Category Archives: Packaging and Testing

By Ron Press, Mentor Graphics Corp

Scan testing is the standard practice for test of integrated circuits. The vast majority of IC production test is based on automatic test pattern generation (ATPG) using the scan logic. Scan ATPG is a mature technology with very predictable and high quality results. It also enables precise defect diagnosis to help yield analysis and improvement. With the growth in the size of ICs and smaller fabrication processes, embedded compression was added to the scan DFT logic, which reduces the growing time to apply tests by a couple of orders of magnitude. Today, embedded compression is commonplace.

However, some devices must be tested when there is little or no tester interface available. In these cases, built-in self-test (BIST) is necessary.  Recently, the growth in ICs for safety critical applications, like automotive and medical, has boosted the demand for BIST. However, more and more ICs need both kinds of test. It turns out that embedded compression and logic BIST use similar types of logic, so it makes sense to save DFT logic area by sharing the compression and BIST logic in a hybrid test solution. The DFT and infrastructure of each technology can also provide advantages to the other technology. This kind of hybrid compression/BIST solution not only saves DFT area, but provides better test quality.

With the hybrid test approach, you have the option to provide embedded compression ATPG patterns from a tester or to have the patterns automatically applied and analyzed within the device logic BIST. You can insert hybrid logic in a top-down flow with a central controller and shared compression decompressor/LFSR and compaction/MISR logic in one or more blocks (Fig 1). You can also do it in a bottom-up flow, which lets you complete the logic insertion in each block, including wrapper isolation chains. The resulting blocks with hybrid test logic can be used in any IC and the logic BIST or embedded compression patterns for the block can be directly retargeted. This plug-n-play logic and pattern approach saves significant ATPG time in the top-level IC.

Embedded compression ATPG provides advantages to logic BIST in a hybrid solution. Because embedded compression ATPG has high quality production defect detection, the logic BIST might not be required to have as high a fault detection. Thus, fewer test points are necessary for random pattern resistive logic, which could be a significant logic BIST area savings. Another advantage that originally came from embedded compression is low power test. The hybrid test approach uses low power shift logic so that the toggle activity can be selected by the user in either ATPG or BIST.

Similarly, logic BIST in a hybrid approach provides advantages for embedded compression ATPG. X-bounding used by logic BIST to remove unknown states is necessary to produce a predictable signature in the MISR. It also makes the circuit much more testable for ATPG, especially if any test points are also added. As a result, the logic BIST infrastructure provided in the hybrid approach causes embedded compression ATPG to have higher coverage and fewer patterns. ATPG is normally the primary means of defect detection, but with logic BIST additional detection is possible due to the high number of detections of each fault (high multiple detection).

These are all compelling reasons why a hybrid test approach is attractive for any user implementing logic BIST. In fact, it is being adopted by automotive IC designers who need both autonomous test and very high-quality production ATPG patterns. What many don’t realize is that it also provides notable advantages for ATPG even if a hard logic BIST requirement doesn’t exist. With this approach, burn-in doesn’t need a tester to apply ATPG patterns since logic BIST could be used and overall ATPG compression and pattern count are improved.

Click to view full screen.

Click to view full screen.

Figure 1. A hybrid test solution with compression (embedded deterministic test) and logic BIST sharing a majority of the decompressor/LFSR and compactor/MSIR logic.

Ron_PressRon Press is the technical marketing manager of the Silicon Test Solutions products at Mentor Graphics. The 25-year veteran of the test and DFT (design-for-test) industry has presented seminars on DFT and test throughout the world. He has published dozens of papers in the field of test, is a member of the International Test Conference (ITC) Steering Committee, and is a Golden Core member of the IEEE Computer Society, and a Senior Member of IEEE. Press has patents on reduced-pin-count testing and glitch-free clock switching.

STMicroelectronics has introduced a new family of gyroscopes specifically optimized for optical image stabilization in smartphones and digital still cameras.

Optical Image Stabilization has become an essential feature in today’s smartphones and digital still cameras. By moving the lens in real time to compensate for physical movement of the camera, it can significantly improve the sharpness of the image, especially when taking photographs in low light, when hand jitter during the longer exposure time would blur images.

