The activated or catalyzed surface conditions for initiating electroless metal deposition were studied by means of transmission electron microscopy and electron diffraction analysis. Four mixed PdCI2/SnCI2 catalysts, including two commercial samples, and five accelerators (NaOH, HC1, H2SO4, NH4OH, and NH4BF4) were used in this study. The acceleration with NaOH gave the finest remaining particles which were almost bare active nuclei, while the acceleration with ammonate group (NH4OH and NH4BF4) coagulated small particles to produce high density particles. The electron diffraction patterns after activation, for the catalysts prepared in our laboratory, showed amorphous broad diffraction rings which were explained as fee structure, while for the commercial catalysts, they showed relatively sharp and netlike profiles which could be attributed to orthorhombic structure. The electron diffraction patterns after acceleration with NaOH became the sharper profiles of fee structure, however in the case of ammonate group, they showed the complicated profiles of non-fee structure. Finally the catalytically active sites or nuclei are discussed.
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