Process-Induced Stress Effect on Reliability of ChipSeal® Passivation Technology

2002 ◽  
Author(s):  
Yeong K. Kim ◽  
Rudolf Krondorfer ◽  
Suresh K. Sitaraman
Keyword(s):  
Residual Stress ◽  
Metal Layer ◽  
Design Guidelines ◽  
Thickness Effect ◽  
Reliability Prediction ◽  
Stress Effect ◽  
Process Technology ◽  
Process Step ◽  
Stress Development ◽  
Induced Stress

It is important to take into consideration the process-induced residual stress into reliability prediction modeling. Lack of process-induced stress may lead to error in reliability prediction. Therefore, careful investigation of the stress development is critical. In this paper, the stress development induced by ChipSeal® passivation process technology has been analyzed. The ChipSeal® passivation technology has been developed to enhance the reliability of commercially-off-the-shelf plastic encaptulated microelectronics component by sealing integrated circuit at the wafer level. The analysis takes every process step into account to investigate the temperature effect on the final residual stress. The section of the fabricated structure has been modeled in two different configurations. The stress developments have been simulated by numerical method, and the results have been analyzed to identify the critical location. Three different lengths of metal layer have been considered to investigate the effect of metal layer length structure. Finally, a response surface method is employed to determine the thickness effect of individual layers and to develop design guidelines to enhance ChipSeal® reliability.

A Process Dependent Warpage and Stress Model for 3D Packages Considering Incoming Die/Substrate Warpage and Assembly Process Impacts

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 001603-001621
Author(s):  
Wei Lin ◽  
Ahmer Syed ◽  
KiWook Lee ◽  
Karthikeyan Dhandapani
Keyword(s):  
Residual Stress ◽  
Process Condition ◽  
Element Model ◽  
Stress Effect ◽  
Assembly Process ◽  
Process Flow ◽  
Process Step ◽  
Die Stress ◽  
3D Packaging ◽  
Bare Substrate

Warpage control and die stress are critical for 3D package assembly. Currently most of the warpage studies, either measurements or simulations, are mainly evaluated at the end-of-line (EOL) for the finished package. However, for 3D packaging such as multiple die stacking or through-silicon-via (TSV), the interaction between warpage and assembly process steps becomes far more important because: (1) Warpage at each single process step will impact the yield of the next process step. (2) Process induced warpage will accumulated and affect the final end-of-line package warpage, and (3) Die stress in the end-of-line package is highly dependent on the incoming die alone residual stress and the assembly process flow. It is required to develop capability to evaluate warpage at each process step following the process flow. In this paper, we use a 2-die TSV package as a test vehicle to collect warpage data at each assembly step. A process dependent finite element model (FEM) method is developed which is capable of capturing the process induced warpage and stress at each process step based on the process condition. Shadow moire is used to measure warpage data at following check points: (1) Incoming bare dies and bare substrate warpage; (2) Die 1 warpage after underfilled on substrate; (3) Die 2 warpage after TCNCP on Die 1; (4) Completed package after molding (end-of-line). Element birth and kill approach is developed in the FEM model to simulate the assembly process flow. In each process step, only the presented components and materials in the model are active while the others are killed. When new parts or materials are added through the assembly flow, they are activated in the model and the related process condition is applied for each step. Using this process dependent modeling approach, excellent correlation of the model results with the actual measured warpage data is achieved at each process step. One factor often been ignored is the incoming bare die warpage and bare substrate warpage effect. They are often assumed flat and stress free. However, as die and substrate become thinner and thinner, their incoming initial warpage or residual stress plays an important role. In this paper, the measured incoming substrate and die warpage data are presented, their impacts to the warpage and stress evolution through the process flow are evaluated. A novel method is also developed in the simulation model which is able to study the incoming die/substrate warpage and residual stress effect.

scholarly journals Material Application of a Transformer Box: A Study on the Electromagnetic Shielding Characteristics of Al–Ta Coating Film with Plasma-Spray Process

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 495 ◽  
Author(s):  
Fei-Shuo Hung
Keyword(s):  
Stainless Steel ◽  
Structural Characteristics ◽  
Steel Substrate ◽  
Pure Aluminum ◽  
Multilayer Coating ◽  
Thickness Effect ◽  
Stress Effect ◽  
Coating Film ◽  
Coating Structure ◽  
Frequency Condition