In addition, to assure maximum reliability, the new 2-axis (L2G3IS) and 3-axis (L3G3IS) gyroscopes operate with a resonant frequency of the sensing mass at around 20kHz. As a result of this high resonant frequency in combination with the mechanical structure, the devices are immune to the damage that could be caused by ultrasonic cleaning equipment (typically operating at around 30kHz) that many customers use to clean devices before equipment assembly.

“In addition to revolutionizing user interfaces with intuitive gesture recognition, MEMS gyroscopes have brought enormous benefits to hand-held digital photography through optical image stabilization. With the LxG3IS family, ST’s proven MEMS manufacturing technology and supply-chain advantage are applied to gyroscopes that are uniquely tailored for image stabilization and offer increased damage protection,” said Fabio Pasolini, General Manager, Motion MEMS Division, STMicroelectronics.

Other key technical features of the new devices include +/-65 dps / +/-130 dps full-scale range, SPI digital interface, embedded temperature sensor, and integrated low- and high-pass filters with selectable bandwidth. The devices operate with supply voltage from 2.4V to 3.6V and are housed in an LGA-16 3×3.5×1 mm package.

According to information and analytics firm IHS, ST’s total MEMS and sensor sales grew more than 19 percent in 2012, reaching a total of approximately $800 million. In the largest of these markets, motion sensors in mobile handsets and tablets, ST’s MEMS sales accounted for 48 percent of the market, well more than twice as large as that of its closest competitor.

Samples of ST’s new 2-axis (L2G3IS) and 3-axis (L3G3IS) gyroscopes are available now and budgetary unit pricing is $2.37 (L2G3IS) and $3.38 (L3G3IS) for orders over 1,000 pieces.

Driven by value-creating applications in mobile phones, automotive, displays and other systems, the global MEMS industry has grown to over $11 billion in 2012, a 10 percent compound annual average growth rate since 2008. The next stage of MEMS industry development is forecast to grow even faster, but industry drivers will diversify to include new technologies, new business models and new manufacturing strategies. How these new growth drivers will impact MEMS device manufacturers, fabless MEMS companies, MEMS foundries,  MEMS equipment and materials suppliers will be the focus of the SEMI International MEMS/MST Industry Forum, held in conjunction with SEMICON Europa (www.semiconeuropa.org), on October  7-8, 2013 in Dresden, Germany.

Under the theme, “Taking MEMS to the Next Level,” leaders from all sectors of the MEMS value chain will address the critical issues enabling and challenging industry growth prospects for the coming 3-5 year period. Keynote speakers include:

  • Benedetto Vigna, executive vice president, STMicroelectronics
  • Ulrich Krumbein, senior principal, Device Physics Discretes, Infineon
  • Ali Foughi, vice president, Marketing and Business Development, InvenSense
  • Barnett Silver, senior vice president, ATREG
  • Dave Thomas, marketing director, Etch Products, SPTS

Other speakers at the two-day conference include technology, manufacturing, application, and business executives from MEMS industry leaders such as, Freescale, IHS, X-Fab, Yole Developpment, Tronics, Lewel Group, Si-Ware Systems, Veeco, EV Group and more. Topics to be discussed include application trends in inertial sensors, microphones, optical, automotive, bio-medical, and other areas. Technology subjects include advanced packaging, system-on-a-chip, advanced deposition and etch processes, wafer bonding, and inspection/test. A special session has been organized that will look at the rise of fabless MEMS companies and the new foundry services and capabilities that have arisen to meet the needs of this sector.

“We are moving beyond the mobile and automotive era to a new level in MEMS industry development,” said Heinz Kundert, president of SEMI Europe. “The next era has not yet been defined, but will be characterized by the emergence of a multitude of new markets and applications, enabled by advanced sensing, manufacturing and integration technologies. No other MEMS conference will be as rich in expertise, diverse in perspective or informed in technology trends as the SEMI International MEMS/MST Industry Forum.”

