Hygroscopic Effects on Swelling and Viscoelasticity of Electronic Packaging Epoxy

2008 3rd International Microsystems, Packaging, Assembly &Amp; Circuits Technology Conference

Hsich

et al. 2008

scarcity of characterization approach and lack of hygroscopic swelling material property. Engineers are also inexperienced in The objective of this paper is focused on the hygroscopic swelling moisture diffusion and hygroscopic swelling modeling. However, effect on polymeric material used in electronic package and thermo-these difficulties can be overcome and will be fully explored in this hygro-structure coupled design and reliability analysis for finger paper. printer package. For moisture absorption/desorption analysis, the ambient environment for temperature and humidity are set to be Polymeric materials transport moisture primary by diffusion, 60°C60%RH, 85OC60%RH and 85OC85%RH, respectively. The which can be analogically modeled in standard Fick's transient transient moisture diffusion analysis described by Fick's equation is diffusion equation. In moisture diffusion model, field variable (local performed to evaluate the overall moisture distribution. Hygroscopic moisture concentration) is discontinuous across different material swelling properties such as coefficient of saturation (Csat), boundaries when it exposed to the same temperature-humidity coefficient of moisture expansion (p) and activation energy (Q) can condition [3][4]. This can be resolved by using temperature-wetness be extracted through TMA (Thermal Mechanical Analysis) and TGA technique for modeling multi-material interfacial moisture diffusion. (Thermal Gravitational Analysis). A three-dimensional solid model The same wetness technique is also applied to model moisture of finger printer package based on finite element ANSYS software is desorption during dry baking and IR reflow process. Aside moisture, developed to predict the thermal-induced strain, hygroscopic temperature loading is another important factor for reliability of swelling and the residual stress distributions. The predicted thermal-plastic IC packages. In order to conduct the integrated thermoinduced displacements were found to be very good agreement with hygro-mechanical analysis the hygroscopic strain is treated as an the Moire interferometer experimental in-plane deformation. The additional term adding to the thermal strain. The particular stress developed finite element 3D model, therefore, is applied to predict pattern and overall stress distribution at stressed region represent the the mechanism of thermo-hygro-mechanical induced stress in potential failure site. The proposed moisture diffusion model is accordance with JEDEC pre-condition standard JESD22-A120. An designated to evaluate the overall moisture distribution and the local analytical expression for the total expansion strain due to thermo-moisture concentration at the critical interfaces. hygro-mechanical coupled effect was proposed and the implementation procedures using software ANSYS were described in From practical view, manufacturing process needs moisture details. A series of comprehensive parametric studies were absorption/desorption data for entire package rather than bulk conducted in this paper.

Section: Introductionmentioning

confidence: 97%

mentioning

confidence: 99%

Hygroscopic Swelling Effect on Polymeric Materials and Thermo-hygro-mechanical Design on Finger Printer Package

2008 3rd International Microsystems, Packaging, Assembly &Amp; Circuits Technology Conference

Hsich

et al. 2008

“…Hygroscopic strains arise due to mismatch of coefficient moisture expansion (CME). Reliability becomes an issue when the moisture gets inside the package and the residual nonuniform moisture distribution induces hygroscopic swelling stress [1][2][3][4][5][6][7][8][9][10]. It is also found that the residual moisture would induce the vapor pressure at leveled temperature and result in popcorn crack failure.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical migration failure on FR-4 PCB by hygro-thermo-vapor pressure coupled analysis

2013 8th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT)

et al. 2013

INTRODUCTIONCorrosion reliability recently becomes an issue due to the trend of miniaturization of electronic products. The phenomenon of electronic corrosion is ionic migration which is also known as electrochemical migration (ECM) by surplus moisture remained inside the package. High temperature may also deteriorate the ECM failure. The hydrated metal ions (positively charged) will migrate towards the cathode and form a dendrite. In this paper, electrochemical migration failure caused by hygro-thermal swelling and residual moisture has been carefully investigated for FR-4 PCB board plated with Cu. An analytical moisture diffusion solution is proposed to determine the moisture distribution and consequent hygroscopic induced strain as well as stress. By applying Fickian diffusion law, the "thermal wetness" analogous technique is used to solve moisture absorption and desorption models. The analytical expression for total expansion strain due to hygro-thermo-vapor pressure coupled effect is implemented using finite element software ANSYS. Finite element predictions reveal the significance of contribution of hygroswelling induced effective stress/strain. Hygroscopic properties such as moisture diffusivity and coefficient of moisture expansion are characterized by an integrated TMA/TGA scheme. Solubility and vapor pressure effect are included to study popcorn failure during reflow process.

“…Numerous previous studies [1][2][3][4][5][6][7][8][9] reported that the damage of plastic packages was mostly caused by uncontrolled humidity environment. The water is condensed in micro-pores and absorbed through the bulk material exterior as well as the interface of two materials.…”

Section: Introductionmentioning

confidence: 99%

“…CME can be measured by the volumetric change with moisture absorption under given humidity and temperature conditions [1,2,7]. An existing TMA/TGA method [3,4] is used to characterize the hygroscopic swelling properties of polymeric materials.…”

Section: Introductionmentioning

confidence: 99%

Thermo-Hygro-Mechanical Design and Reliability Analysis for CMOS Image Sensor

Lee

Journal of Thermal Stresses

et al. 2008

In this paper, the characteristics of polymeric packaging materials for Pre-mold QFN type CMOS Image Sensor (CIS) have been carefully investigated. Hygro-mechanical property, the coefficient of moisture expansion (CME) for different materials was measured through Thermal Mechanical Analysis (TMA) and Thermal Gravitational analysis (TGA) at given humidity and temperature. Moisture absorption/desorption diffusivity were determined under Arrhenius behavior. The transient moisture diffusion analysis described by Fick's equation is performed to evaluate the overall moisture distribution. In accordance with the JEDEC pre-conditioning standard JESD22-A120, reliability and thermal design were carried out due to mismatch of the coefficient of thermal expansion (CTE) and CME for multi-material package of CIS. A threedimensional solid model of CIS based on finite element ANSYS software is developed to predict the thermal-induced strain, hygroscopic swelling deformation and the residual thermo-hygro-mechanical stress distributions. A series of comprehensive parametric studies were conducted in this research.