Influence of temperature, humidity, and defect location on delamination in plastic IC packages

Tay, A.A.O.; Lin, Tingyu

doi:10.1109/6144.814966

Cited by 59 publications

(8 citation statements)

References 22 publications

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“…A plane strain two-dimensional (2D) finite element (FE) model according to [16] was established to simulate interfacial crack growth between epoxy coating and substrate under thermal or hygroscopic stress (see Figure 1), using a commercial FE package ABAQUS, based on linear elastic fracture mechanics [17]. The coating was perfectly bonded to the substrate, except the edge and central pre-cracks at the coating/substrate interface (highlighted in red colour).…”

Section: Finite Element Modelmentioning

confidence: 99%

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Zhou

Liu

et al. 2019

Coatings

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Due to the higher thermal and moisture expansions of epoxy coatings than the rigid substrate, these coatings suffer from high thermal and hygroscopic stresses, leading to coating/substrate interfacial crack growth. Herein, a parametric study was conducted systematically on epoxy coatings incorporated with fillers, in order to understand their effects on coating/substrate interface delamination caused by thermal and hygroscopic stresses. A finite element model (FEM) was developed to determine an indicator J-integral value (Ji), in comparison with a critical JC value to interpret the obtained interface delamination experimental results. FE simulations showed that interfacial pre-cracks located at coating edges were more serious than those at the centre. Once delamination was triggered by thermal shock or moisture absorption, it propagated rapidly along the coating/substrate interface. However, by adding suitable micro-/nano-fillers to the coating the thermal and hygroscopic stresses give lower Ji values, so that delamination crack growth can be effectively controlled. The simulation results demonstrate that the incorporation of fillers with lower Young’s modulus, lower thermal expansion and moisture absorption coefficients, smaller size for soft fillers, larger size for rigid fillers, and suitable aspect ratios for rod-shape fillers to the coatings, are more effective against interface delamination. Hence, useful guidelines for improving the design of epoxy composite coatings against delamination growth can be obtained for different engineering applications.

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Section: Finite Element Modelmentioning

confidence: 99%

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Zhou

Liu

et al. 2019

Coatings

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“…In general, there are three types of failure mechanisms when an electronic package is exposed to humidity conditions. The first type of failure is often referred to 'popcorn failure' [4][5][6][7]. Packaged microelectronic devices are exposed to factory environmental conditions after the opening of protective dry-bags for surface mounting to printed circuit board (PCB).…”

Section: Introductionmentioning

confidence: 99%

Package structural integrity analysis considering moisture

Fan

Zhou

Chandra

2008

2008 58th Electronic Components and Technology Conference

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There are three types of failures when an electronic package is exposed to a humidity environment: the popcorn failure at soldering reflow, the delamination and cracking at HAST without electrical bias, and the corrosion under biased HAST. Despite the difference in failure mechanisms, the common and most contributory factor to moisture induced failures is the degradation of adhesion strength in the presence of moisture. Therefore, understanding interface behavior with moisture becomes a key for package integrity and reliability analysis. In this paper, first, several methods to characterize the interfacial fracture toughness or adhesion strength at elevated temperature with moisture effect are presented. The interfaces between polyimide on silicon chip and underfill (PI/UF) are used as a carrier to investigate the influence of moisture. Both interface fracture mechanics based fracture toughness measurement techniques and the quick-turn method such as die shear test are applied to investigate the interface behaviors with moisture. Details of several sample preparation methods, by which the fracture can be made to stay along the desired interface, are illustrated. Key results on the influence of the moisture on fracture toughness are presented. Next, the hygroscopic swelling characterization techniques are reviewed. Due to the fact that the moisture diffusion is a slow process, specimens used in hygroscopic swelling measurement are often subjected to a non-uniform moisture distribution. This becomes a potential hidden error in obtaining the coefficient of hygroscopic swelling. Analytical solutions have been devised to predict the errors caused by the non-uniform moisture distribution. A simple procedure in obtaining the accurate swelling characteristics is proposed. Both TGA-TMA method and Moiré interferometry method are applied to measure the hygroscopic swelling behaviors of several underfills. A very good agreement between these two methods is achieved. Subsequent to hygroscopic swelling characterization, the paper presents a novel method to allow a time-dependent nonlinear finite element analysis for package deformations and stresses induced by hygroscopic as well as thermal mismatches. This has been a challenging problem since commonly used commercial finite element software such as ABAQUS and ANSYS do not explicitly allow the fully coupled nonlinear thermal and hygroscopic stress analysis. The existing linear superposition method, which couples hygroscopic stress with thermal stress analysis, can not apply to the problem with nonlinear materials such as polymers and solder materials. A fully integrated finite element stress modeling methodology is demonstrated through an example of flip chip package subjected to a multi-step humidity/temperature loading profile. The results of the effect of hygroscopic swelling on the inter-layer dielectric (ILD) and under bump metallurgy (UBM) structures reveals that the overall ILD stresses under HAST can be twice as high as those considered without the moisture effect. The...

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“…( 1 1 ) when the Csat uses the unit of g/cm 3 . In general, the C sat depends on the relative humidity and temperature.…”

Section: Characterization Of Porosity and Free Volumementioning

confidence: 99%

“…C (kg/m 3 ) is the penetrant concentration, t (s) the time, and D (m 2 / s) is the diffusion coefficient or diffusivity of the moisture in the polymer. D is the pivotal parameter determining the rate of transport.…”

Section: Fickian and Non-fickian Kineticsmentioning

confidence: 99%

“…It has been long recognized that moisture plays a key role in the reliability of microelectronic packaging [1][2][3][4]. Moisture absorbed by polymer-based packaging materials can cause substantial changes in material properties, such as coefficient of thermal expansion (CTE), modulus, glass transition temperature (Tg), and viscoelastic behavior.…”

Section: Introductionmentioning

confidence: 99%

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Mechanics of moisture for polymers: Fundamental concepts and model study

Fan

2008

EuroSimE 2008 - International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronic

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Reliability issues associated with moisture have become increasingly important as advanced electronic devices demand for new materials, more function integration and further miniaturization. However, the fundamentals of the mechanics of moisture transport and the subsequent failures in polymers have not been investigated extensively. This paper is devoted to some fundamental concepts of moisture absorption, diffusion, and swelling. The mathematical descriptions of moisture phase transition with temperature, and the governing equations for a deforming polymer with moisture effect are presented. The non-Fickian sorption behavior is discussed and a widely-used two-stage theory is introduced. It has been found that water sorption (immersion into liquid water bath) has very different transport mechanism at surface compared to the moisture sorption (moisture in air). The state of moisture within polymers and its interactions with polymer matrix, fillers and additives are discussed. It has been suggested that, in most of cases, the majority of absorbed water molecules neither show significant interaction with other water molecules nor with their environment. Those 'unbound' moisture stays in free-volumes and does not contribute to hygroscopic swelling. Swelling is caused by water molecules bound to the polymer matrix. Although the free volume fraction is usually in the range of 1% to 5%, the pore size is always below nanometers and not detectable by the conventional measurement techniques such as SEM and mercury intrusion. An approximate estimate of free volume fraction using weight gain data is introduced. A vapor pressure model, which allows the whole-field vapor pressure calculations, is presented. Finally the governing equations for a deforming polymer with the consideration of moisture are developed.

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Influence of temperature, humidity, and defect location on delamination in plastic IC packages

Cited by 59 publications

References 22 publications

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Numerical Simulation of Failure of Composite Coatings due to Thermal and Hygroscopic Stresses

Package structural integrity analysis considering moisture

Mechanics of moisture for polymers: Fundamental concepts and model study

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