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ReviewJ. Jpn. Soc. Colour Mater., 90〔8〕，282–287（2017）

Atmospheric Pressure Plasma Jets for Surface Activation Prior to Bonding and Painting
Christoph Regula＊,†, Joerg Ihde＊ and Sergey Stepanov＊＊ Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Str. 12, 28359 Bremen, Germany†Corresponding Author, E-mail: Christoph.Regula@ifam.fraunhofer.de(Received June 29, 2017; Accepted July 27, 2017)

Abstract
Nowadays the performance, quality, lifetime and most important reliability of many technical products is affected by the adhesion grade ofapplied coatings and adhesives on the substrate materials. However, due to production related contaminations and/or low surface free energyof the materials, the surface state of the substrate is often inappropriate to be direct bonded, coated or painted. Thus, these surfaces have to be
pretreated correspondingly, e.g. cleaned and/or activated, in order to promote the desired adhesion formation.
Along with the increasing use of hybrid-materials in automobile production, aircraft structures as well as new electric engines and highpower electronics, classical wet-chemical pre-treatment processes are often no longer applicable. To improve the quality and long term
stability of the adhesion on different substrates, atmospheric pressure plasma (APP) jets can play a key role for many industrial applications.
The activation of polymers due to the formation of hydrophilic functional groups, e.g. on thermoplastic materials, the removal of instable
oxide layers, e.g. from copper lead frames, and also the precision cleaning for the removal of thin contaminations are typical applications ofAPP-Jets nowadays. The variety of available jet systems allows high speed treatments faster than 100m/min but also handheld applications
for repair and small batch production of thermal sensitive materials. The aim of the paper is to show the spectrum of typical APP-Jets and togive an overview on possible technical applications.
Key-words: Atmospheric pressure plasma, Jet sources, Adhesion, Adhesive bonding, Cleaning, Activation, Surface

1．Introduction
The increasing demand for light weight construction
and challenging design requirements coming in all modern
industries lead to the mixture of dissimilar materials, e.g.
metals and polymers, which have to be properly joined
and protected against environmental degradation properly.
For combined materials with different thermal expansion
coefficients and/or the need to prevent electro-chemicalcorrosion, e.g. for carbon-fiber-reinforced polymers(CFRP) combination with aluminum, adhesive bonding in
combination with adapted paint processes are a suitable way
to overcome these problems.
To maximize the advantages of the adhesive bonding
and painting processes, the surface status of the substrates
is a critical issue. The increasing use of thermoplastic
materials like PPS, PEEK in automotive industry or ETFE inarchitecture elements leads to the demand of flexible, inline
Christoph RegulaDr. Christoph Regula studied physics in Hamburg( Germany ) with focus on thin film deposition andprocesses ( 2002-2008 ), PhD for chemistry in 2011
(Bremen, Germany) in the field of deposition of thin film
coatings by atmospheric pressure plasma technology.
Working at IFAM since 2008 in the Plasma and Surface
Technology department on surface cleaning, activationand functional coatings using plasma technologies.
Special focus is the development of thin film coatings
deposited by inline plasma enhanced chemical vapor
deposition (PE-CVD) technologies.

© 2017 Journal of the Japan Society of Colour Material

compatible pre-treatment processes. These processes shallbe easily adapted to existing production chains in order toreduce pretreatment costs, avoid the use of solvent based
systems and minimize energy costs.
Thus, APP Jet systems e.g.1,2), are highly attractive forthis purpose, since these have been developed and tested
successfully for real technical applications during the last
decade.
These APP-jets are compact systems which can beimplemented easily into existing production lines. Dueto the diversity of the commercially available APP-jetsystems, ranging from high power devices down to compact
handheld devices, individual technical solutions can betailored considering specific product and product demands,e.g. productivity, process cycle times, processing costs etc.
In particular, the APP -Jets can be used for the activationof polymers3) by the incorporation of chemical bondedhydrophilic groups4), which e.g. enables the painting of PPS
with water-based paints or the adhesive bonding of ETFE
film materials used as cladding in the National Aquatics
Center known as the Water Cube in Peking. During the last
20 years, the Fraunhofer IFAM in Bremen (Germany) has
been extensively investigating different APP-jet systems andtheir potential applications for environmental friendly, VOC
reduced and industry-relevant pre-treatment processing priorto adhesive bonding or painting.

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