Category Archives: Materials and Equipment

Cool Your Heels


March 1, 2007

Have you ever taken a Latin dance class? At first glance, everyone comes off as shy, and then the movement heats up. An editor rushed into my office this morning to go over the shaking, twisting, gyrating, and swaying of her Zumba class the night before. The instructor didn’t know much English, but her, “Let’s go babies,” got their attention as everyone twisted into nearly unimaginable postures. They danced muy caliente. Some things are just meant to be hot, while others are not.

In electronics, for instance, all goes better when heat responses are controlled. There are many approaches to mitigating excess heat generated by components crowded into denser, smaller packages and devices. In this supplement, “What’s Cool and What’s Hot,” for instance, Jason Brandi of Henkel talks about new classes of phase change thermal interface materials (PC TIMS) that help with inadequate heat transfer associated with thermal greases and pastes. With wax-based materials, changes occur from solid at room temperature to liquid once excess heat from the devices pushes the material past its melting point. Unlike thermal grease, these TIMS do not migrate out of the interface. In the sidebar to this article, Andy Delano of Honeywell looks at the choice of grease or phase change material. He concludes that the decision of whether to use grease or PCM should include looking at the ease of application, re-workability, cost, shelf-life, and reliability. After 500 cycles, grease’s performance begins to degrade, and by 1000 cycles its temperature has increased by 2°C. On the other hand, PCM’s high viscosity allows it to remain in place and performance is stable.

Bob Conner of Nextreme Thermal Solutions talks about hot spots that exceed average die temperature due to designers’ desire to place transistors in close proximity. Packing high-performance circuits together results in a rise in temperature. Conner suggests using an embedded thermoelectric cooler to cool hot spots, and therefore to increase product performance, reliability, and yield.

In the third article of this supplement, Sarang Shidore of Flomerics writes the most readable article on thermal modeling of semiconductor packages available. Really. He begins by looking at a normal detailed thermal model that reconstructs the physical geometry of a package. Constructing the detailed thermal analysis is added by integrating part mechanical CAD data. If done right, it will predict the temperature at various points within the package – which includes junction, case, and leads – regardless of the environment. This type of analysis fits design simulations with a few packages, but doesn’t work as well for simulations of subsystems or system-level computations with numerous semiconductor packages, because the computational resources required for these large problems would be excessive. Lost yet? Next Shidore goes into explaining two models for handling this type of problem: two-resistor compact thermal models and the DELPHI compact thermal model.

There is just no denying that thermal issues surrounding dense packaging are more important now than ever. The heat of a laptop on your lap can point out that fact. Luckily, there are numerous solutions. Keep reading and we will keep supplying this type of valuable information.

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Gail Flower
Editor-in-Chief

As micro- and nanotechnologies begin to mature, industry salaries increase

By Elizabeth Gardner

Want to know where you stand, in salary, benefits, and bonuses, compared to your small-tech colleagues worldwide? The results of the second-annual Small Times compensation survey shows average small-tech salaries up about 12 percent worldwide.

The survey data was gathered from visitors to Small Times’ Website (www.smalltimes.com) from late December 2006 to early January 2007. The survey attracted 849 responses from 44 countries (up from 37 in 2006), and 41 U.S. states plus the District of Columbia.

Overall, compensation has risen. The average reported salary globally is $96,000, up from nearly $85,000 last year, and the average U.S. salary is $106,000, up from $98,000 last year.

More than half the respondents-56 percent-report that their jobs involve both micro- and nanotechnology. The remainder of the respondents are evenly split between micro-only and nano-only.

Changes in hiring

The technologies as well as hiring practices are starting to mature, even in the smallest of companies. Those who follow the field say that although plenty of person-to-person networking is still going on, it’s more likely that companies are finding new people through newspaper ads, Web job boards, and executive recruiters-and less likely that a newly minted Ph.D. will be exactly what they’re looking for.

Pam Bailey, president of tinytechjobs.com, a job board for the small-tech fields, says there’s been a noticeable increase in postings from companies looking for mid-level technical workers. “In 2005, we saw many more senior-level positions,” she says. “Companies were hiring their thought leaders. In 2006, after those companies obtained funding, they started to build out.” Almost 70 percent of postings on tinytechjobs.com are for scientific or engineering openings. The balance of postings are in product development and manufacturing (a growing area, Bailey says), sales or business development, and academic or government lab research.

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Neil Kane, president of Advanced Diamond Technologies, Romeoville, Ill., has recently ramped up to 11 employees for his young company, which was born out of work in ultrananocrystalline diamond coatings at Argonne National Laboratory. The company recently received a $500,000 National Science Foundation small-business grant to develop UNCD-enhanced seals for pumping applications, and it expects to introduce a diamond-based MEMS product sometime this year.

Kane has advertised for employees in a variety of venues, including Craigslist, tiny techjobs.com, and the Chicago Tribune.

“There are a lot of qualified people with academic backgrounds,” he says. “The overwhelming majority of responses are either recent grads or people coming out of post-doc positions. But we’ve evolved to the point where that’s less interesting and a demonstrated track record is much more important. The company is making the transition from development to shipping products, and we need people who have expertise in managing projects and working in a deadline-oriented environment.”

Kane plans to level off ADT at about 15 employees by year-end and then add employees only as business growth demands them.

Steve Johns, head of corporate and business development at venture capital firm Ardesta, in Ann Arbor, Mich., has helped grow more than a dozen portfolio companies out of infancy and into adolescence, including Sensicore, Discera Inc., and Sensicast. He, too, is looking for people with more experience. “In an early stage technology start-up, [hiring] a Ph.D. student out of a university is almost preferable, because the first work he’ll do is basically an extension of their research,” he says. “But now all of our companies are focused on commercializing that technology and dealing with issues like repeatability and scalability, so we’re looking for people from a commercial environment who have experience taking something all the way to a product. These aren’t research projects anymore.”