SEMICON Europa (www.semiconeuropa.org) is the leading exhibition and conference dedicated to the future of micro- and nanoelectronics design and manufacturing in Europe. Leading companies will exhibit and showcase the latest equipment, materials, software and solutions and over 100 speakers will share information on the latest trends, technologies, processes and techniques in electronic applications, design and manufacturing. SEMICON Europa will be held on Oct 8-10, 2013 in conjunction with the Plastics Electronics Conference and Exhibition (www.plastic-electronics.org) to showcase Europe’s most innovative companies, institutions and people.

By Sean Nealon on September 3, 2013

A team of researchers from the University of California, Riverside’s Bourns College of Engineering have solved a problem that previously presented a serious hurdle for the use of graphene in electronic devices.

Read more: Michigan Tech researchers develop 3D graphene

Graphene is a single-atom thick carbon crystal with unique properties beneficial for electronics including extremely high electron mobility and phonon thermal conductivity. However, graphene does not have an energy band gap, which is a specific property of semiconductor materials that separate electrons from holes and allows a transistor implemented with a given material to be completely switched off.

A transistor implemented with graphene will be very fast but will suffer from leakage currents and power dissipation while in the off state because of the absence of the energy band gap. Efforts to induce a band-gap in graphene via quantum confinement or surface functionalization have not resulted in a breakthrough. That left scientists wondering whether graphene applications in electronic circuits for information processing were feasible.

Read more: Graphene sees explosive demand in a variety of industries

The UC Riverside team – Alexander Balandin and Roger Lake, both electrical engineering professors, Alexander Khitun, an adjunct professor of electrical engineering, and Guanxiong Liu and Sonia Ahsan, both of whom earned their Ph.Ds from UC Riverside while working on this research – has eliminated that doubt.

“Most researchers have tried to change graphene to make it more like conventional semiconductors for applications in logic circuits,” Balandin said. “This usually results in degradation of graphene properties. For example, attempts to induce an energy band gap commonly result in decreasing electron mobility while still not leading to sufficiently large band gap.”

“We decided to take alternative approach,” Balandin said. “Instead of trying to change graphene, we changed the way the information is processed in the circuits.”

The UCR team demonstrated that the negative differential resistance experimentally observed in graphene field-effect transistors allows for construction of viable non-Boolean computational architectures with the gap-less graphene. The negative differential resistance – observed under certain biasing schemes – is an intrinsic property of graphene resulting from its symmetric band structure.

The graphene transistors for this study were built and tested by Liu at Balandin’s Nano-Device Laboratory at UC Riverside. The physical processes leading to unusual electrical characteristics were simulated using atomistic models by Ahsan, who was working under Lake. Khitun provided expertise on non-Boolean logic architectures.

The atomistic modeling conducted in Lake’s group shows that the negative differential resistance appears not only in microscopic-size graphene devices but also at the nanometer-scale, which would allow for fabrication of extremely small and low power circuits.

The proposed approach for graphene circuits presents a conceptual change in graphene research and indicates an alternative route for graphene’s applications in information processing according to the UC Riverside team.

Sand 9, Inc. today announced the first MEMS timing products specifically designed to meet the stringent performance, cost, size and reliability requirements of high-volume mobile applications such as 3G/4G cellular and GPS/GNSS as well as low-power wireless connectivity applications such as Bluetooth® Smart. Sand 9’s TM361 and TM061 are also the only timing products that support integration with mobile and wireless connectivity chipsets, conserving board space and reducing bill of materials.

“Our vision is to disrupt the timing market by completely eliminating discrete quartz components in cellular, GPS and other mobile applications,” said Vince Graziani, CEO, Sand 9. “This is a major milestone for Sand 9. Our unique approach using piezoelectric MEMS has enabled us to develop the first MEMS timing devices that meet the specific requirements for mobile phones as well as applications for the emerging Internet of Things. Size and integration play a key role in both of these markets, and Sand 9 will be spearheading the adoption of integrated timing across the industry.”

“These new platforms hail a paradigm shift in the way the mobile and wireless connectivity industries consider timing,” said Alan Mond, executive vice president, marketing and sales, Sand 9. “By partnering with major semiconductor companies, we can now effectively eliminate the need for external quartz devices. This will allow OEM manufacturers to simplify their system designs, reduce size, improve performance and reliability, and reduce costs.”

