Column
The Power of the
Plasma Pen
Revolutionising adhesion in Electronics Manufacturing
I
n the electronics industry, plasma has already been adopted, PCB and semiconductor manufacturing to improves adhesion for Anisotropic Conductive Film (ACF) in flat panel display assembly, manufacture silicon photovoltaic cells and bond polymers with adhesives. Additional applications include enhancing the performance of inks,
dyes, potting materials, over-moulding and under-fill compounds. Plasma can also be used for surface cleaning of wire and die bond pads and gold-plated contact points to improve connections. “Plasma is a state of matter, like a solid, liquid, or gas.
When sufficient energy is applied to a gas, it becomes ionised, transitioning into the plasma state,” explains says Ryan Blaik, Sales Manager of Corona-based PVA TePla. “With precise application and control, plasma can alter surface properties of printed circuit board PCB and electronic components without compromising the underlying material.” “Tese techniques can boost the bond strength by up to 50 times
in certain cases,” adds Blaik. While there are multiple methods for applying plasma to a
product’s surface, one of the most popular and accessible are plasma ‘pens.’ Tese tools ionise gas, such as air or noble gases, under normal (atmospheric) pressure conditions using electrical discharges. “Te plasma produced from the tip of the pen can be applied
to very specific areas, or the entire part,” explains Blaik, adding that oſten plasma pens are incorporated into automated inline manufacturing processes or controlled by robots.
Solving adhesion challenges For most electronics applications, plasma treatments are utilised to increase the surface free energy of the material. Surface energy is defined as the sum of all intermolecular forces that are on the surface of a material, the degree of attraction or repulsion force of a material surface exerts on another material. When a substrate has high surface energy, adhesives and other
liquids oſten spread more easily across the surface. Tere are several mechanisms for increasing surface energy with plasma, including precision cleaning, chemically or physically modifying the surface, increasing surface area by roughening and by applying primer coatings. “Most materials are initially hydrophobic (they repel water). To
08 April 2025
www.electronicsworld.co.uk
make them bondable, their surface is typically modified to become hydrophilic (attract water),” explains Blaik. “Te plasma pen excels at making raw materials hydrophilic, enhancing their ability to bond effectively with chemical adhesives.” Te plasma pen is particularly effective for preparing
materials in overmolding processes, including polypropylene applications, dip coatings, or any method that involves encasing or encapsulating components. “Te key aspect is enhancing the surface’s wettability,” says Blaik.
“Tis allows the overmold to spread more effectively across the surface and minimises the formation of bubbles or air gaps caused by low-energy surfaces. Te result is a stronger and more reliable bond.” A common application of silicone overmolding is to safeguard
electronic boards against exposure to outdoor weather conditions. Without proper adhesion, silicone can begin to delaminate, not only at the edges of the PCB board but also in the form of small air pockets on, or around, components. Tis can lead to moisture ingress and subsequent corrosion or electrical shorts. Another challenge is the topography of a PCB, which means
silicone must bond to many types of materials, including polymers, metals, alloys, ceramics and the FR-4 board itself, all of which have unique surface energies and chemistries. PVA TePla developed a specific process starting with a precision
cleaning/surface activation treatment followed by the deposition of an inert chemical primer that serves as a tie layer for the overmolding and provides a uniform surface energy for the silicone to bond. Plasma generated from atmospheric air exhibits strong oxidative
properties, making it highly effective for surface cleaning and activation. Layers of absorbed molecules, such as oil and water on metallic surfaces, can be easily removed to improve adhesion. Atmospheric plasma can also be used to oxidise the surface of
plastics to promote adhesion of materials like inks, adhesives, or coatings.
Plasma Pen selection According to Blaik, the choice of atmospheric plasma pen, which varies between blown plasma and corona discharge, oſten depends on the specific application and the type of surface being treated. Blown plasma is created at atmospheric pressure and expelled
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