Design for lead‐free solder joint reliability of high‐density packages

Abstract

The lead‐free solder joint reliability of several printed circuit board mounted high‐density packages, when subjected to temperature cycling was investigated by finite element modelling. The packages were a 256‐pin plastic ball grid array (PBGA), a 388‐pin PBGA, and a 1657‐pin ceramic column grid array. Emphasis was placed on the determination of the creep responses (e.g. stress, strain, and strain energy density) of the lead‐free solder joints of these packages.

Reliability of lead-free solder joints with different PCB surface finishes under thermal cycling

“…The CTE value of Alloy 42 [15], copper [16], nickel [17], FR4 material [16], and SnAgCu solder [18] are 4.4, 17, 13, 16, and 17.6 ppm/ • C, respectively. Thermal fatigue stresses on the solder joints are directly proportional to the mismatch in CTE.…”

A Probabilistic Approach to Predict Thermal Fatigue Life for Ball Grid Array Solder Joints

“…For lead-free solder joints of ball grid array packages, the areas of highest stress occur at edges and corners, resulting in cracks initiating from these locations and propagating along the joint interface as the typical failure mode. 11,12 Thermal cycling induces cyclic strain. This cyclic shear strain causes accumulation of damage due to the fact that thermomechanical fatigue is an accumulation of microstructure dislocation.…”

Effect of reflow numbers on the interfacial reaction and shear strength of flip chip solder joints

“…However, due to concerns about the environmental pollution of lead, lead-free solders are being popular [5]. Currently the common lead-free solder alloys being investigated include Sn-Bi, Sn-Ag, Sn-Ag-Cu and Sn-Cu, all of which have a relatively high Sn content in comparison to the traditional Sn-Pb alloy varieties.…”

“…However, even with these advantages, the Sn-Ag-Cu solders are relatively expansive because of Ag addition in the solder composition. In 2000, National Electronics Manufacturing Initiative (NEMI) recommended to replace eutectic Sn-Pb solder by Sn-Ag-Cu solder in reflow processing and Sn-Cu solder in wave soldering because of its lower cost [5].…”