Characteristics of the Ni–B Film in Printed Circuit Board for High-Power Light-Emitting Diodes

Abstract

To develop metal printed circuit boards for a high-power light-emitting diode package using electroless plated Ni-B films on an all-in-one Al2O3-Al substrate with a 10 nm pore size, the growth mode of an electroless Ni-B film on a screen-printed Ag pattern/Al2O3-Al substrate was studied. So as not to damage the Al2O3-AI substrate, a nearly neutral Ni plating solution bath (pH 6.5) included dimethylamine borane was used. It was confirmed that the Ni-B film was selectively grown on the printed Ag paste layer, without growth on the Al2O3. The structure of the electroless plated Ni-B film was amorphous, and the deposition rate of the film was 1.64 +/- 0.078 nm/sec. According to the increase in plating time, the grain sizes of the electroless plated Ni-B film became bigger, and the surface morphology gradually became flatter. In addition, both the mass difference and the film thickness were changed linearly. From these results, it can be concluded that the electroless Ni-B film on printed Ag paste grows immediately from the beginning, and then grows linearly with increasing plating time.