Archive for March, 2014

Trax personal tracker integrates u-blox GNSS and cellular technologies

Monday, March 31st, 2014

World’s smallest tracking device locates children and pets both outdoors and inside

Swedish WTS (“Wonder Technology Solutions”) has launched Trax, the world’s smallest and smartest personal tracking device for children and pets. Based on a u-blox GNSS receiver module with integrated antenna and cellular module, the tiny tracker can be located anywhere, anytime via a free Android or iPhone mobile phone app.

In addition to real time tracking, Trax provides flexible geofence alerts, and can even monitor how fast your teenager is driving. It also works indoors thanks to a proprietary dead reckoning algorithm that delivers a position even when satellites are out of sight. Accurate down to 1.5 meters, the robust, water resistant device also provides an “augmented reality” mode that helps users locate their trackers using a Smartphone’s built-in camera view.

CAM-M8Q GNSS antenna module provides “drop-in” positioningTo achieve the smallest possible size, Trax takes advantage of u-blox’ CAM-M8Q GNSS receiver module which has a built-in antenna. CAM-M8Q (“Chip Antenna Module”) provides both small size (9.6 x 14.0 x 1.95 mm) and multi-GNSS capability. It is based on a u-blox M8 chip and includes an integrated chip antenna plus SAW filter, LNA, TCXO, RTC crystal and passives. The surface-mount module is also extremely low in height making very thin customer designs possible.

“Trax is the world’s smallest and most versatile personal tracking device available, packed with features designed to provide peace of mind to parents and pet owners almost anywhere in the world,” said Fredrik Danelius, Managing Director at WTS, “By combining the leading GNSS and cellular technologies from u‑blox, we have designed a tiny, reliable, low-cost device that protects our most valuable family members: children and pets.”

Trax comes with an integrated SIM-card and two years of free data and roaming in 33 countries. It is charged via USB and typically lasts between two and four days on a full battery. For wireless connectivity, device integrates a u-blox “SARA-G3” GSM/GPRS module which is footprint compatible with the SARA- U2 UMTS/HSPA module for easy 2G to 3G upgrade.

“Trax is an elegant and sophisticated example of our embedded GNSS and cellular modules combined to protect people’s loved ones”, said Pasi Alajoki, Area Sales Manager at u-blox, “It is an extremely important application of our mobile communications and global positioning technology where performance, size and power consumption play a critical role. We are proud WTS chose u-blox for Trax.”


About u-blox

Swiss-based u-blox (SIX:UBXN) is the global leader in wireless and positioning semiconductors for the automotive, industrial and consumer markets. Our solutions enable people, vehicles and machines to locate their exact position and wirelessly communicate via voice, text or video. With a broad portfolio of chips, modules and software solutions, u-blox is uniquely positioned to allow OEMs to develop innovative solutions that enable mobility quickly and cost-effectively. With headquarters in Thalwil, Switzerland, u‑blox is globally present with offices in Europe, Asia and the USA.
www.u-blox.com

About WTS

WTS, Wonder Technology Solutions, is committed to improving the lives of people by providing products and services with a high customer value that are reliable, fun, intuitive and smart. WTS seeks to revolutionize location-based services through smart technology and innovative design. WTS has innovated, designed and developed Trax, a small personal GPS-tracker that can be monitored on an App or web interface. Trax is specifically designed for children 2-7 years old and pets. These users require a product that is small in size, lightweight and doesn’t get in the way of play. Parents and pet owners require reliable products. Trax is designed with high quality components and smart technology that meet all the above requirements. Its appearance, features and functions are unique on the market.

www.traxfamily.com

Attach Rate of Embedded In-dash Factory-installed Navigation Units to Increase to 38% Globally by 2019

Thursday, March 27th, 2014

Once a luxury item, embedded in-car navigation systems are now increasingly becoming less expensive and are offered in mass-market cars.At the same time, more and more car navigation units are becoming connected and multi-functional as they converge with other technologies in the car.

