Jillian Y. Evans

Quality Conformance and Qualification of Microelectronic Packages and Interconnects

Three--Dimensional Stacked Dies. Cofired Ceramic Substrates. Organic Laminated Substrates and Chip--on--Board. High--Density Interconnects and Deposited Dielectrics. Wire and Wirebonds. Tape Automated Bonds. Flip--Chip Bonds. Device and Substrate Attachment. Cases. Leads. Lead Seals. Lid Seals. Material and Product Evaluation Methods. Rework Methods. Bibliography. Index.

Packaging factors affecting the fatigue life of power transistor die bonds

This paper presents an overview of die bond fatigue and a study of packaging and assembly factors and their influence on power transistor cyclic life. Power transistors with soft solder die bonds will fail by catastrophic failure, under cyclic conditions, as fatigue cracks develop and propagate through the die bond. Susceptibility to catastrophic failure increases over the life of the device, as crack growth through the die bond destroys the capability of the device to transfer heat. Power cycling tests followed by failure analysis show that die bond thickness has the most significant effect on catastrophic failure, followed by die bond thickness variation. Analysis shows, that for a given device, the die bond is not uniform and that the nonuniformity or die tilt (ratio of average to minimum thickness) influences device life by affecting strain concentration and crack growth. Oxygen content in the package, also influences device life to a lesser extent, as indicated by a statistical analysis of residual gas analysis results compared to cyclic life. This can be explained by crack closure effects during the development of die bond fatigue cracks. These findings further the understanding of die bond physics of failure and underscore the importance of optimizing die bond thickness in design and limiting variations and oxygen content in hermetic metal packages, during device manufacturing and assembly.

Simulation of fatigue distributions for ball grid arrays by the Monte Carlo method

Abstract Any approach to qualification of advanced technologies during product development must include an assessment of variation expected in product life over the life cycle. However, testing product design options in development, to approach an optimal design is costly and time consuming. Hence, simulation of product life distributions for virtual qualification can be a valuable tool to evaluate and qualify design options. This paper presents a physics of failure-based approach to virtual qualification of advanced area array assemblies against solder fatigue failure. The approach applies Monte Carlo simulation to evaluate solder joint fatigue life distributions, given material property variations and manufacturing capabilities. Preliminary results using the simple Engelmaier model as the basis of simulations are presented. Simulation results are compared to data accumulated from two test environments and two ball grid array product types. The results reveal some of the limitations of the Engelmaier model as a basis for simulation. They also show the potential of this approach to virtual qualification for design and manufacturing capability assessment in development.

Product integrity and reliability in design

I: Concepts.- 1. Introduction to Product Integrity and Reliability Assessment.- 2. Elements of Probability for Reliability Assessment.- 3. Concepts in Reliability for Design Jillian.- II: Failure Mechanics.- 4. Overstress Failure and Load - Strength Interference.- 5. Elements of Fatigue and Related Mechanisms.- 6. Applications of Finite Element Analysis and Whole Field Stress Measurement.- 7. Elements of Corrosion.- 8. Failures in Electronic Assemblies and Devices.- 9. Case Studies in Product Failure and Failure Analysis.- III: Testing and Failure Analysis.- 10. Introduction to Testing and Test Effectiveness for Reliability Assessment.- 11. Design and Analysis of Statistical Experiments.- 12. Accelerated Testing and Data Analysis.- 13. Failure Analysis of Assemblies and Devices.- 14. Case Studies in Product Development and Improvement.- Appendices.

Failures in Electronic Assemblies and Devices

Electronic assemblies consist of a hierarchy of interconnection as we see in Figure 8.1. Semiconductor devices, the chips or die, are most often packaged in plastic encapsulation and soldered to a printed wiring board. The board provides the supporting structure for the parts and the surface area necessary for the circuit. This interconnect structure may present many reliability issues for products and electronic systems. In this chapter, we continue to build our knowledge of the mechanics of failure, applying much of Chapters 4, 5, 6, and 7 to electronic assemblies and devices.

Effects of humidity and temperature cycling on 3-D packaging

Three dimensional electronics packaging technologies are emerging for many electronics system applications. Characterizing failure mechanisms, was the focus of this research. Accelerated testing and observing samples at various stages of the testing, with an Environmental Scanning Electron Microscope, were the primary methods used. Interfacial debonding of polyimides and fatigue cracking in bus structures were observed in humidity cycling and thermal cycling. These failures were the result of differential expansion of polyimide adhesives and dielectrics and interfacial degradation by moisture absorption.

Development of acceleration factors for reliability testing of mechanical equipment

Accelerated life tests allow for reduction of test time to demonstrate targeted life of a component for a given level of reliability. This is accomplished by increasing loads on the component or by compressing the time scale in relation to the service environment. The acceleration factor provides a quantitative estimate of the relationship between the test condition and the field condition for this purpose. This paper provides a detailed process, for developing acceleration factor models for reliability testing of mechanical components. Several examples are given for various types of mechanical components undergoing wear-out processes.

Effect of humidity cycling on reliability of overlaid high density interconnects

The authors present a finite element simulation, performed to observe the stresses generated in a typical high-density interconnect structure as a result of swelling mismatches due to water absorption. They focus on stresses which could cause de-adhesion and microbuckling of dielectric films due to humidity cycling. Numerical analysis was used to examine the potential failure sites, modes, and failure mechanisms.<<ETX>>

Introduction to Product Integrity and Reliability Assessment

The goal of any product development and design effort is to produce a product that will be successful in the marketplace, resulting in maximum value or utility to the producer of the product. In order to effectively achieve this goal, products must be rapidly and efficiently designed and developed and must be of high integrity. We can define product integrity as the ability of a product to meet or exceed a customer’s expectations for performance, quality and durability over the life of the product. The term product integrity was adapted for the text title in order to produce a focus on failure prevention in design and development, rather than on reliability calculations, which are often emphasized in reliability engineering texts. In this context, we will introduce a process for reliability assessment.

Design and Analysis of Statistical Experiments

Statistical Experimental Design (SED), also referred to as Design of Experiments (DoE), is a valuable tool in reliability assessment. When properly set up and executed, designed experiments can serve to identify principal factors contributing to product unreliability or identify key factors on which to apply improvement and corrective action resources in manufacturing. In addition, designed experiments can be the basis of developing models for damage assessment by including multiple stresses or loading conditions, material properties and manufacturing variations.