For its top managers, Ardesta has had good luck with both large and smaller recruiting firms and favors those who specialize regionally as well as by industry. Johns says many positions are still filled by tapping into personal networks.

Carbon nanotubes have made significant strides toward commercial viability in the past couple of years. This trend has benefited companies such as Nantero, Woburn, Mass., which has grown beyond the point where it can rely on the employees’ personal networks to fill all vacancies. Now at about 40 employees, Nantero is using carbon nanotubes to develop next-generation semiconductor devices and recently patented a technique to position them reliably on silicon wafers-a major step in developing industrial-scale production techniques.

Chief executive Greg Schmergel, who gained his start-up experience in the dot-com boom, hopes to hire at least half a dozen more employees by year-end. “We have employees from all over the world-Asia, Europe, and the U.S.-which is testament to the fact that we have to cast our net very wide to find the people we need,” he says. Schmergel favors both boutique recruiters who specialize in small tech and, perhaps counterintuitively, the large Web job boards like Monster and Hotjobs.

“Maybe we have better success because if someone goes on one of those sites and types in ‘nanotechnology,’ they don’t get very many hits,” Schmergel says.

Analysis overview

The Small Times compensation survey asked 24 questions covering job title, company size, location, level of education, experience, hours worked, salary, bonuses, and benefits. Seventy-two percent of respondents are from the U.S. (almost identical to last year), with the balance from 44 other countries, from Australia to Zimbabwe. The respondents are highly educated: 31 percent hold master’s degrees, and 42 percent hold doctoral degrees-up from 36.7% last year. “This may help explain the overall salary increase from 2006,” says Small Times publisher Patti Glaza.

The group is weighted toward executives and researchers. Forty-four percent are in management: 17 percent are C-level executives (CEOs, CFOs, CTOs, etc.), while 8 percent are at the vice-president level and another 20 percent are managers. About 33 percent of respondents report their title as scientist, engineer, or researcher. These breakdowns are consistent with the 2006 data.

The respondent group is 86 percent male. The female respondents are on the young side; about half earned their bachelor’s degree during the 1990s or 2000s. Fewer of the male respondents, 37 percent, earned their bachelor’s degree in those same decades; 46 percent completed theirs in the 1970s or 1980s.

The majority of survey respondents’ employers are either very small or very large firms. Thirty-seven percent work for companies with 50 or fewer employees, and 31 percent work for employers with more than 2,500 employees.

Private-sector workers predominate. Sixty-five percent of respondents report being employed by manufacturers (13 percent), engineering or design firms (12 percent), corporate research and development (12 percent), materials or instrument suppliers (10 percent), micro/nano component integrators (4 percent), or a service firm such as law, consulting, or marketing (10 percent). In the public sector, 20 percent of respondents work in education or university research, and 6 percent worked in government labs.

Executive compensation-global and U.S.

Just as last year, the title of “Partner” is associated with the highest average compensation this time around. The partner respondents are generally involved with either law firms or consulting firms.

Among C-level executives globally, two categories-chief technical/science officers and CFO/COO/chief marketing officers-report higher average salaries than the president/CEO/managing director category (see chart on page 29). However, there were relatively few respondents in the CFO/COO/chief marketing officer and CTO/CSO categories, and the small numbers may skew the reported average salaries.

Only 42 percent of chief executives report receiving a bonus in 2006; among those who did, the average was $50,000.

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A few chief executives report receiving bonuses in seven figures-happy news for them, but bad news for survey number-crunchers who compute average compensation. To keep the averages from being misleadingly large, and causing unwarranted bitterness in the small-tech community over the size of its bonuses, Small Times dropped these “outliers” when it was computing the bonus averages. In fact, bonuses worldwide range from less than $100 to a robust $3 million. The median bonus reported by respondents for 2006, both globally and in the U.S., is $7,000, for all categories of companies and job titles.

Further down the management ladder, vice presidents of technology and related functions out-earn vice presidents of marketing, sales, operations, and business development, reflecting again the industry’s overall valuation of technical expertise. Technical managers were also a couple of rungs above operational managers.

For respondents from the U.S. only, salaries are significantly higher for CTO/CSOs, at an average of $157,000. U.S. CEOs make slightly more than the global average, at $132,000. Chief operating officers, marketing officers, and financial offers make slightly less on average compared with the global group, at about $137,500.

Engineer/researcher compensation-global and U.S.

Among the employees who make up the technological backbone of small-tech employers worldwide-the engineers, the scientists, and the researchers-engineers report both the highest 2006 salaries, with an average of $83,000, and the largest 2006 bonuses, at an average of 16 percent of salary. Scientists worldwide make an average of $77,000, with a bonus of seven percent of salary, and researchers make $70,000, with a bonus of 11 percent.

Corporate research and development operations pay the highest average salary to this category of workers, at just over $97,000, followed by materials and tools suppliers, industry or government organizations, and component manufacturers, all in the low $90,000s. University researchers aren’t starving, at an average salary of almost $80,000, but their pay still isn’t up to that in the private-sector level.

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U.S. respondents report higher salaries than the global average, but the overall pattern is the same. Engineers report $94,000 in salary with an average bonus of 17 percent. Scientists report average salaries of $90,000 with a seven percent bonus, and researchers report average salaries of $80,000 with a nine percent bonus.

Education and age – global and U.S.

Both worldwide and in the U.S., salaries and bonuses generally increase with education.

