MODELING RATE DEPENDENT DURABILITY OF LOW-Ag SAC INTERCONNECTS FOR AREA ARRAY PACKAGES UNDER TORSION LOADS

The thesis discusses modeling rate-dependent durability of solder interconnects under mechanical torsion loading for surface mount area array components. The study discusses an approach to incorporate strain-rate dependency in durability estimation for solder interconnects. The components under study are two configurations of BGAs (ball grid array) assembled with select lead-free solders. A torsion test setup is used to apply displacement controlled loads on the test board. Accelerated test load profile is experimentally determined. Torsion test is carried out for all the components under investigation to failure. Strain-rate dependent (Johnson-Cook model) and strain-rate independent, elastic-plastic properties are used to model the solders in finite element simulation. Damage model from literature is used to estimate the durability for SAC305 solder to validate the approach. Test data is used to extract damage model constants for SAC105 solder and extract mechanical fatigue durability curve

Risks in global transport

Abstract. The background of this project is that the case company delivers its products to customer all over the world using different supply chains. Currently, the products are packed and shipped in relatively similar packages without considering the specific requirements of the various supply chains, which raises the concern of poor packaging performance. Meaning that the packaging system was not designed to meet the supply chain requirements which ultimately leads to product damage or quality deterioration. The purpose of this thesis is to define the conditions that the product and the industrial package are exposed to in the various supply chains, as they flow from the Alfa Laval facility in Lund to the customers. The identification of the supply chain conditions will provide essential data that can be used as a foundation to enhance the industrial package’s performance and increase the protection of products during transport. The methodology used is an abductive research using systems thinking, in which theoretical knowledge was combined with empirical data collected through various methods to answer the research questions and provide suggestions for improvements. The data collection methods were interviews, observations, internal documents examination, data loggers and GPS trackers. The Conclusions were that the product and the industrial package are exposed to various risks that can be classified as mechanical, chemical & biological or miscellaneous risks. The occurrence of risks and the extent of damage they can cause are influenced by factors related to the product & its package, the communication between the forwarders, the climatic conditions, the human factor and finally factors related to activities of transport, handling & storage. The shipped cargo was exposed to high humidity shocks throughout the different supply chains. The cargo was not exposed to more damaging conditions in developing countries, as high humidity levels and shocks were also recorded within the production facility in Lund and during handling in EU countries (e.g. at ports)

Characterising Solder Materials from Random Vibration Response of their Interconnects in BGA Packaging

Solder interconnection in electronic packaging is the weakest link, thus driving the reliability of electronic modules and systems. Improving interconnection integrity in safety-critical applications is vital in enhancing application reliability. This investigation qualifies the random vibration response of five essential solder compositions in ball grid array (BGA) solder joints used in safety-critical applications. The solder compositions are eutectic Sn63Pb37 and SnAgCu (SAC) 305, 387, 396, and 405. Computer-aided engineering (CAE) employing ANSYS FEA and SolidWorks software is implemented in this investigation. The solder Sn63Pb37 deformed least at 0.43 µm, followed by SAC396 at 0.58 µm, while SAC405 deformed highest at 0.88 µm. Further analysis demonstrates that possession of higher elastic modulus and mass density culminates in lower solder joint deformation. Stress is concentrated at the periphery of the solder joints in contact with the printed circuit board (PCB). The SAC396 solder accumulates the lowest stress of 14.1 MPa, followed by SAC405 at 17.9 MPa, while eutectic Sn63Pb37 accrues the highest at 34.6 MPa. Similarly, strain concentration is found at the interface between the solder joint and copper pad on PCB. SAC405 acquires the lowest elastic strain magnitude of 0.0011 mm/mm, while SAC305 records the highest strain of 0.002 mm/mm. These results demonstrate that SAC405 solder has maximum and SAC387 solder has minimum fatigue lives

Bearing distribution packs of the pharmaceutical products in dynamic lab and in the real distribution environment

The main purpose of the package testing is to determine whether or not the package can provide adequate protection of the product. The purpose of this study is to detect bearing of different pharmaceutical products in the dynamic laboratory and in real distribution environment. Pharmaceutical industry in normal operation applies many regulations and rules. One of those is to record all events in the distribution process. The analysis compared the results reached in dynamic lab with those of the real distribution cycle and all losses and damages entered in the Belupo Ltd. Data base during last 12 months. As test methods used: ASTM D 5276 - Drop Test of Loaded Containers by Free Fall; ASTM D 642 - Determining Compressive Resistance of Shipping Containers, Components, and Unit Loads; ASTM D 999 - Vibration Testing of Shipping Containers; ASTM D 4728 - Random Vibration Testing of Shipping Containers. Results obtained in a laboratory and in real situation are not comparable. Therefore it is important to include new tests with focused simulation witch will confirm accuracy of results. Database of damages shows the protection and security measures in distribution cycles for our products, and financial losses caused within distribution can be calculated from those data

