The development of high frequency induction heating embedded coil

Abstract

The miniaturization of components and systems has been progressing rapidly due to the developments in Micro-Electro-Mechanical (MEMS). The greatest advantage of micro injection molding is that it can massively produce micro-components rapidly with low-cost. Due to the poor flow capability of melting plastics into micro channel, and the additions of the engineering-plastics and fibers, it is difficult to inject the melted plastics into the cavities of the mold. In order to apply the microinjection technique in the fabrication of microfluidic chip, raising cavity surface temperature will be one of the solutions and reduce the cycle-time. High mold temperature not only improves the replication capacity of micro-structures but also effectively reduces molecular orientation. Therefore, developing systems for rapidly heating and cooling for injection of microfluidic chip is the main objective of this study. Numerical computations of eddy currents and heat conduction have been carried out by using the finite-element method (FEM). A simulation tool is also developed by integration of both thermal and electromagnetic analysis modules of ANSYS. Coil current, coil to plate distance and heating time are varied for both experiments and simulations. Several modifications, such as spacing in between coil turns, the distance of the workpiece and the coils, and dimensional parameters, are carried out. The capability and accuracy of simulations on the induction heating are verified from experiments, the simulated temperature distributions show reasonable agreement with measured results. To evaluate the feasibility and efficiency of induction heating on the mold surface temperature control. The size of mold plate heated by induction heating is 80×70×10 mm3. The mold plate can be rapidly heated from room temperature to about 120°C in 20 s. The simulation of the mold surface temperature with respect to time is consistent with measured results.