Effect of component standoff height on thermo-mechanical reliability of ball grid array (BGA) solder joints operating in high-temperature ambient

Abstract

Effect of standoff height (SH) on thermo-mechanical reliability of solder joints inminiaturised surface mount components in consumer electronics which operates in high-temperature ambient is studied. This work investigates the effect of CSH on ball grid array (BGA) solder joints which operates in high homologous temperature in mission critical systems and seeks to utilise the findings of this investigation to minimise the accumulated strain energy density in the joints. The study focuses to underpin the relationship between CSH and shear strength of the joints while it determines the effect of long high-temperature operations on integrity of the soldered joints. It identifies the failure site and mode in the joints and examines failed surfaces to provide information on the morphology of the material microstructure. The results demonstrate that increase in CSH decreases the shear strength of the solder joints and at prolonged operations in high-temperature of about 150 degrees centigrade, solder joint shear strength decreases due to significant formation and growth of brittle intermetallic compound at the interface between substrate pad and solder bulk. EDS analysis shows that this region is characterized by high Tin/Cu content and demonstrates failure mode of crack initiation, propagation and pad lifting.

Effect of stand-off height on the shear strength of ball grid array solder joints under varying pad sizes

“…The effects of component standoff-height (CSH) controlled by the relationship between diameter of PCB bond pad and diameter of die bond pad on high-temperature reliability of flip chip lead-free solder joint was conducted by [1,3,10] using finite element method (FEM) tool. It was concluded from the study that the reliability of solder joint in flip chip assembly decreases as CSH decreases, low CSH promotes fatigue cracks at interconnects between IMC at the die side and solder region and that the reliability of solder joints operating at elevated temperatures is dependent on CSH, thickness of IMC and solder volume.…”

Estimation of Solder Ball Collapse Height in Semiconductor Packaging Using Theoretical and Solid Modeling Techniques

“…This study presents simplified techniques developed for predicting solder ball collapse height that would be very useful for package designers to use and make the design and development much faster. Aside from being necessary in meeting the overall package thickness requirement even during the design stage, accurate prediction of solder ball collapse height is also very important as it several studies [8][9][10][11][12][13]] that solder joint shape and height have significant effect on solder joint reliability or fatigue life. The accuracy of any solder joint reliability modeling would be dependent on the accuracy of the solder joint shape and height estimation.…”