Localized Ligand Induced Electroless Plating (LIEP) Process for the Fabrication of Copper Patterns Onto Flexible Polymer Substrates

Abstract

The “ligand induced electroless plating (LIEP) process” is a simple process to obtain localized metal plating onto flexible polymers such as poly(ethylene terephtalate) and polyvinylidene fluoride sheets. This generic and cost‐effective process, efficient on any common polymer surface, is based on the covalent grafting by the GraftFast process of a thin chelating polymer film, such as poly(acrylic acid), which can complex copper ions. The entrapped copper ions are then chemically reduced in situ and the resulting Cu0 species act as a seed layer for the electroless copper growth which, thus, starts inside the host polymer. The present work focuses on the application of the LIEP process to the patterning of localized metallic tracks via two simple lithographic methods. The first is based on a standard photolithography process using a positive photoresist masking to prevent the covalent grafting of PAA in designated areas of the polymer substrate. In the second, the patterning is performed by direct printing of the mask with a commercial laser printer. In both cases, the mask was lifted off before the copper electroless plating step, which provides ecological benefits, since only the amount of copper necessary for the metallic patterning is used.

On the chemical grafting of titanium nitride by diazonium chemistry

“…Metallic thin films on desired surfaces with strong adhesion can be obtained as clearly demonstrated in previous publications. [12][13][14] More importantly, success in modification of titanium nitride with amino groups would extend the application of this ceramic material towards biosensor development. 15 Hence it is worth underlying the importance of development of efficient organic coating techniques for covalent functionalization of titanium nitride surface.…”

Surface functionalization of cyclic olefin copolymer with aryldiazonium salts: A covalent grafting method

“…In this case, iron powder is added as a chemical reducer to generate the aryl radical [39]. This wet chemical treatment called Graftfast process is employed to modify polyvinylidene fluoride membranes, poly(ethylene terephthalate), acrylonitrile-butadiene-styrene polymers and polyvinylchloride (PVC) polymers [39][40][41][42]. Chehimi et al also observed that the aryl radical generated from aryldiazonium salt could be covalently grafted onto a polymeric surface such as poly(methyl)methacrylate [43].…”

Selective adsorption of catalyst and copper plating for additive fabrication of conductive patterns and through-holes

“…Sintering free, high conductivity and the usage of non-noble metal as conductive material are the strengths of this process. But the poor adhesion of the patterns is the major problem for the lack of interaction between catalyst and polymer substrate [23][24][25][26][27]. Self-assembly of polyelectrolyte, surface grafting of polymer, surface modification of coupling agent, etc.…”