[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Regulation of energy density and efficiency in transparent ceramics by grain refinement

https://www.tandfonline.com/doi/pdf/10.1080/14686996.2019.1640072

Reliability issues of lead-free solder joints in electronic devices

Comparing the mechanical and thermal-electrical properties of sintered copper (Cu) and sintered silver (Ag) joints

The advancement of silicon carbide (SiC) power devices with voltage ratings exceeding 10 kV is expected to revolutionize medium- and high-voltage systems. However, present power module packages are limiting the performance of these unique switches. The objective of this research is to push the boundaries of high-density, high-speed, 10-kV power module packaging. The proposed package addresses the well-known electromagnetic and thermal challenges, as well as the prominent electrostatic and electromagnetic interference (EMI) issues associated with high-speed, 10-kV devices. The high-speed switching and high voltage rating of these devices causes significant EMI and high electric fields. Existing power module packages are unable to address these challenges, resulting in detrimental EMI and partial discharge that limit the converter operation. This article presents the design and testing of a 10-kV SiC mosfet power module that switches at a record 250 V/ns without compromising the signal and ground integrity due to an integrated screen reduces the common-mode current by ten times. This screen connection simultaneously increases the partial discharge inception voltage by more than 50%. With the integrated cooling system, the power module prototype achieves a power density of 4 W/mm3.

/pdf/10-kv-sic-mosfet-power-module-with-reduced-common-mode-noise-tzly6uhdxp.pdf

10-kV SiC MOSFET Power Module With Reduced Common-Mode Noise and Electric Field

Wide bandgap (WBG) power devices with voltage ratings exceeding 10 kV have the potential to revolutionize medium- and high-voltage systems due to their high-speed switching and lower ON-state losses. However, the present power module packages are limiting the performance of these unique switches. The objective of this article is to push the boundaries of high-density, high-speed, 10-kV power module packaging. The proposed package addresses the well-known electromagnetic and thermal challenges, as well as the more recent and prominent electrostatic and electromagnetic interference (EMI) issues associated with high-speed, 10-kV devices. The module achieves low and balanced parasitic inductances, resulting in a record switching speed of 250 V/ns with negligible ringing and voltage overshoot. An integrated screen reduces the common-mode (CM) current that is generated by these fast voltage transients by ten times. This screen connection simultaneously increases the partial discharge inception voltage (PDIV) by more than 50%. A compact, medium-voltage termination and system interface design is also proposed in this article. With the integrated jet-impingement cooler, the power module prototype achieves a power density of 4 W/mm3. This article presents the design, prototyping, and testing of this optimized package for 10-kV SiC MOSFETs.

/pdf/design-and-experimental-validation-of-a-wire-bond-less-10-kv-2tsh9go2lc.pdf

Design and Experimental Validation of a Wire-Bond-Less 10-kV SiC MOSFET Power Module

A double-sided 1200-V/600-A multichip half-bridge insulated gate bipolar transistor (IGBT) module was fabricated utilizing molybdenum as stress-relief buffer and sintered nanosilver as die-attachment. By using the double-sided packaging, the volume, parasitic inductance, and junction temperature were decreased significantly, and thus the higher power density could be achieved. However, the thermomechanical stress was also increased. In this paper, molybdenum instead of the most common copper was used as a stress-relief buffer between chips and substrate, and thus the thermomechanical stress decreased greatly without significantly increasing the junction temperature. Specifically, by using molybdenum instead of copper as the buffer material, the simulation results showed that the IGBT junction temperature at total power loss of 200 W only increased by 5.2% (2.22 °C), but the corresponding thermomechanical stress decreased by 9.8% (5.58 MPa), and the sintering residual stress decreased by 20.1% (48.88 MPa). Thermal performance, static and dynamic electrical performance, and reliability via power cycling test of the double-sided module were also characterized experimentally. No degradation of the power devices proved that the way to double-sided packaging power devices could be used for future manufacturing of high-power density power module.

Reliability Improvement of a Double-Sided IGBT Module by Lowering Stress Gradient Using Molybdenum Buffers

Pressureless sintering of nanosilver paste as die attachment on substrates with ENIG finish for semiconductor applications

The thermal characterisation of insulated gate bipolar transistor (IGBT) module is very important, since the production consistency and reliability are affected when IGBT is exploited in high temperature. To investigate the transient thermal behaviour of IGBT, a transient thermal impedance (Z th) measurement system was built using the electrical method with gate-emitter voltage as temperature-sensitive parameter. Factors affecting the Z th measurement, such as environment temperature, heating power, duty cycle and heating time, were discussed in detail. The Z th of each component within IGBT module was measured by selecting right heating time before thermal equilibrium. It is found that the Z th measurement has high accuracy and repeatability, which is helpful to understand how thermal performance of IGBT module varies with architecture and material properties for power electronic packaging.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-pel.2014.0120

Electrical method to measure the transient thermal impedance of insulated gate bipolar transistor module

High temperature application and long-term reliability are the future development trends of IGBT (insulated gate bipolar transistor) module. This article proposes a 1200-V/50-A IGBT module using the current-assisted sintered nanosilver as die attachment and high-temperature solder as substrate attachment. We measured and compared the electrical and the thermal characteristics, and the reliability of the proposed IGBT modules with those of the commercial IGBT module of the same level. The proposed IGBT modules show consistency with commercial IGBT module in electrical performance, which also proved the feasibility of the current-assisted sintering. The thermal impedance of the proposed IGBT module decreased by 17.2% compared with that of the commercial one. And, the thermal shock test shows that higher resistance to thermomechanical fatigue can be successfully achieved.

Meiyu Wang

Papers

Design and Experimental Validation of a Wire-Bond-Less 10-kV SiC MOSFET Power Module

Reliability Improvement of a Double-Sided IGBT Module by Lowering Stress Gradient Using Molybdenum Buffers

Pressureless sintering of nanosilver paste as die attachment on substrates with ENIG finish for semiconductor applications

Electrical method to measure the transient thermal impedance of insulated gate bipolar transistor module

A Method for Improving the Thermal Shock Fatigue Failure Resistance of IGBT Modules