Ina Stankeviciene

Laser-induced selective copper plating of polypropylene surface

Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

Laser-induced selective metal plating on PP and PC/ABS polymers surface

Fabrication of circuit traces is the most challenging task in the Molded Interconnection Device (MID) technology. The technical difficulties which can be met when producing conductive trace are spatial selectiveness and adhesion of a plated metal. On the other hand, the technique used to manufacture circuit should be cost-effective as well. Considering this background, two methods of selective plating induced by a laser are presented here. This manuscript consists of two parts. In the first part, we describe new PP and PC/ABS masterbatch with carbon-based additives for laser direct structuring (LDS) approach. Moreover, the second part of the paper represents a new technology for MID: Selective Surface Activation Induced by Laser (SSAIL). This new technique for selective surface plating enables to use standard plastics without any LDS additives. In both cases, metal deposition was performed by electroless plating. Nanosecond and picosecond lasers were applied for polymer surface treatment. The narrowest width of a copper-plated line was less than 23 μm. The Scotch tape test was applied to measure the adhesion of a plated metal.