ATOTECH ~ ~ ~ T S ~ H ~ ~ ~ GmbH, BERLIN

Advances in Methods for Plating on Plastics Tout Advantages over

Convent iona 1 Technologies Alternative plating procedures negate the need for chromic sulfuric acid, resulting in a more environmentally friendly

process for electroplaters.

lie beginning of commercial metal plating of plastic materi-

als dates back to tlie 60s. This was the time when ABS (acrylonitrile- butadiene-styrene) was discovered as a basic material for an adhesively strong coating with outstanding moulding characteristics.

Today, electroplating of plastics is-more than ever-subject to change. While the electroplating of plastics, with usually ABS and ABC/PC blends as the substrate, is applied for decorative plating tech- niques in the industry, functional and decorative coating of innova- tive materials is increasingly gain- ing significance.

This is a great challenge for today’s plating companies, since these innovative materials cannot be coated satisfactorily using tlie conventional tech ni q Lies (e. g . , through the use of cliroinium-sul- furic acid). Therefore, innovative systems and processes, which take into account these new challenges, had to be developed. This means, apart from conventional coating technologies, the implementation of alternative processes.

The 90s saw a revolution in metal plating of plastics: The “Futuron” technology or “Direct Metallization,” developed by Atotech, for tlie first time allowed direct coating of plastic surfaces.

The main benefit of Futuron over conventional techniques is seen in

at all the steps inherent ss metal-plating become

To date, these steps

were absolutely necessary for tlie plating of a dielectric material. In the conventional process, electro- less “chemical” nickel and copper baths were used after the plastic

Figure 1: Process Noviganth AK vs, Futuron.

www.metaIfinishing.com March 2007 I metalfinishing I 35

Fig. 2 -ABS and ABS/PC after the chromic-sulfuric acid, PA after swelling.

FINISHING EQUIPMENT SYSTEMS Auto Tecliiiology Cotnpany acquired UNIFIED CQlJIPMENl SYSTEMS (UCS) foniierly UJ)YI I f E EQ1JIf’MI N 1 CO Stniidard, custom and “hard to find” parts for all UDYLI I f inachiiies are availnble using the origiiial engineering and design data The Company w i l l continue to engineer a i d manufacture the CYCLLMAS I kK, SENIOR SPLIT-KAlI , C and b

Enviroimental ’I est Chambers Cyclic Corrosion Chambers Salt 1 og & Huiiiidity Chambers Walk-in, Drive-in and Multi Gas test chambers

Centrifugal Dryers 75 to 800 pound capacity Choice o f m sizes Heating available for fast drying

Auto Technology Company 20026 Progress Drive Strongsville 0 Ohio 44149

nww autotcchiiolonv net 0 salesiiijautotcclinologv net fel 1-800-433-8336 0 Fax (440) 572-7820 !

I I

Circle 066 on reader information card or go to www.metalfinishlng.com/advertisers

WW ORRCOM

239 East Stephenson Street, Freeport, IL 61032 (Tel) 815-235-6020 (Fax) 815-232-2150 sonic@upcorp.com

Circle 067 on reader information card or go t o www metalfinishing com/advertisers

surface had been prepared and acti- vated. The galvanic coating was then applied to the electroless chemical deposition.

With Futuron no electroless chem- ical metal plating is used. A poteii- tial source of error is thereby elimi- nated in the plating-on-plastics process as well as the associated costs to operate such a process.

S o far, chromic sulfuric acid has been used as the etching process oil a large scale, and many years later plating of ABS and ABS/PC is still based on the same principle.

By the use of alternative etching solutions it is now possible to apply adhesively strong coatings on a mul- titude of plastics, which had been previously unable to electroplate. An organic solvent is generally used as the swelling medium combined with a subsequent conditioning step. These process steps form the basis for adhesive metal plating.

In recent years, polyamide (PA) has proven to be a plastic material suit- able for a great variety of industrial applications.

