Inorganic Analysis

Gideon Analytical Laboratories received a Printed Circuit Board (PCB) with contamination on several capacitor sleeves, connector pins, and an oscillator. An electrolytic capacitor is a capacitor whose anode (+) consists of pure aluminum foil with an etched surface, covered with a uniformly very thin barrier layer of insulating aluminum oxide, which operates as a dielectric. The electrolyte, which covers the rough surface of the oxide layer, operates as the second electrode, the cathode (-). E-caps have the largest capacitance values per unit volume compared to the two other main conventional capacitor families, ceramic and plastic film capacitors, but much smaller capacitance than similarly sized supercapacitors. Aluminum electrolytic capacitors are divided into three subfamilies by the type of electrolyte. There are non-solid (liquid, wet) aluminum electrolytic capacitors, solid manganese dioxide aluminum electrolytic capacitors, and solid polymer aluminum electrolytic capacitors. Basic parts to an electrolytic capacitor include anode foil, a dielectric, cathode foil, cathode oxide layer, non-solid electrolyte, paper spacer, conducting polymer, among other materials. An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices. The goal was to identify the contamination on the capacitor sleeves, connector pins, and an oscillator.

Gideon Analytical Laboratories received a printed circuit board (PCB) with suspected failing multi-layered ceramic capacitors (MLCC). Multilayer ceramic capacitors are fixed value capacitors in which ceramic the material acting as the dielectric. It is made up of two or more alternating layers of ceramic and a metal layer acting as the electrodes. There are various types of materials that could function as the dielectric in a capacitor, for example, glass, porcelain, paper, or mica. Each PCB has four suspected failing MLCCs, and the goal was to determine the cause of these failures.

Gideon Analytical Laboratories received several lighting tracks for failure analysis. They all had what appeared to be arcing which caused severe copper pitting, melting of the Noryl, and distortion of the power bus bar. The neutral bus was also pitted but not nearly as bad as the power rail. Electrical arcing is an electrical breakdown of a gas that produces an ongoing electrical discharge. The current through a normally non-conductive medium such as air produces a plasma; the plasma may produce visible light. An arc discharge is characterized by a lower voltage than a glow discharge, and it relies on thermionic emission of electrons from the electrodes supporting the arc. An arc between two electrodes can be initiated by ionization and glow discharge, as the current through the electrodes is increased. The breakdown voltage of the electrode gap is a function of the pressure, the distance between electrodes and the type of gas surrounding the electrodes. When an arc starts, its terminal voltage is much less than a glow discharge, and current is higher. An arc in gases near atmospheric pressure is characterized by visible light emission, high current density, and high temperature. NORYL resins are a rare example of a homogeneous mixture of two polymers. Most polymers are incompatible with one another, so tend to produce separate phases when mixed. The two polymers compatibility in NORYL resins is due to the presence of a benzene ring in the repeat units of both chains. The goal was to determine why there was electrical arcing on these lighting tracks.

Gideon Analytical Laboratories received several plated steel parts, including coupons, hinges, and shoulder nuts. The goal was to determine if these parts were RoHS compliant. RoHS is short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment; it was initially created by the European Union in February of 2003. To be RoHS compliant, devices have to be free from the following hazardous substances: Lead, Cadmium, Mercury, Hexavalent chromium, Polybrominated biphenyls, and Polybrominated diphenyl ether. There are a number of electronics components that potentially could contain these restricted substances like solders printed circuit boards, lamps and bulbs, batteries, and metal parts. Closely linked to RoHS is the Waste Electrical and Electronic Equipment Directive (WEEE).

Gideon Analytical Laboratories received several liquid-crystal displays (LCDs) that had fading issues; there were five failing LCDs and a good LCD for comparison. An LCD is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. LCDs are extremely common in electronic devices such as laptops, digital clocks, and watches, pocket calculators, microwave ovens, or CD players. LCDs are also used in televisions and produce a sharp and vivid image. LCDs are can be small, inexpensive to manufacture, and do not draw a lot of power. The LCDs that were received had fading issues on the side closest to the seal. The fading had occurred over time. The goal was to determine the cause of these failures.