Those who hold a bachelor degree in science report an average salary of $86,000. Holders of M.S. degrees reported an average salary of $91,000. Holders of Ph.D., J.D., and M.D. degrees report an average salary of $102,500. Average bonuses follow a similar pattern.

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Survey respondents with an associate degree and master of arts degree report compensation that appears unusually large compared with that of other degree holders (for example, the average salary for those with an associate degree was only a few hundred dollars less than the average for those with a bachelor of science degree). However, both those figures are probably anomalous, stemming from the low number of respondents holding those degrees (only three percent of respondents hold an associate degree).

Those with associate degrees and M.A. degrees are disproportionately represented among sales and marketing job titles. And M.A.s account for 13 percent of those who hold the title of president, CEO, or managing director-but less than five percent of survey respondents overall.

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The bulk of respondents received their degrees in the 1990s (27 percent), the 1980s (28 percent), or the 1970s (20 percent). More-recent graduates account for 15 percent of the respondents.

For the most part, age equates to earning power. Employees who earned their bachelor’s degree in the 1960s have the highest salaries of any age group, with an average of $135,000. New graduates earn less than half that, at $65,000, and average salaries climb steadily with each decade.

Hours worked-U.S. and global

Small-tech workers work hard. Globally, 75 percent of respondents work more than 40 hours a week, and 31 percent report working more than 50 hours weekly. Nine percent work more than 65 hours. Perhaps the most industrious group is in India, where a full 20 percent of respondents report working more than 65 hours a week.

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In the U.S., 77 percent of respondents report working more than 40 hours a week, and 30 percent work more than 50 hours. Eight percent work more than 65 hours a week.

Those putting in the longest hours are more likely to be at a lab bench than a desk: 14 percent of university researchers fall into the more-than-65-hours category, as do 10 percent of those who work for component manufacturers.

Not surprisingly, the people at the top put in the most grueling hours on average: One-third of presidents and CEOs work more than 50 hours a week. Other C-level employees report similar schedules. Engineers and scientists are more likely to make it home for dinner: less than 10 percent work more than 50 hours a week, and about 75 percent work between 36 and 50 hours.

Regional variations-U.S.

Respondents from the U.S. are scattered throughout the country. While the West Coast is home for 29 percent of those who specified a state, other regions aren’t far behind: 23 percent are from the South, 22 percent from the Northeast, and 18 percent from the Midwest. Eight percent are from the Mountain States.

Small-tech geographic salary patterns mirror those in the larger economy, according to the U.S. Bureau of Labor Statistics. Respondents in the Pacific region report the highest average salary, at $115,000. The Northeast was slightly less, at $112,000, followed by the South, at $97,000, the Midwest, at $95,000, and the Mountain States, at $93,000.

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On the other hand, the Northeast reports the highest 2006 bonuses, with an average of almost $30,000, followed by the Pacific and the South at $25,000 each, the Midwest at $12,000, and the Mountain States at $8,600.

Time in organization-U.S.

For U.S. employers, longevity means more money, but only up to a point. The sweet spot for compensation among survey respondents is 11 to 20 years with an organization, which nets an average salary of $125,500. For tenures of 21 to 30 years, the average salary drops to $110,000, and for more than 30 years, it pops back up to $116,000.

Respondents who have been with their companies from one to five years report an average salary of about $97,000, and from six to ten years, $105,000.

Benefits-U.S.

Down slightly from 2006, 86 percent of U.S. respondents report that their employers offer health insurance. Manufacturing companies and educational institutions are slightly more likely to offer health insurance, while consulting and sales companies are somewhat less likely to do so. Seventy-seven percent of respondents say their employers offer dental insurance.

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Only 29 percent of respondents report receiving stock options as an employee benefit, down from last year’s survey in which 33 percent of participants said they received stock options. Of those who report receiving them this year, 22 percent work for a component manufacturer or fabricator, 22 percent work for a supplier of materials or tools, and 19 percent work in a corporate research and development laboratory.

Ardesta’s Johns says the jury is still out on stock options for small companies. “They’re a great way to share ownership in a company and get everyone pursuing the common goal of making sure that the options are worth something someday,” he says. “But it’s not like the old days. We have to spend more time explaining stock options and the notion of wealth than we did five or ten years ago, when everyone knew the impact that options could have. People are [now] just as likely to want to skip the options in favor of a higher salary.”

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Three-quarters of respondents say their employer offers a 401(k) account or the equivalent. Employers most likely to offer the accounts are manufacturers, corporate research and development laboratories, government laboratories, and suppliers of materials and tools. These are also the employers most likely to offer a matching contribution to the employee’s account. Overall, 61 percent of U.S. employers offer a matching contribution.

The same types of employers are also more likely to offer traditional defined-benefit pension plans, though in keeping with national trends, only 21 percent of survey respondents say their employers offer such plans.

Changes in compensation-U.S.

Compensation in the small-tech industries is more than keeping pace with inflation, for the most part. A quarter of respondents say their salaries increased five percent or more in 2006, and 29 percent are expecting such increases in 2007. Forty-three percent say their salaries went up less than five percent in 2006, and 44 percent are expecting the same for 2007. Twenty-nine percent of respondents say their salaries had stayed the same in 2006, although only 25 percent are expecting 2007 to be similarly static. Only three percent report pay cuts in 2006, and only one percent expect the same for 2007.

New Products


March 1, 2007

Electronics-cooling Software

CFdesign V9 is a CAD-driven, electronics-cooling and thermal management simulation software that synthesizes simulation, CAD, and process automation to create thermal solutions for electronics and package design. Blue Ridge Numerics, Charlottesville, VA, www.cfdesign.com.

