Surface modification and metallization of polyimide using gold colloids as a seed layer

Abstract

Herein we report on metallization of Cu on to surface-modified polyimide resin, the method of which relies on potassium hydroxide-induced modification of the polyimide surface to introduce carboxylic acid groups and incorporation of gold colloids as a seed layer through reduction of chloroauric acid. The contact angle of modified polyimide surface with water changed from 70 to 35 due to the hydrolysis of polyimide. Secondary amine group on the surface was detected with attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectrophotometry, suggesting that tertiary amine group has turned into secondary group. In addition, on the basis of hydrophilic behavior, we succeeded in depositing gold colloids on the chemically modified surface. SEM image of copper electroless plated on polyimide surface indicated that copper particles were compact and about $ 300 nm in diameter. It showed that gold colloids provide an excellent conductive layer to catalyze the electroless plating of Cu on polyimide surface.

Direct metallisation of polyetherimide substrates by activation with different metals

“…The concentrations and temperatures applied in these two processes can be altered to produce the desired outcome. As such, the temperature and concentration of the different metal ions solutions were selected based on successful process conditions reported in the literature [5,12,16,[20][21][22]37]. To apply consistency between samples during the reduction process, the same reducing agent, NaBH4, was used using identical operational conditions for all metals.…”

Modification of Cu nanoparticles with a disulfide for polyimide metallization

“…[1][2][3] For the fabrication of FPCs, polyimides (PIs) are good candidates as dielectric and packaging materials because they have excellent physical and chemical properties, such as high thermal stability, good mechanical strength, low dielectric constants, and superior chemical resistance in acidic environments. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] However, the surface metallization of PI films, which are employed as conducting circuits after pattern etching, is a big challenge since the metal thin film usually cannot tightly adhere to the PI surface. A conventional method that coats a layer of adhesive on the PI surface to attach a metal foil has been widely used for the surface metallization of PI.…”

“…4,[7][8][9]11,18,20 Alternatively, many new approaches for metalizing PI surfaces, such as physical and chemical techniques (e.g., plasma modification, laser modification, surfactant grafting, and chemical reaction, etc), have been proposed. 4,8,9,[11][12][13][14][15][16][17][18][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Regarding the surface metallization of PI films, Ng et al 35 wrote a review of various techniques and proposed a direct-writing approach for copper patterning onto the PI films. Based on considerations of process cost, a wet process seems to be a good approach because its cost is lower than that of a dry one.…”

“…These doped cations were then reduced to metal nanoparticles and inserted into the sublayer or aggregated on the PI surface, depending on the reduction approach and conditions. 12,[14][15][16]20,21 Usually, the metal nanoparticles formed on the PI surface cannot directly act as a conducting film due to high electrical resistance. Therefore, an electroless plating process is subsequently performed in order to increase the thickness of the conducting film.…”

“…Electroless copper (ELC) and nickel (ELN) plating are two typical metallization processes used for the purposes mentioned above. 8,9,13,15,18,20,21,27 Palladium is a common but expensive catalyst for ELC plating because ELC plating cannot be triggered by bulk copper. 36,37 However, when the particle size of copper is reduced to the nanoscale, the copper nanoparticles (CNPs) possess high activity that can catalyze the oxidation of an aqueous reductant.…”