There is no doubt about it: as we are now at the beginning of a new millennium, we are about to experience a major technological jump in electronics production: Now that component manufacturers have figured out how to produce non-housed, function-tested chips in a reliable manner, new bonding techniques such as chipscale packaging(CSP) and flip-chip applications can supply this sector with high growth rates, particularly given the quantum leap in miniaturisation they are about to make possible.The consequences of this trend for the manufacturing industry was a major focal point of Productronica 99, the World's Fair for Electronics Production held at the New Munich trade Fair Centre in November.
Productronica 99 serves as an orientation aid for circuit manufacturers, their customers and electronics developers, and, as such, shows them what direction production engineering is expected to move in during the next few years. The latest machines and techniques from the most important industrial regions in the world were on display, showing the importance of PCB technology today. The materials, systems and processes used to manufacture PCBs were presented in a total of three halls and, for the first time ever, a congress on PCB manufacturing will be held in conjunction with Productronica. The European PCB Convention (EPC) focused on the effects of miniaturisation and featured a series of technical lectures dealing with practical approaches to the problems facing the electronics-manufacturing sector.
Trends
The absence of 'bulky' housings has allowed design engineers to achieve considerably higher packaging densities than with conventional SMD (surface-mounted device) technology. This, in turn, opens up completely new possibilities for electronics developers who can now create final products that are not only more powerful, but more compact and lighter-weight at the same time. In the years to come, this will inevitably result in a large increase in share of portable electronics on the market in general. An excellent example of this trend can be seen in the field of mobile communications. According to the ZVEI and VDMA trade associations, eight million GSM telephones were sold in Germany last year alone, a figure which is expected to increase to more than 11 million new mobile phones sold in 1999. And mobile communications accounts for only a portion of all potential applications that manufacturers of terminal devices are working hard to develop as we approach the new millennium. Prominent experts speaking at the VDE/VDI PCB Conference in March in Bad Nauheim, assume that the share of portable electronics will increase to 60% of overall electronics production by the year 2010.
Still, ever-increasing pin counts are presenting manufacturers with new challenges as they discover that conventional techniques are no longer cost-effective when it comes to manufacturing highly complex assemblies for the latest terminal-device applications. As a component carrier and the most important connecting element available, the PCB is directly affected by this leap in technology. As a result of miniaturisation, PCB technology has undergone profound change. During the past few years, new production techniques have made it possible to manufacture extremely complex PCBs featuring components with extremely high pin counts. With this in mind, microvia technology - which caused a minor sensation in the multilayer sector - is an important issue. Instead of connecting the individual layers of the PCB electrically, eg through-holes which are drilled mechanically and then metalplated, the layers are connected by so-called 'microvias', ie tiny holes less than 100 µm in diameter which are created using lasers or by means of photolithography. The extremely small diameter of the microvias provides for a dramatic increase in linkage density. Furthermore, the use of new, ultrathin materials such as RCC (resin-coated copper) and liquid dielectrics in PCB manufacturing has made it possible to produce circuits which are both lighter-weight and - because paths are shorter - faster.
PCB/semiconductor technology?
These advances in the field of PCB technology are making entirely new types of components possible. For example, µBGAs (micro ballgrid arrays) and CSPs (chip scale packages), which are very popular in assembly manufacturing, can not be implemented without extremely complex carrier circuits. As a result, PCB technology is moving that much closer to semiconductor technology. The printed circuit from yesteryear has mutated into an interposer, ie a 'rewiring substrate' for non-housed semiconductor components with high pin counts. Although the share of so-called HDI (high-density interconnection) circuits on the PCB market is still comparably low, given the rapid pace of growth in this sector, there is hardly a circuit-board manufacturer around who can afford not to deal in very fine line PCBs. This is particularly true because getting started in this type of high-tech production entails somewhat of a 'learning phase' until the necessary precision can be produced in adequate quantities. The major problem is that manufacturing PCBs is an extremely complex procedure comprising several very different steps. Besides the microvia technique, PCB manufacturing involves a number of critical work steps that can have a significant influence on production quality. Among other things, they include high-precision (µ-range) registration, pattern structuring, metal-coating, surface finishing as well as optical and electrical testing. Furthermore, mastering HDI technology in a reliable manner means optimising each of these areas.
