Destructive Physical Analysis Research Articles

Validation and traceability of XRF and SEM‐EDS elemental analysis results for solder in high‐reliability applications

A procedure and calibration samples were developed for X‐ray fluorescence spectrometry and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) analysis methods for Sn and Pb amounts in solder and coatings. Test methods are needed by laboratories that perform destructive physical analysis of high‐reliability electronics for MIL‐STD‐1580B. Calibrants are prepared by evaporative deposition of multiple, alternating quantities of pure Sn and pure Pb having mass per unit area proportional to mass fractions of Sn and Pb in a solder being mimicked. Validation reference materials are prepared by evaporative deposition of thin films of SRM 1729 Tin Alloy (97Sn–3Pb). Films are created on high‐purity Ni foil to mimic some actual electronics structures and prevent charging during SEM‐EDS measurements. Maximum thickness of films prepared this way must be kept below approximately 1 µm to ensure that the entire thickness is probed by the primary X‐ray or electron beam and that measured X‐rays come from the entire thickness of all films. Detailed procedures are presented, and method performance was characterized. The primary purpose is to create calibrations for Sn and Pb that are simple to implement and establish traceability to the international system of units. The secondary purpose is to validate calibrations using a certified reference material to prove that, for simpler structures of thin solder coatings on metal, both X‐ray fluorescence and SEM‐EDS provide accurate results. Keeping films thin may be unrealistic in comparison with some, if not many, electronic structures, but this approach enables a laboratory to demonstrate competence in a controlled manner. Copyright © 2014 John Wiley & Sons, Ltd.

A Microscopic Safety Mechanism Study for Li Ion Battery

As the large number of LiB has powering in wide ranges of devices in a variety of usage and environmental conditions, there were several LiB field incidents. Many LiB safety mechanisms studies were devoted to understand the safety hazard and to prevent field safety incidents. Many researches have focused on the inherent safety of the battery materials and on the simulation of the cell abuse conditions. The thermal behavior and stability of the LiB cell and its component were studies by the DSC (Differential Scanning Calorimetry), ARC (Accelerating Rate Calorimeter) and other tools. Many LiB degradation and safety mechanisms were proposed from those results. Meanwhile, some LiB safety standard and approval test are in place to minimize hazard or to prevent field safety incidents, which simulate batteries in the thermal, electrical and mechanical abuse conditions. However frequent LiB field incidents on the certified batteries have still causing big concerns on its safety. Many field incident analysis reports identified that there are important difference between reported LiB safety mechanisms in papers, abuse testing in standards and the real field incidents. And those concluded the battery field incidents almost originated due to the cell internal short circuit that was not predictable at the point of cell manufacturing process and certifciation or approval testing process. There are many factors which can induce cell internal short circuit; -metal impurity in the electrode matrials, -metal particle during cell manufacturing process, -flaw in separator, - flaw in cell design and manufacturing, - defected by electric, mechanical and thermal impact and so on. This paper studied a mechanism of the cell internal short circuit by using microscopic techniques. This technique checks the status of a cell design and manufacturing status of a cell model, which may cause a cell internal short circuit during in use if the cell has flaw. We performed two types o f the "Destructive Physical Analysis" testing to identify a cell's latent possibility of inducing internal short circuit; 1) by measuring the gap between separator and anode and cathode in the jellyroll or cell stacking (sepertor shrinkage allowance at room/high teperatture and cell electrode geometry) by microscopic techniques; 2) by checking the position and status of insulation mechanism in the cell (Electrode tab insulation, Application of insulation, Supplementary Insulation, Internal short avoidance, Position of insulation material). This paper shows the relationship between the status of a cell model and the simulation result of the cell abuse testing (Electric testing, and thermal testing and mechanical testing). This paper identifies the battery safety mechanism which is representing the real field failures and incidents. Attached image file shows relationships between cell design/manufacturing status of a LiB cell and cell abuse simulation testing result.

Effective Methods to Screen out Li-Ion Cells with Subtle Defects

Several methods are currently being used to predict and reject lithium-ion cells for soft or subtle shorts. Some of the methods include self-discharge tests at full SOC, self-discharge tests at 0% SOC, self-discharge tests at very low SOC, etc. An elaborate test program was carried out to compare these tests and determine if these are a true reflection of contaminants or other defects inside a lithium-ion cell. Cycle life testing of cells that failed the criteria established as well as destructive physical analysis with SEM and EDS analysis were also carried out on the samples tested under these different self-discharge tests protocols. In addition, traditional tests carried out at NASA-JSC to stringently screen cells for defects and internal shorts will also be discussed. This paper will address the topic of whether there are good methods to detect internal cell defects in li-ion cells.

