## 1 Introduction  
The rapid advancement of hybrid electric vehicles (HEVs) and other power electronic systems has increased the demand of highly reliable bonding technologies in the power modules. The operation of power modules at high powers and frequencies, along with high integrability and miniaturization capability is highly desired [1]. Moreover, the utilization of next-generation semiconductor material; silicon carbide (SiC), instead of the conventional materials offers lower power loss, higher switching speed, and higher operating temperature, which has recently exceeded 175 \({}^{\circ}\)C and even reached 200 \({}^{\circ}\)C [2]. As the bonding layers are also exposed to such high temperatures, the performance metrics and reliability of joints should be improved. Sn-based soldering is conventionally used in die-attach applications; however, the maximum operating temperature is limited to lower than 175 \({}^{\circ}\)C in Sn-Ag-Cu solders. Therefore, alternative bonding technologies with higher heat tolerance are in great demand. Silver sinter bonding technologies are representative technologies for next-generation power modules, which have been reported to provide outstanding thermal and electrical conductivity and highly reliable performance [3; 4; 5; 6; 7; 8; 9]. Although the traditional sintering process requires complicated pressure-assistance, optimized bonding materials for pressureless bonding have recently emerged as powerful alternatives [10; 11; 12; 13]. However, high-cost and low compatibility with conventional soldering processes inhibit the industrial use of these materials. Another low-cost bonding method, copper sinter bonding, has been researched, as it provides excellent conductivity, high-temperature durability and high electrical migration resistance [14; 15; 16]; however, surface coating of Cu particles or reducing the atmosphere for the sintering process was generally required because of its oxidation affinity under storage in air, which inhibits sintering. Thus, inexpensive and highly reliable bonding technologies are being investigated for advanced power modules. Recently, low-temperature bonding utilizing the sintering of Cu particles with the transient liquid-phase of Sn-based solder, called Cu-Sn transient liquid-phase sintering (TLPS), has been proposed as a low-cost technology for high temperature electronic applications [17]. Once the solder is completely transformed into a Cu-Sn intermetallic compound (IMC) during the reflow process, a bonding layer with high re-melting temperature can be obtained. Several studies have demonstrated the high bondability and high-temperature resistance of the Cu-Sn system [18; 19; 20; 21] and similar Ni-Sn and Ag-Sn systems [22; 23; 24]. These studies focused on the realization of \"dense\" IMC bonding layer and high joint strength using a low-temperature and short-time bonding process based on interdiffusion control between the metal particles. The \"dense\" IMC joints might exhibit high strength at elevated temperatures; however, it has been reported that the stiffness and brittleness of the IMCs cause strength reduction or joint fracture through thermal cyclic operations [25; 26; 27; 28; 29]. Further, the addition of resin into TLPS layer has been extensively investigated in the field of electronic packaging. For example, [PERSON] et al. [30] reported that the TLPS polymer adhesives exhibit a stable electrical connection and can be used as a laminate-based microvia to interconnect electronic devices. [PERSON] [31] also demonstrated the feasibility of the TLPS conductive adhesives for surface mount technology (SMT). Moreover, underfilled mold resins are widely used as reinforcement of solder bumps for highly integrated electronic packaging [32]. These resins are usually expected to show relatively rigid mechanical properties to reinforce \"metallic\" joints. Therefore, deterioration of resins, which includes delamination, decomposition, void formation, etc., are vital issues for these resins.