Fig. 1. Devices and experiment process related with PLD. (a) Schematic of PLD device and process; (b) SiC chips before and after deposition; (c) cross section microstructure of deposited silver micro-and nano-particles composite film; (d) micro- and nano-particles in deposited film

Fig. 2. Sintering process using SMNCF and atmosphere-controllable HTS test. (a) Placement of SiC chip; (b) physical diagram of self-developed chip module auxiliary pressure sintering interconnection equipment; (c) schematic of the cross section of sintered sample; (d) working principle of tube furnace fixed with gas mixing device

Fig. 3. Variation of shear strength of sintered joints using SMNCF and hybrid Ag paste on storage time

Fig. 4. Variation of microstructure of sintered joints with holding time under atmospheric and vacuum environments

Fig. 5. Pore evolutions in sintered joints under atmospheric and vacuum environments. (a) Variation of porosity with holding time; (b) variation of average pore cross section area with holding time

Fig. 6. Microstructure evolutions of sintered layer during HTS tests in which the oxygen concentration is controllable. (a)(b) Microstructure of sintered layer in inert gas environment at heat preservation for 200 h and 400 h; (c)(d) microstructure of sintered layer in 20% concentration O₂ atmosphere at heat preservation for 200 h and 400 h; (e)(f) microstructure of sintered layer in 100% concentration O₂ atmosphere at heat preservation for 200 h and 400 h; (g) variation of porosity of sintered layer at heat preservation; (h) variation of average pore cross section area of sintered layer at heat preservation

Fig. 7. Influence mechanism of oxygen on pore evolution process of sintered joints during HTS tests. (a) Schematic of nanoparticle clusters with sintered necks and grain boundaries after sintering; (b) SEM image of polycrystalline structure in sintered layer before HTS tests; (c)(d) schematic of silver oxide extruded near grain boundaries and necks in nano-volcanic eruption effect; (e)(f) schematic of dynamic decomposition of extruded silver oxide and secondary sintering of newly-formed silver nanoparticles