Fundamentals of Surface Activation

Although plastic can replace metals like aluminum and copper in many appliances due to its light weight, it cannot match the reliability of these metals. One way to improve the reliability of plastic is surface activation. Moreover, the technique can also be used to improve the physical properties of metals like conductivity, immunity to corrosion etc. Every industry relies on this technique for a number of purposes including metalizing, cleaning and improving adhesion.

What is Surface Activation?

Metal or plastic surfaces are treated with different chemicals, plasma or UV rays which energizes molecule and changes the atomic structure of the material up to the depth of few microns. It increases the polarity of the surface being treated thus increasing its wettability. On a commercial scale, surface activation is mostly used to enhance the surface tension of metals and plastics. In automobile, medical devices and aircraft industry, surface activation is used to make the material suitable for printing calibrations and adhesion.

Methods of Surface Activation

While there are a number of ways to treat metal surfaces, some of the most commonly used methods of polymer and metal activation are:

1. Chemical Activation

Polymers consist of hydrocarbons which have low surface tension, but for adhesion high surface tension is required. One way to improve the surface tension of metals and plastic is to form different functional groups on the surface of the material being treated. Mostly strong acids are used as activation agents. The technique is cost-effective but the by-products formed in the chemical activation are not volatile. So it is recommended to quickly clean the surface of the material after activation.

2. UV Exposure

Another way to increase the surface tension of a material without changing its properties is the use of ultra violet radiations. Usually this method of surface activation is used to increase the conductivity of metal surfaces. When a metal is exposed to high intensity UV radiations, the surface particles gain energy and jump to the excited state. Although UV exposure is one of the most reliable ways of improving the properties of metals, it is quite expensive.

3. Plasma/Corona Treatment

Unlike chemical activation, plasma/corona treatment enhances the surface tension of a material without changing its properties drastically. Plasma is generated by oxidizing a hydrocarbon fuel at a very high temperature in the presence of air. When plasma particles react with a metal or plastic surface they energize the surface molecules thus increasing their mobility. This turns a non-polar surface into a semi-polar surface with improved wettability.

Significance

Surface activation is not only a commercial technique of increasing surface tension of different materials, but it is also used in IC fabrication industry for improving the properties of semi-conductors. According to modern research, this technique can considerably reduce the cost of IC fabrication by improving the conductivity of cost-effective semi-conductors. Moreover, the technique is also very common in medical device manufacturing industry, where it is used for printing calibrations on syringe barrels, medicine bottles etc. Automobile manufacturers also use this technique to strengthen the bonding between different parts. The technique is also used for reducing the risk of corrosion in metals.