The melting temperatures of most lead-free solder alloys are somewhat higher than that of eutectic Sn/Pb solder, and many of the alloys tend to wet typical contact pads less readily. This tends to narrow down the fluxing and mass reflow process windows for assembly onto typical organic substrates and may enhance requirements on placement accuracy. Flip chip assembly here poses some unique chall...

Sn-Pb eutectic solder alloy is extensively used in microelectronics packaging interconnects. Due to the high homologous temperature, eutectic Sn-Pb solder exhibits creepfatigue interaction and significant time-, temperature-, stress-, and rate-dependent material characteristics. The microstructure is often unstable, having significant effects on the flow behavior of solder joints at high homolo...

While the situation varies from country to country, nearly one year after the EU RoHS Directive came into force implementation of lead-free solder is progressing steadily. For lead-free soldering to be considered successful it is not sufficient just to have dealt with the challenges of mass production. It is also necessary to establish that the soldered joints produced are at least as reliable ...

This paper presents and discusses issues relevant to solidification of a chosen lead-free solder, the eutectic Sn-3.5%Ag, and its composite counterparts. Direct temperature recordings for the no-clean solder paste during the simulated reflow process revealed a significant amount of undercooling to occur prior to the initiation of solidification of the eutectic Sn-3.5%Ag solder, which is 6.5 C, ...

In the past few years, many studies have reported on the formula of solder metal alloy materials. This paper discusses the influence of organic materials characters, the decomposing rate of flux in lead-free solder paste and coefficients of thermal expansion (CTE) of halogen-free mold compounds during the on-board reliability test, and the failure mechanism in both 63Sn/37Pb and Sn–3.5Ag–0.5Cu ...

background and aims. in order to fabricate prostheses with high accuracy and durability, soldering techniques have been introduced to clinical dentistry. however, these prostheses always fail at their solder joints. the purpose of this study was to evaluate the effect of gap distance on the tensile strength of base metal solder joints. materials and methods. based on ada/iso 9693 specifications...

Reflow soldering in a nitrogen atmosphere is a common process consideration in surface mount technology assembly. This is because the use of nitrogen in reflow equipment may benefit the process as well as the quality of the end product, where it can increase the reliability of the solder joint. So far, many papers have reported effects of cooling speed, type of solder pastes and solder fluxes o...

The electronics industry is undergoing a materials evolution due to the pending Restriction of Hazardous Substances (RoHS) European Directive. Printed wiring board laminate suppliers, component fabricators, and printed wiring assembly operations are engaged in a multitude of investigations to determine what leadfree (Pbfree) material choices best fit their needs. The size and complexity of Pbfr...

Although lead-free soldering has been main stream in the industry since 2006 with the replacement of the eutectic SnPb system by the SnAgCu system, the development of drop-in lead-free alternatives for high melting high lead solder alloys is still far from mature. The BiAg alloy exhibits acceptable bulk strength, but very poor ductility and wetting. Therefore, it is not acceptable as an option....

The solder joint reliability of ceramic chip resistors assembled to laminate substrates has been a long time concern for systems exposed to harsh environments such as those found in automotive and aerospace applications. This is due to a combination of the extreme temperature excursions experienced by the assemblies along with the large coefficient of thermal expansion mismatches between the al...