Silicon-on-diamond (SoD) Wafers

Silicon-on-diamond (SoD) wafers are created through a proprietary chemical vapor deposition (CVD) process that deposits highly uniform diamond thin films onto large-diameter substrates (up to 300 mm). sp3 Diamond Technologies, Inc., Santa Clara, CA, www.sp3inc.com.

Precision Temperature Sensors

High-precision, remote-diode temperature sensors use TruTherm thermal management technology to maintain lowered temperatures in 65- and 90-nm microprocessors. National Semiconductor Corporation, Santa Clara, CA, www.national.com.

Prefluxed Preforms

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Indium and SAC 305 solder alloy preforms reportedly improve heat dissipation from components attached to a substrate. Targeting components such as power amplifiers and power devices, the prefluxed preforms are pre-engineered to ensure complete surface coverage during die-attach. Indium Corporation of America, Clinton, NY, www.indium.com.

Thermal Interface Material

The EPM-2493 is an electronic packaging thermal interface material designed for low outgassing applications. Its low viscosity and outgassing properties meet requirements for high-temperature, high-stress, and low-contamination products, and handle drastic temperature cycling. NuSil Technology, Carpinteria, CA, www.nusil.com.

Heat Sinks for LEDs

Introduced to cool OSRAM DRAGONstick LEDs and other linear LED devices, the ATS-486, 503, and 504 mitigate the intensity of heat generated by high-output LEDs. Fabricated from extruded aluminum, the products feature low-profille spread-fin arrays to maximize surface area, and disperse heat through convection air flow. Advanced Thermal Solutions, Inc., Norwood, MA, www.qats.com.

Silicone-free TIM

The SF3000 GORE POLARCHIP thermal interface material targets silicone-sensitive applications. The soft silicone-free thermal gap pad eliminates outgassing and oil migration (bleeding) problems associated with silicone. W.L. Gore & Associates, Elkton, MD, www.gore.com.

Adaptable Thermal Solution

A proprietary thermal cooling technology, WayCool uses capillary fluid displacement to transfer heat away from electronics, such as LEDs, eliminating the need for active cooling devices. The product’s scalability allows heat transfer from a source towards large, accessible surface areas. OnScreen Technologies, Inc., Portland, OR, www.onscreentech.com.

Electronics-cooling Software

CFdesign V9 – developed for design, mechanical, electro-mechanical, thermal, and product-development engineers – is a CAD-driven, electronics-cooling and thermal management simulation software that synthesizes simulation, CAD, and process automation to create thermal solutions for electronics and package design. Fluid-flow and heat-transfer analysis capabilities are integrated into the design process. Auto mesh-sizing performs a topological interrogation of the geometric model and assigns mesh sizes based on curvature, geometric gradients, and proximity to other components. A rules-on-parts feature detects MCAD part names within an assembly, then automatically assigns volumetric boundary conditions, such as heat-generation data and material properties. Accelerant Solver programming uses proprietary CPU-optimization algorithms to reduce generation time for simulation results from previous iterations – 40 to 2,000%, depending on design complexity. Analysis supplies users with board, junction, and case temperatures; heat transfer from junction to board; and heat transfer from junction to case for each component in a design. Other attributes include process-automation scripting, which allows users to create project-specific scripts for repetitive analysis development; and a design-review server that distributes computations across a network. The software supports various BGA, flip chip, SOIC, SOP, and QFP styles of package design. Blue Ridge Numerics, Charlottesville, VA, www.cfdesign.com.

Silicon-on-diamond (SoD) Wafers

Silicon-on-diamond (SoD) wafers are created through a proprietary chemical vapor deposition (CVD) process that deposits highly uniform diamond thin films onto large-diameter substrates (up to 300 mm). This layer is covered with a thin layer of silicon, providing a known interface on a thermally-conductive substrate. The materials-based thermal management approach reduces junction temperatures by increasing thermal conductivity, and lowers current leakage in comparison with similar substrates. Diamond’s thermal conductivity and metallization capacity reportedly enable micro- and nanofabrication applications, such as MEMS and traditional packages. sp3 Diamond Technologies, Inc., Santa Clara, CA, www.sp3inc.com.

Precision Temperature Sensors

High-precision, remote-diode temperature sensors uses TruTherm thermal management technology to maintain lowered temperatures in 65- and 90-nm microprocessors. The sensors, with transistor-mode beta compensation, resolve inaccuracy problems caused by variations in the internal diodes of deep sub-micron microprocessors, microcontrollers, ASICs, and FPGAs. By improving temperature readings, the sensors lower cooling-fan speed to reduce acoustic noise, and also manage excessive heat to prevent malfunction. LM94 is a hardware monitor that measures temperatures in up to four remote-diode-connected transistors, as well as its own die. The sensor monitors the dynamic power supply voltage, thermal throttling functions, and input/output pins. LM95234, LM95241, LM95233, and LM95235 monitor temperatures through four, two, or one diode. National Semiconductor Corporation, Santa Clara, CA, www.national.com.

Prefluxed Preforms

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Indium and SAC 305 solder alloy preforms reportedly improve heat dissipation from components attached to a substrate. Targeting high-power components, such as power amplifiers and power devices, the prefluxed preforms are pre-engineered to ensure complete surface coverage during die-attach. Materials for advanced packaging include indium, indium/silver, gold/tin, eutectic tin/lead, and SAC alloys. Preforms can be flux-coated, and either fused or non-fused. The material can be engineered to any thickness – as thin as .0005 in. Common sizes, from as large as 2 in., range from squares to rectangles, disks, and custom or complex shapes. The preforms allow for thermal stability and heat transfer at the packaging interface level, either between the chip and heat-spreader/thermal lid, or between the heat-spreader/thermal lid and heat sink. Indium Corporation of America, Clinton, NY, www.indium.com.

