Passives

Focus of this work is the development of novel capacitors regarding higher integration density, higher temperature and higher voltage stability as well as simplified mounting and assembly. The devices rely on a proprietary manufacturing technology developed at Fraunhofer IISB to expand applicability of silicon capacitors from memory and logic level applications to power electronics. Present devices achieve a continuous operating voltage of up to 900V. Thus, they are ideal suited for the application in fast switching power modules with 1200V SiC power MOSFETs.

Using silicon technology, a capacitor with high integration density for high operating temperatures is implemented for a replacement of SMD capacitors. A particular focus is on dissipative snubber circuits. [More…]

Glass foils and glass-ceramics are promising materials to replace foil capacitors and ceramic MLCCs for applications using operating voltages of 600 V and beyond. In contrast to ceramic capacitors, these materials are extruded from thicker material and the defect density is minimized. [More…]

Snubber Device

Using silicon technology, a capacitor with high integration density for high operating temperatures is implemented for a replacement of SMD capacitors. A particular focus is on dissipative snubber circuits.

General Description

A deep trench in silicon filled with SiO2 or Si3N4 as dielectric and doped  poly-silicon as electrode forms the capacitor. The bulk silicon can be used to  form the series resistor of a passive RC-snubber. The bottom side contact consists of a solder- and sinterable metal stack. The top side contact consists of bondable aluminum, or is solder- and sinterable on request. High voltage versions feature a polyimide passivation. These devices constitute to a disruptive technology for ceramic and foil capacitors at operating voltages of 75 V and above combining high integration density and excellent reliability.

Features

  • Low parasitic inductance (pH) compared to discrete solutions (nH)
  • Available as bare-die
  • High thermal conduction of Si substrate with low transition resistances
  • Detailed understanding of failure mechanism and exact life-time prediction: Elimination of early failing devices
  • Outstanding reproducibility and homogeneity of the fabrication process

Advantages

  • Higher switching speeds and increased efficiency of the system, e.g. energy converter
  • Simplified mounting together with power switches or ICs
  • More efficient spread of the thermal power dissipation to the heat sink
  • Increased mean-time-to-failure resulting in lower failure rate in the field
  • Excellent device tolerances, minor deviations
  • Custom designs regarding capacitance, resistance and voltage stability available

Benefits

  • Increasing sales volume due to an innovative product with increased system efficiency and SOA
  • Less labor time, higher profit due to faster mounting process and less rework
  • Secure and reliable systems with reduced downtime in the field

Capacitors and Dielectrics

Glass foils and glass-ceramics are promising materials to replace foil capacitors and ceramic MLCCs for applications using operating voltages of 600 V and beyond. In contrast to ceramic capacitors, these materials are extruded from thicker material and the defect density is minimized.

Thin glass

© Fraunhofer IISB

Thin Glass: New dielectric material with high operating temperature capability

  • Novel dielectric material for high voltage applications
  • Dielectric constant of εr = 5.1
  • Breakdown field strength of 590 kV/mm @ 25μm
  • Low dependence of temperature, frequency and DC-Bias
  • High energy density
  • Flexible glass makes roll-to-roll-processes possible

Ceramic

© Fraunhofer IISB

Ceramic: New materials appear on the horizon

  • New ceramic material with high dielectric constant (in cooperation with research partners)
  • High dielectric constant εr >3500
  • Breakdown voltage of 500 V
  • High temperature applications

CAPACITORS Characterization for power electronic applications

© Fraunhofer IISB

Capacitors with novel dielectrics for power electronic

What we aim for 

  • Characterization of new capacitors
  • Evaluation of their potential for power electronic applications
  • Evaluation and modelling of life time and reliability
  • Reduction of volume and cost
  • Improving the thermal management, increasing the power density

Characterization

  • Impedance analysis of dielectric materials and capacitors dependent on frequency, temperature and voltage (DC bias)
  • Hysteresis of capacitors and dielectric materials
  • Leakage current (temperature-dependent)
  • Thermal behavior, thermal impendance and resistance
 

Monolithic RC-Snubbers and Capacitors

[ PDF 0.40 MB ]

 

 

Silicon Integrated RCD-Snubber Networks

[ PDF 0.40 MB ]

 

 

Capacitors

[ PDF 0.22 MB ]