Characterization of Silicone Gel for High Temperature Encapsulation in High Voltage WBG Power Modules

2017 ◽  
Vol 2017 (1) ◽  
pp. 000312-000317
Author(s):  
Adam Morgan ◽  
Xin Zhao ◽  
Jason Rouse ◽  
Douglas Hopkins
Keyword(s):  
High Temperature ◽  
Thermal Aging ◽  
Dielectric Strength ◽  
Material Structure ◽  
Power Module ◽  
Leakage Currents ◽  
Test Vehicle ◽  
Silicone Gel ◽  
Power Modules ◽  
Silicone Gels

Abstract One of the most important advantages of wide-bandgap (WBG) devices is high operating temperature (>200°C). Power modules have been recognized as an enabling technology for many industries, such as automotive, deep-well drilling, and on-engine aircraft controls. These applications are all required to operate under some form of extreme environmental conditions. Silicone gels are the most popular solution for the encapsulation of power modules due to mechanical stress relief enabled by a low Young's modulus, electrical isolation achieved due to high dielectric strength, and a dense material structure that protects encapsulated devices against moisture, chemicals, contaminants, etc. Currently, investigations are focused on development of silicone gels with long-term high-temperature operational capability. The target is to elevate the temperature beyond 200°C to bolster adoption of power modules in the aforementioned applications. WACKER has developed silicone gels with ultra-high purity levels of < 2ppm of total residual ions combined with > 200°C thermal stability. In this work, leakage currents through a group of WACKER Chemie encapsulant silicone gels (A, B, C) are measured and compared for an array of test modules after exposure to a 12kV voltage sweep at room temperature up to 275°C, and thermal aging at 150°C for up to more than 700 hours. High temperature encapsulants capable of producing leakage currents less than 1μA, are deemed acceptable at the given applied blocking voltage and thermal aging soak temperature. To fully characterize the high temperature encapsulants, silicone gel A, B, and C, an entire high temperature module is used as a common test vehicle. The power module test vehicle includes: 12mil/40mil/12mil Direct Bonded Copper (DBC) substrates, gel under test (GUT), power and Kelvin connected measurement terminals, thermistor thermal sensor to sense real-time temperature, and 12mil Al bonding wires to manage localized high E-Fields around wires. It was ultimately observed that silicone gels B and C were capable of maintaining low leakage current capabilities under 12kV and 275°C conditions, and thus present themselves as strong candidates for high-temperature WBG device power modules and packaging.

Temperature Dependence of High Dielectric Strength Potting Materials for Medium Voltage Power Modules

2015 ◽  
Vol 12 (4) ◽  
pp. 212-218
Author(s):  
Chad B. O'Neal ◽  
Matthew Feurtado ◽  
Jennifer Stabach ◽  
Ty McNutt ◽  
Brandon Passmore
Keyword(s):  
High Temperature ◽  
Leakage Current ◽  
Dielectric Strength ◽  
Operating Voltage ◽  
Power Module ◽  
Dielectric Thickness ◽  
Medium Voltage ◽  
Current Test ◽  
Power Modules ◽  
High Dielectric

Voltage insulation inside power modules is paramount for functional and reliable operation. Dielectric potting materials are stressed as the overall size of these modules is reduced due to size, weight, and cost considerations while the operating voltage of these modules continue to increase. In particular, voltage ratings of silicon carbide (SiC) device technologies will continue to increase above 6.5 kV into the tens of kilovolts in the future. SiC devices are also often operated at higher junction temperatures to take advantage of the high-temperature capabilities of the material. As the module temperature increases, the dielectric strength of insulating materials in the module tends to decrease, which is a serious concern for a compact power module operating at many kilovolts. A plurality of high-temperature-rated, high dielectric strength potting materials was tested for voltage breakdown and leakage current up to 30 kV and 250°C. A range of different materials, both conventional and novel, were tested, including silicones and Parylene. Materials were selected with a dielectric strength >20 kV/mm, an operating temperature range of 200°C or higher, and low hardness and modulus of elasticity with the intent of demonstrating the capability of blocking 20 kV or more in a reasonable thickness. A custom test setup was constructed to apply the voltage to test samples while measuring the breakdown voltage and simultaneously recording the leakage current. Test coupons were designed to provide a range of dielectric thicknesses over which to test the dielectric strength. Although voltage isolation may increase with increased dielectric thickness, the volt per millimeter isolation rate often decreases. The performance degradation of these materials over temperature is plotted, and insulation thicknesses are suggested for use with medium voltages at operating temperatures above 175°C.