Metal Matrix Composites

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Metal matrix composites for chips in RADAR, aerospace electronics, weapons systems, and other high-temperature applications include copper-clad molybdenum copper (Cu-clad Mo/Cu), molybdenum copper (Mo/Cu), aluminum silicon carbide (AlSiC), and tungsten/copper (W/Cu). These composites dissipate heat in semiconductors. The products suit LDMOS packages, base plates, and spreaders. AMETEK Specialty Metal Products, Eighty Four, PA, www.ametekmetals.com.

Thermal Interface Material

The EPM-2493 is an electronic packaging material (EPM) designed for low outgassing applications. The thermal interface material (TIM) has a low viscosity and low outgassing properties to meet requirements for high-temperature, high-stress, and low-contamination products. It is designed to handle drastic temperature cycling. The formula is said to be easily dispensed with conventional systems. NuSil Technology, Carpinteria, CA, www.nusil.com.

Electronics-cooling Design Software

With direct representation of CAD geometries and thermal-conductivity distributions generated from local trace and via densities, Icepak 4.3 software handles complex geometries and offers automation features for thermal modeling. An automatic hex-dominant mesher handles grids of unlimited size and complexity due to an unstructured generator program. Direct CAD import and Icepak libraries offer thermo-electric cooler modules, materials data, and modeling of temperature-dependant powers, as well as enhanced macros and correlations for automatic specification of heat-transfer coefficients. Operators can import trace and via details from MCM/BRD and Gerber files to account for the effect of traces and vias on thermal management. Fluent, Inc., a wholly owned subsidiary of ANSYS, Inc., Canonsburg, PA, www.ansys.com.

Heat Sinks for LEDs

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Introduced to cool OSRAM DRAGONstick LEDs and other linear LED devices, the ATS-486, 503, and 504 mitigate the intensity of heat generated by high-output LEDs to extend service life and minimize maintenance. The heatsinks reduce LED temperature by 53% at the thermocouple mounting pad. Fabricated from extruded aluminum, the products feature low-profile spread-fin arrays to maximize surface area, and disperse heat through convection air flow. The heatsinks are available un-anodized, black anodized, with thermal tape, or without thermal tape. Advanced Thermal Solutions, Inc., Norwood, MA, www.qats.com.

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Heat Spreader Material
Aluminium silicon carbide (AlSiC), a metal matrix composite, provides high-performance, lower density lids and heat spreaders for flip chip packaging and optoelectronics. AlSiC, a RoHS-compliant material, reportedly enables a tailored coefficient of thermal expansion (CTE) for compatibility with various electronic devices and assemblies; the isotropic CTE value of AlSiC can be adjusted for specific applications by modifying the Al-metal/SiC-particulate ratio. CTE matches eliminate thermal-interface stacking, increasing reliability. AlSiC exhibits a high thermal conductivity for efficient thermal dissipation, avoiding bows and flexing in package and substrate. A net-shape fabrication process produces the composite material while fabricating the product geometry to allow rapid prototyping for high-volume advanced thermal management solutions. The unrestricted geometry enables engineered features, such as capacitor or resistor pockets, in flip chip lids. The cast lid can integrate high-thermal-conductivity inserts (>1000 W/mK) or cooling tubes for more advanced thermal management solutions. Ceramics Process Systems Corporation, Chartley, MA, www.alsic.com.

Silicone-free TIM

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The SF3000 GORE POLARCHIP thermal interface material (TIM) targets silicone-sensitive applications. The soft silicone-free thermal gap pad eliminates outgassing and oil migration (bleeding) problems associated with silicone. Because of its high compressibility, the conductive material fills air gaps between heat-generating devices and heatsinks, spreaders, or metal chassis, increasing heat dissipation from the package. The fluoropolymer composite comprises an expanded polytetrafluoroethylene (ePTFE) matrix populated with boron nitride (BN) particles. As BN particles create thermal conductivity, the ePTFE mass maintains low elastic modulus for conformability and compressibility, while reportedly reinforcing the assembly against wear. The TIM family is available in rolls or sheets, die-cut or continuous, with pressure-sensitive adhesive on one side. Pre-cut pieces suit automated assembly processes. W.L. Gore & Associates, Elkton, MD, www.gore.com.

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Adaptable Thermal Management Solution
A proprietary thermal cooling technology using fluid displacement, WayCool transfers heat away from high-heat-generating electronics, such as LEDs. The technology is adaptable across various end markets, including advanced gaming systems, medical equipment, computing systems, and photovoltaics. Independent of the thermal conductivity of the heatsink material, the product’s capillary network of microchannels allows transport of fluid at a rapid rate. This reportedly ensures active removal of hot fluid from the area contacting the heat source and replacement with colder fluid. It can eliminate the need for active cooling devices. The product’s scalability allows heat removal from the source towards large, accessible surface areas; its hollow, honeycomb-like structure is said to reduce cost and weight. OnScreen Technologies, Inc., Portland, OR, www.onscreentech.com.

BY BOB CONNER, Nextreme Thermal Solutions

anufacturers and OEMs need a package-level cooling solution that provides cooling in close proximity to the chip, to cool hot spots and smooth out non-uniform power dissipation. Existing thermal management solutions are aimed at uniformly cooling the entire die. Applying uniform chip cooling solutions inefficiently reduces hot spot temperature, because cooling the rest of the chip is unnecessary and requires a larger heatsink. Moreover, bigger heatsinks are not an option in many applications.

