Le plus de PUS

A l’écoute des évolutions du marché, PUS a compris que des alliages spécifiques étaient nécessaires pour chaque type de soudure. L’atomiseur de PUS est particulièrement adapté aux fabrications de petit et moyen volume pour ces alliages spécifiques.
PUS veut être un conseil indépendant et pragmatique sur les vrais performances des alliages, loin des modes commerciales ou des brevets.
LOW SAC
OUR VIEW: On copper pads, the classical IMC that is formed after soldering using a SAC alloy is Sn5Cu6. The shape of this IMC is usually a needle shape. Furthermore, IMC is always a brittle material. This is actually harmful for drop test behavior where breakage will occur near this IMC layer. Effect of Ni and Ag on Interfacial Reaction and MicrostructureINTERMETALLIC LAYER
OUR VIEW: For high quality solder joint, thermo-cycling behavior is generally a key-point. But be careful! Which kind of thermo-cycling are we speaking of? Soak time, temperature gap will change the rating of an alloy. For example SAC is better than SnPb on -40°C/60°C temperature range while SnPb is the best on -40°C/125°C gaps! Effect of Ag content on the microstructure of Sn‐Ag‐Cu based solder alloysTHERMOCYCLING
OUR VIEW: Lead Rich alloys are still widely used, especially for die attach. A simple lead free alternative doesn’t exist into nature where BiAg based alloys will lead to poor wetting, SnSb with Sb lower than 10% may have a too low melting point and Zn based alloys can lead either to poor wetting or large IMC.LEAD FREE HIGH TEMPERATURE SOLDERS
OUR VIEW: SAC Alloys and the most famous of them, the SAC305 generally shows a huge undercooling effect. While the melting point of this eutectic is 217°, the solidification starts at 195°C when using a 10°C per minute cooling rate. Using higher cooling rate is always possible, but not always practical when dealing with massive substrates because it can lead to thermal stress. This undercooling effect is directly related to the size of Ag3Sn precipitates into the substrate than can influence badly the behavior of the solder joint. Melting and Freezing Characteristics of Common Lead-free AlloysUNDERCOOLING OF SAC ALLOYS
LOW SAC
OUR VIEW: On copper pads, the classical IMC that is formed after soldering using a SAC alloy is Sn5Cu6. The shape of this IMC is usually a needle shape. Furthermore, IMC is always a brittle material. This is actually harmful for drop test behavior where breakage will occur near this IMC layer. Effect of Ni and Ag on Interfacial Reaction and MicrostructureINTERMETALLIC LAYER
OUR VIEW: For high quality solder joint, thermo-cycling behavior is generally a key-point. But be careful! Which kind of thermo-cycling are we speaking of? Soak time, temperature gap will change the rating of an alloy. For example SAC is better than SnPb on -40°C/60°C temperature range while SnPb is the best on -40°C/125°C gaps! Effect of Ag content on the microstructure of Sn‐Ag‐Cu based solder alloysTHERMOCYCLING
OUR VIEW: Lead Rich alloys are still widely used, especially for die attach. A simple lead free alternative doesn’t exist into nature where BiAg based alloys will lead to poor wetting, SnSb with Sb lower than 10% may have a too low melting point and Zn based alloys can lead either to poor wetting or large IMC.LEAD FREE HIGH TEMPERATURE SOLDERS
OUR VIEW: SAC Alloys and the most famous of them, the SAC305 generally shows a huge undercooling effect. While the melting point of this eutectic is 217°, the solidification starts at 195°C when using a 10°C per minute cooling rate. Using higher cooling rate is always possible, but not always practical when dealing with massive substrates because it can lead to thermal stress. This undercooling effect is directly related to the size of Ag3Sn precipitates into the substrate than can influence badly the behavior of the solder joint. Melting and Freezing Characteristics of Common Lead-free AlloysUNDERCOOLING OF SAC ALLOYS