Polyamide is inherently stronger and more rigid than ABS or ABS/ PC. As a thermoplastic, polyamide can be readily processed froin a liq- uid state. It has temperature stabil- ity from -30°C to around 110°C. In addition to this, it has excellent low-friction behavior and good thermal coefficiency expansion characteristics with the metals that are later electroplated. Polyamide

March 2007 I metalfinishing I36 www.metalfinishing.com

has high impact strength, a small amount of memory (elasticity), is abrasion resistant, and vibration reducing l.

The low-fusion viscosity of polyamides makes them easy to work. Put simply, polyamides have outstanding physical properties, combined with low weight and also low manufacturing costs.

Polyamide is differentiated by the number of polar amid groups (PA 6, 11, 12, GG), which, at the same time, indicate the difference in the mate- rial compared to ABS-/ABS-PC blend plastics. Although the princi- pal application of chromic-acid- etching solutions attacks polyamide to a certain extent, it does not obtain the required deco- rative results. Another influencing variable are the fillers (in general, minerals such as glass fibers)

Circle 031 on reader information card or go t o www.metalfinishing.com/advertisers

www.metalfinishing.com March 2007 I metalfinishing I 37

which-depending on their condi- tion-must be considered in the pre-treatment (Figures 2 & 3).

The elimination of chromic sulfu- ric acid as the etching solution and the short but reliable pre-treatment of new substrates with a new swelling and conditioning solution is a further advantage of this novel process. The sweller and the coinpo- sitioii of the subsequent solutions must be carefully tuned, since only carefully optimized parameters ensure good metal plating, with good adhesion.

A process that is suitable for one type of plastic may be unsuitable for another, as each individual plas- t ic material behaves differently. Even the slightest modifications within a plastic type may give devi- ating results at equivalent pretreat- ment methods. Both various pig- ments and a diversity of fillers can

Fig. 4 - Application example automotive industry.

Save Time and Money!!! rs

Eliminate disposable media

Backwashing process performed

Double your filter efficiency and

All-plastic corrosion resistant

replacement costs

minutes

increase productivity

construction ideal for many aggre a p p I i ca t i o n s

AF SeriesTM Corrosion-Resistant Filters

Global Filtration Systems, Inc. iiol,llc,iy ~lv ls lon Aspill A i l l c l w

Rt 25 PO. Box 10, Tamworth, NH 03886 Phone. 603-323-7777 9 Fax, 603-323-7007 www alobalfiltratlonsvstems com * E-mail info@ qlobalfiltrationsystems com

Circle 008 on reader information card or go to www.metalfinishing.com/advertisers Circle 035 on reader information card or go to www.metalfinishing.com/advertisers

March 2007 I metalfinishing I 38 www.metalfinishing.com

influence plastic characteristics. Another influence, not to be under- estimated, is the molding of the plastic material prior to the plating process. The development of new processing technologies and equip- ment will lead to potential savings in terms of raw material and energy.

Atotech’s new polyamide pre- treatment method, Noviganth PA, offers many benefits for the electro- plater, as no chromic-sulfuric acid is needed. The system is distin- guished among other things by its ease of use and short but reliable pre-treatment. The system is espe- cially suitable for mineral filled polyamides, which, for example, are used for door handles in the auto- motive industry. Thus, plating a strong but light plastic, such as polyamide, is seen as a contribution to the automotive industry’s endeavors to reduce the weight and

fuel consumption of vehicles. Smoothness of the surface (e.g.,

“orange skin”) iii the plating of plas- tics plays an important role for appearance and adhesion of finished parts.

With newly developed polyamide resins, such as Toyobo T772, the surface finish of the plated part resembles that of ABS or ABS/PC.

This swelling and conditioning step should ensure uniform rough- ening and functionality of the sur- face. These steps form the ideal basis for the subsequent activation of the surface with precious metal ions, usually palladium-containing processes. Only an optimized pre- treated surface will result in per- fectly adhesive metal deposition. In an activation step, palladium will be adsorbed on the surface. The reduction step reduces the palladi- um, while a catalytic activation of the surface is generated on the plastic, which can then be nickel- plated.