An efficient way to smooth out these hot spots is to cool the high-heat flux areas locally, which minimizes over-cooling of the adjacent silicon. Mitigating hot spots through non-uniform heat transfer close to the on-chip heat source is the primary driver for innovation in electronic cooling.

One technology that addresses this problem is an embedded thermoelectric cooler (eTEC) (Figure 1). These devices cool hot spots to increase product performance, reliability, and yield while reducing cost. An eTEC is a miniature, solid-state heat pump fabricated with a nano-structured thin film using semiconductor processing techniques. eTECs operate by the Peltier effect: when an electric current is driven through a circuit containing two dissimilar materials, heat is absorbed at one junction (the cold side) and released at the other junction (the hot side). The thin-film eTEC materials have high electrical conductivity and poor thermal conductivity to maximize current flow and minimize heat flowing back from the hot side to the cold side. Unlike conventional bulk thermoelectric coolers (TECs) that are made with 1- × 1- × 1-mm pellets assembled into a large array between two ceramic substrates, eTECs fabricated with thin films are small, thin, fast, efficient, and reliable. An eTEC cools a hot spot by moving heat from low to high thermally conducting materials. The devices are site-specific; hot spot cooling minimizes total heat transfer, reducing heatsink size.


Figure 1. Embedded thermoelectric cooler (eTEC)
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Minimum input power is needed to cool the hot spot. Small size and weight allow for unobtrusive integration in close proximity to the hot spot. A solid-state design ensures reliability; high-heat flux cools concentrated hot spots. A fast response time promotes rapid cooling and heating to maintain a precise temperature. Active cooling management is achieved by varying input current to the eTEC. Wafer-fabrication scalability enables low-cost, volume production. Additionally, the devices are optimized for non-uniform cooling to complement uniform cooling solutions.

How It Works

The eTEC is located over the hot spot between the backside of the die and the spreader (Figure 2). The active side of the die is face-down towards the substrate. Some of the heat flows through the solder balls to the substrate. Most of the heat flows through the backside of the die, the first thermal interface material (TIM1), the heat spreader (which forms the lid of the package), the second thermal interface material (TIM2), and finally through the heat sink to ambient. The hot side of the eTEC is soldered to the heat spreader, providing an excellent thermal interface. The same TIM1 that is used to interface the die to the heat spreader is used to interface the die to the eTEC’s cold side.


Figure 2. Flip chip IC with eTEC cooling a hot spot
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Reducing the hot spot temperature with a uniform cooling solution requires either a larger heatsink or faster fan speed. In Figure 3, the y-axis depicts the thermal driving force – hot-spot temperature (Thot spot) – ambient temperature (Tambient). This value is increasingly limited to just 50 to 60ºC, because the Thot spot must be kept below approximately 100ºC for CMOS ICs and the Tambient, which is typically ~40ºC, is driven up as increasing integration and shrinking system footprints force designers to dissipate more heat in a smaller volume.


Figure 3. eTEC creates temperature inversion for hot-spot cooling.
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The x-axis in Figure 3 represents the thermal resistance of each component in the thermal stack. The total thermal resistance (Rthermal) to the heat flow, responsible for Thot spot – Tambient temperature rise, is typically broken down as follows: 40-45% from the heat sink thermal resistance (Rsink); 40-45% from the IC package, which is the thermal resistance of die plus TIM1 plus heat spreader (Rdie + RTIM1 + Rspreader); and 10-15% from the TIM2 thermal resistance (RTIM2). The slope of the line is the heat transfer rate, q = (Thot spot -Tambient)/ Rthermal), which is analogous to the flow of electric current through a conductor (I = ΘV/Relectrical), where the temperature difference is analogous to ΘV (voltage difference) and q (heat transfer rate) is analogous to I (current).

Conclusion

An eTEC provides an efficient, non-uniform cooling solution to reduce Thot spot. This technology reduces the temperature at the TIM1-to-heat-spreader interface, creating a temperature inversion. The eTEC serves as a heat pump to move heat from the IC and TIM1, which have low thermal conductivity; and toward the heat spreader, which has a high thermal conductivity. Temperatures inside the IC package are reduced where it matters most, while the temperature of the case and heat sink increase above ambient by a very modest amount. This temperature change is proportional to the fractional increase in total dissipated package power, which is typically 2 to 3%, resulting from the operation of the eTEC used to cool a small hot spot. Spot-cooling only the hot spots reduces the overall amount of heat that must be removed from the chip, since the eTEC does not pump heat from the “background.”

eTECs also work with any other viable cooling solution an IC manufacturer uses, as all require knocking down the top of the hot spot. They fit well into existing packaging methodologies and extend the life of current thermal management solutions such as heat spreaders, thermal interface materials, heat sinks, and fans. They can also be used in conjunction with emerging thermal management solutions, such as liquid microchannel coolers, providing a considerable volume and weight savings.

BOB CONNER, VP, marketing & business development, may be contacted at Nextreme Thermal Solutions, 3040 Cornwallis Road, Mailstop: 13981, Research Triangle Park, NC 27709-3981; 919/485-2774; E-mail: [email protected].

By Meredith Courtemanche, assistant editor

Theories on thermal management rival, in number and variety, strategies for winning the Super Bowl or baking the perfect loaf of bread. Will running the ball wear down the defense? Should you knead the dough with one hand or two? Will a focus on design preempt debate on substrate materials? Every thermal management approach is designed to mitigate excess heat generated by electronic components crowding into denser, smaller packages and devices. Speaking to members of IMAPS New England chapter and the American Ceramics Society (ACerS), Jonathan Margalit, Ph.D., developer of new business for thermal management-related applications at H.C. Starck Inc. (Goslar, Germany), presented an elegant equation to sum up thermal management and ground Starck’s advances in the field with refractory metals. Margalit focused on molybdenum (Mo) and tungsten (W), materials that he saw as a good match for silicon (Si).


