Ephraim Suhir

Portland State University | PSU · Departments of Mechanical and Materials Engineering and Electrical and Computer Engineering

We suggest a simple geometrical parameter reflecting the combined effect of the chip width, the pad width, and the underchip thickness of the molding compound on the propensity of a plastic electronic package to a moisture-induced failure. We use this parameter to analyze the experimental data for the moisture level leading to such a failure. We sh...

The Network Interface Unit (NIU) enclosures might be subjected, during the 10–15 years of their projected service life, to various dynamic loads. They will experience also harsh environmental effects. In this study, we analyze the dynamic strength and long-term reliability of a thin-walled NIU enclosure made of a preweathered polycarbonate. Dynamic...

Finite element modeling of the state of stress in optical fibers embedded into an epoxy adhesive, which is surrounded by a metal enclosure, is carried out for various geometric configurations with consideration of the local multi-material mismatch effects. The objective of the analysis is to predict the overall response of, and local stress disturb...

Mechanical reliability of epoxy molding compounds in plastic packages depends on the stress level at the chip corners. In this analysis we evaluate the effect of radii of curvature at the corners and the interfacial delamination on the thermally induced stresses caused by the thermal contraction mismatch of the epoxy and silicon. We found that, in...

The objective of this review is double-folded: to show materials scientists, mechanical engineers and reliability physicists not involved in electronics, photonics, micro-electronic-mechanical-systems (MEMS) or MOEMS (optical MEMS) engineering what kind of value they could bring to this important “high-tech” area, as well as to demonstrate to “high...

A highly focused and highly cost-effective failure-oriented-accelerated-testing (FOAT) suggested about a decade ago as an experimental basis of the novel probabilistic design for reliability (PDfR) concept is intended to be carried out at the design stage of a new electronic packaging technology and when high operational reliability (like the one r...

Improvements in ergonomics engineering can be achieved through better work environment and other traditional efforts that directly affect human behaviors and performance. There is also a significant potential, however, for the improvement in ergonomics engineering tasks and problems through better understanding the role that various uncertainties p...

A simple and physically meaningful analytical (“mathematical”) predictive model is developed for the evaluation of the sizes of the zones of inelastic deformations, if any, at the ends of a soldered electronics assembly in a packaged IC device. The emphasis is on the IC devices intended for space applications and on the incentive for using column‐g...

Three probabilistic analytical (“mathematical”) human-system-integration (HSI) models and their application in ergonomics engineering are addressed. The general concepts are illustrated by numerical examples. It is concluded that such models should always be considered, in addition to computer simulations, in every critical HSI effort.

In this brief-review some important published work on burn-in-testing (BIT) in electronics and photonics (E&P) manufacturing is considered. The emphasis is on the role and significance of modeling and, particularly, on analytical (“mathematical”) modeling. All the results and conclusions are equally applicable to micro-electronics systems (MEMS) an...

There is an obvious analogy between the challenges that an aircraft pilot has to cope with when fulfilling his/her long-term mission or when encountering a short-term abnormal situation, and the challenges that a surgeon faces during his/her "mission", a surgical operation, which is always a highly challenging and sometimes unpredictable effort. Ka...

There is an abundance of useful verbal information and recommendations on how to make the best choice when referring a patient for surgery or when seeking the right surgeon for your own operation. A quantitative approach is suggested here on how this could be done through assessing the probability of success and/or the Mean-Time-To-Failure (MTTF) o...

The recently suggested probabilistic design-for-reliability (PDfR) concept in microelectronics and photonics reliability engineering enables quantifying the static fatigue (delayed fracture) lifetime and the corresponding (in effect, never-zero) probability of failure of optical silica fibers intended for open space (outside the spacecraft) applica...

Burn-in testing (BIT) is a costly undertaking. Predictive modeling enables shading useful light on what and how should be tested, if at all. Three analytical (“mathematical”) predictive models recently suggested by the author are addressed in this mini-review: 1) A model based on the analysis of the infant mortality portion (IMP) of the bathtub cur...

The two analytical (“mathematical”) probabilistic predictive models considered in this analysis suggest that (1) the nonrandom time-derivative of the long-term mortality rate at a rather arbitrary initial moment of time for a particular type of species of interest can be viewed as a suitable physical or biological criterion, a sort of a figure of m...

