TDK Corporation offers the new L860 NTC thermistor chip which may be embedded directly into power modules and utilised within sintering and AI-heavy wire bonding. Its characteristics correspond to the common MELF-R/T curve with R100 of 493-Ohm. The lead-free chip is intended for a broad temperature range of -55C to +175C, has dimensions of 1.6mm x 1.6mm x 0.5mm.
Unlike traditional SMD NTC chips, the leadless NTC chip is mounted horizontally. For electrical bonding, the product is installed on the bottom with a Ni/Ag thin-film electrode for sintering on the DCB board of power modules. In contrast, the upper electrode comprises a Ni/Au thin-film electrode for aluminium wire bonding. Soldering processes are not required.
Compared to other technologies, this solution demonstrates an outstanding thermal coupling of NTC chips to power modules, which, in turn, generates a very short response time and high-precision temperature measurement and control. The efficiency of power modules is typically highest when operating close to their power limits; however, a precise temperature control is essential to operate at these limits. Typical operating temperatures are in the range of 100C but may slightly increase to 175C.
The device is ideal for integration into IGBT and IPM modules.