Quantification of Underfill Influence to Chip Packaging Interactions of WLCSP

2018 ◽  
Author(s):  
Huayan Wang ◽  
Shuai Shao ◽  
Vanlai Pham ◽  
Panju Shang ◽  
Cheng Zhong ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Thermal Loading ◽  
Strain Difference ◽  
Consumer Electronics ◽  
Image Correlation ◽  
Normal Strain ◽  
Wafer Level ◽  
Element Analysis ◽  
Corner Crack ◽  
Underfill Material

Wafer Level Chip Scale Package (WLCSP) has been a favorable packaging solution for compact portable consumer electronics. The microelectronics industry introduced Extra Low K (ELK) to enhance electric performances with the cost of diminishing mechanical reliability. The ELK itself and its interfaces are highly fragile and susceptible to fracture. ELK cracking under bumps and ELK inter layer delamination (ILD) from die corners are often observed during and after solder reflow and qualification process such as accelerated thermal cycling (ATC). In this study, the underfill selection and its fillet formation influence to the Chip Packaging Interactions (CPI) of WLCSP was investigated through an experimental technique and numerical analysis. For the experimental assessment, thermo-mechanical interactions between die corner and underfill was investigated. Digital image correlation (DIC) technique with optical microscope was utilized to quantify the deformation behavior and strains of cross-sectioned WLCSP die corner subjected to thermal loading from 25°C to 125°C. The results clearly show captured deformations of die corner area under thermal loading. For the fillet formation influence, it shows that the high underfill fillet configuration gives higher normal strain at the die corner area during thermal cycling. For the underfill selection, it clearly shows that the strain difference at corner solder during thermal cycling caused by two different type of underfill material. Finally, finite element analysis (FEA) was conducted by simulating the thermal loading applied in the experiments and validated with experimental results. Then, using the FEA analysis, parametric study for underfill material properties and fillet height were performed on the ELK reliability of WLCSP. Energy release rate of the die corner crack were obtained and used as damage indicators for die corner ELK delamination.

Development and Challenges of Warpage for Fan-Out Wafer-Level Package Technology

2016 ◽  
Vol 2016 (1) ◽  
pp. 000524-000528
Author(s):  
Mu-Hsuan Chan ◽  
Yu-Po Wang ◽  
Ivan Chang ◽  
James Chiang ◽  
George Pan ◽  
...  
Keyword(s):  
Process Optimization ◽  
High Performance ◽  
Thermal Loading ◽  
Material Selection ◽  
Measurement Data ◽  
Structure Design ◽  
Wafer Level ◽  
Element Analysis ◽  
Geometry Design ◽  
Wide Range

Abstract Fan-out wafer-level-packaging (FO-WLP) technology has been widely investigated recently with its advantages of thin form factor structure, cost effectiveness and high performance for wide range applications. Reducing wafer warpage is one of the most challenging needs to be addressed for success on subsequent processes. Therefore, the majority of studies focus on the ratio of die and compound thickness, structure design. In order to optimize the warpage for success on subsequent processes, it is indispensable to consider whole wafer process including thermal loading and stress. In this study, reducdution of wafer warpage at each process was proposed in terms of material selection, and process optimization through finite element analysis (FEA) and experiment. Wafer process dependent modeling results were validated by experimental measurement data. The mutual relationship and effects of material property, compound thickness, and corresponding thermal influences were both investigated and addressed. Key parameters were identified based on FEA modeling results: thickness ratio of die/compound andmolding compound materials. Therefore, the geometry design with balanced die/compound ratio is optimal for warpage improvement. The effect of process will be discussed and should be considered for future package warpage characterization. Such findings have been successfully used in process optimization to reduce wafer warapge after grinding process.

