Selective Deposition of Silver Layers via Jet Metal Technology for the Production of Antennas

Koen Staelens, Business Development Manager
Jet Metal Technology

Since the start of the company in 2007, Jet Metal Technologies focused its efforts to place its unique in-line metallization technology by spraying on the market for decorative applications in cosmetic and spirit bottle applications. In such decorative applications a layer stack consisting of a base coat varnish (15-20 m), a thin silver layer (~80 nm) and a protective top coat varnish (15-20 m) is used. The many advantages of the Jet metal technology led to great success as nearly 20 industrial lines in Europe and North & Middle America were installed and produce annually millions of metallized spirit bottles, scent bottles and caps for big players like Coty, Hennessy, LOral, Louis Vuitton, Procter and Gamble and Pernod-Ricard. (see Figure 1)

Figure 1. Ceramic tiles, Perfume & spirit bottles all produced with the Jet Metal metallization technology.

Figure 1. Ceramic tiles, as well as perfume & spirit bottles all produced with the Jet Metal metallization technology.

In many industries where metallization technologies like plating, sputtering or evaporation is utilized, users are facing stricter environmental controls on chemical waste and feel continuous pressure to reduce further their costs. Therefore more and more customers are qualifying the Jet Metal technology as a green and cost efficient alternative for existing metallization technologies or to replace intermediate production steps.

Metallization and Selective Metallization Technology
Jet Metals metallization method is using standard painting to spray simultaneous two aqueous based solutions onto a substrate at ambient pressure and temperature, leading to a chemical reaction, forming a metal layer onto the substrate.

The two solutions, one being the oxidant containing the metal salt of the metal that the user wants to deposit, the other the reductant, are both water based, solvent and Palladium free and CMR (Carcinogenic, Mutagenic or Toxic to Reproduction) free so completely in line with the REACH legislation. Using compressed air and a double nozzle spraying paint gun, the reducing and oxidizing agent are simultaneously sprayed onto the substrate surface, starting an oxido-reduction reaction and instantly forming a thin metal layer as shown in Figure 2.

Figure 2. Principle of the Jet Metal metallization process.

Figure 2. Principle of the Jet Metal metallization process.

The ratio of the sprayed oxidizing and reducing solutions are adapted to give an optimal stoichiometric electrochemical reaction onto the surface. The end result of this reaction is a compact, dense and high adherent metallic film on the substrate surface. Most commonly via the Jet Metal technology, Ag and Ni are deposited in layer thickness from 20 nm up to 7-10 m.

The Jet Metal metallization technology can be applied on many substrate geometries (small / big, easy / complex, 2D / 3 D shape) and basically all substrate material choices, whether it is an electrically conducting or non-conducting surface. The range of substrates goes from metals, metal alloys (like Zamak), over glass, all types of textiles, ceramics, silicon, to a long list of plastics and composites to even wax. The only prerequisite to apply the technology is linked with the use of water based solutions: in order realize an evenly well distributed metal layer over the surface, a good substrate wettability is needed which can be achieved via a pre-treatment step with the help of a flame, plasma or corona. Once the required layer thickness is reached, deionized water is sprayed onto the surface to stop all reactions and the substrate is dried with the help of compressed air, so there is no need for a curing step.

Figure 3. Principle of the Jet Metal selective metallization process.

Figure 3. Principle of the Jet Metal selective metallization process.

By adding one more step to the above described process, a selective, conductive pattern can be realized: an alkali sensitive organic ink, which will be used as a negative mask, is printed on the substrate with the help of an ink jet printer or screen printing system. As the oxidant and reducing agent have a pH >10, these pH values allows the modification / loss of adhesion of the printed ink towards the substrate. During the final step of the process (spraying with deionized water) the ink layer is removed, leaving only metallization where there was no ink printed: a selective coating is achieved, and the result is the exact opposite of the pattern designed with the ink as shown in Figure 3.

Combining the above advantages with the well-known advantages of painting technology like the ease of getting familiar with the technology and the capability to produce parts inline without breaks on an industrial scale, makes the Jet Metal technology an ideal choice where thin metal layers are needed.

Figure [4]. Patch antennas made with Silver selective metallization technology versus a standard Cu plated patch antenna (left).

Figure [4]. Patch antennas made with Silver selective metallization technology versus a standard Cu plated patch antenna (left).

Use of Jet Metal Technology to Manufacture Antennas
When using Jet Metals selective metallization process to create simple 2,45 GHz patch antennas on FR4 substrate as shown in Figure 4 and then comparing these patch antennas with Cu plated standard antennas, we proved feasibility that the Jet Metal technology can be used to manufacture antennas matching the performance of existing products.

The results obtained with the Jet Metal patch antennas are comparable to those obtained with a reference patch in terms of adaptation, realized gains and intrinsic gains around the resonance frequency. This means that the silver layer obtained with Jet Metal process works like the standard copper layer.

Conclusions
The technical advantages of the Jet Metal technology in combination with the Jet Metal business model (design & implementation of industrial process tools, supplying the consumables for the process and offering all necessary support services) offers a green and cost effective, industrial solution for the manufacturing of antennas.

For more information on Jet Metal technology, please visit www.Jetmetal-tech.com or contact Koen Staelens, Business Development Manager at K.STAELENS@jetmetal-tech.com

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