Semiconductor packaging drives innovative products
Gone are the days when semiconductor manufacturers developed functional elements for development engineers and then took them to market. Now the most important aspect to be taken into consideration when designing a new semiconductor is the actual application and the product for which it is being designed.
The rapidly growing market for portable systems and chip cards is a good example. In this case, the most important factors include not just price and weight, but a high level of system integration, superior reliability, robustness and ergonomic considerations. In other words, the design process extends beyond the functional semiconductor crystal. In many cases, how a semiconductor is packaged to create a 'link' to the outside world is the deciding factor. Whether ball-grid array, CSP, flip-chip or a more conventional design is used is ultimately determined by the final product.
The requirements to be met by any given package differ greatly and depend above all on the application. Future packaging trends were very much an issue at Productronica 99. In the case of consumer goods, the most important considerations include low cost and high mechanical strength against shocks and impacts. For components used in automobiles, package requirements are determined by environmental influences such as moisture, salt spray, extreme operating temperatures as well as reliability, optimised weight and predefined dimensions. In high-end products like workstations, servers and supercomputers, the most important factors include wiring density, size, weight, signal transmission and power density. The one thing that all applications have in common is the trend toward smaller, lighter packages, high electrical efficiency and low cost.
Of course, semiconductor technology also determines the requirements to be met by the package. Decreasing lead widths mean smaller terminal-pad sizes and a larger number of I/Os. ICs are becoming increasingly complex, require higher clock frequencies and chip sizes are increasing, and customised packaging must take these factors into account. High pin counts, short conductor paths and good thermal dissipation are required for complex semiconductor circuits of this kind.
Chip-and-wire or flip-chip?
Whether the chip is attached directly to the board using the chip-on-board technique or integrated into an SMD housing, most ICs are wired using the chip-and-wire technique. The fair had a good showing of all the latest developments related to the chip-and-wire technique. Although insufficient for a number of applications, this technique is definitely limited when it comes to newer generations with large numbers of I/Os. Depending on type, high-speed bonders have a capacity of 'just' eight bonds per second which limits productivity. Flip-chip technology, which avoids the use of the chip-and-wire technique, is a possible solution. In this case, the contact pads of the IC are metallised and 'equipped' with a solderable bump. Then the flip-chip is soldered directly onto the circuit board. The conventional form of this technique, which consists of sputtering, photolithography and electroplating, can be used to create bumps with a pitch of 50 µm. In the future, this expensive process is expected to be replaced by a mask-free technique that combines chemical nickel with stencil printing of the solder bumps. This low-cost process is currently being used for pitches of 170 µm, but the trend is toward 100 µm.
High density calls for a new approach
Because geometry and the position of the contact pads on the IC can restrict flexibility, the flip-chip technique is not a feasible solution for high-density products in the long term. Ball-grid arrays, on the other hand, represent a possible approach. In the case of BGAs, the leads must be expanded and distributed across the surface of an intermediate carrier, which is associated with its own problems. In most cases, this type of packaging also requires the use of the chip-and-wire technique, which can limit productivity. As a result, the chip-scale package (CSP) appears to be the package of the future. One of the primary advantages of CSP is that it is compatible with SMD technology. The fair also examined the latest approaches to problems like testability and selecting a cost-effective wiring technique. Given increasingly smaller wiring paths on the IC (as small as 0,15 µm in the future) and growing chip sizes, the trend is toward planar wiring on the chip. One approach is known as wafer level packaging. In this technique, the active surface is covered by a polymer dielectric. A layer of solder balls can then be applied to the top layer of the chip (either sequentially or by stencil printing) and are used to bond the chip to the circuit carrier later.
Packaging will continue to play a key role in the future. New system requirements, larger chip dimensions, higher pin rates, higher clock frequencies and growing dissipation power must all be taken into account. However, it is also important that the package be compatible with conventional processes like SMD technology - a tough challenge for package manufacturers.
High-tech materials and process-optimisation
Developments in the sector for materials used in electronics manufacturing are influenced by the ongoing miniaturisation of electronic products, the growing number of applications and more stringent requirements regarding environmental compatibility and on-the-job safety.
Productronica 99 was able to give electronics manufacturers a chance to inform themselves on the latest developments in this sector. Special-purpose chemicals, lacquers, resists, fluxes, soldering pastes, cleaning agents, adhesives, casting compounds and a number of other materials for the electronics-manufacturing sector were on display. The demands placed on materials have increased in keeping with technological developments. What were once relatively simple base materials and auxiliary substances are now high-tech materials which have been customised for specific applications or process-optimised consumable materials.