Gideon Analytical Laboratories received two surface mount (SM) tantalum capacitors that had internal resistive shorts. Capacitors are passive, two-terminal electrical components used to store energy. They vary in construction, but all have at least two electrical conductors that are separated by an insulator, known as a dielectric. Tantalum capacitors are a type of electrolytic capacitor, which are ubiquitous in electronic circuits. Tantalum capacitors have a high capacitance per volume and weight and are more expensive than any other commonly used capacitor. The goal was to determine the causes of these internal resistive shorts.

Gideon Analytical Laboratories received three samples in polyethylene bottles to develop an analytical procedure for determining chloride using an ion chromatograph. Ion chromatography is a process that allows the separation of ions and polar molecules based on their charge. Using ion chromatography, one can identify concentrations of major anions, including elements like sodium, lithium, calcium, and many others. Aqueous samples are quantitatively measured in the parts-per-million range.

The two solutions were diluted 1:25 with DI water (18.2megaohm) water from a point of use Millipore purification system. The samples were then analyzed by ion chromatography; it was carried out with an instrument that consisted of HP1050 pump and autosampler with a Dionex AMMS suppressor and conductivity detector. Data was captured using an HP Chemstation. Displayed in the table below is the ion chromatograph readings of the respective samples. The picture shows the first sample (in red) at 3.4 PPM and the second sample (in blue) at 35.1 PPM. The results of the ion chromatography revealed the certain presence of chloride; absolute identity was made by spike, subtraction, and standards.

Gideon Analytical Laboratories received four 220 picofarad AVX capacitors for failure analysis. There are a variety of capacitors, including ceramic, aluminum, film, and tantalum, but all serve the same purpose, which is to store electrical charge. They are passive electrical components with at least two electrical conductors separated by an insulator (dielectric). The four220 picofarad AVX capacitors were giving low resistance readings.

Failure analysis ensued. The four 220 picofarad AVX capacitors were inspected for mechanical cracks, which would propagate upon voltage; no cracks were found on the external ceramic. The capacitors were measured and tested on a curve tracer since they had low resistance, otherwise, an IR meter would be used. The current was gradually increased to the point where dendrites would burn out. The resistance was measured again. No change occurred. The capacitors were baked and then retested again; no appreciable change occurred in resistance measurements. These test results indicate there was most likely an internal problem with the capacitor.

Gideon Analytical Laboratories received six pulse transformers, three of which were failures, three of which were reliable. The objective was to determine the cause of the failures and inspect the unused transformers for anything that could contribute to the cause of failures. Transformers are devices that transfer electric energy from one circuit to another, usually with a change in voltage. Pulse transformers are transformers optimized for transmitting rectangular electrical pulses. Ideally, pulse transformer designers try to minimize voltage droop, rise time, and pulse distortion. Gideon Analytical Laboratories conducted a thorough failure analysis on these pulse transformers.

Gideon Analytical Laboratories received several amplifier units were supplied to ascertain the difference between a new vintage resistor, which failed, and the older one, which functioned normally. A resistor is a passive electrical component that enacts electrical resistance in a circuit. These resistors were measured at 22 ohms.

Failure analysis was performed on the resistors. It was not known if the resistors were from the same vendor or whether the power dissipation of the thick film was the same. A cross-section analysis revealed no differences in the alumina used for the substrate or construction of the film on the substrate. Since no differences were revealed during the cross-section, SEM-EDS analysis was performed. EDS analysis revealed some significant differences in the old and new resistors; the peaks were clearly different in the old resistor. Titanium and chromium were present and silver and ruthenium were absent. The film composition determines the resistance values and the surge current the film can tolerate.

Gideon Analytical Laboratories received an Areovox Z26P6045M21 45uF 600V capacitor for failure analysis. Capacitors are passive two-terminal electrical components used to store electricity in an electric field. Inside most capacitors, there are two metal plates separated by a non-conducting substance (dielectric). Filter capacitors are used for filtering undesirable frequencies and removing voltage or signal spikes in electronic circuits. They are utilized in a variety of applications. Gideon Analytical Laboratories performed failure analysis the Areovox Z26P6045M21 45uF 600V capacitor.

