Amorphous Cores

Amorphous metals are produced using a rapid solidification technology where molten metal is cast into thin solid ribbons, by cooling at a rate of one million °C/second. Amorphous magnetic metal has high permeability due to no crystalline magnetic anisotropy. Amorphous cores are made from a very thin Iron based amorphous ribbon, approximately 25 µm thick. Amorphous ribbon is wound into toroidal and oval shapes. Our enhanced ribbon

Low Losses

Amorphous magnetic cores have superior magnetic characteristics, such as lower core loss, when compared with conventional crystalline magnetic materials. This is because the amorphous structure responds to changes in magnetic fields (alternating AC fields) more readily than other materials, providing a BH loop that essentially exhibits no hysteresis losses.

Magnetic field changes also induce currents, called eddy currents, which are an additional source of loss. These losses become significant at higher frequencies when using thicker laminations. The super thin nature of the amorphous ribbon limits these losses by reducing the circulation of these eddy currents.

increasingly lower flux densities as the frequency increases. In order to compensate for running at lower flux densities, significantly more material is needed. Even with additional material higher temperatures still occur. Another contributor to lowering losses is the I2R of the winding. A physically smaller amorphous core reduces the mean length per turn, hence the I2R copper losses and copper costs are lower. Further improvements can be realized by using Nanocrystalline C-Cores.

In each of the above options, the winding can be accomplished on a separate mandrel and assembled onto the C-Core after the winding process. Litz wire (a special type of multistrand wire) is commonly used for high current/high frequency designs. However, terminating litz wire for these applications can be expensive. An alternative to consider is disc or edge winding. This involves winding a rectangular wire that has a relatively high aspect ratio on its edge. The quasi-planar structure of this thin rectangular wire reduces the skin effect, but not as much as when using litz wire. Although copper or aluminum foil can also reduce skin effect properties, other parasitic winding effects need to be considered when using this winding method. Other advantages of using amorphous cores are: lower copper loss, reduced DCR, smaller size, and improved heat dissipation.

We produce rectangular shapes of amorphous metal cores by stacking layers of laminations made from amorphous metal ribbon. An adhesive rated for a continuous operating temperature of 155°C holds the laminations together.

These cores are ideal candidates for PFC boost inductor applications in power supply ranges from 300 to 6kW (for higher power design see Powerlite). Microlite 100μ are tape wound amorphous toroidal cores with a small gap, which allows the core to achieve permeabilities less than 245. The amorphous metal core is stable over a wide temperature range and offers a design with fewer and smaller gaps than comparable E-core ferrites. The fewer gaps and smaller gap size greatly reduces EMC concerns from fringing flux and stray field. Most designs can be constructed with few turns and lower losses providing a smaller more cost effective design. In some cases these cores maybe a good alternative for differential input inductors, and SMPS output inductors. Various standard core sizes are available. For the ultimate PFC boost inductor solution contact us directly on our new Advanced Amorphous A-AL material.

Nanocrystalline amorphous metal is produced by rapid quenching a molten alloy to produce a amorphous metal and then heat treating this alloy at higher than its crystallization temperature The alloy forms Nanocrystalline grain size of approximately 10 nm in the amorphous metal.

Annealing changes BH loopsM type material is done with no magnetic field applied during annealing M type material is done with no magnetic field applied during annealing We produce H and L type BH loops by annealing with magnetic fields oriented either parallel or perpendicular to the ribbons surface. Advantages are:

• High saturation magnetic flux density, more than 1 Tesla
• High permeability over 10,000u at 100kHz
• Excellent temperature characteristics. Very high Curie temperature (570°C) resulting in small permeability variation (less than +/-10%) at a temperature range of -40°C to 150°C.
• Less affected by mechanical stress. Because of the low magnetostriction permeability and core loss changes have very small changes.
• Very low audio noise emission. Lower magnetostriction significantly reduces audible noise emission when the voltage and current applied to the core at audible frequency range.