Damage Evaluation of TBC by Rapid Thermal Cycling Test Utilizing a Laser Irradiation

2019 ◽  
Vol 827 ◽  
pp. 361-366
Author(s):  
Yusuke Hayashi ◽  
Kento Suzuki ◽  
Masayuki Arai ◽  
Kiyohiro Ito ◽  
Tsuyoshi Higuchi ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Laser Irradiation ◽  
Thermal Loading ◽  
Ceramic Coating ◽  
High Heat Flux ◽  
Thermal Cycling Test ◽  
Element Analysis ◽  
Cross Sectional ◽  
Cycling Test ◽  
Rapid Thermal Cycling

Thermal barrier coating (TBC) is deposited onto the gas turbine blade surface in order to protect the substrate from high-temperature combustion gas. Cracks and delamination of the ceramic coating which come from high heat flux loading are serious problem in TBC. In this study, the rapid thermal cycling device utilizing laser irradiation was developed. It was then investigated how the damage progresses in the ceramic coating exposed to cyclic rapid thermal loading. As a result, a sintering layer was formed in the surface of the ceramic coating, although such phenomenon was not recognized in TBC sample tested by the conventional thermal cycling test using an electric furnace. It was also revealed from the cross-sectional observation that the vertical crack was initiated at the surface of TBC and propagated into sintering layer. Finally, mechanical factors of those damages from finite element analysis using the TBC model including sintering progress was discussed

Comparative Studies on Solder Joint Reliability of Plastic and Ceramic Ball Grid Array Packages of the Same Form Factor Under Power and Accelerated Thermal Cycling

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
S. B. Park ◽  
Rahul Joshi ◽  
Izhar Ahmed ◽  
Soonwan Chung
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Thermal Loading ◽  
Ball Grid Array ◽  
Element Analysis ◽  
Severe Condition ◽  
Experimental Stress Analysis ◽  
Computational Fluid Dynamics Analysis ◽  
Accelerated Thermal Cycling ◽  
Ball Grid Array Packages

Experimental and numerical techniques are employed to assess the thermomechanical behavior of ceramic and organic flip chip packages under power cycling (PC) and accelerated thermal cycling (ATC). In PC, nonuniform temperature distribution and different coefficients of thermal expansion of each component make the package deform differently compared to the case of ATC. Traditionally, reliability assessment is conducted by ATC because ATC is believed to have a more severe thermal loading condition compared to PC, which is similar to the actual field condition. In this work, the comparative study of PC and ATC was conducted for the reliability of board level interconnects. The comparison was made using both ceramic and organic flip chip ball grid array packages. Moiré interferometry was adopted for the experimental stress analysis. In PC simulation, computational fluid dynamics analysis and finite element analysis are performed. The assembly deformations in numerical simulation are compared with those obtained by Moiré images. It is confirmed that for a certain organic package PC can be a more severe condition that causes solder interconnects to fail earlier than in ATC while the ceramic package fails earlier in ATC always.

Solder Joint Reliability in Underfilled Flip Chip Package With a Consideration of Chip-Package-Interaction (CPI)

2011 ◽  
Author(s):  
Jae B. Kwak ◽  
Da Yu ◽  
Tung T. Nguyen ◽  
Seungbae Park
Keyword(s):  
Mechanical Behavior ◽  
Flip Chip ◽  
Thermal Loading ◽  
Solder Bump ◽  
Image Correlation ◽  
Specimen Preparation ◽  
Solder Bumps ◽  
Low K ◽  
Underfill Material ◽  
Dic Technique

