Abstract:
Electronic devices are developing towards miniaturization, integration, and high frequency with the development of electronic industry. The soft magnetic cores require better loss characteristics and higher reliability becaues their magnetic properties would decline due to the sharply increased magnetic loss and serious heating with the high-frequency application. In this work, high-performance soft magnetic composites with phosphate-bismaleimide@Fe structure were prepared by phosphating treatment and bismaleimide (BMI) coating, and the effects of insulation coating methods on the reliability of soft magnetic composites were investigated. The results indicate that the excellent comprehensive magnetic properties of soft magnetic composites have been obtained as the content of BMI resin is 2wt% and the compaction pressure is 800 MPa, the effective permeability is 32.2, the total loss is 1181 kW/m
3 under the condition of 50 mT@200 kHz and the quality factor
Q can reach 46.2 at 1 MHz. Moreover, it is found that the resin layer between iron powder particles can play a role of stress buffer to reduce the formation of internal stress and the total loss of soft magnetic composites. The aging of soft magnetic composites due to the oxidation of the magnetic powders which was proved by flourier infrared spectrum analysis. The phosphating treatment and BMI coating can effectively slow down the aging to improve the high-temperature reliability of soft magnetic composites and perform stable magnetic properties after long-term accelerated aging test at 180℃.