Jonathan Margalit, Ph.D., developer of new business at H.C. Starck, Inc.
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Refractory metals, by definition, withstand high heat, due to their high melting temperatures. Low thermal-expansion rates with these dense metals make them an attractive match for glass and ceramics. Tungsten offers a melting point of 3400°C; molybdenum melts at about 2625°C. Since both are fairly good electrical conductors, they make good thermal conductors. But the most compelling argument for a thermal management product based on refractory metals is the thermal compatibility factor: the coefficient of thermal expansion (CTE) for silicon (3.5) matches closely with those of tungsten (4.0) and molybdenum (5.45). Using these metals in packages, argues Margalit, gives designers a passive, rigid heat spreader that will coexist with ceramics, Si, GaAs, and other component materials, reducing the risk of warpage and breakage in high heat.

For practical application of refractory metals, Margalit outlined the equation that served as a basis for thermal research. The thermal conductivity of the heat spreader (λ) divided by the difference in CTE between the die and substrate (∆ CTE) renders the thermal compatibility of materials, as well as the efficiency of the heat spreader. Along with Starck colleagues Dincer Bozkaya, Baerbel Kloss, and Jonathan Tuck, Margalit manipulated the capabilities of refractory metals to integrate with this equation, creating a targeted, passive, adaptable heat spreader.

Starck introduced copper (Cu) into the equation to create a layered Cu/Mo/Cu structure similar to an insulated metal substrate (IMS). Copper, with much higher conductivity than refractory metals (close to 400, compared to the 100-200 range of Mo and W), channels heat away from the package; molybdenum, with a high melting point, prevents overexpansion and warpage. In this form the limitations of refractory metals become apparent. Molybdenum is an inherently dense element – the layered stack is hard to flatten into a thin, even heat spreader viable for use in advanced packages. The company is developing a product, Viatherm, to address this issue, and to give manufacturers more precise control over thermal management. The product builds on the Cu/Mo/Cu concept, introducing chemically etched holes – vias – through the molybdenum, which in turn fill with copper. The result is a thinner, less dense, striated product with copper “chambers” supported by molybdenum. This system, which could apply with other materials to make Cu/W/Cu or another layered heat spreader, maximizes the high conductivity (λ) of copper and the desirable CTE of molybdenum. It is controllable, allowing designers and manufacturers to etch more vias over a hot spot within the package. The product is also produced with known and established materials and processes, as Margalit pointed out, an aspect that brings the theory of striated, layered metals for thermal management into an appealing light in terms of ramp, testing, and commercial availability.

This kind of advanced thermal management that manipulates material properties and physical structure to maximize cooling in a passive heat spreader targets high-power, dense electronics in high ambient temperatures. Consider high-brightness LEDs (HB LEDs), a market sector expected by analyst firm Strategies Unlimited to steadily grow by 15-20%, reaching $8.3B in 2010. Margalit looked favorably upon applications for refractory-metals-based thermal management in large-scale display and automotive HB LEDs, where ambient temperatures surrounding packaged LEDs reach extremes. Refractory metals offer useful strength at temperatures as high as 1000°C, which seems high unless one considers usage in a massive cluster of HB LEDs forming a display in the Las Vegas desert, or in HB-LED headlamps operating for long periods close to a V8 engine in a car. Refractory metals aren’t the only approach to thermal management, but the range of applications and adaptability of the elements suggest that these heat spreaders will be part of the thermal management equation as Moore’s law squeezes chips to even smaller nodes.

Achtung Baby!


March 1, 2007

When the Irish rock band, U2, named their 7th album Achtung Baby they released a new, exciting sound of far off places, using electronica, dance influences, and guitar effects. So, of course for our first Roadshow in Germany, Switzerland, Austria, and Liechtenstein, we named the tour similarly.

U2’s Achtung Baby, recorded in Berlin, was responsible for a renewed sense of optimism in the band’s sound through infusing more European rock into the band’s traditional music. European innovation in advanced packaging equipment also meets the proliferation of packaging styles in the packaging market, giving new life and specific precision needed for automating the back-end of the assembly process.