ABI Research expects the attachment of embedded in-dash factory installed navigation units to increase from 22% at the end of 2013 to 38%by 2019, representing a CAGR of 13.6%. “However, this growth will be eclipsed by the number of smartphone-based navigation devices used in the car, particularly off-board devices, where navigation is performed in the cloud as opposed to on the device,” comments Gareth Owen, principal analyst at ABI Research. The company forecasts that shipments of handset-based navigation services will reach 1.68 billion globally by 2019.

These findings are part of ABI Research’s Automotive Infotainment Research Service. ABI Research’s car infotainment database provides detailed installed base and forecasts of the car infotainment market. New data added in this release include Market Data about rear-seat entertainment displays and forecasts of smartphone integration technologies such as MirrorLink and “iOS in the Car.” The database also includes detailed forecasts of Bluetooth penetration in cars and automotive app downloads and revenues.

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Nondestructive Acoustic Inspection of IGBT Modules in Transportation

Thursday, March 20th, 2014

For users of IGBT modules in transportation and automotive applications, acoustic imaging provides additional data probable long-term reliability.

IGBT Modules in Transportation Applications

Isolated-gate bipolar transistor (IGBT) modules are semiconductor power devices used in electric railway traction chains (ERTCs), electric automobiles and numerous other applications within and outside of transportation. They serve as very efficient high-speed switches. First manufactured around 1990, they have undergone many improvements, and have contributed significantly to the expanded use of ERTCs versus diesel railway systems in the past few decades. IGBTs are also becoming widely used in variable power drives in mine milling and other applications where the ability to control and vary the speed of the electric motor saves significant energy.

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Figure 1: Ultrasound pulsed into an IGBT module by the scanning transducer (bottom) is reflected as an echo by all material interfaces, but most brightly by the interface between a solid material and a gap. [Diagram courtesy Sonoscan, Inc.]

In ERTCs, energy from external sources goes through several power conversion steps before delivery to the electrical traction motors. The final step is the IGBT module, whose switching controls both train speed and braking. Frequent switching and high current loads (hundreds of amperes with blocking voltages of 6000 V, yielding hundreds of kilowatts) make this a very demanding environment, especially in terms of thermal buildup. Efficient dissipation of thermal energy from the module is critical.

An IGBT module consists of several individual IGBT devices. Beneath each device is the die attach material bonding it to a substrate. Below the substrate are one or more layers leading to a metal heat sink at the bottom. The efficiency with which heat is dissipated via this route is critical to the long-term survival of the IGBT module in its high-stress environment.

The power demands of the traction motor may require frequent switching of the IGBT module. The pattern of switching may result in localized hot spots within the module. The various layers of material in the module have different coefficients of thermal expansion (CTE); the extreme nature of the environment makes cracking and delamination between materials real dangers. A delamination or crack in the thermal pathway downward from the IGBT device will block heat from reaching the heat sink below. The local increase in temperature may cause a portion of the IGBT device to overheat and burn out.

Module Inspection by Acoustic Micro-Imaging

Because internal anomalies within an IGBT module can cause unexpected field failures in what are expensive, high-performance devices, some form of nondestructive inspection is useful. What has emerged in the last few years is the use of acoustic micro-imaging to inspect the module before final assembly. Acoustic micro-imaging uses ultrasound to make visible gap-type defects (voids, delaminations, non-bonds) as well as non-planarity of elements such as the ceramic plates, or rafts. In the die attach bonding the IGBT to the raft, there may be voids or non-bonds that will impede heat flow. In the material attaching the raft to the heat sink, voids or cracks can impede heat flow. These gap-type defects tend to expand during service as a result of thermal cycling. The thickness of the attachment material may also be uneven.

The stage at which acoustic inspection is performed varies from manufacturer to manufacturer. The raft with components attached may be imaged alone before heat sink attach to make visible anomalies in the die attach material, although these anomalies can also be seen by scanning the heat sink surface after the heat sink has been attached. Many companies avoid imaging from the top side of the module because of the possibility that water, used to couple the ultrasonic transducer to the module, may damage circuitry.