TM361

As the first product based on Sand 9’s Temperature Sensing MEMS Resonator (TSMR) platform, the TM361 targets the replacement of temperature-sensing crystals (TSXs) for cellular transceiver and GPS/GNSS/WiFi wireless connectivity combo chips. The TM361 is a MEMS resonator with a built-in temperature sensor and heater for temperature compensation and calibration.

The TM361 features:

  • Ultra-small size—at just 0.76 x 0.68 x 0.50 mm wafer-level chip scale package (WLCSP), the TM361 is designed for cost-sensitive System in Package (SiP) applications.
  • Performance—the TM361 offers 10x better thermal coupling than quartz by physically integrating the temperature detector with the MEMS resonator. This results in high-precision temperature compensation at < 10 ppb/s.
  • Quality—no activity dips/hysteresis, which improves GPS-lock and reduces LTE packet loss, enabling far fewer service disruptions.
  • Best-in-class shock and vibration resistance—offering < 0.1 ppb/G, the TM361 supports use even in harsh environments.

TM061

As the first product based on Sand 9’s MEMS Resonator (MR) platform, the TM061 meets the demands of the Internet of Things (IoT), wireless-everywhere ecosystems necessitating devices that are rugged, low-power, low-cost and very small in size. The TM061 is a MEMS resonator only, and does not include a temperature sensor, heater or oscillator circuit. It serves as a quartz crystal replacement for low-power wireless connectivity applications such as Bluetooth Smart. Like all MEMS timing products from Sand 9, it can be overmolded without impacting performance, providing the size reduction required to enable the IoT.

The TM061 features:

  • Ultra-small size— with the same miniature footprint as the TM361, the TM061 is 50% smaller than the smallest conventional quartz device.
  • Ruggedness—the TM061 is several orders of magnitude more resistant to shock and vibration than quartz, making it ideally suited to wireless sports and fitness applications.
  • Low Power—the TM061 requires less than 300 μA when paired with a typical 1.8V oscillator.

“The proliferation of mobile phones and the rapid growth of the Internet of Things have dramatically changed the way we communicate with each other and with our digital environment,” said Jérémie Bouchaud, director and senior principal analyst, MEMS & Sensors, IHS. “While system-on-chip innovations have contributed to this massive proliferation, timing has been the exception, because quartz does not support integration. With the advent of integration-ready system-level timing solutions from companies such as Sand 9, however, this is bound to change.”

Sono-Tek Corporation, a global ultrasonic spray technology company, announces a just completed expansion of their laboratory testing facility, located at their corporate headquarters in Milton, NY. The recent acquisition of new equipment, including an SEM microscope for on-site analysis of coatings performed in the lab, led to some reorganization and physical expansion of the facility itself, in order to provide a better workflow for customers and visitors, in addition to some increased elbow room.

sono-tek expands testing facility

The new equipment now installed, in particular the SEM microscope, enables Sono-Tek to gauge process variables by providing immediate on-site analysis of coatings requiring very precise deposition characteristics, such as photoresist onto MEMs, fuel cell coatings, medical implantable device coatings and other nanomaterial coatings. In addition, a new corona surface treatment has been installed, to better prepare substrates for improved surface tension characteristics prior to coating. Acquisition of at least one more surface treatment tool is planned as well.

Located in the heart of the Hudson Valley, Sono-Tek is pleased to help bring these high tech applications for precision semiconductor and advanced energy close to home.

"Access to equipment such as this new SEM is beneficial not only to Sono-Tek customers, but to the surrounding community of colleges and other research institutions in New York for advancing research and manufacturing of future innovations in our area," said Steve Harshbarger, Sono-Tek’s President. "We envision our lab continuing to grow in the coming years, as new applications for ultrasonic spray coating continue to develop."