Research on Identifying and Avoiding Counterfeit Electronic Components

As the poor development of domestic semiconductor industry in China, the manufacturing of electronic equipments highly depends on the import of electronic components, especially monolithic integrated chips. Unfortunately, numerous counterfeit parts have been found in the supply chain because of the embargo, obsolete and other complicated reasons. Once these counterfeit electronic components were used, they can have devastating effects on the security and reliability of the electronic equipments. This paper analyses the reason of the emergence, source and types of counterfeit electronic components, and expound the method of identification and avoiding use of those counterfeit parts in the process of electronic equipments manufacturing, which is based on destructive physical analysis of electronic components and the database of basic characteristics information of imported electronic components.

Damage threshold determination and non-destructive identification of possible failure sites in PIN limiter

In this work, we employ a circuit simulation tool to investigate the signature of the change in S-parameters curves with the degradation of PIN limiter circuit parameters. Unique correlations can be established for all the circuit parameters, and this provides a good way to identify possible failure sites before destructive physical analysis of the degraded limiters.

Destructive Physical Analysis of Components of Cycled and Abused Li-ion Cells

not Available.

Comparison of the capacity fade of Sony US 18650 cells charged with different protocols

A new varying current decay (VCD) protocol, which charges the Li-ion battery at a faster rate, was developed. The performance of the battery charged using the VCD protocol was compared with the performance of batteries charged with conventional constant current–constant voltage (CC–CV) and constant voltage (CV) protocols. The destructive physical analysis tests at the end of 150 cycles indicated higher impedance for the cells cycled using the VCD protocol compared to the cell charged using the conventional (CC–CV) mode. The observed increase of the impedance was due to a small increase of the potential above the cut-off value of 4.2 for short times. A complete capacity fade material balance as a function of number of cycles was performed in order to account for the total capacity loss due to different charging protocols used. The loss of primary active material (Li +), the secondary active material (LiCoO 2/carbon) and the rate capability losses were determined for Sony US 18650 Li-ion cells and compared for different charging protocols.

Reliability Evaluation and Failure Analysis for NTC Thermistor

Failures of NTC thermistor are analyzed. Visual inspection, electrical parameter test, non-destructive test, and destructive physical analysis were performed on the field samples to identify the root cause of failure. It was found that the predominant failure mechanism was the copper migration of dumet (copper-clad alloy) at glass-PVC interface for glass-coated chip type NTC thermistor molded with PVC. Next, an accelerated life test is designed to predict the lifetime. Temperature, voltage, and humidity are considered as accelerating variables. Under the assumptions of a general life-stress relationship and Weibull lifetime distribution, the parameters of life-stress relationship and acceleration factor for the migration are estimated by analyzing the test data.

Three-dimensional x-ray laminography as a tool for detection and characterization of BGA package defects

Non-destructive examination of the layers of a built-up substrate was achieved using three-dimensional (3-D) x-ray microlaminography, with successful separation of layers as thin as 8 /spl mu/m. The same technology was used to create reconstructed images of both surface and internal details of inner solder balls in a ball grid array package soldered to a printed circuit board. Microlaminography was also used to identify bond-wire shorts in the plane of the solder resist of a ball grid array assembly, and these were subsequently verified by destructive physical analysis. This plane is 20 /spl mu/m thick and immediately adjoining a plane of copper traces; the success demonstrates the capability of microlaminography to resolve and separate very fine detail internally within IC structures. The limits of capability of this machine were also determined; it was found that a crack of approximately 5 /spl mu/m wide in a copper trace of a BGA was not detected by the machine. As an introduction, the technology and methodology of 3-D x-ray microlaminography are explained. The results from a microlaminography system adapted for failure analysis in integrated circuit packaging are presented. It is shown that such results could not be extracted by two-dimensional (2-D) x-ray or other nondestructive methods.

