simple. It consists of bombarding the work with accelerated ions which collide with the surface atoms of the work. Each bombarding ions, as a result of collisions, dislodges surface layer.
It consists of an electron gun discharging free electrons into a chamber filled with argon gas. The gas is ionized by electrons. The top of the chamber is known as ion-beam generating apparatus. At the other end, the workpiece is fixed to a table which can be oscillated and rotated so that different points on the work surface can be subjected to an ion beam.

Accuracy :

• Etching rates vary up to 2000 Å per min.
• Accuracy of the etching process is considerably high mainly due to the small amount of material removal.
• Tolerances in the vicinity of + 50  Å  to - 50  Å  are possible.

Applications of IBM :

• It is applied mostly in micro-machining of electronic components.
• Typical materials that can be etched included glass, alumina, quartz, crystal, silica, agates, porcelains, numerous metals, cermets and oxides.
• It is also be used to deposit materials such as platinum, tungsten and silicon oxide insulators on another material substrate.

Advantages of IBM :

• IBM is almost universal.
• No chemical reagents or etching are required.
• Etching rates are easily controlled.
• There is no undercutting as with another chemical etching process.

Disadvantages of IBM :

• IBM is relatively expensive.
• Etching rates are slow.
• No heat is generated so there is little possibility of some thermal or radiation damage.