 

In 2012, the IC industry saw a two percent decline, but Yole Développement’s research reveals the MEMS sector managed another 10 percent growth to become an $11B business. Analysts expect a 12-13 percent CAGR through 2018 to create a $22.5B MEMS market, growing to 23.5 billion units. We have identified a number of changes as old MEMS products mature and new ones emerge. Cell phone demand drove strong growth for MEMS devices. Inertial sensor maker InvenSense continued to prove the worth of its fabless model with a ~30 percent increase in sales. Triquint saw 27 percent growth as its BAW filters won more slots in smartphones.

Yole Développement’s report shows markets for inkjet heads and DLPs have matured, but we see huge growth on the horizon for combination inertial sensors and for MEMS timing devices. Combination inertial sensors are starting to see high volume adoption in both consumer and automotive markets, and will quickly account for a signifi cant part of inertial sensor sales. Yole Développement’s report identifies new innovative MEMS devices that continue to emerge. Yole expect to see a number of them start production, though not reach significant volumes for a few years. MEMS autofocus could come to market shortly. Big smartphone players are now looking at adding environmental sensors for heat and humidity, and MEMS devices could win those slots.

Consumer is still the leading MEMS application with increasing needs for sensory interface. Yole Développement’s report ranks the top MEMS suppliers. In 2012, for the fi rst time, the top two MEMS suppliers on our annual Top 30 MEMS companies ranking are suppliers of inertial sensors, rather than of inkjet heads or micro-mirror actuators that have long dominated the sector. STMicroelectronics is the first company to grow a $1 billion MEMS business, surpassing Texas Instruments. The second sensor supplier, Robert Bosch, has also pushed ahead of Texas Instruments and Hewlett Packard for the first time. The expanding demand for MEMS in both smartphones and automotive applications is creating a rising group of players, that can expect to see solid sales in their future.

Yole Développement’s report shows how the results of MEMS players top 30 and companies with the largest growth clarify just how much the smartphone market is driving MEMS demand. AAC Technologies had strong sales of MEMS microphones that propelled them to 90 percent growth and $65 million in MEMS revenues, putting them in the Top 30 for the first time. More microphones in more phones also helped propel sales to grow more than 20 percent at both Infineon and Knowles. Yole Développement’s analysis shows that very few MEMS players have more than one device in production. Only big manufacturers such as STMicroelectronics or Robert Bosch have different devices in production.

Although there are many MEMS devices that have been in development for many years now (auto focus, micro fuel cells), Yole Développement’s analysis shows that crossing the gap from development to industrialization is still challenging. Consumer and mobile applications are the fastest growing areas for MEMS, having a strong impact on many developments happening at the moment. The report shows that pressure sensors started to be produced in large volumes for cell phone applications in 2012 and MEMS microphones are still growing, boosted by the integration of multiple microphones in smartphones. It is interesting to note the market for standalone accelerometers is decreasing as mobile devices increasingly use combo sensors. There is high demand for compact devices, partially offset by the growth of 6-axis e-compass for low-end smartphones. Adoption of 6-axis IMUs is now strong and 9-axis combos should follow within a few years. This push from the consumer side drives MEMS players to adopt new strategies.

InvenSense, Inc., a provider of MotionTracking system on chip devices, is relocating its headquarters to 1745 Technology Drive, San Jose, California. To accommodate continued company growth, InvenSense is moving into a 130,000 square-feet of office space near San Jose Airport and several important customers and partners.

This announcement is made in conjunction with InvenSense opening a new office in Shenzhen, China to meet the needs of its growing customer base in southern China. The new office, which includes sales, applications and support personnel will be the company’s 2nd office in China. InvenSense has its China headquarter office located in Shanghai, China.

“InvenSense is going through a significant growth in market share as it enables the next generation of MEMS System on Chip (SoC) market. As a result, we are scaling our operations with a new regional office and new corporate headquarters,” said Behrooz Abdi, CEO and president, InvenSense, Inc.