In general, acoustic imaging tends to be carried out before encapsulation of the module, not because encapsulation hinders imaging—the whole module thickness can be imaged after encapsulation by scanning the heat sink surface—but because identification of anomalies before encapsulation permits rework of these expensive modules.

Not all makers of IGBT modules currently use acoustic micro-imaging as a nondestructive method to find internal structural defects, but the number of companies that do use this relatively new technology is growing rapidly. A firm that manufactures relatively low-cost modules that will be used in relatively low-risk applications may perform no acoustic inspection, or may inspect only a small percentage of production. The percentage may increase if there is a sudden increase in defects in the small sample. Makers of the higher-performance, higher-cost IGBT modules used in transportation are much more likely to use acoustic inspection, and to inspect 100% of some module types because the consequences of failure can be severe.

What an Acoustic Micro-Imaging System Sees

Acoustic microscopes are able to make delaminations, cracks and other gap-type defects visible by pulsing very high (up to 100 MHz) frequency ultrasound into the module and collecting the return echoes. An ultrasonic transducer scans the surface of the heat sink on the bottom side of the module and inserts thousands of pulses per second during scanning. At various depths within the module, a single pulse may encounter any or all of these conditions:

    1) A homogeneous solid having no internal defect—the bulk of the heat sink, for example. No echo is returned.

    2) The well-bonded interface between two solids—the heat sink and the solder, for example. A medium amplitude echo is returned and collected because one portion of the pulse is reflected while the other portion is transmitted across the interface and travels deeper into the module. The amplitude of the reflected echo can be calculated from the density and acoustic velocity of the two materials. In a grayscale acoustic image, these echoes range from light gray to dark gray. Note that the transmitted portion of the pulse may travel deeper into the module and be reflected by deeper interfaces.

    3) The interface between any solid material and a gap. Even if the gap is as thin as 0.01 micron, >99.99% of the pulse is reflected as an echo by the solid-to-air interface at the top of the gap. Echoes from gaps have the highest amplitude of any internal feature in an IGBT module. In a grayscale acoustic image, gaps (delaminations, cracks, voids, etc.) are bright white.

Handling and Imaging IGBT Modules

How an IGBT module is handled during acoustic imaging is largely a matter of preference. The ultrasonic transducer must be coupled to the surface of the module by a liquid. Typically a small jet of water is used to create a constant link between the transducer and the module surface. Modules can be imaged either before or after overmolding with an encapsulant. Before overmolding, some modules are imaged from the top side, with the ultrasound being pulsed downward through the die. Others are imaged from the bottom side, with the ultrasound being pulsed upward through the heat sink (see Figure 1). Where there is concern that the die should not be in contact with water, the heat sink is the preferred route. With either method, the imaging results are similar; i.e., delaminations or voids in the die attach material below the die are visible whether the pulse is inserted into the die or into the heat sink. One advantage of imaging before overmolding is that defects that are found by acoustic imaging can often be repaired.

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Figure 2: Gray areas are solder-to-ceramic reflections, but the irregular white shapes are heat-blocking voids within the solder bonding the heat sink to this module. [Acoustic image courtesy Sonoscan, Inc.]

Figure 2 is the acoustic image specifically of the solder layer that bonds the rectangular heat sink on the bottom side of this IGBT module to the raft above the heat sink. Dark gray areas are well bonded; the irregular white areas are voids (air bubbles) within the solder that reflect ultrasound very brightly, and that will also block heat coming from the die. This solder layer has so many heat-blocking voids that the module is unlikely to survive for long in the extreme environment in which it will be installed.

In the gray (solid-to-solid) areas of Figure 1, a portion of the ultrasonic pulse was reflected and another part traveled deeper into the module. If there are several internal solid-to-solid interfaces, as there are in an IGBT module, the same pulse at the same x-y position may be reflected from several depths. The arriving echoes are of course separated in time. Figure 1 was made by using for imaging only those echoes that arrived within a time gate corresponding to the thickness of the solder layer. The process of defining the depth to be imaged is called gating. If the entire thickness of the module were gated—including multiple interfaces—the results might be hard to interpret.

