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In this paper, authors developed miniaturizeddouble side cooling packaging for SiC (silicon carbide) highpower inverter module using new material solutions towithstand high temperature condition over 220oC. Instead ofconventional thick wire bonding on the device, the flip chipbonding for high power source and gate interconnections aredeveloped. For the drain interconnection, copper clips areattached using high temperature endurable interconnectionmaterials. By utilizing these flip-chip structures, the powermodule with double side cooling design was enabled effectivelyfor the heat dissipation induced by high power switchingoperation. Through the thermal modeling and characterization, the power module's package thermal dissipation performancewas found to be enhanced by 2 times compared with theconventional single side cooling type power module. To copewith the increased maximum junction temperature limit tooperate wide band gap power devices the novel packagingmaterial and its process which can endure up to 220 oC weredeveloped also. Bi and Ag based high temperature solder wasapplied for the flip-chip bumping for SiC device on the DBC(direct bonded copper). The copper clip was applied on thedevice backside as drain interconnection to DBC also. Hightemperature endurable EMC (epoxy molding compound) andTIM (thermal interface material) were also evaluated. Thepackaging process was optimized and developed along with themodeling. Through the reliability assessment, we could showthe potential applicability of double side cooling power modulewith flip-chip and clip bonding design and it would be usefulfor the SiC and GaN based high power module and highjunction and environmental temperature endurableapplications for the near future.

Ag sintering has been widely studied as a lead-free die attach solution for power electronics. A soak time of a dozen minutes at the sintering temperature is necessary to establish strong bond strength by the conventional heating method. Chemical bonding can be achieved by various parameters associated with the metallurgical bond of the adjacent surfaces. In this study, attaching technology between Au coated Si die and Au coated Si substrate was developed by applying Ag sintering materials which can work at temperature up to 350°C. It was concentrated on finding so called "pressure-less sintering and pressure sintering" procedure in air and N2 environment. The sintering was performed in air or N2 at temperature range from 180°C to 280°C for 10 minutes to 3 hours. Highest shear strength was obtained at 200°C of sintering temperature bonded for 3 hours.

While leadframe has come a long way as a cost effective substrate, there is still limitation over its design rule. In this article, the authors have developed and put to test a SiC based PQFN using 70μm single metal layer substrates, allowing further miniaturization and complex design of PQFN. New high temperature EMC with a Tg of 241°C and lead free bismuth silver solder are adopted. Reliability tests and RDS,on results showed that the materials adopted in the development does not degrade the MOSFET's functionality and all samples passed reliability and power cycling tests.

The SiC based high power 3 phase inverter module with double side cooling structure was developed. By applying flipchip bonding of SiC based high power DMOSFET device on DBC substrate, the source and gate bonding could be achieved. The drain interconnection was done by copper clip attach. The developed structure can provide the flat structure for both top and bottom surfaces, which can be effectively utilized for double side cooling design for high power heat dissipation. In addition to power module design with double side cooling capability, the high temperature endurable material set which can endure over 220°C device junction temperature such as high temperature interconnection, encapsulation and TIM (thermal interface materials) are developed and identified. Through the thermal, mechanical, electrical modeling & characterization and the reliability test for the developed functional test vehicles, the author could demonstrate the possibility of flip-chip based double side cooling capable high power module structure which can be utilized to high power and high temperature endurable applications for future wide band-gap device such as SiC and GaN based inverter modules.

While the advantages of high temperature electronics in the form of hermetic ceramic packaging are numerous, their deployments are being limited by the maximum environmental pressure. Literature [1] has shown that to withstand 30kpsi pressure for instance, a flat ceramic lid of at least 3mm will be required for a cavity size of 10.16mm × 10.16mm. Lid thickness will have to increase if the cavity size is increased. However, by filling the cavity with high temperature endurable material, thickness requirement can be eliminated from consideration, maintaining low package profile [2]. The approach has been demonstrated through a timer / temperature sensor circuitry embedded in a 31.75mm × 10.92mm cavity and successfully passed a combined HPHT of 30kpsi and 300°C until the end of targeted 200 hours.

Integrated Circuited devices fabricated on SiC instead of Si allows higher operating temperatures for the future automotive, aerospace, and green and renewable energy industry. With higher temperature interfaces and contacts between the chip and package, new packaging interconnection materials able to sustain high temperature operations need to be explored. This work demonstrates the assembly of a dual-side cooled high power 3-phase inverter module that was 32mm × 30mm with 6 SiC DMOSFET attached by flip chip technology. Rheological modeling using FVM (Finite Volume Method) based simulation was carried out and validated for the dispense pattern of silver sintering material used in high power electronics flip chip attach. Further details of assembly process flow, assembly challenges, reliability assessment and future works will be discussed in the full manuscript.

For downhole drilling applications, packages will have to endure extremely harsh conditions, which can easily reach a temperature of 300°C. At such high temperatures, the commonly adopted solder materials are lead-based as they are more readily available in paste and solder ball forms. While multiple studies have been performed on eutectic goldgermanium solder and its reliability at high temperature, little work has been done on the processing and assembly of the material into a flip chip package. This paper aims to study the feasibility of gold-germanium solder assembly through laser jetting process optimization. It is observed that Ge phase coarsening does not occur with laser jetting, compare to reflow process.

As oil and gas industries ventured further and deeper into the earth or ocean in search for new reservoirs, the requirements of depth, pressure and temperature are ever expanding. Conventionally, ceramic based hermetic sealed packaging is used for high temperature endurable package. However, for the case of highly pressurized application, the stress on the package is substantial and the hermetically sealed ceramic package cannot survive under a high pressure up to 30kpsi. To overcome this limitation, the authors are proposing to fill high temperature and high pressure endurable protective materials inside of ceramic substrate cavity to absorb the package internal stress caused by the external high pressure loading. The reliability of the package has been successfully demonstrated under combined 30kpsi isostatic pressure and 300°C temperature (HPHT) aging condition for 500 hours as well as thermal cycling condition for 500 cycles.