Comparison of properties between Pr–Fe–B and Nd–Fe–B thick-film magnets applied to MEMS.

We investigated the possibility of R (Nd or Pr)–Fe–B thick-film magnets applied to MEMS. First, an enhancement in the thickness of the Si oxide layer on a Si substrate enabled us to increase the adhesion force between the Si substrate and Nd–Fe–B film. Then, after depositing a glass buffer layer on the Si substrate to obtain a thicker Si oxide layer, we compared the mechanical characteristics and magnetic properties of both Pr–Fe–B and Nd–Fe–B films. As the thickness of the glass buffer layer increased, the thickness of the Pr–Fe–B film could be enhanced without mechanical destruction. We had difficulty in exceeding the thickness of 100 μm in Nd–Fe–B films. Moreover, the (BH)_max value of a 127-μm-thick Pr–Fe–B film was higher by approximately 30 kJ m⁻³ than that of a 92-μm-thick Nd–Fe–B film. The obtained results suggest that a Pr–Fe–B thick-film magnet is more suitable for MEMS applications. [ABSTRACT FROM AUTHOR]