Electronic Components and Technology Conference 

About: Electronic Components and Technology Conference is an academic conference. The conference publishes majorly in the area(s): Flip chip & Soldering. Over the lifetime, 9147 publications have been published by the conference receiving 102861 citations.

Effect of simulation methodology on solder joint crack growth correlation

Abstract: A generalized solder joint fatigue life model for surface mount packages was previously published by the author. The model is based on correlation to measured crack growth data on BGA joints during thermal cycling. It was subsequently discovered by Anderson et. al. that the ANSYS/sup TM/ 5.2 finite element code used in the model had an error in its method for calculating plastic work. It was shown that significant error in life prediction could result by using a recent version of the code where the bug has been fixed. The error comes about since the original crack growth constants were derived based on plastic work calculations that had the bug. In this paper, crack initiation and growth constants are recalculated using ANSYS/sup TM/ 5.6. In addition, several other model related issues are explored with respect to the crack growth correlations. For example, 3D slice models were compared to quarter symmetry models. Anand's constitutive model was compared with Darveaux's constitutive model. It was shown that the crack growth rate dependence on strain energy density always had an exponent of 1.10+/-0.15. This is in the range of the original correlation, so the accuracy of relative predictions should still be within+/-25%. However, the accuracy of absolute predictions could be off by a factor of 7 in the worst case, if the analyst uses a modeling procedure that is not consistent with that used for the crack growth correlation. The key to good accuracy is to maintain consistency in the modeling procedure.

Constitutive relations for tin-based-solder joints

Abstract: Extensive data on 62Sn36Pb2Ag, 60Sn40Pb, 96.5Sn3.5Ag, 97.5Pb2.5Sn, and 95Pb5Sn solder are presented. All of the data were collected on soldered assemblies to properly account for the effects of grain size and intermetallic compound distribution. Tensile and shear loading were employed in the strain rate range between 10/sup -8/ and 10/sup -1/ s/sup -1/ and the temperature range between 25 and 135 degrees C. It is remarkable to note that all of the data can be fit to the same general form of constitutive relations; i.e., only the constants depend on the solder alloy. The derived constitutive relations are used to predict solder joint response under thermal cycling. Based on the calculated hysteresis loops, it is apparent that each solder will have a different acceleration factor between field use cycling and accelerated test cycling. >

Fatigue life models for SnAgCu and SnPb solder joints evaluated by experiments and simulation

Abstract: In recent years, many solder fatigue models have been developed to predict the fatigue life of solder joints under thermal cycle conditions. While a variety of life prediction models have been proposed for near eutectic SnPb(Ag)-solder joints in the literature, not enough work has been reported in extending these models to lead-free soldered assemblies. The development of lie prediction models requires a deep insight into failure modes, constitutive models for the themnomechanical behavior of solders and an experimental reliability database. This is needed for the correlation of experimentally determined cycles-to-failure to simulation results by fmiteelement analysis. This paper describes in detail the life-prediction models of SnPh(Ag) and SnAgCu solder joints for thermal cycle conditions. To obtain reliable FEM input and to verify simulation results, a variety of material testing and experimental fatigue data is necessary. The accuracy of lieprediction tools has also become critically important, as the designs need to he evaluated and improved with a high degree of reliability, not through relative comparison but by providing absolute numbers. This work deals with the effect of different solder interconnect alloys (Sn59Pb40Agl and Sn95.5Ag3.8Cu0.7) and the effect of different package types (PBGAs, CSPs, Flip Chip on FR-4 with and without underfill) on the fatigue life. Different temperature cycling conditions are applied.

Accumulated creep strain and energy density based thermal fatigue life prediction models for SnAgCu solder joints

Abstract: Pb free solder is fast becoming a reality in electronic manufacturing due to marketing and legislative pressures. The industry has pretty much concluded that various versions of SnAgCu solder alloy offer the best alternative for eutectic Sn/Pb solder currently in use. With the current trend of cheaper, faster, and better electronic equipment, it has become increasingly important to evaluate the package and system performance very early in the design cycle using simulation tools. This requires life prediction models for new solder alloy systems so that the package-to-board interconnect reliability can be predicted for various environmental and field conditions. This paper describes in detail the life prediction models for SnAgCu solder joints. The models are based on published constitutive equations for this alloy and thermal cycle fatigue data on actual components. The approach uses advanced finite element modeling and analysis techniques and is based on mechanics of deformation. Both accumulated creep strain and creep strain energy density based models are developed. The model has been correlated with a number of data points and predicts life within 25% in most cases. The framework of modeling and prediction methodology described here is fully compatible with the framework used for SnPb solder previously.

Effect of thermal aging on board level drop reliability for Pb-free BGA packages

Abstract: The drive for Pb-free solders in the microelectronics industry presents several new reliability challenges. Examples include package compatibility with higher process temperatures, new solder compound failure mechanisms, and the selection of the proper Pb-free alloy to maximize product lifetime. In addition to the challenges posed by the Pb-free material conversion, the migration of market focus from desktop computing to portable applications is changing the critical system failure mode of interest from conventional temperature cycling (T/C) induced solder fatigue opens to drop impact induced solder joint fracture. In this paper a study was conducted to investigate the influence of intermetallic compound (IMC) growth on the solder joint reliability of Pb-free ball grid array (BGA) packages under drop loading conditions. Thermal aging at homologous temperatures between 0.76 and 0.91 with microstructural analysis was conducted to analyze the solid phase IMC growth at the solder to BGA pad interface. Component level,ball shear and pull tests were also conducted to investigate the aging effect on solder joint strength. A key finding from this work is that Kirkendall voids formed at the bulk solder to package bare Cu pad interface under relative low 100/spl deg/C aging. Void formation and coalesce is shown to be the dominant mechanism for solder joint strength and board level drop reliability degradation.