Chang-Chi Lee

Thermal–Mechanical Coupling Analysis for Coupled Power- and Thermal-Cycling Reliability of Board-Level Electronic Packages

In this paper, we apply the sequential thermal-mechanical coupling analysis that solves, in turn, the transient temperature field and subsequent thermomechanical deformations to investigate thermal characteristics along with fatigue reliability of board-level thin-profile fine-pitch ball-grid-array chip-scale packages under coupled power- and thermal-cycling test conditions. Pure thermal-cycling and pure power-cycling test conditions are also examined and compared. From the comparison of different test conditions, we note that the presence of power cycling leads to significant deviations of junction and mold-top temperatures from the thermal-cycling profile. Nevertheless, for components away from the die, the deviations are less significant. As the power specified to the test vehicle is low, temperature histories on the components induced by coupled power and thermal cycling can be approximated by superposition of the temperature histories induced by pure power cycling and the ones by pure thermal cycling. For the test conditions proposed in this paper, pure power cycling leads to the longest fatigue life among all. For coupled power and thermal cycling, the involvement of power cycling reduces the fatigue life of the test vehicle by about 50% as compared to pure thermal cycling.

Transient Thermal Analysis for Board-Level Chip-Scale Packages Subjected to Coupled Power and Thermal Cycling Test Conditions

In this work, thermal characteristics of a board-level chip-scale package, subjected to coupled power and thermal cycling test conditions defined by JEDEC, are investigated through the transient thermal analysis. Tabular boundary conditions are utilized to deal with time-varying thermal boundary conditions brought by thermal cycling. It is obvious from the analysis that the presence of power cycling leads to a significant deviation of the junction temperature from the thermal cycling profile. However, for components away from the die, the deviation is insignificant. Moreover, for low-power applications, temperature histories from coupled power and thermal cycling are approximately linear combinations of temperature histories from pure power cycling and the ones from pure thermal cycling.

Thermal-mechanical coupling analysis for coupled power and thermal cycling reliability of chip-scale packages

The sequential thermal-mechanical coupling analysis, which solves in turn the transient temperature field and subsequent thermo-mechanical deformations, is carried out in this paper to investigate thermal characteristics along with fatigue reliability of board-level thin-profile fine-pitch ball grid array chip-scale packages under coupled power and thermal cycling test conditions. Pure thermal cycling and pure power cycling test conditions are also examined and compared.

Coupled Power and Thermal Cycling Reliability of Board-Level Package-on-Package Stacking Assembly

In this paper, the sequential thermal-mechanical coupling analysis, which solves in turn the transient temperature field and subsequent thermomechanical deformations, is performed to investigate thermal characteristics along with fatigue reliability of a board-level package-on-package (PoP) stacking assembly under coupled power and thermal cycling test conditions. Effects of powering sequences on thermal characteristics and fatigue reliability of the PoP are examined. The numerical analysis shows that coupled power and thermal cycling creates temperature excursions based on the thermal cycling profile. Also, reliability of the PoP is highly related to the range of temperature excursions and the degree of deviation of the temperature profile from the thermal cycling profile.

Study of factors affecting warpage of HFCBGA subjected to reflow soldering-liked profile

Abstract Package warpage is an important factor to the effect of yield of board assembly, delamination, solder joint fatigue reliability and other thermal stress issues. Reduction of warpage is always the ultimate purpose for enhancing the service life. HFBCGA equipped only peripheral stiffener ring is selected to investigate the effect of heating rate, with and without ball mounted, moisture sensitivity level, white-coated paint on package and glass gratings to the warpage subjected to a reflow soldering-liked profile. Releasing viscoelasticity at processing temperature, maintaining structural rigidity of the residual solder, certain moisture resistivity at MSL 3, and light white paint help on reducing the warpage along the reflow soldering-liked profile.

Board-level Reliability of Package-on-Package Stacking Assemblies Subjected to Coupled Power and Thermal Cycling Tests

In this work, the sequential thermal-mechanical coupling analysis, which solves in turn the transient temperature field and subsequent thermomechanical deformations, is performed to investigate thermal characteristics along with fatigue reliability of a board-level package-on-package (PoP) stacking assembly under coupled power and thermal cycling test conditions. Effects of powering sequences on thermal characteristics and fatigue reliability of the PoP are examined.

Board level power cycling and thermal cycling fatigue reliability of chip-scale packages

In this paper, the sequential thermal-mechanical coupling analysis, which solves in turn the transient temperature field and subsequent thermomechanical deformations, was carried out to investigate board-level fatigue reliability of a thin profile and fine pitch ball grid array (TFBGA) chip-scale package under accelerated power cycling test conditions. Experiments for steady-state and transient thermal dissipations were conducted to verify the thermal analysis. Comparing between numerical results for power cycling and thermal cycling, it is noticed that for the tests with similar low and high temperature extremes, power cycling results in a much longer fatigue life than thermal cycling, which indicates that thermal cycling is a more conservative criterion than power cycling is in evaluating the fatigue resistance of the electronic packages.

High-power-used thermal gel degradation Evaluation on board-level HFCBGA subjected to reliability tests

HFCBGA is a thermally enhanced FCBGA with its heat spreader extending heat conduction area by connecting itself to the rear side of the silicon die. A thermal interface material plays an important role as a heat conduction path. The thermal performance should be checked not only at time zero, several types of reliability tests have to be examined to cover the field condition faced by end user. Temperature cycling test, highly-accelerated temperature and humidity stress test and multiple reflows are chosen for investigating thermal resistance of junction to case of a selected thermal gel.

Thermal Characteristics and Thermomechanical Reliability of Board-Level Stacked-Die Packages Subjected to Coupled Power and Thermal Cycling Test

The sequential thermal-mechanical coupling analysis, which solves in turn the transient temperature field and subsequent thermomechanical deformations, is performed to investigate thermal characteristics along with fatigue reliability of a board-level stacked-die package under coupled power and thermal cycling test conditions. Different powering conditions and sequences are compared. From the numerical results, we note that under coupled power and thermal cycling tests, reliability performances of a board-level stacked-die package should be similar as long as the total power dissipation prescribed to the package is identical, regardless of how the power distributes among separate dies.

Examination of thermal performance of board-level QFP with unattached drop-in heat spreader

We evaluate the board-level thermal performance of QFP with an unattached drop-in heat spreader numerically. The die is given a power and induced thermomechanical deformations and corresponding gap distributions on the unattached interface between the heat spreader and the die pad are calculated through the 3D thermal-mechanical coupling analysis incorporated with contact methodologies. Thermal performances of the package with different interfacial conditions are examined and compared.