MEMS, HDI, embedded passives and LEDs present a sea change in the way boards are designed and built, and could shift the market back to the West.

One result of outsourcing is a loss of ability to understand new technologies on a basic level because they are not on the factory floor. From understanding comes opportunity. In response to IP and product piracy and the hypercompetitive marketplace in technology, many smart companies now involve only their closest partners in research and development programs. Those not a part of the group may never see new enabling technologies. This is what has happened to North America and Europe to a dangerous degree.

Today, in many cases, management, government, the military and even the scientific community do not understand the enabling technologies that can help spur a new economic renaissance. While focusing on nanotechnology, biotech or energy on a micro scale, we have lost the ability to make it simpler, more efficient and lower cost. This mistake has been repeated to the point it almost has become a maxim. Whether televisions, VCRs or cellphones, the business model in many cases has been technology development in Europe or North America, followed by exporting of manufacturing to lower cost regions. The West needs a healthy manufacturing sector to survive, and the interconnect is at the center of that capability.

Interconnect technology is not standing still. Amazing developments will help create the future (Figure 1). But we have to understand these opportunities and commit to seeing them through. Today, only a few factories in North America and Europe build substantial numbers of high-density interconnects. In 2008, one of the major drilling machine manufacturers counted approximately 150 laser drills, a critical tool for HDI, in North America. Globally, its census of the installed base is 3,600-plus units, primarily in Asia. A number of Asian manufacturers have 150-plus units in a single factory.

Today, HDI is a mainstream product, but only a small percentage of the circuit boards are built in North America. Markets include handheld devices, HDTV control boards, iPods and MP3 players, Bluetooth devices, high-end notebooks, GPS systems, automotive engine controls, cameras, digital watches, hard drives, and many other products. HDI is an enabling technology for smaller, lighter and faster electronics for military, aerospace and medical applications (Figure 2). The technology drivers are miniaturization, packaging, high frequency, I/O density and, in most cases, cost. Almost every inkjet printer cartridge in the world contains HDI. HDI circuit boards are, in fact, an extremely cost-effective technology, and hundreds of millions of units are produced each year.

North American demand for bare board HDI technology is in the billions of dollars, but the vast majority is imported. Recent data indicate that North American production of HDI boards was approximately $200 million, while known orders from a limited range of customers willing to share their data totaled over $1.1 billion (Table 1). Imports of products containing HDI boards are in the many billions of dollars. Most of this is in high-volume products.

However, HDI has not yet made the transition to many applications where the North American interconnect fabrication base feels it can compete successfully. The scale and cost of some technologies can appear daunting. The infrastructure that existed in the 1990s is now smaller. Today, these solutions are available on the open market. The hard work has been done. One of the critical reasons for success in Asia was the entire interconnect supply chain worked together to achieve common goals. Designers, OEMs, fabricators and assemblers co-developed efficient and lower-cost solutions, and understand how to use the technology effectively.

Embedded components. Coupled with the explosion in HDI use is the potential for embedded component technology. Embedded capacitance and resistance within the printed circuit board has been available for years, but had limited acceptance in North America. A major change in OEM philosophy toward embedded components occurred several years ago when the handheld manufacturers began a major push to reduce costs and increase functionality in a very limited form factor. Prototypes were manufactured in North America, but production went almost immediately to Asia. Yields climbed rapidly as designs were optimized. In some cases, functionality was placed on the chip (Figure 3). However, the seeds of a new idea had been planted. Today, embedded component technology has been growing along a path similar to HDI at its outset.

Manufacturing boards containing embedded actives and passives requires a high level of precision and absolute quality control. Once embedded, components typically cannot be repaired. It has to be done right the first time. While initial efforts in North America emphasized design rules and special materials, the Japanese approach uses either modified SMT components or die-attach devices. Chipsets including a CPU and memory are attached to the organic substrate using copper posts, microvias and copper plating. Some processes for passive devices use thin-film resistors; others use low-profile 0402, 0603, and 1005 resistors and capacitors.

The technical benefits include reduced I/O count, reduced component count, significantly improved interconnect reliability, vibration resistance, improved high-frequency transmission, reduced footprint and simplified routing (Figure 4). Heat dissipation can be enhanced by direct mounting on copper lands. Panel thickness also can be reduced considerably. In most cases, it is simply a better product.

Current applications include stacked memory, memory cards, BGAs, modules, portable electronics, sensors, fuel cells and automotive devices. Use in military and aerospace applications is growing as well because of the combination of advantages offered. One of the highest volume applications to date has been watches used by runners, which include GPS, distance, speed and pace information. In automotive and energy transmission applications, supercapacitors capable of discharging 50A at 4V are a game changer. One inch square and 100 µm thick, these components have the advantage of being embedded in very high volume, further driving this opportunity.