Development of laboratory and field scale passive vibration assisted rotary drilling tools

The Drilling Technology Laboratory (DTL) at Memorial University of Newfoundland has been focused on increasing drilling efficiency through the utilization of downhole vibrations, also known as Vibration Assisted Rotary Drilling (VARD). The pursuit of VARD technologies is split between active and passive vibrations and the current thesis looks at the design, development, and testing of a Passive Vibration Assisted Rotary Drilling tool (pVARD). The pVARD tool acts as a spring and damper inside the bottom hole assembly of the drill string. It is a system that is tuned to utilize the natural vibrations of the drilling process to increase drilling efficiency and rate of penetration. Two different tools were designed. First, a laboratory scale tool designed to allow analysis into pVARD to be performed on the DTL’s inhouse small drilling simulator. This would allow for rapid testing of many spring damper configurations. The second, a field scale tool, that would be used with six-inch drill bits in the DTL’s first field trial of VARD technology. Powered by a water well drilling rig, this tool would be used to drill shale and granite and explore the pVARD technology on an industrial scale. Both tools required the design of axial and torque taking members as well as the arrangement of the spring damper system. Specific design attention was paid to making the tools easily reconfigurable so that different spring damper arrangements could be tested, both in the lab, and the field. This investigation explores the testing results of these two tools as compared to one another, as well as learning from the operation of them in the field and how these learning will be used to improve the next generation of pVARD tools

Brayton heat exchanger unit development program (alternate design)

A Brayton Heat Exchanger Unit Alternate Design (BHXU-Alternate) consisting of a recuperator, a heat sink heat exchanger, and a gas ducting system, was designed and fabricated. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. Emphasis was on double containment against external leakage and leakage of the organic coolant into the gas stream. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement, including the close-coupled integration of the BHXU-Alternate with the Brayton Rotating Unit (BRU)

Power systems research at MSFC

Power systems research reviews at Marshall Space Flight Cente

Development of convective reflow-projection moire warpage measurement system and prediction of solder bump reliability on board assemblies affected by warpage

Out-of-plane displacement (warpage) is one of the major thermomechanical reliability concerns for board-level electronic packaging. Printed wiring board (PWB) and component warpage results from CTE mismatch among the materials that make up the PWB assembly (PWBA). Warpage occurring during surface-mount assembly reflow processes and normal operations may cause serious reliability problems. In this research, a convective reflow and projection moire warpage measurement system was developed. The system is the first real-time, non-contact, and full-field measurement system capable of measuring PWB/PWBA/chip package warpage with the projection moire technique during different thermal reflow processes. In order to accurately simulate the reflow process and to achieve the ideal heating rate, a convective heating system was designed and integrated with the projection moire system. An advanced feedback controller was implemented to obtain the optimum heating responses. The developed system has the advantages of simulating different types of reflow processes, and reducing the temperature gradients through the PWBA thickness to ensure that the projection moire system can provide more accurate measurements. Automatic package detection and segmentation algorithms were developed for the projection moire system. The algorithms are used for automatic segmentation of the PWB and assembled packages so that the warpage of the PWB and chip packages can be determined individually. The effect of initial PWB warpage on the fatigue reliability of solder bumps on board assemblies was investigated using finite element modeling (FEM) and the projection moire system. The 3-D models of PWBAs with varying board warpage were used to estimate the solder bump fatigue life for different chip packages mounted on PWBs. The simulation results were validated and correlated with the experimental results obtained using the projection moire system and accelerated thermal cycling tests. Design of experiments and an advanced prediction model were generated to predict solder bump fatigue life based on the initial PWB warpage, package dimensions and locations, and solder bump materials. This study led to a better understanding of the correlation between PWB warpage and solder bump thermomechanical reliability on board assemblies.Ph.D.Committee Chair: Dr. Ume, I. Charles; Committee Member: Dr. Book, Wayne; Committee Member: Dr. Kim, Yeong; Committee Member: Dr. Pan, Jiahui; Committee Member: Dr. Sitaraman, Suresh; Committee Member: Dr. Wu, C. F. Jef

Reliability evaluation of stacked die BGA assemblies under mechanical bending loads

This thesis presents a reliability evaluation of stacked die ball grid array (BGA) assemblies under mechanical bending loads. The test specimens used in this investigation were four die stacked BGAs assembled on printed circuit boards (PCBs) with eutectic tin-lead solder and gold over nickel finishes, both as-reflowed and after aging. The failure envelopes of both types of specimen were quantified in terms of PCB flexural strain and strain rate. The experimental data from cyclic bending tests at three strain amplitudes with a constant strain rate have been used to determine the effect of strain amplitudes on cycles to failure. The experimental data from cyclic bending tests were combined with the data from impact tests to determine the effect of strain rate to cycles to failure. The failure sites associated with each test condition were identified, and failure site transition phenomena are reported and discussed