Holger Gerisch, European sales manager for Advanced Packaging, introduces Brigitte Wehrmann, SUSS MicroTec’s manager of communications in the lithography division, to the whirlwind Roadshow tour. Here, Gerisch displays SUSS’s 2006 Attendees Choice Award.
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Dietrich Tonnies, Ph.D., explains how photoresist spray coating is done in MEMS production.
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Engineers work on specific customer-related problems using the company’s Gamma systems for flexible, clean, and coating processes in a cluster arrangement.
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A SUSS engineer looks at extremely small features in checking the mask alignment process.
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Engineers squat low to see how the flexible robotic handler is working out.
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Clemens Mitte, SUSS engineer, reads and interacts with precision as he makes adjustments.
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Gerisch; centrotherm’s Heike Bundschuh, marketing; Uwe Keim, product manager; Uwe Schiele, sales; and Gail Flower gather at the company’s entrance.
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The new building at centrotherm follows feng shui designs with construction turning to the lines of the nearby river, trees, and landscaped balls in pleasing arrangements.
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One of their oldest installed furnaces (1966) is at hand, labeled with the owner/president’s name: H.C. Hartung.
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The VLO 300 is used for vacuum soldering.
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Schiele, Flower, and Bundschuh gather in the lunchroom.
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On to Austria, where Flower and Gerisch met with Ulrich Mengele, Mengele PMC GmbH; and Datacon’s Hannes Kostner, manager advanced technology.
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Kostner had lots of equipment to talk about and show us in the demo center.
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Kostner explains the latest piece of equipment in the lab, the EVG540C2W, to Flower.
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One of the areas of activity for Datacon is the production of the HF Tag based on copper-plated antenna for RFID.
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Datacon has a fully equipped workout club for its health-conscious employees.
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Flower gets a bear hug in a local Tyrolean restaurant.
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We tried to take in the misty, foggy winter views of large country homes, this one in Switzerland.
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The team, under new general manager, Richard Boulanger, looks at Alphasem’s whole picture when Gerisch; Evelyn Enzersberger, marketing communication specialist; product manager of business development Reto Rechsteiner; and Flower said, “Hello.”
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Daniel Buergi demos the SwissLINE die-attach system for us.
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Oliver Harnisch, technical support manager poses with Alphasem’s Easyline.
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Markus Stofer, Patrick Inauen, and Emil Vaupotic show us how the SwissLINE die bonder can process adhesive tape applications, as well as dispense-based applications and interposer combinations in 3-D stacked die or system-in-package (SiP) applications.
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Here, high-tech companies are dispersed between farms where barns connect to main buildings.
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Rustic chalet homes in the mountains near Triesen, Liechtenstein, often have high-tech solar units on their rooftops.
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At OC Oerlikon Corporation, Sven E. Jarby, head of marketing and communications; and Regula Kobler, management assistant, met with Flower and Gerisch at their headquarters.
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Technicians work with Shuttleline Etch, a flexible load-locker system for R&D and small substrate production.
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Jarby with Hans Auer, product marketing manager, PVD wafer.
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Outside Oerlikon’s headquarters stands a large bike rack to encourage a healthy lifestyle.
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Johann Bylek, Advanced Packaging’s former sales manager; Markus Wimplinger, director business unit technology development and IP; Flower; Friedrich Paul Lindner, vice president, chief technology officer; and Hermann Waltl, senior vice president of sales, gather at the entrance to EV Group’s modern building.
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Waltl; Lindner; Stefan Pargfrieder, business development manager; and Wimplinger meet for lunch in the guest dining room with the Roadshow crew.
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The factory floor displays a wide variety of EVG equipment.
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Lindner reviews which equipment does what.
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The countryside and mountains of Austria eventually give way to our final destination in Munich.
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February 27, 2007 – Taiwan Semiconductor Manufacturing Co. (TSMC), recent beneficiary of relaxed government regulations regarding transfer of process technologies to mainland China, will likely utilize used equipment from NXP Semiconductor in order to triple the output from its 200mm, 30,000 WPM capacity site in Shanghai, according to the Taiwan Economic News.

Citing unnamed chip-equipment suppliers, the papers analyzed the field of European chipmakers currently running 200mm operations, and pointed to NXP as the likely source for the tools, since the firm is currently pursuing a plan to streamline its fab assets. A deal to purchase the used equipment could cost $800-$1000 million, the paper noted.

TSMC’s Shanghai operation, upgrading from 0.25-micron to 0.18-micron process technologies per government approval, is slated to bump capacity to as much as 90,000 wafers/month capacity, in order to meet strong interest from customers including Broadcom, Spreadtrum, CSR and OmniVision, according to the paper.

TSMC isn’t the only foundry in China looking to the used tool market to add capacity — days ago Japanese DRAM firm Elpida Memory Inc. said it has agreed to sell 200mm wafer processing equipment from its Hiroshima facility to Cension Semiconductor Manufacturing Corp. in Chengdu, where it will be operated by domestic chipmaker Semiconductor Manufacturing International Corp. (SMIC).

February 26, 2007 – Air Products has agreed to refurbish semiconductor equipment owned by or consigned to Babcock & Brown Electronics Management, an equipment leasing firm, out of Air Products’ Chandler, AZ facility. Repair and refurbishment will be performed prior to resale, adjusted to meet customers’ requirements for reliability and refurbishment “to the most recent configuration possible,” and in some cases involving the tool OEM.

Combining forces for refurbished tools will result in better availability of high-quality used and refurbished equipment that minimizes risk to customers, noted BBEM senior exec Mike Herman, in a statement. “The combined resources of Air Products and BBEM further strengthen the BBEM strategy of becoming a global supplier of semiconductor capital equipment and of maximizing cost efficiency and ROI at all stages of equipment life,” he said.

The venture is “a natural fit” for Air Products, which services more than 1000 tools worldwide with its legacy tool service business, and boasts experience in refurbishing, repairing, decommissioning, and relocating tools, added company VP Corning Painter.

February 23, 2007 – Japanese DRAM firm Elpida Memory Inc. said it has agreed to sell 200mm wafer processing equipment from its Hiroshima facility to Cension Semiconductor Manufacturing Corp. in order to narrow its focus to 300mm chipmaking operations.

The toolset will be transferred to Cension in Chengdu, where it will be operated by domestic chipmaker Semiconductor Manufacturing International Corp. (SMIC), according to Elpida. The companies say they will now further negotiate details of the transfer.

“Elpida expects that the Hiroshima Elpida’s 200mm equipment will be used more efficiently by SMIC, and we have intention to continue to provide support to customers who have placed orders for production of 200mm wafer line products,” the company said, in a statement.

Andigilog Completes Series B


February 22, 2007

(February 22, 2007) TEMPE, AZ &#151 Andigilog received $18 million in a series B financing round, with four new investors and three returning venture capital companies. The thermal management solutions company will use this funding to penetrate for desktop, notebook, and cooling fan markets; and to extend its product portfolio.