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Through an aggressive product development program which includes experiment and simulation, Amkor has developed the next level of WLCSP (CSPnltrade), a product which exhibits superior board level reliability when subjected to drop impact, a strong requirement for portable electronics. Failure mechanism of WLCSP under drop test has been established. Depending on type of WLCSP and test board design,...
Since lead was banned from the solder joints, mechanical tests of microelectronic components and modules have gained much importance not just in mobile electronics but quite in general. The standardized JEDEC drop test is commonly used. It delivers repeatable results for a wide range of loads in the components mounted on the well specified test PCB. As yet the JEDEC drop test is time consuming and...
The thermomechanical fatigue of solder joints on the system level is more complex to predict than on the board level. The damage of the solder joints of an electronic device in an ECU (electronic control unit) depends on the thermal expansion mismatch between the materials of the device and the PCB (printed circuit board), so called local mismatch, as well as on the global deformation of the PCB induced...
The board level drop test is intended to evaluate and compare the drop performance of surface mount electronic components. The JEDEC standardize for board level drop test address test board construction, design, material, component locations and test conditions etc. However, in actual drop test conditions, continued drops usually loosen up the mounting screw, which is not considered in JEDEC. This...
This investigation is aimed at the stability of press-fit interconnections for MID. Moulded interconnect devices (MID) are 3-dimensional substrates produced by thermoplastic injection moulding for large-series applications. The assembly process of press-fit interconnections has been correctly modelled with a FE-Software. With this model the behaviour of the mechanical contact pressure, which decreases...
Interface fracture properties are increasingly requested in electronic packaging, be it for design problems or reliability issues. We demonstrate an induced delamination of the epoxy molding compound and die silicon interface, and propose a mixed mode chisel testing setup (MMC) and its experimental procedure. The MMC addresses several drawbacks of existing methods. The work includes samples from package...
The scope of the paper is to present the result of combining experimental and simulation methodologies to determine mechanical material properties at high strain rates. Miniature bulk specimens which have a diameter comparable to BGA joints are used in the experiments. Stress-strain data recorded at high strain rates proof the high resolution capability of a novel tensile setup. A FEM model of the...
The lifetime of a solder joint is mainly determined by its creep behaviour. Creep arises from the stresses inside the solder joints as a consequence of the thermomechanical mismatch of the board and the substrate. The stress state is heavily influenced by the anisotropy of tin. To understand the damage process in solder joints, the influence of the anisotropic microstructure must be understood. In...
The electronic industry drive for miniaturization and increasing functional integration forces the development of feature sizes down to the nanometer range. Moreover, harsh environmental conditions and new porous or nano-particle filled materials introduced on both chip and package level - low-k and ultra low-k ILD materials in back-end of line (BEoL) layers of advanced CMOS technologies, in particular...
Multi-physics multi-scale modeling issues in various stages of the LED manufacturing, 3D-SiP, and nano interconnects have been discussed. Molecular dynamics (MD) and finite element method (FEM) have been used to study the scale effect of the material properties and the prediction of the module behaviors which are critical to LED fabrication. We propose a new concept to integrate multi-physics/multi-scale...
This paper investigates the degradation behaviour of lead-free Sn96.5Ag3.0Cu0.5 solder. A series of isothermal mechanical cycling tests under different conditions has been conducted. The tests were monitored in-situ with a high magnification camera system. Optical observations are presented from selected tests, showing the surface morphology during testing. In addition to the optical investigation,...
This work will present case studies of three types of flexible printable circuits subjected to different loading conditions in order to evaluate their technologies regarding mechanical reliability. Typical causes of failure in electronic devices are associated with mechanical stress, moisture, heat from transportation and field use. Typically manufacturers carry out tests to evaluate the reliability...
The paper presents extended creep properties of eutectic SnAg3.8Cu0.7 solder using dog bone shaped tensile specimen to extend the data for the Alpha-Omega Model. The tensile test machine was carefully modified with respect of solder material requirements in terms of stress free specimen mounting and assurances of high stable stress conditions. Furthermore the tensile tester is able to measure the...
This study examines the effect of cyclic damage on the constitutive response of Sn3.0Ag0.5Cu (SAC305) solder material. Cyclic damage is induced through isothermal, mechanical cycling tests at high strain rate and room temperature, using a modified lap-shear microscale specimen (180 mum wide solder joint). The elastic, plastic, and yield response of the cycled solder joints are measured as a function...
In this paper, a leading indicators based approach has been developed for prognostics and health monitoring of electronic systems. The approach focuses on the prefailure space and methodologies for quantification of damage progression and residual life in electronic equipment subjected to shock and vibration loads using the dynamic response of the electronic equipment. Traditional health monitoring...
When assessing the mechanical durability of electronic assemblies, the focus is generally on the solder interconnect. However, in many package styles, such as BGAs (ball grid arrays), LGAs (land grid arrays), MLFs (micro lead frame) and QFNs (quad flat no-lead), the Cu trace emanating from the solder pad may be the weakest failure site, especially if the solder joint is copper-defined rather than...
Embedding of discrete semiconductors into substrates has the advantages of achieving high degree of miniaturization, good electrical performance and possible low cost. A MOSFET power package based on the embedded die technology was developed and the demonstrators were built. To reduce cost and time-to-market, thermo-mechanical virtual prototyping is applied to support the package development. 2D and...
Flexible substrates (polymers) for plastic electronic products are far less stable to environmental factors, like heat and moisture, than currently used non-flexible substrates (silicon). This introduces problems during the lithography process of these products. This study presents a thermo-mechanical model of PEN foil; an organic material often used as flexible substrate for plastic electronics....
In this paper we discuss the influence of solder joint geometry on the lifetime of a flip chip assembly. Geometry variations caused by variations of solder volume, pad configuration, and pad size on the printed circuit board (PCB) were taken into account. Typically these parameters vary due to technological fabrication tolerances. Consequently, the influence of such design aspects on system reliability...
A continuum damage model is proposed for Sn3.0Ag0.5Cu solder alloy in pure shear conditions. Experimental tests were performed on specific torsion samples to adjust material parameters of the continuum damage model. The main advantage of this method is to introduce damage process in the mechanical behaviour law of SnAgCu solder. Damage process highly affects the mechanical behaviour of solder alloy...
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