Since the introduction of Cu/low-k as the interconnect material, the chip-package interaction (CPI) has become a critical reliability challenge for flip chip packages. Revision of underfill material must be considered, which may compromise the life of flipchip interconnect by releasing the stresses transferred to the silicon devices from the solder bumps, and thereby maintain the overall package reliability. Thus, it is important to understand the thermo-mechanical behavior of solder bumps. In this study, the solder bump reliability in flip chip package was investigated through an experimental technique and numerical analysis. For the experimental assessment, thermo-mechanical behavior of solder joints, especially the solder bumps located at the chip corners where most failures usually occur was investigated. Digital Image Correlation (DIC) technique with optical microscope was utilized to quantify the deformation behavior and strains of a solder bump of flip-chip package subjected to thermal loading from 25°C to 100°C. As a specimen preparation for DIC technique, a flip-chip specimen was cross-sectioned before a manual polishing process followed by wet etching method in order to generate natural speckle patterns with high enough contrast on the measuring surface. Finally, finite element analysis (FEA) was conducted by simulating the thermal loading applied in the experiments, and validated with experimental results. Then, using the FEA analysis, parametric study for underfill material properties were performed on the reliability of flip chip package, by varying the glass transition temperature (Tg), Young’s modulus (E), and coefficient of thermal expansion (CTE). Averaged plastic work of the corner solder bump and stress at the die side were obtained and used as damage indicators for solder bumps and low-k dielectrics layer, respectively. The results show that high Tg, and E of underfill are generally desirable to improve the reliability of solder interconnects in the flip chip package.

scholarly journals Design of a Unique Device for Residual Stresses Quantification by the Drilling Method Combining the PhotoStress and Digital Image Correlation

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 314
Author(s):  
Miroslav Pástor ◽  
Martin Hagara ◽  
Ivan Virgala ◽  
Adam Kaľavský ◽  
Alžbeta Sapietová ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Experimental Testing ◽  
Digital Processing ◽  
Image Correlation ◽  
Optical Systems ◽  
Hole Drilling ◽  
Element Analysis ◽  
Thin Specimen ◽  
Comparison Of The Results

This paper presents a uniquely designed device combining the hole-drilling technique with two optical systems based on the PhotoStress and digital image correlation (DIC) method, where the digital image correlation system moves with the cutting tool. The authors aimed to verify whether the accuracy of the drilled hole according to ASTM E837-13a standard and the positioning accuracy of the device were sufficient to achieve accurate results. The experimental testing was performed on a thin specimen made from strain sensitive coating PS-1D, which allowed comparison of the results obtained by both methods. Although application of the PhotoStress method allows analysis of the strains at the edge of the cut hole, it requires a lot of experimenter’s practical skills to assess the results correctly. On the other hand, the DIC method allows digital processing of the measured data. However, the problem is not only to determine the data at the edge of the hole, the results also significantly depend on the smoothing levels used. The quantitative comparison of the results obtained was performed using finite element analysis.

scholarly journals Reliability Evaluation of Fan-Out Type 3D Packaging-On-Packaging

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 295
Author(s):  
Pao-Hsiung Wang ◽  
Yu-Wei Huang ◽  
Kuo-Ning Chiang
Keyword(s):  
Finite Element ◽  
Thermal Cycling ◽  
Glass Substrate ◽  
High Speed ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Design Parameters ◽  
Time To Failure ◽  
Wafer Level ◽  
Fine Pitch

The development of fan-out packaging technology for fine-pitch and high-pin-count applications is a hot topic in semiconductor research. To reduce the package footprint and improve system performance, many applications have adopted packaging-on-packaging (PoP) architecture. Given its inherent characteristics, glass is a good material for high-speed transmission applications. Therefore, this study proposes a fan-out wafer-level packaging (FO-WLP) with glass substrate-type PoP. The reliability life of the proposed FO-WLP was evaluated under thermal cycling conditions through finite element simulations and empirical calculations. Considering the simulation processing time and consistency with the experimentally obtained mean time to failure (MTTF) of the packaging, both two- and three-dimensional finite element models were developed with appropriate mechanical theories, and were verified to have similar MTTFs. Next, the FO-WLP structure was optimized by simulating various design parameters. The coefficient of thermal expansion of the glass substrate exerted the strongest effect on the reliability life under thermal cycling loading. In addition, the upper and lower pad thicknesses and the buffer layer thickness significantly affected the reliability life of both the FO-WLP and the FO-WLP-type PoP.