We consider a situation, when braking is the only way to avoid obstruction of an automotive vehicle or a railroad train with a suddenly detected steadfast obstacle blocking the path. The velocity at the moment of the impact is viewed as a natural and a suitable criterion of the severity of the impact and, hence, of the very likelihood of the accide...

A probabilistic approach is applied to assess the required and the available retrorocket-phase (RRP) power needed to prevent, to an extent possible, unsafe landing of a spacecraft on a planet, such as, e.g., Mars. It is shown that the available power of the rocket engines should exceed considerably the required power at this phase to make sure that...

By employing quantifiable and measurable ways to assess the role of various uncertainties associated with the mental workload (MWL) and human capacity factor (HCF), and treating a human-in-the-loop (HITL) as a part, often the most critical part, of the complex man-instrumentation-equipment-vehicle-environment system, one can improve dramatically th...

The objective of this brief review is to demonstrate how analytical (“mathematical”) probabilistic predictive modeling (PPM) can be effectively employed to predict the outcome of a Human-System-Integration (HSI) mission or an extraordinary situation, when the reliability of an instrumentation (both its hard- and software) and human-in-the-loop (HIT...

This analysis is aimed at quantification, on the probabilistic basis, of the significance of driver fatigue and drowsiness (DD) in automated and manual driving conditions; the impact of driving time on the probability of an accident, because of the driver’s fatigue and possible drowsiness, and the observation that age groups of 20–25 and 65–70 are...

Carbon nano-tubes (CNTs) and carbon nano-fibers (CNFs) are characterized by a number of unique and extraordinarily attractive physical/mechanical properties. Examples are high Young’s modulus, high tensile strength, low coefficient of thermal expansion (CTE), and high thermal conductivity. These unique properties of CNTs and CNFs lead to many poten...

It has been recently demonstrated, mostly in application to the aerospace domain, how probabilistic analytical modeling (PAM) could effectively complement computer simulations in various human-system-integration (HSI) related situations, when the system’s reliability and the human’s performance contribute jointly to the never-zero probability of an...

The last three phases of landing of a spacecraft on Mars, the parachuting phase (PP), the retro-rocket phase (RRP) and the freefall phase (FFP), are of major importance, as far as the spacecraft's safe landing is concerned. The characteristics of these phases are addressed considering inevitable uncertainties that affect their times, altitudes and...

Astronaut's performance is critical to assure success and safety of an outer space mission. For the given mental workload (MWL), astronaut's long-term performance is affected by his/hers human capacity factor (HCF), while the astronaut's short-term performance depends also on his/hers current state of health (SoH). It is suggested that the roles of...

Automated driving (AD) specifications require that the human driver takes over, if an off-normal situation, such as a possible collision occurs. A critical problem is due in this case to the short time available to the driver to intervene and to take appropriate actions. It has been recently demonstrated, mostly in application to the aerospace doma...

It is shown how the kinetic multi-parametric Boltzmann-Arrhenius-Zhurkov (BAZ) equation that has been recently suggested in the field of electronic and photonic reliability evaluations can be effectively employed to quantify, on the probabilistic basis, the survivability of species (life forms) both on Earth and in the outer space. The general conc...

Automated driving (AD) is likely to encounter situations, when vehicle control is handed from the system to the human driver. Such situation may occur, e.g., when a steadfast obstacle is suddenly detected in front of the moving vehicle, and emergency breaking is the only way to avoid collision. Probabilistic analytical modeling (PAM) is applied in...

According to the Automated Driving Roadmap ERTRAC 17, only vehicles of Level 5 may not need human interference. The current adaptive cruise control system or more advanced automated driving solutions below Level 5 require, therefore, that a human driver takes over, if an extraordinary situation occurs. A critical safety problem may be caused by the...

Three practically important reliability-related questions for solder joint interconnections (SJIs) in automotive electronics, and particularly in its actuator and sensor electron devices, are addressed in this analysis: Could inelastic strains in the solder material be avoided by a rational physical design of the IC package, and, if not, could the...

