Plasma Cleaner - Active Principle

A plasma cleaner usually employs oxygen and/or argon to clean or desmear substrate surfaces. In a low pressure plasma system, oxygen acts to oxidize contaminant species which are then removed from the surface by vacuum and drawn out of the system by the vacuum pump. Argon is a large and inert gas and functions more like a molecular sand blaster. In the correct energetic field it will be accelerated to the contaminated surface and nock contaminates into the vacuum to be drawn away by the vacuum pump. There a number of low cost plasma systems that can be used as a plasma cleaner.

Plasma Cleaner - Use

A plasma cleaner can be used to clean a variety of materials for a variety of applications. One common application is desmearing. In printed circuit board (PCB) fabrication this is the process of cleaning the PCB after mechanical machining. PCBs often need holes drilled through them for mechanical fastening of diodes and the like. This drilling process leaves smear, burnt polymer residue, that would cause a short circuit if not removed. Low pressure plasma is ideal for desmearing since the smear is obliterated and then drawn from the surface by action of the vacuum pump.

Low Cost Plasma Systems

Low cost plasma systems are well suited for many plasma process applications that do not require an exact degree of control such as general plasma cleaning. Low cost plasma systems do not contain gauges or sensors that are needed for more sophisticated plasma processing. In the low cost systems one can approximate the plasma density and pressure by the color and color density of the plasma glow viewable through the glass port.

Low Cost Plasma

Low cost plasma system users can quickly learn how to visually determine when a plasma treatment system is producing adequate plasma to achieve a desired outcome. Plasmas are often purple with the plasma density and brightness being proportional to amount of gas being used and effectiveness of the vacuum. Since there is an optimum gas to vacuum ratio and the vacuum pump operates at a fixed rate, the gas can be adjusted to achieve the maximum color intensity. The electrode voltage is also fixed in low cost plasma systems and thus does not need to be considered.