Gideon Analytical Laboratories received several contaminated lead screw assemblies. Also received were three insulin samples, one grease sample, and several new parts making up the lead screw assembly. Lead screws are designed to translate turning/rotary motion into linear motion. The contamination on the shaft of the assembly was primarily concentrated between the bearing and the ball seal. The goal was to identify and determine the cause of the contamination.

Gideon Analytical Laboratories primarily used FTIR and SEM-EDS analysis for diagnostics. FTIR analysis was initially performed using an Analect DS-20 FTIR with an Analect XAD microspectrophotometer equipped with a small chip, high sensitivity MCT detector. The FTIR analysis revealed that the contaminate had a high degree of hydration, oxygen, and salt. The large contamination of salt will tend to migrate towards hydrated substances. The FTIR analysis also revealed that APIDRA was an integral component of the contaminate. SEM-EDS analysis was utilized to determine whether the contaminants were coming from the inherent materials or an outside source.

Gideon Analytical Laboratories received metallurgical corrosion failures from lamp sockets. The materials and the insulation protection was compared to distinguish the difference between the two lamp sockets. The lamp sockets were overheating and melting the wire insulation in the application. These sockets are a type of bi-pin lamp fitting. Bi-pin lamp fittings are for use in incandescent (especially halogen) and some fluorescent lights. MR16 refers to the lamp construction and overall diameter at its largest circumference. The failed socket is pictured below, at left, it showed extensive overheating and melting of the wire insulation.

Gideon Analytical Laboratories received three axial-lead resistors for failure analysis (pictured in the first picture directly below). A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Their purpose is for creating a precise quantity of resistance for insertion into a circuit; they are typically constructed of metal wire or carbon and engineered to maintain a stable resistance value over a wide range of environmental conditions. Gideon Analytical Laboratories was tasked to identify the cause of failure in these resistors.

Gideon Analytical Laboratories received two failed 510K, two used 510K operating for about 3 weeks, and two virgin resistors for failure analysis. A resistor is a component of a circuit that resists the flow of electrical current. It has two terminals across which electricity must pass, and it is designed to drop the voltage of the current as it flows from one terminal to the other. Resistors are primarily used to create and maintain known safe currents within electrical components. The epoxy coating on the failed and used resistor was not as hard as the virgin part. The coating peeled easily and exposed the underlying aluminum metal on the alumina shaft. Therefore, the first suspicion is that something in the process is altering the coating integrity of the epoxy on the resistor. All the resistors were examined for contamination on the epoxy coating by using SEM-EDS to identify any detrimental elements. There is a chloride peak on top of the coating. Normally, chlorides do not attack the epoxy coating nor do they diffuse through the coating to the aluminum metal. As these chlorides were found on the top of the coating, the coating was marked as to the location. SEM-EDS identified chloride. The Si is coming from residual silicates used as binders epoxy coating and the silicone potting material. The chloride was coming from a cleaning product before conformal coating. Gideon Analytical Laboratories can solve all kinds of contamination issues with components and IC. Use Gideon the next time your company needs IC or component failure analysis.

Gideon Analytical Laboratories examined the extrusion marks on the tungsten IC probes wires versus a Monel K500 IC probes via SEM. MONEL K500 is a nickel-copper alloy, precipitation hardenable through additions of aluminum and titanium. MONEL K500 retains the excellent corrosion resistant characteristics of 400 and has enhanced strength and hardness after precipitation hardening when compared with 400. Alloy K500 has approximately three (3) times the yield strength and double the tensile strength when compared with 400. MONEL K500 can be further strengthened by cold working before the precipitation hardening.

Relays are very susceptible to contamination because the leads are made of copper and vulnerable to corrosion and leakage current if not protected from the environment.

The liquid shown here was thought to have come from the flux residue and, therefore, an organic analysis FTIR was required as opposed to inorganic XRF. However, the liquid was acidic in nature and XRF was employed. The material was a filled, glass fiber reinforced material containing a phosphorus species along with an antimony/bromine fire retardant package. The original formulation likely contained antimony oxide and a poly-brominated organic, such as diphenyl ether or a tetra-bromo BPA polyester or polycarbonate. The bromic acid has leached out of the fire retardant material. This material is not compatible with most electronic circuits or components.