David DiPaola is managing director for DiPaola Consulting a company focused on engineering and management solutions for electromechanical systems, sensors and MEMS products.  A 17-year veteran of the field, he has brought many products from concept to production in high volume with outstanding quality.  His work in design and process development spans multiple industries including automotive, medical, industrial and consumer electronics.  He employs a problem solving based approach working side by side with customers from startups to multi-billion dollar companies.  David also serves as senior technical staff to The Richard Desich SMART Commercialization Center for Microsystems, is an authorized external researcher at The Center for Nanoscale Science and Technology at NIST and is a senior member of IEEE. Previously he has held engineering management and technical staff positions at Texas Instruments and Sensata Technologies, authored numerous technical papers, is a respected lecturer and holds 5 patents.  To learn more, please visit http://www.dceams.com.   

Product validation is an essential part of all successful MEMS new product developments.  It is the process of testing products under various environmental, mechanical or electrical conditions to simulate life in an accelerated manner.  Testing early and often needs to be a daily routine and not just a popular phase used in meetings.  This blog will cover proven methods to accurately perform MEMS product validation while mitigating potential issues resulting in repeated tests and non accurate results. 

Measurement system analysis or MSA is a methodology to qualify the measurement system that will be used to characterize the product.  In the context of MEMS, this could be a function test system for characterizing the performance of a MEMS pressure sensor by applying known pressures / temperatures and measuring sensor output.  The first step of MSA is to calculate total system accuracy determined by a tolerance stack of subcomponent errors traceable to NIST reference standards.  This will ensure your test system has the accuracy needed to properly characterize the samples.  In addition, system linearity of the true and measured value with minimal bias change and stability of the measurement system over time should be demonstrated.  Lastly, a Gage R&R (using average and range or ANOVA methods) in percent of process variation (not tolerance) should be completed to demonstrate repeatability and reproducibility for each test system utilized.  An excellent reference for MSA is aiag.org, Measurement System Analysis.   

Verification of the test system setup and function of the equipment is an important step prior to the start of validation.  Often times, improper test set up or malfunctioning equipment results in repeated tests and delayed production launches.  This is easily avoidable by documenting proper system setup and reviewing the setup thoroughly (every parameter) prior to the start of the test.  Equally important, the engineer should verify the system outputs are on target using calibrated tools after the tools themselves are verified using a known good reference. 

We all like to believe that customer specifications are well thought out and based on extensive field and laboratory data.  Unfortunately, this is not always the case.  Hence it is prudent for engineers to challenge areas of the customers’ specifications that do not appear robust.  Neither the customer nor the supplier wins if the product meets the defined specification but fails in the field.  The pain of such events is pervasive and extremely costly for all parties.   As parts complete laboratory tests, take the added step of comparing the results to similar products in the field at the end of life and ensure similar degraded appearance.  When ever possible, test products to failure in the laboratory setting to learn as much as possible about failure mechanisms.  When testing to failure is not possible, perform the validation to 3 – 5X the customer specification to ensure proper margin exists mitigating the risk of field failures.  Furthermore, always take advantage of field tests even if limited in duration.  They can provide valuable information missed in a laboratory validation. 

As briefly stated earlier, a function test or product characterization is the process of applying known inputs such as pressure, force, temperature, humidity, acceleration, rotation, etc. (sometimes two or more simultaneously), measuring the output of the MEMS product and comparing it to the desired target.  This is completed to ensure the product is compliant with the stated performance specification from the manufacturer.  As product life is accelerated through the validation, the device function should be characterized multiple times during the test to understand product drift and approximate time of failures.  It is recommended to perform function tests three to eight times at periodic (equally spaced or skewed) intervals during the validation after the initial pretest characterization.  As an example, I often test products at intervals of 0, 25, 50, 75 and 100 percent of the validation. 

Use of test standards is highly encouraged as it brings both consistency and credibility to validations performed.  Several organizations develop test standards for general use such as ASTM, JEDEC, AEC, Military and more.   When a product is tested to standards widely excepted in the industry, the intended audience is more likely to accept the results than if a non-familiar possibly less stringent test method was applied.  Some commonly used standards include ASTM B117 (salt spray), JEDEC JESD22-A106B (thermal shock), Automotive Electronics Council AEC-Q100 (stress test for integrated circuits) and MIL-STD-883 (various environmental tests) just to mention a few.  A list of validation standards used across the MEMS industry can be found in the MEMS Industry Group Member Resource Library, Standards Currently in Use at MEMS Companies.