Reliability evaluation of a silicon-on-silicon MCM-D package

This paper presents the results of reliability testing on a multichip module technology with active silicon substrates. The modules use flip-chip technology to attach silicon chips to the active substrate and this assembly is then packaged into a plastic ball grid array package. Performance was evaluated using two custom designed test chips incorporating thermal, thermomechanical, electrical and reliability test structures. A rigorous environmental test sequence including temperature, cycling, humidity, highly accelerated stress test and power cycling were carried out on the demonstrators. A full destructive physical analysis was then performed, consisting of die/substrate shear, wire bond pull tests and microsectioning.

Corrosion in plastic packages-sensitive initial delamination recognition

The interface between the molding compound (MC) and the chip surface is of considerable interest for failure analysis on plastic-packaged chips. Scanning acoustic microscopy (SAM) is widely used for nondestructive evaluation in this field. Prior research of stressed components has shown that some delaminations containing microbridges, or "spongy" elements, are undetectable by SAM. Corrosion proves to be a sensitive mechanism for detecting these failures. In certain cases corrosion can be detected quasinondestructively by IR microscopy, while conventional destructive physical analysis and optical microscopy remain the easiest way to assess it. Degradation of the interface molding compound and chip is detectable by SAM at a later stage.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Destructive physical analysis results of Ni/H 2 cells cycled in low earth orbit regime (II)

Six 48-Ah individual pressure vessel Ni/H 2 cells containing 26 and 31% KOH electrolytes have been on a low earth orbit cycle-life test. Three cells containing 31% KOH have failed after an average of 6400 cycles while the other three with 26% KOH have cycled for an average of 19 500 cycles. We have carried out post-cycle characterization tests and destructive physical analyses (DPA) of all cells. The DPA included visual inspections, measurements of electrode thickness, scanning electron microscopy, chemical analyses, and measurements of nickel electrode capacity in an electrolyte flooded cell. A gradual decrease of the usable cell capacity at high rate (1.4 C) was the failure mode of all cells tested. Decrease of the usable capacity was due to decrease in the utilization of the active material with cycling mainly due to build-up of low rate capacity (residual capacity) and undischargeable active material. Cycle life of one of the cells might have been shortened prematurely due to the breakage of the cell core. Many gradual changes occurred with cycling at a rate which is independent of the KOH concentration. Each of these individual changes are difficult to be attributed to be the direct cause of the utilization decrease. However, an involved interaction of the changes might be responsible for the decrease.

Defect-damped electromechanical resonances of Pb(Mg1/3Nb2/3)O3 multilayer capacitors

Abstract This paper focuses on the damping effect of delaminations and pores on the electromechanical resonances of ferroelectric Pb(Mg1/3Nb2/3)O3 multilayer capacitors. Using a linear approximation, defect-damped dielectric spectra of the capacitors have been calculated at given boundary conditions and porosities. Under 20V dc bias, two batches of 200 capacitors were measured to examine the theoretical analysis. The damping factor ηi and porosities Pi determined from the measured data represent the delaminations and pores in capacitors respectively. A general agreement between destructive physical analysis and this investigation has been achieved.

Physical and chemical analysis of a NH 2 cell

A cycled aerospace nickelhydrogen (NiH 2) cell was subjected to destructive physical analysis to determine the reason for a capacity loss after 5967 cycles at 60% depth of discharge. The positive plates in the cell were analyzed in terms of chemical composition, active material utilization, charge efficiency and thickness increase. The microstructure of a cross section of the positive plate was determined by backscattered electron image analysis. The results suggest that the capacity loss in the cell is caused by low charge acceptance and low active material utilization at the positive plate. The oxidized nickel species content of the positive plate increased due to corrosion of the nickel sintered skeleton. This appears to circumvent the orderly reaction of the active material. Microstructural analysis has indicated that a new phase of active material is formed with cycling.

Flip-Chip Bump Bonding Reliability and Process Improvement

ABSTRACTLong term reliability of flip-chip bump bonding for application in infrared detector interconnection is investigated. The effectiveness of a thin film nickel as diffusion barrier for reducing indium-gold intermetallic formation is studied by accelerated life test and destructive physical analysis. A new interconnect structure replacing the conventional bump-to-bump configuration is described.

Acoustic Emission Testing of Multilayer Ceramic Capacitors

A new technique for detecting physically defective multilayer ceramic capacitors is described. This technique is based upon the acoustic energy emitted when a defective device is subjected to compressional stress. Strong correlation is shown between the acoustic energy emitted and the severity of physical defects as determined through destructive physical analysis. In addition correlation is shown between the presence of physical defects and abnormal performance during accelerated life tests.