Direct metallisation of polyetherimide substrates by activation with different metals

• Published in: Surface & coatings technology 2019-02, Vol.360, p.285-296
• Main Authors: Jones, Thomas D.A., Ryspayeva, Assel, Esfahani, Mohammadreza N., Shuttleworth, Matthew P., Harris, Russell A., Kay, Robert W., Desmulliez, Marc P.Y., Marques-Hueso, Jose
• Format: Article
• Language: English
• Subjects: Adhesion tests; Adhesive strength; Chromium; Cobalt; Copper; Density; Direct metallisation; Electrical interconnect; Electrical resistivity; Electroless copper; Electroless plating; Gold; Ion exchange; Iron; Metal catalyst; Nanoparticles; Nickel; Organic chemistry; Palladium; Photoreduction; Polyetherimide; Polyetherimides; Pretreatment; Seeds; Silver; Substrates; Sulfuric acid; X ray photoelectron spectroscopy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2019.01.023

This article reports the performance of different metallic ions and nanoparticles (Ag, Cu, Ni, Pd, Cr, Co, Au and Fe) used as seed layers, formed by chemical or optical reduction, for the electroless Cu plating of metal tracks onto polyetherimide (PEI). Plated Cu performance was tested by adhesion, electrical conductivity, plating rate, XPS, SEM, XRD and EDX analysis. The application of Cu and Ag seeds resulted in high quality electroless Cu deposits presenting strong adhesion properties and high conductivity ((2.0 ± 0.5) × 107 S/m and (3.6 ± 0.2) × 107 S/m, respectively) compared with bulk copper (5.96 × 107 S/m). Performance is attributed to the high surface density and uniformity of seed layers. Of the metals, only Ag ions were photoreduced under the conditions applied and were subsequently used to electroless Cu plate high quality track features of 150 μm width. The application of sulphuric acid pre-treatment to PEI prior to Ag ion exchange, improved the photoinitiated track formation process, as demonstrated by a threefold increase to both photoinduced Ag nanoparticle density on the surface and electroless Cu plating rate, as well as improved electroless Cu adhesion to PEI. [Display omitted] •Successful demonstration of chemical reduction (Ag, Cu, Ni, Pd, Au and Fe) onto PEI•High quality electroless Cu plating onto Au and Ag nanoparticle catalysts on PEI•High quality electroless Cu micro-circuitry on PEI (3.6 ± 0.2) × 107 S/m•Photoreduction of metal ions on PEI surface•Threefold increase to nanoparticle density and electroless Cu plating rate