Temperature dependence of high dielectric strength potting materials for medium voltage power modules

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000249-000255 ◽  
Author(s):  
Chad B. O'Neal ◽  
Brandon Passmore ◽  
Matthew Feurtado ◽  
Jennifer Stabach ◽  
Ty McNutt
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Leakage Current ◽  
Dielectric Strength ◽  
Simultaneous Recording ◽  
Operating Voltage ◽  
Power Module ◽  
Dielectric Thickness ◽  
Power Modules ◽  
High Dielectric

Voltage isolation inside power modules is paramount for functional and reliable operation. The dielectric potting materials are further stressed as the overall size of these modules is reduced due to size, weight, and cost considerations while the operating voltage of the modules continue to increase. Voltage ratings of silicon carbide device technologies will continue to increase above 6.5 kV into the tens of kilovolts in the future. Silicon carbide devices are also often operated at higher junction temperatures in order to take advantage of the high temperature capabilities of the material. As the module temperature increases, the dielectric strength of insulating materials in the module tend to decrease, which is a serious consideration for a compact power module operating at many kilovolts. A plurality of high temperature rated, high dielectric strength potting materials were tested for voltage breakdown and leakage current up to 30 kV and 250 °C. A range of different materials, both conventional and novel, were tested including silicones and parylene. Materials were selected with a dielectric strength greater than 500 V/mil, an operating temperature range of 200 °C or higher, and low hardness and modulus of elasticity with the intent of demonstrating the capability of blocking 20 kV or more in a reasonable thickness. A custom test setup was constructed to apply the voltage to test samples while measuring the breakdown voltage and simultaneous recording the leakage current. Test coupons were designed to provide a range of dielectric thicknesses over which to test the dielectric strength. Although voltage isolation may increase with increased dielectric thickness, the V/mil isolation rate often decreases. The performance degradation of these materials over temperature is plotted and deratings are suggested for use with medium voltages at operating temperatures above 175 °C.

A High Current (>1500A) Power Module for High Temperature, High Performance Applications Using SiC TMOS Power Switches

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000402-000406
Author(s):  
B. Passmore ◽  
J. Hornberger ◽  
B. McPherson ◽  
J. Bourne ◽  
R. Shaw ◽  
...  
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Extreme Environment ◽  
Wide Bandgap ◽  
Power Module ◽  
Power Modules ◽  
Power Switches ◽  
Bandgap Semiconductors ◽  
Transition Times ◽  
Switch Position

A high temperature, high performance power module was developed for extreme environment systems and applications to exploit the advantages of wide bandgap semiconductors. These power modules are rated > 1200V, > 100A, > 250 °C, and are designed to house any SiC or GaN device. Characterization data of this power module housing trench MOSFETs is presented which demonstrates an on-state current of 1500 A for a full-bridge switch position. In addition, switching waveforms are presented that exhibit fast transition times.

Study of the electrical and thermal properties of a silicone elastomer filled with silica for high temperature power device encapsulation

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 1-9 ◽  
Author(s):  
E. Sili ◽  
M.L. Locatelli ◽  
M. Bechara ◽  
S. Diaham ◽  
S. Dinculescu
Keyword(s):  
High Temperature ◽  
Temperature Limit ◽  
Silicone Elastomer ◽  
Power Device ◽  
Maximum Temperature ◽  
Power Devices ◽  
Power Module ◽  
Temperature Range ◽  
Dimethyl Siloxane ◽  
Silicone Gels