Analysis of a Virtual Prototype First-Stage Rotor Blade Using Integrated Computer-Based Design Tools

2006 ◽  
Author(s):  
Michel Arnal ◽  
Christian Precht ◽  
Thomas Sprunk ◽  
Tobias Danninger ◽  
John Stokes
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Thermal Loading ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Life Assessment ◽  
Element Analysis ◽  
Pressure Losses ◽  
Cooling Channels ◽  
Internally Cooled

The present paper outlines a practical methodology for improved virtual prototyping, using as an example, the recently re-engineered, internally-cooled 1st stage blade of a 40 MW industrial gas turbine. Using the full 3-D CAD model of the blade, a CFD simulation that includes the hot gas flow around the blade, conjugate heat transfer from the fluid to the solid at the blade surface, heat conduction through the solid, and the coolant flow in the plenum is performed. The pressure losses through and heat transfer to the cooling channels inside the airfoil are captured with a 1-D code and the 1-D results are linked to the three-dimensional CFD analysis. The resultant three-dimensional temperature distribution through the blade provides the required thermal loading for the subsequent structural finite element analysis. The results of this analysis include the thermo-mechanical stress distribution, which is the basis for blade life assessment.

scholarly journals Validation of Welding Simulations Using Thermal Strains Measured with DIC

2011 ◽  
Vol 70 ◽  
pp. 129-134 ◽  
Author(s):  
Maarten De Strycker ◽  
Pascal Lava ◽  
Wim Van Paepegem ◽  
Luc Schueremans ◽  
Dimitri Debruyne
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
Circular Cross Section ◽  
Welding Process ◽  
Weld Bead ◽  
Image Correlation ◽  
Steel Tubes ◽  
Element Analysis ◽  
Strain Evolution ◽  
The Cross

Residual stresses can affect the performance of steel tubes in many ways and as a result their magnitude and distribution is of particular interest to many applications. Residual stresses in cold-rolled steel tubes mainly originate from the rolling of a flat plate into a circular cross section (involving plastic deformations) and the weld bead that closes the cross section (involving non-uniform heating and cooling). Focus in this contribution is on the longitudinal weld bead that closes the cross section. To reveal the residual stresses in the tubes under consideration, a finite element analysis (FEA) of the welding step in the production process is made. The FEA of the welding process is validated with the temperature evolution of the thermal simulation and the strain evolution for the mechanical part of the analysis. Several methods for measuring the strain evolution are available and in this contribution it is investigated if the Digital Image Correlation (DIC) technique can record the strain evolution during welding. It is shown that the strain evolution obtained with DIC is in agreement with that found by electrical resistance strain gauges. The results of these experimental measuring methods are compared with numerical results from a FEA of the welding process.

Finite Element Analysis of a Gasketed Flange Joint Under Combined Internal Pressure and Thermal Transient Loading

2007 ◽  
Author(s):  
Muhammad Abid ◽  
Javed A. Chattha ◽  
Kamran A. Khan
Keyword(s):  
Finite Element Analysis ◽  
Steady State ◽  
Internal Pressure ◽  
Thermal Loading ◽  
Flange Joint ◽  
Element Analysis ◽  
Transient Loading ◽  
Thermal Transient ◽  
Transient Thermal ◽  
Bolted Flange

Performance of a bolted flange joint is characterized mainly by its ‘strength’ and ‘sealing capability’. A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. In the available published work, thermal behavior of the pipe flange joints is discussed under steady state loading with and without internal pressure and under transient loading condition without internal pressure. The present design codes also do not address the effects of steady state and thermal transient loading on the structural integrity and sealing ability. It is realized that due to the ignorance of any applied transient thermal loading, the optimized performance of the bolted flange joint can not be achieved. In this paper, in order to investigate gasketed joint’s performance i.e. joint strength and sealing capability under combined internal pressure and transient thermal loading, an extensive nonlinear finite element analysis is carried out and its behavior is discussed.

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