Impact life prediction modeling of TFBGA packages under board level drop test

Reliabilit!- perfonnance of IC packages during drop impact is critical, especially for handheld electronic products. Currently. thcrc is no detailed test standard in the industry to advise on the procedures for board level dmp test. nor there is any model Ilia1 providcs good correlation with experimental ineasiircinents of acceleration and impact life. In this paper; detailed drop tests and simulations are pcrfonned on TFBGA (Thin-profile Fine-pitch BGA) and VFBGA (Vey-thinprofile Fine-pitch BGA) packages at board level using testing procediires developed in-house. The packages are susceptible to solder joint failures, induced by a combination of PCB bending and iueclwnical shock during impact. The critical solder ball is obsewed to occur at the outennost comer solder .joint_ and fails along the solder and PCB pad interface. Various testing parameters are studied experimentally and analytically. to understand the effects of drop heightl drop oricntation, number of PCB mounting screws to fixture. position of component on board: PCB bending: solder material, and etc. Drop height, fclt thickness, and contact conditions are used to fine-tune the shape aud level of shock pulse required. Board level drop test can be better controlled. compared with system or product level test such as impact of mobile phone. which sometimes has rather unpredictable results due to higher complexity and variations in drop orientation. At tlie same time, dynamic simulation is perfonncd to compare with esperiniental results. The model established has close values of peak acceleration and impact duration as measured in actual drop test. The failure mode and critical solder ball location predicted by modeling correlate well with testing. For the first time, an accurate life prediction model is proposed for board level drop test to estiinatc the number of drops to failure for a package. For the correlation cases studied. the nminmm nonual peeling stresses of critical solder joints correlate well with the mean impact lives measured during the drop test. The uncertainty of impact life prediction is within M drops, for a typical test of 50 drops. With this new model, a failure-free state can be detennined, and drop test performance of new package design can be quantified. and fuliher enhanced through modeling. This quantitative approach is different from traditional qualitative modeling. as it provides both accurate relative and absolute impact life prediction. The relative performance of package may be different under board level drop test ,and thennal cycling test. Different design guidelines should be considered, depcnding on application and area of concern

Board level drop test and simulation of TFBGA packages for telecommunication applications

Integrated vapor pressure, hygroswelling, and thermo-mechanical stress modeling of QFN package during reflow with interfacial fracture mechanics analysis

Overview of wire bonding using copper wire or insulated wire

In this paper, thermal cycling tests and finite-element analysis (FEA) for a plastic ball grid array package with Sn-3.8Ag-0.7Cu lead-free solder joints have been performed. The solder joint fatigue lives were predicted and compared by using different 2-D and 3-D FEA models. The effects of solder constitutive models and fatigue life models on solder fatigue life prediction have been investigated. In order to obtain fatigue parameters, new averaging volumes were proposed for the solder fatigue life prediction. Different reference temperatures were simulated to investigate its effect on the solder fatigue life prediction. The effect of intermetallic compound thickness on solder joint fatigue life prediction was also investigated.

Fatigue Reliability Analysis of Sn–Ag–Cu Solder Joints Subject to Thermal Cycling

Board level solder joint reliability modeling and testing of TFBGA packages for telecommunication applications

Reliability assessment and hygroswelling modeling of FCBGA with no-flow underfill

Comprehensive board-level solder joint reliability modeling and testing of QFN and PowerQFN packages

With shrinking of chip sizes, Wafer Level Chip Scale Packaging (WLCSP) becomes an attractive and holistic packaging solutions with various advantages in comparison to conventional packages, such as Ball Grid Array (BGA) with flipchip or wirebonding. With the advancement of various fan-out (FO) WLPs, it has been proven to be a more optimal, low cost, integrated and reliable solution compared to fan-in WLP because of the greater design flexibility in having more input/output (I/O), improved mechanical and thermal performance. In addition, FO-WLP shows superior high-frequency electrical performance due to its shorter, finer and simpler interconnection scheme compared to flipchip packaging. eWLB (embedded wafer level BGA) is a type of FO-WLP that enables applications requiring smaller form factor, excellent thermal performance and thin package profiles and it has the potential to evolve into various configurations with proven yields and manufacturing experience based on more than 8 years of high volume manufacturing of over 1.5B unit shipment. This paper discusses the recent advancements in robust board level reliability performance of eWLB for automotive application, where a review of a Design of Experiment (DOE) study will demonstrate improved Temperature Cycle on Board (TCoB) reliability. Several DOE studies were planned and test vehicles were prepared with various variables, such as materials, redistribution layer (RDL) design, copper (Cu) and under bump metallurgy (UBM) thickness, and a printed circuit board (PCB) pad design. The final test vehicle passed over 1000 times temperature cycles (TC) with optimized design factors of these parametric studies and reliability tests. To investigate potential structural defects after the reliability test, both destructive analyses were performed under industry standard test conditions, Daisy chain test vehicles were used for TCoB reliability performance.

Reliability of eWLB (Embedded Wafer Level BGA) for Automotive Radar Applications

With the increasing requirement for lead-free solders, it is desired to know how different solder alloys affect on reliability of microelectronic assembly. Some fatigue life models for Sn-Ag-Cu (SAC) solder have been developed by researchers. The Ni-dopant lead free solder is increasingly used in electronic packages due to its good drop performance. Currently, it lacks the fatigue life model for Ni doped SAC solder. In this paper, thermal cycling test and finite element simulation were conducted for 5 FBGA (Fine pitch BGA) assemblies with Sn-Ag-Cu-Ni (SACN) lead free solder. The thermal fatigue life prediction model was developed for FBGA assemblies with SACN solder by combining experimental and simulation results. The good correlation between predicted and experimental lives was achieved. In addition, the effect of geometry and loading condition on solder joint predicted life was investigated based on the finite element simulation result and the developed life model.

Daniel Yap

Papers

Board level solder joint reliability modeling and testing of TFBGA packages for telecommunication applications

Reliability assessment and hygroswelling modeling of FCBGA with no-flow underfill

Comprehensive board-level solder joint reliability modeling and testing of QFN and PowerQFN packages

Reliability of eWLB (Embedded Wafer Level BGA) for Automotive Radar Applications

Thermal cycling fatigue model development for FBGA assembly with Sn-Ag-based lead-free solder