Characterisation of silver particles used for the Low Temperature Joining Technology

Mechanical properties of nano-silver joints as die attach materials

“…Other impurities like copper, potassium and sodium are also typically found in the nanoscale Ag paste in the range of less than 1000 ppm, although it has been reported on rare occasion that the copper content may rise to ∼2700 ppm [31]. Sodium or potassium salts of the fatty acids which were used as lubricants for the milling process, were also detected in the Ag paste [31].…”

“…In general, the process steps of using nanoscale Ag paste were quite similar to that of micron-scale Ag paste [31][32][33][34]. There were also some reports which describe a different approach compared to micron-scale Ag sintering-eliminating the preheating stage before the die attachment step [35][36][37][38][39][40][41][42].…”

“…This review gives a short summary of available techniques with emphasis on synthesis of Ag nanoparticles to formulate Ag paste for die attach application. Generally, the Ag nanoparticles of sizes less than 20 nm are precipitated from Ag salts to form agglomerates with sizes ranging from 800 to 3500 nm [31]. Reducing agents like ascorbic acid [40,56], hydrazine monohydrate [57], sodium citrate [58] or sodium citrate dihydrate [59], polyvinylpyrollidone [50], ethylenediaminetetraacetic acid (EDTA) [60], sodium sulfite [61] and sodium borohydride [62] were added into Ag salts like nitrates, sulphates or chlorates or Ag-ammonia complexes [62].…”

“…Adapted from the Sigma-Aldrich websites [16]. [16,67], poly(diallydimethyl ammonium chloride) (PDDA) [16,67], polyacrylic acid (PAA) [16,67], polystyrene sulfonate (PSS) [16,67], triethylene glycol [32], methyloctylamine [40,56], dodecylamine [66], hexadecylamine [33], myristyl alcohol [46], 1-dodecanol [35], 1-decanol [35] stearic acid, oleic acid, palmitic acid [31], dodecanethiol [33] 2 Binder Ethyl cellulose [68], polyvinyl alcohol [16], polyvinyl butyral (PVB) [16,67], wax [16,67] 3 Solvents/thinner Isobornyl cyclohexanol (IBCH) [36], texanol [16,67], terpineol [16,40,41,67], butyl carbitol [33], toluene [33], xylene [40], ethanol [40], phenol [40].…”

“…Typically, nanoscale Ag paste is transferred to the substrate by spray coating, foil transfer, dispensing [44], stencil or screen printing [31] and dipping [43].…”