For the OEM, one of the significant advantages in using embedded components is IP protection. Hardware can be concealed and key design elements protected. Reverse engineering becomes more difficult by orders of magnitude, and security or encryption devices eventually can be embedded as well. In a world that runs on time to market, this simple benefit could be measured in the millions of dollars.

For the assembler, this means radically fewer joints to solder, and fewer opportunities for field failures.

In the long run, the real advantage is that radically new designs can be envisioned and enabled. The US Army Land Warrior Project envisioned biometrics, communications, medical capabilities and weapons systems integrated into a whole that projected the capabilities of the individual soldier far beyond today into the realm of science fiction. Much of the requisite technology already exists, but must be miniaturized, simplified and made more cost-effective. Information gathering and telematics will require simplified and rugged packaging solutions, and the opportunities in medical electronics alone are amazing. As 3G and 4G wireless technologies roll out, HDI/embedded will be integral to enable new features and applications. Apple, RIM, Nokia, Motorola and others have shown what can be done when video, wireless and other features are integrated in new and amazing ways.

Meso-MEMS/microfluidics. The latest initiatives in interconnect technology incorporate functions previously placed on a chip in some cases or completely new architectures based on those technologies. Microelectromechanical Systems (MEMS) have been in volume use for a number of years, primarily at the semiconductor level. The applications today include accelerometers used in airbags, MEMS gyroscopes used to detect yaw, car tire pressure sensors and many other applications. The DLP chip used in flat-panel televisions and many other applications consists of hundreds of thousands of micro mirrors that switch on and off. Microfluidic MEMS, such as pumps, valves, heating elements and channels, enable technologies such as the inkjet printers, as well as the 100-plus million printer cartridges sold each year. SEMI calculated the global market for MEMS in 2006 at over $40 billion.

MEMS technology is rapidly migrating to the interconnect for a variety of reasons. Inkjet printer cartridges, one of the first MEMS applications, developed at Hewlett Packard in 1979, use both HDI and MEMS because the technical and economic advantages make the most sense in the application. It is very high tech, but must be manufactured at very low cost. Meso MEMS, or those used on printed circuit substrates, originated at Motorola in the early 2000s (Figure 5). The ability to place MEMS on silicon is proven, but the penalty in increased packaging real estate on the chip and hermetic packaging requirements required in many applications becomes cost-prohibitive. Printed circuit boards today have crossed the 0.001" geometry line that semiconductors crossed in 1960, and thus many MEMS applications can be migrated to Meso-MEMS at much lower cost. A Meso-MEMS switch might require 0.001" to 0.005" line/space capability, and offer the advantage of much higher current capacity. Other Meso-MEMS opportunities include laboratory-on-a-chip (LOC), RF switches, valves and pumps.

LOC applies single or multiple laboratory processes onto the silicon. This is especially useful for analytical and medical applications. They offer significant advantages in portability, lower chemical costs and better process control in chemical and biochemical reactions. Analytical integrity is also enhanced because of the integration of functionality, isolation of samples, and precise volumes and metrics. Point-of-care applications will blossom as costs are reduced. Meso-MEMS is one tool to do so.

LEDs. A last niche application for printed circuit substrates is lighting. LED technology has already had a significant impact, from traffic lights to automotive brake lights to display technology. Energy savings of 90% or more, and lifetimes that are orders of magnitude longer than conventional incandescent or fluorescent lighting, make LEDs attractive. With close to 20% of North American energy demand consumed by lighting, the energy and economic impact is considerable. Even now, printed circuit substrates are being integrated into LED arrays. The application will accelerate as the availability of printable electroluminescent materials and organic LED (OLED) materials and solid-state lighting opportunities grow. The printed circuit board is an ideal low-cost substrate in many applications.

The combination of these technologies results in an active interconnect that goes far beyond the limitations of today’s conventions. When combined with optoelectronic components, RF designs or other technologies, it is obvious the printed circuit board will undergo a complete redefinition. The interconnect has become the nexus and cortex of technology. The trend is toward high-mix/low-volume and flexible response. Implementing HDI/embedded requires significant investment and a change in the way the factory floor is run. The benefits, however, quickly will be seen in more stable business relationships, technology partnerships, and significantly improved margins and yields.

Matthew Holzmann is president of Christopher Associates (christopherweb.com); matt.holzmann@christopherweb.com.

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