Due to the inherent nature of flip-chip assembly, the solder joints lie beneath the device and therefore are not amenable to visual inspection. Hence, it is important at the design stage to ensure that solder defects such as joint separation or joint shortening do not occur in the assembly. As a first step, the solder joint is modeled using a level-set approach. Unlike conventional fronttrackin...

An automated visual inspection system has been developed for use with surface mount devices (SMDs) on a printed circuit board (PCB). The system is capable of inspecting minute solder joints of fine pitch components as small as 0.3mm pitch QFP leads. A solder joint is judged using a height image and an intensity image that are detected by a unique confocal height sensor. A solder joint is classi...

This paper presents the characterization of the mechanical properties of three lead-free solder alloys 95.5Sn-4.0Ag-0.5Cu (SAC405), 96.5Sn-3.0Ag-0.5Cu (SAC305), and 98.5Sn-1.0Ag-0.5Cu (SAC105) at the solder joint scale. Several actual ChipArray ball grid array (CABGA) packages were cross-sectioned, polished, and used as test vehicles. Compressive tests were performed using a nanocharacterizatio...

An accelerated thermal cycle experiment comparing similarly constructed area array devices representing Land Grid Array (LGA) and Ball Grid Array (BGA) technology with 0.254, 0.30, and 0.40mm diameter SAC305 solder balls was performed. The devices were subjected to three thermal cycle conditions in order to promote 2nd level solder fatigue. Failure data was compared using Weibull analyses. The ...

Last year’s ITC started a lecture series on unpowered opens testing. All papers last year recognized the importance of an effective method of detecting solder opens and all used some electrical method to detect solder opens, the most common manufacturing defect on today’s surface mount printed circuit boards. However non-electrical methods are available today with significant benefits such as h...

The lifetime of the solder joint between base plate and ceramic substrate is usually tested by passively heating and cooling the IGBT module (thermal cycling). This provokes failures (delamination) in that solder layer. But, the IGBT and diode dies are actively heated in the application. Other failure modes (e.g. bond wire lift off) are addressed and limit the lifetime. This kind of stress is u...

Experiments using eutectic Sn–3.5% Ag solder paste were conducted with the objective of examining the conjoint influence of copper particles addition and rapid cooling on microstructural development. The composite solder mixture was made by thoroughly mixing a pre-weighed amount of copper particles with a commercial Sn–3.5% Ag solder paste. The experiments were quite similar to the heating and ...

A solder fatigue model for the 63Sn/Pb solder alloy has been previously introduced which characterizes the creep fatigue phenomena of the solder by combining nonlinear finite element modelling with experimental thermal fatigue lives of various flip chip assemblies. The model correlates the amount of creep strain energy dissipated per thermal cycle with the characteristic Weibull life of the cri...

The effect of Ni impurity on the self-diffusivity of bSn in the (1 0 1) symmetric tilt grain boundary is investigated. Using molecular dynamics simulations over a temperature range of 300–450 K. It is shown that Ni solute decreases the grain boundary self-diffusivity of bSn as the amount of solute in grain boundary increases. We also study the solute effect on the diffusive width of grain bound...

A novel and direct method to measure the stress-strain properties of surface mount solder joints is proposed in this paper. The specimen used in the experiments is a quad flat pack (QFP)-solder-printed circuit board (PCB) assembly and the fabrication of solder joints makes use of conventional surface mount technology (SMT). Mechanical cycling and thermal shock testing can be conducted directly ...