Bonding strength of multiple SiC die attachment prepared by sintering of Ag nanoparticles

Abstract

a b s t r a c t 3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously been attached using sintering of Ag nanoparticle paste on AlN-based direct bonded copper substrates with 5\0.1 m thick NiP\Au finish. The effect of preparation and sintering parameters including time of drying the printed paste, sintering temperature and time, and pressure, on the average shear strength for multiple die attachments was investigated. The surfaces of the die attachments after the shear tests were observed and the individual shear strength values correlated with the "apparent" porosity and thicknesses of the corresponding die attachments (sintered layer). The results obtained are further discussed and compared with typical data reported in existing literature. Main conclusions include: (i) the present shear strength values and their variations are comparable with those reported for single die attachment samples, (ii) the effects of sintering parameters can be ascribed to the effectiveness of the organic content burnout and appropriate rate of growth and coalescence of the Ag nanoparticles during the sintering process, and (iii) thickness values of the sintered Ag die attachments may be taken as nondestructive measurements to monitor/evaluate the quality of die attachment during power electronic module manufacturing/assembly process.

Time-Efficient Sintering Processes to Attach Power Devices Using Nanosilver Dry Film

“…The present average shear strengths in the range of 26.1MPa to 46.6MPa are also comparable with those of the sintered silver joints using wet silver pastes which took longer processing time [16,17]. For example, the shear strengths were 15.7 to 80 MPa for those sintered joints prepared at sintering temperatures of 220 to 300°C, pressures of 1 to 20 MPa and sintering times of 60s to 1800s [11,[17][18][19]. From the above comparisons, it can be seen that the dry nanosilver film with lower amount of organics could indeed have impacts on the microstructures and properties of the sintered joints.…”

“…The variations of the porosity data series for all the 13 trials are quite low with the coefficients of variation (SDs divided by means) below 10%. In the previous work [11], sintered die attachments were produced using nanosilver paste as the raw material, and the final sintering of the dried paste (at 130°C for 10 to 45 min) was performed at 240 to 300 °C under 1MPa to15MPa for 1 to 8 min. The reported "apparent" porosity values (using SEM image-analysis method) were 15.3% to 23.4%.…”

Rapid formation of intermetallic joints through ultrasonic-assisted die bonding with Sn–0.7Cu solder for high temperature packaging application

“…These wide band-gap semiconductor devices, such as SiC power devices, provide great opportunities to develop power electronic systems with increased power densities, high reliability in extreme environments and higher integration density [1][2][3][4][5]. However, one big challenge is how to solve assembly and materials problems coupled with packaging of SiC devices.…”

“…Many researchers have investigated bonding techniques that involve sintering of Ag nanoparticles, because Ag has high thermal and electrical conductivity, and Ag nanoparticles can be produced easily and be sintered at relatively low temperatures due to their high stability against oxidation [14][15][16][17]. However, Ag is expensive and is poorly resistant to migration.…”

“…Good candidates for high temperature applications are eutectic alloys of Au-Sn (280°C) and Au-Ge (356°C), but it is not rational to apply Au to a large area die attach due to its extremely high cost. Although a new die-attachment structure using pure zinc solder for SiC die attachment was proposed [11], it has certain drawbacks: a high bonding temperature (more than 420°C) causing irreversible damage or accelerated aging affects to the electronic devices [12]; a poor ductility and limited oxidation resistance due to Zn [13].Many researchers have investigated bonding techniques that involve sintering of Ag nanoparticles, because Ag has high thermal and electrical conductivity, and Ag nanoparticles can be produced easily and be sintered at relatively low temperatures due to their high stability against oxidation [14][15][16][17]. However, Ag is expensive and is poorly resistant to migration.…”