A method for electroless deposition of aluminum or an aluminum alloy on a substrate surface is provided. The method includes activating the surface of the substrate to be coated by applying a coating of a catalyst metal; preparing a mixture of urea (NH.sub.2CONH.sub.2) and anhydrous aluminum chloride (AlCl.sub.3) having a 2:1 molar ratio of AlCl.sub.3:NH.sub.2CONH.sub.2 to obtain a Lewis acid room temperature ionic liquid (RTIL) optionally containing an alloy metal salt; dissolving a hydride reducing agent in an aprotic anhydrous solvent to obtain a hydride solution; mixing the hydride solution and the AlCl.sub.3:NH.sub.2CONH.sub.2 RTIL to obtain an electroless Al solution; exposing the activated surface of the substrate to the electroless Al solution; and removing the electroless Al solution from the substrate surface; wherein upon exposure of the activated substrate surface to the electroless Al solution, an Al or Al alloy coating is obtained on the activated substrate surface.

Methods of metalizing vias are disclosed. A method of metalizing at least one via includes contacting a substrate with a sacrificial metal sheet. The substrate includes a first surface, a second surface, and the at least one via extending between the first surface and the second surface and the first surface or the second surface of the substrate contacts a surface of the sacrificial metal sheet. The method further includes applying a solution comprising metal ions to the substrate and the sacrificial metal sheet such that a Galvanic displacement reaction occurs between the sacrificial metal sheet and the metal ions in the solution until the metal ions form a metal coating on at least one surface of the at least one via.

Methods for forming thin, pinhole-free conformal metal layers on both conducting and non-conducting surfaces, where the morphology and properties of the metal layers are tuned to meet desired parameters by adjusting the concentration of ionic liquids during the deposition process. The formed metal films contain tunable properties for solar and electronic use and provide specific advantages for non-conducting surfaces, which are otherwise unsuitable for electroplating without the presence of the formed metal films. The disclosed methods do not require the presence of a voltage or external electric field but form the metal films through an electroless technique using electrostatic interactions between negatively charged nanoparticles. In addition, the disclosed methods are compatible with solution phase processing and eliminate the need to transfer the surfaces into a vacuum chamber for a chemical or physical vapor deposition to form a metal layer.

Provided are chrome-free adhesion pretreatment processes for use on a variety of reinforced or unreinforced plastics and polymers, such as polyimides, polyetherimides and polyvinylchloride. The pretreatment process can be performed in a combination of two sequential operations, which includes treating with a first solution containing nitric acid and subsequently treating with a second solution that includes sulfuric acid and periodate ions. Alternatively, the pretreatment process can be performed by treatment with a single combined composition that includes nitric acid, sulfuric acid, and periodate ions. The pretreatment processes, either done in two separate solutions, sequentially, or in one combined solution, produce an adherent surface for further metallization of the article, with adhesional values of the metal layer higher than those achieved using conventional chromic acid pretreatment processes.