In order to take the full advantage of the high-temperature SiC and GaN operating power devices, package materials able to withstand high-temperature storage and large thermal cycles are required. However, a survey of the commercially available silicone gels mostly used for power module encapsulation, highlights that this type of materials exhibits a maximum temperature limit for continuous operation of about 260 °C. A slight extension of this temperature range might be obtained by using silicone elastomers with hardness still remaining measurable on the Shore A scale. The aim of this paper is to study a silicone elastomer poly(dimethyl)siloxane (PDMS) with silica fillers, with a specified maximum operating temperature of 275 °C, in order to evaluate its ability for high temperature power device encapsulation. First, the nature and size of the filler microparticles were determined using scanning electron microscopy (SEM) observations coupled with energy dispersive X-ray spectroscopy (EDX) analysis. Second, the results of the thermal and electrical properties of this elastomer over a wide temperature range show that this type of insulating materials presents promising initial properties for the encapsulation of high temperature power devices.

A High Performance Power Module with >10kV capability to Characterize and Test In Situ SiC Devices at >200°C Ambient

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000149-000158
Author(s):  
Xin Zhao ◽  
Haotao Ke ◽  
Yifan Jiang ◽  
Adam Morgan ◽  
Yang Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
High Voltage ◽  
High Performance ◽  
Power Module ◽  
Module Design ◽  
Power Modules ◽  
Operational Temperature ◽  
Full Power ◽  
Temperature Applications

Abstract This paper presents design, fabrication and characterization details of a 10kV power module package for >200°C ambient temperature applications. Electrical simulations were performed to confirm the module design, and that the electric field distribution throughout the module did not exceed dielectric capabilities of components and materials. A suitable copper etching process was demonstrated for DBC layout, and a high melting point Sn/Pb/Ag solder reflow process was developed for device and component attachment. To monitor the operational temperature of the module, a thermistor was integrated onto the substrate. A new silicone gel, having a working temperature up to 210°C, was evaluated and selected for encapsulation and, of great importance, for passivation of high voltage (10kV) SiC dies. An additive manufacturing ‘Design Process’ was developed and applied to printing the housings, molds, and test fixtures. Also, cleaning processes were evaluated for every step in the fabrication process. To verify performance of the modules, mechanical dies were mounted on the substrates, and a high temperature testing setup built to characterize the modules at high temperature. Measurements indicated that the module can operate up to 12kV within 25°C to 225°C, with less than 0.1 μA leakage current. The packaging was used for full-power characterization of developmental 10kV SiC diodes, and proved that the power module packaging satisfied all requirements for high voltage and high temperature applications. This work successfully validated the processes for creating high voltage (>10 kV) and high temperature (>200°C) power modules.

Development of a Silicon Nitride High Temperature Power Module

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000172-000179
Author(s):  
Michael J. Palmer ◽  
R. Wayne Johnson ◽  
Mohammad Motalab ◽  
Jeffrey Suhling ◽  
James D. Scofield
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Metal Matrix ◽  
Coefficient Of Thermal Expansion ◽  
Matrix Composites ◽  
Power Module ◽  
Ceramic Fracture ◽  
Power Modules ◽  
Active Metal ◽  
Cte Mismatch

Silicon nitride (Si3N4) offer potential advantages as a substrate for high temperature power packaging. Si3N4 has higher fracture strength than alumina and aluminum nitride. The coefficient of thermal expansion (CTE) of Si3N4 is ~3 ppm/°C and the thermal conductivity ranges from 30–50W/m-K. Active metal brazed Cu-Si3N4 substrates are commercially available for power modules. However, the large mismatch in CTE between Si3N4 and Cu results in ceramic fracture and delamination with the wide temperature thermal cycling ranges encountered in high temperature applications. In this work Cu-Carbon and Cu-Mo metal matrix composites have been investigated to reduce the CTE mismatch. The process details are presented along with finite element modeling of the proposed structure. Ultimately, the proposed structure was unsuccessful.

High Temperature (250 °C) Silicon Carbide Power Modules With Integrated Gate Drive Boards

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000297-000304 ◽  
Author(s):  
B. Reese ◽  
B. McPherson ◽  
R. Shaw ◽  
J. Hornberger ◽  
R. Schupbach ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
High Performance ◽  
Single Phase ◽  
University Of Arkansas ◽  
Power Module ◽  
Power Modules ◽  
Gate Driver ◽  
Switch Position ◽  
The University

Arkansas Power Electronics International, Inc., in collaboration with the University of Arkansas and Rohm, Ltd., have developed a high-temperature, high-performance Silicon-Carbide (SiC) based power module with integrated gate driver. This paper presents a description of the single phase half-bridge module containing eight Rohm 30 A SiC DMOSFETs in parallel per switch position. The electrical and thermal performance of the system under power is also presented.