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Figure 3: Gated on the raft, scanning reveals intentional spaces (white) between ceramic elements, but also small defects (arrows). [Acoustic image courtesy Sonoscan, Inc.]

Figure 3 was gated on the rafts below the solder. The straight bright white lines are not defects but intentional lateral gaps between the plates. The two white areas marked by arrows, however, are probably defects.

Because some portion of the arriving pulses was reflected by bonded interfaces within this gate, the voids in the solder, which are above this gate, now appear as dark acoustic shadows. Each one has the shape it had in Figure 1. Here, however, they block the returning ultrasound that would otherwise create medium-gray or bright white pixels.

The solder or other adhesive bonding the heat sink to the rafts is often the subject of acoustic imaging because it may contain voids or other defects that will block heat transfer. But it is also important to know how thick the solder is across a single raft, or across the entire module. To measure and display the thickness, the return echoes are read in a different way. Instead of selecting a pixel color by the amplitude of the echo, software measures the difference in time between the echo from the top of the solder (the solder-to-heat sink interface) and the echo from the bottom of the solder (the solder to raft interface).

The time difference method, as it is known, measures the transit time through the solder at each of the thousands or millions of x-y coordinates where a pulse is inserted into the module by the scanning transducer. The time is then converted into distance.

Figure 4 is the time difference image showing the solder thickness over a single raft. The color spectrum ranges from the thickest solder, which is pink and has a thickness of about 360 microns, to the thinnest, which is black (lower left corner) and indicates no or almost no solder. The curved nature of the individual colors suggests that warpage is present, most likely in the raft.

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Figure 4 (Left): Colors used in this acoustic image measure solder thickness, not the interface reflectivity. Pink is thickest; orange and black are thinnest. [Acoustic image courtesy Sonoscan, Inc.] | Figure 5 (Right): By using arbitrary, non-adjacent colors and assigning each to a 45-micron thickness of the solder, the color map simplifies evaluation of the solder bond and the identification of rejects. [Acoustic image courtesy Sonoscan, Inc.]

Most of the voids in this image are bright red, indicating that the distance from the top of the solder to the top of the void was very small—i.e., the voids are mostly at the top of the solder, nearly touching the heat sink. Because the void reflects all of the ultrasound, there is no measurement of the overall solder thickness where there is a void.

It is often more useful to bypass the full-spectrum map and use a map having arbitrary colors to emphasize accept and reject thicknesses. Figure 5 shows the same raft as in Figure 3 mapped with arbitrary colors. The thickest solder is bright red. Each individual color has a thickness of 45 microns; the red area has a maximum thickness of 360 microns, and thus a range of 315 to 360 microns. Pale blue ranges from 270 to 315 microns. The assembler can use this map to quickly assess the accept/reject status of the module. The range of thickness in this map is essentially from 0 to 360 microns. Probably only a few of the middle colors—brown, yellow, purple, for example—would fall within the acceptable range for a given application. This color map makes it easy to spot unacceptable solder thicknesses, and to identify modules that can be reworked.

Conclusion

What acoustic imaging gives to the users of IGBT modules in transportation roles is the ability to know a great deal about the probable long-term reliability of a given module. The acoustic imaging is carried out by the maker of a module, but a potential buyer should be able to learn the results, or whether acoustic imaging was performed on a given module, along with the results of x-ray inspection, electrical testing, high-temperature operation, and other tests. The rapid increase in the use of acoustic imaging by the manufacturers of IGBT modules demonstrates that they recognize the value of having and providing this data. Go to www.sonoscan.com for more information.


tom_adamsTom Adams is a freelance writer and photographer based in New Jersey, U.S.A. He has written more than 500 articles for technical and scientific trade magazines. His articles have appeared in more than 50 magazines in 15 countries in North America, Europe, and Asia.