In this study we present the results of two experiments. In the first one, a Ta–Al–SS (stainless steel (SS)) multilayer coating structure was prepared using plasma spraying equipment to investigate the coating structure and interface properties. In the second one, Ta–Al on multilayer glass was prepared using the sputtering process to measure the thickness effect of thin film on electromagnetic wave shielding (EMI) characteristics and on the design of high-power switchboard covers. According to the experimental results, the multilayer structure of Ta–Al on SS improves the mechanical properties of a stainless steel plate by enhancing the explosion-proof property. An appropriate thickness of the plasma-sprayed pure aluminum layer can increase the adhesion to the stainless steel substrate and buffer the stress effect. After heat treatment (annealing), the Ta–Al–SS multilayer structural characteristics are excellent and suitable for shielding effects at different temperatures and humidity, which can be used as a reference for the engineering application of communication rooms and base power stations. According to EMI test of multi-coated glass (Ta–Al–glass), by increasing the thickness of Ta layer, we cannot effectively improve full-frequency EMI shielding with improved shielding at low-mid frequency condition. In addition, the Ta–Al interface formation of an Al–Ta–O compound layer can improve the adiabatic effect to reduce the thermal conductivity.

Micromechanical Modeling of Viscoplastic Behavior of Laminated Polymer Composites With Thermal Residual Stress Effect

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Qiang Chen ◽  
Xuefeng Chen ◽  
Zhi Zhai ◽  
Xiaojun Zhu ◽  
Zhibo Yang
Keyword(s):  
Residual Stress ◽  
Polymer Matrix Composites ◽  
Micromechanical Model ◽  
Thermal Residual Stress ◽  
Micromechanical Modeling ◽  
Multiscale Approach ◽  
Stress Effect ◽  
Accurate Analysis ◽  
Rate Dependent ◽  
Residual Stress Effect

In this paper, a multiscale approach has been developed for investigating the rate-dependent viscoplastic behavior of polymer matrix composites (PMCs) with thermal residual stress effect. The finite-volume direct averaging micromechanics (FVDAM), which effectively predicts nonlinear response of unidirectional fiber reinforced composites, is incorporated with improved Bodner–Partom model to describe the viscoplastic behavior of PMCs. The new micromechanical model is then implemented into the classical laminate theory, enabling efficient and accurate analysis of multidirectional PMCs. The proposed multiscale theory not only predicts effective thermomechanical viscoplastic response of PMCs but also provides local fluctuations of fields within composite microstructures. The deformation behaviors of several unidirectional and multidirectional PMCs with various fiber configurations are extensively simulated at different strain rates, which show a good agreement with the experimental data found from the literature. Influence of thermal residual stress on the viscoplastic behavior of PMCs is closely related to fiber orientation. In addition, the thermal residual stress effect cannot be neglected in order to accurately describe the rate-dependent viscoplastic behavior of PMCs.

Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2011 ◽  
Author(s):  
Kohta Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of the stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the thermal residual stress distribution appears in the stacked chips due to the periodic alignment of metallic bumps, and they deteriorate the reliability of products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are discussed quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of 4 gauges with different crystallographic directions. This alignment of strain gauges enables to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made by silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper layer was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the rigid joint formation by alloying with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed experimentally that both the hound’s-tooth alignment between a TSV (Through Silicon Via) and a bump and control of mechanical properties of electroplated copper thin films used for the TSV and bump is indispensable in order to minimize the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process induced stress in 3D stacked chips quantitatively.

scholarly journals Superlayer Residual Stress Effect on the Indentation Adhesion Measurements

1999 ◽  
Vol 594 ◽  
Author(s):  
Alex A. Volinsky ◽  
Neville R. Moody ◽  
William W. Gerberich
Keyword(s):  
Residual Stress ◽  
Sputter Deposition ◽  
Work Of Adhesion ◽  
Stress Effect ◽  
Aluminum Films ◽  
Nanoindentation Testing ◽  
Deposition Parameters ◽  
Thin Aluminum ◽  
Residual Stress Effect ◽  
Sputter Deposited

AbstractThe practical work of adhesion has been measured in thin aluminum films as a function of film thickness and residual stress. These films were sputter deposited onto thermally oxidized silicon wafers followed by sputter deposition of a one micron thick W superlayer. The superlayer deposition parameters were controlled to produce either a compressive residual stress of 1 GPa or a tensile residual stress of 100 MPa. Nanoindentation testing was then used to induce delamination and a mechanics based model for circular blister formation was used to determine practical works of adhesion. The resulting measured works of adhesion for all films between 100 nm and 1 μm thick was 30 J/m2 regardless of superlayer stress. However, films with the compressively stressed superlayers produced larger blisters than films with tensile stressed superlayers. In addition, these films were susceptible to radial cracking producing a high variability in average adhesion values.

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