In the validation of MEMS products, it is tempting to perform the testing on units from one wafer that has yielded 1000 pieces.  However, this is a single window in time and does not properly reflect the true process variation that can occur.  A better sampling approach for validation is taking units from multiple wafers within a lot and across multiple wafer lots.  Equally important, differing raw material lots should be used (one example is the starting SOI wafers).  This will ensure supplier, equipment, process, operator and time sensitive factors are well understood.  

Controls are another method to learn valuable information about the products being validated and the equipment being used.  A basic control could be as simple as a product that is function tested at each stage of the test, but does not go through any of the validation (i.e. sits on a shelf at room temperature).  This will give an indication if something has gone wrong with your test system should the same errors be seen in both experimental (parts going through validation) and control groups.  Another use of a control is testing a product that has previously passed a given validation (control group) while simultaneously testing a product that has under gone a change or is entirely new (experimental group).  This will provide information on whether the change had any impact on the device performance or if the new device is as capable as a previous generation.          

Lastly validation checklists are a valuable tool to ensure each test is set up properly before the test begins.  Without the checklist, it is easy to over look a step in pursuit of starting the test on time to meet a customer’s schedule.  Below is a sample validation check lists for thermal shock.  This can be modified for other tests as well. 

Thermal Shock Validation Checklist

 

  • Perform proper preventative maintenance on the environmental chambers before the start of the test to prevent malfunction during the test
  • Identify appropriate control and experimental groups and ensure proper sampling from multiple wafers and lots
  • Document sample sizes
  • Identify a proper validation standard or customer specification to define the test
  • Document pass / fail criteria for the devices under test
  • Create a test log and record any time an event occurs (i.e. start of test, end of test, devices removed from thermal chamber for testing, etc.)
  • Verify calibration of measurement reference and trace it back to a national standard
  • Verify the measurement reference with appropriate simple test.  (i.e. thermal couple’s accuracy and repeatability with boiling water, room temperature, ice water and other known sources)
  • Measure the temperature of the hot and cold chambers with an accurate and verified reference prior to the start of the test (i.e. thermal couple ± 1°C)
  • Verify chamber temperature is consistent across the part loading
  • Verify the time it takes the thermal load to reach the desired temperature (i.e. -40°C) and that its within test guidelines
  • Measure the transition time between hot and cold chambers and verify its within test guidelines
  • Complete all necessary MSA on test equipment and document the results
  • Engrave serial number on each device (paint pen can be easily removed)
  • Document the location of devices in environmental chamber with digital photograph
  • Record serial number and manufacturer for environmental chambers used
  • Determine and document periodic intervals for device function test
  • Continuously monitor environmental chamber temperature for the duration of the test using an appropriate chart recorder
  • Document location of thermal couple (photo) and verify it is located close to parts
  • Monitor device output continuously during the test
  • Check on the environmental chamber daily to ensure no malfunctions have occurred and monitor daily cycle count
  • Create a test in process sign with appropriate contact information for support staff
  • This will likely prevent individuals from accidentally turning off the environmental chamber or changing temperature profiles without notifying you
  • Document any changes to this specification for future reference

Product validation is a critical tool to learn about MEMS performance over a laboratory based accelerated life.  Its an excellent method to validate theory and ensure product robustness in the field.  The due diligence presented in this blog will help engineers avoid seemly small mistakes that cause repeated tests, inaccurate results and missed customer deadlines. 

Light and proximity sensors in mobile handsets and tablets are set for expansive double-digit growth within a five-year period, thanks to increasing usage by electronic giants Samsung and Apple. Light and proximity sensors can detect a user’s presence as well as help optimize display brightness and color rendering.

Revenue for the sensors is forecast to reach $782.2 million this year, up a prominent 41 percent from $555.1 million in 2012, according to insights from the MEMS and Sensors Service at information and analytics provider IHS. The market is also expected to grow in the double digits for the next three years before moderating to a still-robust eight percent in 2017. By then, revenue will reach $1.3 billion, as shown in the figure below.

