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Partnering July, 2020

Outsourcing Plasma Treatments for Surface Modification

By Jeff Elliott

clean surfaces, apply protective coat- ings, and enhance surface wettability. For many, the application of plasma- applied coatings and surface treat- ments can play a significant role in new product development. As a result, the industry is ag-


gressively investigating and applying plasma to products that require a treatment step for cleaning and de- contamination, surface conditioning or to promote adhesion.

lasma treatments are often used to improve adhesion of dissimi- lar materials, deposit coatings,

“Manufacturers are continuous-

ly looking for unique ways to techno- logically advance their products to be the market leader,” says Michael Barden of PVA TePla. “Often, the top-tier products incorporate some form of advanced coating to function- alize the surface.” However, when manufacturers

want plasma-treated parts or compo- nents without having to invest in in- house equipment, the solution is to utilize a contract processor. In this approach, parts are sent in, treated and returned within a few days, or

up to a week for larger volumes. For small or infrequent batches, this can lower the price per part significantly.

Common Applications The most common application

for contract processing is to improve the bonding power of chemical adhe- sives, whether metal to plastic, sili- con to glass, polymers to other poly- mers, biological content to microtiter plates, or even bonding to PTFE. It also is used often to clean, activate, chemically graft, and deposit a wide range of chemistries on the surface of parts or components. According to Barden, many con-

tract processing projects involve using plasma to create a high-energy surface to resolve bonding issues with chemical adhesives. Plasma treatments are utilized to increase the surface free energy of the materi- al to be bonded. When a substrate has a high

surface energy, it tends to attract. For this reason, adhesives and other liquids often spread more easily across the surface. This wettability promotes superior adhesion. Adhesion promotion can be

achieved by increasing the surface free energy through several mecha- nisms, including precision cleaning, chemically or physically modifying the surface, increasing surface area by roughening and primer coatings. The net effect is a tremendous im- provement in bonding. In some cases, bond strength can be improved up to 50 times. “When a surface is really hy-

drophobic, like Teflon, it is very diffi- cult to bond to it,” says Barden. “If you apply a liquid or adhesive, by na- ture it pools and will not spread ef- fectively across the surface.” There are several plasma meth-

ods employed to increase surface en- ergy, including physical and chemi- cal plasmas along with PECVD coat- ing surfaces. Silicon, another materi- al widely used in the industry for its low surface energy, often is utilized as an over-molding compound to pro- tect electronic boards from extreme conditions. Unfortunately, the topography

of a PCB means the silicone must bond to many types of materials, in- cluding polymers, metals, alloys, ce- ramics, and the FR-4 board itself, all of which have unique surface ener- gies and chemistries. Without proper adhesion, sili-

cone can begin to delaminate, not only at the edges of the PCB board but also in the form of small air pock- ets on, or around, components. This

can lead to moisture ingress and sub- sequent corrosion or electrical shorts. “In terms of surface energy, the

best strategy is to deposit a thin film coating over everything so the sili- cone only has to bond to one surface energy,” says Barden. “A process using plasma can basically harmo- nize all of the many surfaces and turn it into one.”

Expertise in Plasma Treatment Ideally, contract processors

should bring a combination of re- sources for plasma R&D and experi- ence with many customer types in markets beyond medical devices. Working with a contract processor

The net effect of plasma treatment is tremendous

for bonding. In some cases, bond strength can be improved up to 50 times.

also has advantages when it comes to tapping into the years of technical expertise applying a variety of plas- ma treatments. This can often speed research and development efforts sig- nificantly. “Because we see the similarities

in the types of materials being treat- ed, our experience allows us to devel- op and optimize custom proprietary processes quickly and efficiently, sav- ing our customers significant time and money in the development phase of product development,” says Bar- den.

However, with a background in

plasma equipment manufacturer, the contract processor can provide critical insight on validation, produc- tion methods, fixturing, as well as hardware and software modifica- tions.

Depending on the application

and complexity, customers face strict industry requirements and often have unique processing require- ments,” explains Barden. “Generally, we have existing solutions for most of the things, so usually that is not a concern.” As for turnaround time, it de-

pends on the quantity and complexi- ty of the processing. A single batch can be completed in an hour, and larger batches of a few thousand parts can be treated and shipped

within a day or two. Contact: PVA TePla America,

Inc., 251 Corporate Terrace, Corona, CA 92879 % 951-371-2500 E-mail: Web: r

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