During past decades Micro Electro Mechanical Systems (MEMS) have been developed and presented in the market. It is important to find new processes and methods to facilitate MEMS production regarding to growing demand of MEMS devices in IoT, smart and intelligent systems, consumer electronics and medical applications. In this paper, Ni–P layer deposition on insulator substrates is presented. The layer is deposited based on chemical reactions in electroless process. There is a similar method, electroplating, for metal deposition but the substrate must be conductor to transfer electrons and provide essential conditions for electroplating. Electroplating process is not applicable for insulator substrates, while the proposed electroless process can be useful. Different steps, materials, conditions and experimental results for Ni–P electroless are presented. A fabrication process for DC contact RF MEMS switch based on Ni–P electroless is introduced, too. As one advantage of this process, Ni and Ni–P are ferromagnetic material and any suspended structure can be actuated by magnetic fields. It will be beneficial when applying other actuation mechanisms like electrostatic, thermal or piezoelectric are difficult or impossible to be applied.

Ni–P electroless on nonconductive substrates as metal deposition process for MEMS fabrication

Tailoring optical and resistance properties of the functional CuAlxOy semiconductor for applications as thermal infrared imagers

Polyetheretherketone (PEEK) and its fiber-reinforced materials are thermoplastic polymer materials with broad application prospects. Depositing Ni-P alloy on them can improve their poor conductivity and electromagnetic shielding performance, and further expand their application field. The application effect of the plated parts is significantly impacted by the bonding strength between PEEK and coating. The bonding strength between non-metallic substrate and coating is largely influenced by the surface characteristics of the substrate. Therefore, it is significant to study how the surface roughness of PEEK materials and the modified fibers in materials affect the adhesion of the coating. In this study, Ni-P alloy was electroless deposited on PEEK, 30% carbon-fiber-reinforced PEEK (CF30/PEEK), and 30% glass-fiber-reinforced PEEK (GF30/PEEK) with varying surface roughness. The influence of surface roughness and modified fibers on the coating adhesion was studied. Additionally, the effect of the concentrations of nickel sulfate, sodium hypophosphite, pH, and temperature on the deposition rate of the coating was investigated for the three materials. Based on the highest deposition rate, the process parameters were then optimized. The results demonstrated that as surface roughness increased, adhesion between substrate and coating first increased and then decreased. The surface roughness Ra of 0.4 μm produced the highest coating adhesion. Additionally, fiber-reinforced PEEK adhered to coatings more effectively than PEEK did. The mechanism of the difference in bonding strength between different PEEK-modified materials and coatings was revealed. The optimal process parameters were: nickel sulfate: 25 g/L, sodium hypophosphite: 30 g/L, pH: 5.0, and temperature: 70 °C.

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Nguyen-Tran Thuat

Papers

Selected-area growth of nickel micropillars on aluminum thin films by electroless plating for applications in microbolometers