Warpage Evaluation of High-Temperature Sandwich-Structured Power Module for SiC Power Semiconductor Devices

2015 ◽  
Vol 12 (3) ◽  
pp. 153-160 ◽  
Author(s):  
Takeshi Anzai ◽  
Yoshinori Murakami ◽  
Shinji Sato ◽  
Hidekazu Tanisawa ◽  
Kohei Hiyama ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Cycle ◽  
Coefficient Of Thermal Expansion ◽  
Fabrication Process ◽  
Power Module ◽  
Ceramic Substrates ◽  
Soldering Temperature ◽  
Power Semiconductor ◽  
Power Modules ◽  
High Temperature Operation

This article presents a sandwich-structured SiC power module that can be operated at 225°C. The proposed power module has two ceramic substrates that are made of different materials (Si3N4 and Al2O3). The SiC devices are sandwiched between these ceramic substrates. The module also has a baseplate soldered onto the ceramic substrate. Conventional power modules use baseplate materials with a large coefficient of thermal expansion (CTE), for example, Cu (17–18 ppm/°C and Al (23–24 ppm/°C). In the fabrication process, the soldering temperature reaches 450°C because Au-Ge eutectic solder is used. A problem was found in the fabrication process of the module because of the high soldering temperature and CTE mismatches of the components. Furthermore, for high-temperature operation, a thermal cycle of −40°C to 250°C will be needed to ensure reliability and it is important to decrease the warpage of the module during the thermal cycle. By using stainless steel (CTE: 10 ppm/°C) for the baseplate, the warp-age measured at room temperature was reduced to one-third that of a module using a Cu baseplate. Further, the warpage displacement from 50°C to 250°C was also reduced.

High Temperature Dielectric Properties of Polyimide/Boron Nitride Nanocomposites: Nanoparticle Size and Filler Content Effects

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000096-000099
Author(s):  
F. Saysouk ◽  
S. Diaham ◽  
M.-L. Locatelli
Keyword(s):  
High Temperature ◽  
Boron Nitride ◽  
Filler Content ◽  
Average Diameter ◽  
Dielectric Strength ◽  
Dc Conductivity ◽  
Nanocomposite Films ◽  
Breakdown Field ◽  
Leakage Currents ◽  
The One

An interesting way to improve high temperature polyimides (PI) electrical properties by filling it with boron nitride nanoparticles (BN) is proposed in this study. The filler content (from 0 to 60 vol.%) and the average diameter size (35 nm and 120 nm) of these nanoparticles have been varied. The preparation of the patented PI/BN nanocomposite films was performed following an optimized process in order to obtain a good dispersion of the nanoparticles in the films. The nanocomposite films were electrically characterized in the range 200–350 °C. In the case where the nanoparticles had the smallest size, the DC conductivity and leakage currents decreased from 4 to 6 orders of magnitude when the PI/BN films were compared to the neat PI films. The improvement of this property was obtained by a small amount of nanoparticles (1.6 vol.%). Results also show an increase in the dielectric strength of 1 MV/cm for a filler content of 42 vol.%. In the case where the nanoparticles had a larger size, a small improvement was seen on the DC conductivity and leakage currents. In contrast, the breakdown field was lower than the one of the neat PI, due to aggregate formation within the films.

Crystallization effect on the dielectric strength of fluorinated parylene at high temperature

2012 ◽  
Vol 15 (2-3) ◽  
pp. 157-168 ◽  
Author(s):  
Mireille Bechara ◽  
Rabih Khazaka ◽  
Sombel Diaham ◽  
Marie-Laure Locatelli ◽  
Pierre Bidan
Keyword(s):  
High Temperature ◽  
Dielectric Strength ◽  
Crystallization Effect
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