Numerous accidents are due to situation awareness degradation. However, as there exist many different causes and human factors are not well understood, it is very difficult for experts to provide probability risks assessments. It is proposed here to simplify the problem by classifying accidents according to the main demons that degrade situation aw...

In this paper it is shown that the bathtub-curve (BTC) based time-derivative of the failure rate at the initial moment of time can be considered as a suitable criterion of whether burn-in testing (BIT) should or does not have to be conducted. It is also shown that the above criterion is, in effect, the variance of the random statistical failure rat...

Application of the concept of interfacial compliance in analytical thermal stress modeling in electronics and photonics engineering is addressed. The review is based mostly on the author’s research conducted during his tenure with Bell Labs (Basic Research, Area 11, Murray Hill, NJ), University of California (Santa Cruz, CA), Portland State Univers...

The “head-in-pillow” (HnP) defects in lead-free solder joint interconnections of Integrated Circuit (IC) packages with conventional (small) standoff heights of the solder joints, and particularly in packages with fine pitches, are attributed by many electronic material scientists to the three major causes: attributes of the manufacturing process, s...

The Boltzmann–Arrhenius–Zhurkov constitutive equation is employed to assess the fatigue lifetime of a solder material subjected, during failure-oriented-accelerated-testing (FOAT), to temperature cycling and experiencing plastic deformations (low cycle fatigue condition). The damage caused by a single cycle is quantified, in accordance with Hall’s...

The “head-in-pillow” (HnP) defects in lead-free solder joint interconnections of IC packages with conventional (small) stand-off heights of the solder joints, and particularly in packages with fine pitches, are attributed by many electronic material scientists to the three major causes: 1) attributes of the manufacturing process, 2) solder material...

Bathtub curve (BTC), the reliability “passport” of an electronic product, is affected by two major irreversible processes: the decreasing with time statistics-related failure rate (SFR) process and increasing with time physics-of-failure-related failure rate (PFR) process. The first process dominates at the infant-mortality portion (IMP) of the cur...

In this review, some major aspects of the current underfill technologies for flip-chip (FC) and fine-pitch-ball-grid-array (FPBGA), including chip-size packaging (CSP), are addressed, with an emphasis on applications, such as aerospace electronics, for which high reliability level is imperative. The following aspects of the FC and FPGGA technologie...

A simple analytical thermal stress model is suggested for a typical flip-chip (FC) lidded package design. The model is based on the concept of the interfacial compliance. The addressed design consists of a silicon FC bonded to an organic substrate and covered by a lid. The lid is configured in such a way that its mid-portion is bonded to the back s...

High operational reliability of an electronic material or a device intended for aerospace applications is critical, and, in the author’s opinion, cannot be assured, if the underlying physics of failure is not well understood and the never-zero probability of failure is not predicted and made adequate for the particular material, device and applicat...

A previously developed analytical thermal stress model is used for the assessment of the effect of the glasstransitiontemperature (Tg) of the underfill encapsulant and the thickness of the underfill-solder composite bond (USCB)on the induced stresses. The calculations were carried out for two Tg levels, above and below the operation and testingtemp...

Two advanced probabilistic design-for-reliability (PDfR) techniques are addressed in application to the prediction, quantification and assurance of the reliability of aerospace electronics: 1) Boltzmann-Arrhenius-Zhurkov's (BAZ) model, which enables to develop a simple, easy-to-use and physically meaningful methodology for the evaluation of the pro...

The bonding layer in flip-chip assembly designs is characterized, unlike in epoxy bonded assemblies, by a relatively high effective Young’s modulus of its composite material, which is comprised of high-modulus solder and low-modulus epoxy encapsulant (underfill). Simple, easy-to-use and physically meaningful tri- and bi-material analytical stress m...

The recently suggested probabilistic design-for-reliability (PDfR) concept and particularly its physically meaningful and flexible Boltzmann–Arrhenius–Zhurkov (BAZ) model, can be effectively employed as an attractive replacement of the widely used today purely empirical and physically unsubstantiated power law relationship for assessing the static...

In this review we consider publications addressing the dynamic response of electronic materials to shocks and vibrations. The emphasis is on the second level solder joint interconnections (package-to-substrate) and on the board-level drop testing.