The present method shows that a highly adhesive and decorative coating of polyamides can be ensured. Apart from extending the spectrum for production with regard to the above plastics, further advantages are achieved with the in o di fi e d o f polyamides. For example, better coating results are obtained not only through the fact that chromic-sulfuric acid is no longer necessary technically, as in the case of conventional processes, but also with respect to ecological concerns in the use of Cr(V1) or hexavalent chrome.

Atotech’s processes have gained a worldwide reputation as proveii methods for the metal plating of ABS, ABS/PC blends, PA, PC, and other plastics, and they are quali- fied by many major automotive manufacturers. Besides the auto- motive applications, numerous major manufacturers in the sani-

p r e- t r ea tm en t

You’ve got anodizing problems. \Ve’ve got anodizing solutions custom-designed to meet your needs, your d e l i ~ q ~ schedule and your cost parameters.

First, we listen to porir rcqniremeots. Then, using state-of-the-art Cornputer i\ided Design, oiir engiiineers input those requirements 8s part of the design process to produce wliatjou need to precisely fit your operation, whetlier it is

titanium or aluiiiinum r;tcks or fasteners. And solving ixoblems at

away So call or c k k today Clieckoiit the F,4Q’\ 111 onr Technical Data wtion

~

4QYears of Serving Customers

Northbrook, IL 60062 CSA Toll-free 888-922-0052 (outcidc IL) Dit ect 847-111-4841

E-Mal tiisrewski@VuIcaiiiuin coin ww7w.Vulcanium.com

Circte 053 on reader information card or go to www.metalfinishing.com/advertisers Circle 014 on reader information card or go to www.metatfinishing.com/advertisers

w . m e t a l f i n i s h i n g . c o m March 2007 I metalfinishing I 39

tary industry have full confidence in these processes. The described systems are associated ~ i t h highly adhesive, premium-quality, and extremely decorative coatings. Users will truly benefit from these characteristics, as economic and technical advantages are realized.

1. H. Domininghaus, Die I<unststoffe und ihre

Eigenschaften, 5. lieu bearbeitete und erweiterte Auflage, Springer; (1998)

2. Witt, W., Kunststoffe 9, S. 498- 504; 1983

3. Fahnler, F., Merten, F. Kuiiststoffe 75, S. 157-163; 19S5

4. Kunststoff-Metallisierung, Eugen G. Leuze Verlag, Saulgau Wiirtt; 1991

5. Brandes, M., Dr. C. Fels, MO Nr.

6. Technische Dokumentation 9; 2002

Atotech Deutschland GmbH; 2003.

Manola Brander has been involved with surjiacc technology since 1989 She pined Atotech Deutschland GmbH zn 1990, first working zn research and develop- naent, and later swztched to woi*ldwzde pi-oduct management of plating on plas- tics and mpperprocesses. For more info!.- matzon, contact Atot-ech Deatschland GmbH 90537 Feucht Bernd Monch Pi.oduct Marketzng Manages POP Deutschland Tel 0 91 28 / 725-425, (fax) 0 91 28 / 725-421; (e-mail) b e r n d . m. o e n c h @ a t o t e c h . c o m , www atotech.com.

Remember when.. . - “Customer Service” really meant ~ u s t ~ m ~ r Service7

- You didn’t need a minimum order7

- Your supplier formulated products for your needs?

- Your lab results were timely, free and meant something7

-A real person answered the phone?

fashio~ed, but at we sf8 remember when

Circle 65 on reader information card or go to www.metalfinishing.com/advertisers

oating Thickness Measurement Copper thickness measurement on pc-boards

including copper thru hole readings. Thickness measurement of metallic coatings

over nuts, bolts, and screws.

re! www. Fisc h e r-Tec h no I ogy. co m I -800 - 24 3 -84 I

Circle 016 on reader information card or go to www.metalfinishing.com/advertisers

March 2007 I metalfinishing I40 www.metalfinishing.com