Minoru Kobayashi

Development of coil winding process for radial gap type electromagnetic micro-rotating machine

This paper presents a manufacturing process for forming the coil winding on a cylindrical core to make a stator for a micro-generator. A cylindrical stator 1 mm in diameter and 0.5 mm in length was fabricated. This stator consists of a cylindrical core made of permalloy and six coils of copper wire with a cross section of 7 M m X 15 ,U m which were wound 20 turns per coil and with 2 pm thick polyimide insulation layers. The stator was fabricated by securing the coil onto the core die, and electroplating the remaining area with permalloy. A micro-generator 1.2 mm in diameter was fabricated incorporating this stator, and the voltage induced by the generator was measured. The examination revealed that the newly developed process is applicable to the manufacture of electromagnetic microdevices.

Coil winding process for radial gap type electromagnetic devices with cylindrical stator

This paper presents a fabrication process for forming a cylindrical stator incorporating micro-coils. Micro-coils are formed on a silicon substrate using the semiconductor processing technique. The substrate is then covered with a die having the shape of the stator teeth to fill the coils with a magnetic material by electroplating. After electroplating, the die and unwanted part of the core are eliminated. The substrate is also removed by etching it on the reverse side to obtain a sheet in which coils and teeth have been formed. After a sacrifice layer is formed on the surface of a separately fabricated 2-pole magnetized permanent magnet rotor, the sheet is wound utilizing magnetic force. This is inserted into a die and the gaps are filled with a magnetic material to form a core back to complete the cylindrical stator. Using this process, a prototype of an integrated stator and rotor were fabricated in an integrated manner. They were fixed to a housing and the sacrifice layer was eliminated to complete the generator. The voltage induced by generator rotation was measured.