“The continued growth of the smartphone and tablet markets serve as the foundation of a bright future for light sensors,” said Marwan Boustany, senior analyst for MEMS & sensors at IHS. “Market leaders in these areas are driving the growth, with Apple pioneering their adoption and Samsung later taking the lead in their usage.”

Sensor segments

There are three types of light and proximity sensors: ambient light sensors (ALS) that measure the intensity of the surrounding light enveloping a cellphone or tablet to adjust screen brightness and save battery power; RGB sensors that measure a room’s color temperature via the red, green and blue wavelengths of light to help correct white balance in the device display; and proximity sensors that disable a handset’s touch screen when it is held close to the head, in order to avoid unwanted input, and also to turn off the light in the display to save battery power.

Overall, the compound annual growth rate for the sensors from 2012 to 2017 equates to 19 percent.

Driving this growth is the shift in use from ALS to RGB in mid- to high-end smartphones; the growing deployment of proximity sensors with gesture capabilities compared to just simple proximity sensors; and the price premiums associated with such changes in usage.

Aside from their most conspicuous use in wireless communications typified by handsets and tablets, light sensors are also utilized in various other applications. These include consumer electronics and data processing for devices like televisions, laptops and PC tablets; the industrial market for home automation, medical electronics and general lighting; and the automotive space for vehicle displays and car functionalities like rain sensors.

Samsung and Apple are leaders in sensor use

Both Samsung and Apple have made use of light and proximity sensors in recent years, helping the sensor market grow in no small measure.

In 2010, Apple included an RGB and proximity sensor for its iPhone 4 and an RGB sensor in its iPad, even though the sensors were subsequently dropped in the iPhone 4S, iPhone 5 and later iPads. Apple let go of the sensors, which were made available at that time in a combination—or combo package—in favor of discrete solutions consisting of individual proximity as well as ALS sensors for its products. While combo sensors offer the convenience of a single configured package and sourcing from a single supplier, discrete solutions can offer flexibility in the choice of sensor.

Samsung, meanwhile, has gone on to use light and proximity sensors in even larger quantities than Apple. Last year Samsung included an RGB, proximity and infrared (IR) combo sensor, for both its Galaxy SIII smartphone and flagship Galaxy Note 2 device that the company termed as a “phablet.” This year, Samsung deployed a discrete RGB sensor in its latest smartphone, the Galaxy S4, switching from a combo package due to lack of availability of a combo sensor with gesture capability. Samsung’s move toward using RGB sensors in its high-end handsets currently sets the tone for the RGB sensor market given Samsung’s high unit sales. Such a move by the South Korean maker is expected to open the door for other brands to also include RGB sensors in their handsets and tablets, IHS believes.

The new gesture functionality, such as that found in the Galaxy S4, will see especially vigorous growth in the years to come, with revenue enjoying an astonishing 44 percent compound annual growth rate from 2013 to 2017. Maxim Integrated Solutions of California provides the discrete gesture solution for the Galaxy S4, but Japan’s Sharp will be producing a combo sensor product with gesture capabilities by September this year.

Sensor suppliers and buyers tussle

Samsung and Apple are the top buyers of light sensors, accounting for more than 50 percent of light sensor revenue last year. Samsung pulled away from Apple after impressive 90 percent growth in sensor purchases between 2011 and 2012, compared to Apple’s 54 percent growth rate of spend during the period.

This is due to Samsung’s shift toward RGB sensors in its Note 2 and SIII devices, which command higher average selling prices. In third place after Samsung and Apple is a collective group of original equipment manufacturers from China. Included here are global players with significant name recognition like Huawei Technologies, ZTE and Lenovo, as well as a multitude of lesser-known companies such as Coolpad and Xiaomi.

Meanwhile, the top sensor suppliers are Austrian-based ams via its Taos unit in Texas, which supplies to Apple; and Capella Microsystems from Taiwan, the top light sensor supplier to Samsung. Together the two manufacturers furnish more than half of the light sensor market. Other important sensor makers are Avago Technologies from California and Sharp from Japan.