In this paper, we described an approach in automation, the visual inspection of solder joint defects of surface mounted components on a printed circuit board, using a neural network with fuzzy rule-based classification method. Inherently, the solder joints have a curved, tiny, and specular reflective surface. This presents the difficulty in taking good images of the solder joints. Furthermore, ...

The combination of higher lead-free process temperatures, smaller print deposits, and temperature restraints on electrical components has created difficult challenges in optimizing the reflow process. Not only are the electronic components and the PWB at risk, but the ability to achieve a robust solder joint becomes difficult, especially if the PCB is thermally massive. In addition, the constan...

Currently, the portable electronic products trend to high speed, light weight, miniaturization and multifunctionality. In that field, solder joint reliability in term of both drop impact and thermal cycling loading conditions is a great concern for portable electronic products. The transition to lead-free solder happened to coincide with a dramatic increase in portable electronic products. Sn–A...

Recent investigations have revealed that Pb-free solder joints may be fragile, prone to premature interfacial failure particularly under shock loading, as initially formed or tend to become so under moderate thermal aging. Depending on the solder pad surface finish, different mechanisms are clearly involved, but none of the commonly used surface finishes appear to be consistently immune to embr...

As the second part to a paper presented at the 2004 SMTA Pan Pacific Symposium, this paper further summarizes the results from technical qualification of the Ni/Pd/Au process. Whereas the previous paper examined the wire bonding capabilities of this surface finish, this second paper focuses specific attention to BGA applications. In these investigations, the solder joint integrity is measured u...

A new method of assembling MEMS is being developed that uses solder surface tension force to manipulate and assemble MEMS 3-D structures. Modeling is critical to design solder joints for precision assembly. An accurate model has been developed based on the principle of surface energy minimization. Using Surface Evolver software, this model considers three-dimensional MEMS configurations with di...

The ever increasing power density in modern semiconductor devices requires heat dissipation solution such as heat sink to remove heat away from the device. A compressive loading is usually applied to reduce the interfacial thermal resistance between package and heat sink. In this paper, both experimental approaches and numerical modeling were employed to study the effect of compressive loading ...

The trend of miniaturization, light weight, high speed and multifunction are common in electronic assemblies, especially, for portable electronic products. In particular, board-level solder joint reliability, in term of both mechanical (e.g., drop impact) and thermo-mechanical (e.g., thermal cycling) loads is of great concern for portable electronic products. The transition to lead-free solder ...

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....

Reliability of QFP (quad flat package) solder joints after thermal shock was investigated for PCB’s and connecting leads plated with several different alloy coatings before soldering. Sn–8 wt%Zn–3 wt%Bi (hereafter, Sn–8Zn–3Bi) was selected as a solder, and FR-4 PCB’s finished with Cu/Sn, Cu/OSP and Cu/Ni/Au were used as substrates. The leads of the QFP were Cu plated with Sn–10 wt%Pb, or Sn, or...