Several screws were presented to Gideon Analytical Laboratories due to corrosion. The screws were analyzed with SEM-EDS. The micrograph indicates the spot where this screw was analyzed. Chloride was found on the spot where corrosion was found.

Gideon Analytical Laboratories can identify the source and cause of corrosion allowing the customer to implement the corrective action immediately.

Gideon Analytical Laboratories performed analysis on several Melexis US2881 Sensors when the designer found shorts on the returned product from the field.

Melexis US2881 sensors are bipolar Hall-effect switches designed in mixed signal CMOS technology. They have a wide voltage operating range from 3.5V to 24V, have high magnetic sensitivity, and a chopper-stabilized amplifier stage, and are suitable for automotive or consumer applications.

Analysis revealed tin crystals (whiskers) spread throughout the top and bottom of the PCB, shorting out the MOSFET as well as the Hall sensor. Micrograph (left) and SEM-EDS analysis confirmed the presence of tin whiskers causing a short in both positive and negative leads. The tin whisker growth took place over several days to develop without voltage and with conditions known to promote growth.

Gideon Analytical Laboratories performed failure analysis on one opened splitter module LPF-200 PCB encapsulated in the black urethane potting material and housed in plastic. The PCB was burnt in one spot, and in that spot, a cavity existed under the carbonized epoxy of the PCB adjacent to the PTH. The trace line had a number of craters strongly suggesting an “electromigration” of copper. In order for electromigration to occur with copper a voltage, an acid and medium (moisture) must be present.

Gideon Analytical Laboratories received electrolytic capacitors for chloride analysis according to a prior analysis technique for determining the presence of chloride. The chloride analysis technique was developed because chlorine is a known catalytic corrosive element on aluminum.

The analysis was performed using an SEM-EDS system giving elemental analysis in relation to the intensity of the element at a specific wavelength or energy level (Kev). Since Kev (energy levels) for specific elements do not change, these are used to identify the elements in the sample. One of many SEM-EDS spectra pictures is at the top right. The analysis was performed on the tab, the lead, the fillet, the shank and the stitching where anode foil attaches.

Gideon Analytical Laboratories performed failure analysis on several Sky CKC-1C-12VDC 12A/120V relays. These relays have a contact resistance of 100 Mohms and have a surge resistance of 1000V. The devices had a liquid on the inside surface and corrosion on several of the leads. The liquid and corrosion is pictured at the top left.

The drop was analyzed using FTIR. The liquid was thought to have come from the flux residue and, therefore, an organic analysis FTIR is required as opposed to inorganic (XRF). The pH is 0.0. The liquid is very acidic. Since the liquid appears to be inorganic, an XRF was performed. A 2-microliter aliquot of DI water was added to a region showing a large number of droplets. The drop was moved about the surface and then recovered using a 2µ1 capillary and transferred to a Prolene film mounted on an XRF sample cup. The XRF sample cup consisted of Chemplex XRF sample cup cat. No. 1430 and a Prolene thin film cover (4µm Prolene, Chemplex cat. No. 426). The backside of the sample cup was removed to permit application of the sample solution to the back of the Prolene film.

Gideon Analytical Laboratories performed failure Analysis on a failed RJR26 Bourns Potentiometer. The application failure was noticed when a lower than expected resistance value and, eventually, open in the potentiometer.

A potentiometer (or pot) is a simple electromechanical transducer. It converts rotary or linear motion from the operator into a change of resistance, and this change is used to control the resistance within a circuit. The pot (also known as a rheostat) is essentially a variable wire wound resistor or a carbon or metal film with a swiper. A potentiometer is an example of a voltage divider consisting of resistors in series. It is commonly used to create a reference voltage, or to get a low voltage signal proportional to the voltage to be measured, and may also be used as a signal attenuator at low frequencies. For direct current and relatively low frequencies, a voltage divider may be sufficiently accurate if made only of resistors.