Electronic labels and chip cards, for example, are manufactured like throw-away products in extremely large quantities. Sophisticated ultra-high-frequency systems, on the other hand, are produced in extremely small quantities. Naturally, different standards of quality call for different materials. And given today's demanding technical and economical requirements, this applies to products and processes which are similar, as well. Generally speaking, most companies strive to achieve zero-defect processes and a high level of (world-class) quality.
Materials conceived for modern technologies are in demand: they must be cost-effective and, as globalisation increases, they must be available around the world. For this reason, the manufacturers of materials and substances used in electronics manufacturing are working hard to develop innovative products that are suitable for the world market. Much to the user's benefit, this results in ongoing improvement as well as a number of new materials for the electronics-manufacturing sector.
Along with the latest development trends in electronics production, two developments are particularly noteworthy:
* Rapid growth of electronics assemblies with so-called advanced-package assemblies on high-density interconnect (HDI) boards.
* Demand for and the introduction of lead-free electronic products.
Both of these developments are having an enormous influence on electronics materials. Entirely new technologies are needed to ensure optimum performance at an optimum price.
Due to their delicate structures and minimum dimensions, advanced-package assemblies - which include CSPs, flip-chips and other components - call for the use of higher-quality materials and auxiliary substances both for packaging and assembly. Manufacturing HDI boards, for example, calls for new, thin base materials and/or photo-polymers. At Productronica 99, many major suppliers introduced HDI products. The manufacturers and users of PCBs also showed a great deal of interest in new multifunctional surface-refinement techniques which are suitable for wire bonding as well as for soldering.
Trends in materials
Soldering pastes and SMD adhesives demonstrate a close link between materials and processing technologies. They form a system and precision coordination of all variables is necessary for the process to function properly. Suppliers of machines and materials are developing advanced process solutions. Lead-free soldering was a hot topic at the fair, and for two reasons: Not only has the European Commission submitted a draft for a 'lead-free' guideline that would apply to electronics products, but lead-free products from Japan are already on the market, and they carry a 'lead-free label' comparable to Germany's environmental-testing label (which is issued only to products that comply with some of the strictest standards in the world). This is putting manufacturers under an enormous amount of pressure. A quick response to the situation is essential and the phrase 'he who hesitates is lost' certainly applies to the electronics industry.
A decade after the environmental risks of using CKW and FCKW to clean assemblies became common knowledge and corresponding bans were in place and despite today's considerably higher packaging densities, cleaning after soldering is no longer a widespread practice, above all due to no-clean and no-residue fluxes and soldering pastes. Electronic assemblies are only cleaned to meet special requirements, and a number of newly developed, environmentally sound cleaning agents are now available. The examples of developments in the electronics-manufacturing materials sector described above show that recent improvements are certainly comparable to those that apply to electronic components. Manufacturing new types of components and electronic systems is only possible using new and improved materials. For this reason, the materials and substances for electronics manufacturing on display at Productronica 99 made attending the fair a worthwhile experience for everyone.
Prospects for the new millennium
If you can believe market analysts like Technology Forecasters, electronic manufacturing services (EMSs) will generate some US$ 120 billion in worldwide sales during 1999 alone. This segment is expected to grow at a rate of between 25 and 30% during the next few years - enormous market volume and indicative of the trend that some 35 to 40% of all electronics in the world will be manufactured by EMS companies in the future.
And what are these service providers expected to look like? At some point in the future, there will be between five and seven global companies with production facilities in every possible country in the world, and they will cover more than 40% of all market volume. Globalisation, alliances and takeovers will dominate the profiles of these top companies, among other things, because they will have to heed the rules of the stock exchange and the interests of their stockholders. However, one rule will definitely apply to small and large service providers alike: because they produce better, faster and more cost-effectively than in-house manufacturing operations - and they have to out of necessity - they give OEMs an opportunity to concentrate on their primary responsibilities and bring their products to market more quickly. Furthermore, instead of selecting service providers solely on the basis of conventional criteria, like whether or not their manufacturing services include delivering the products to the final customer, many electronics companies are far more interested in the possibility of selling a portion of their manufacturing operation to the EMS at some point in the future.
This form of global outsourcing has hidden advantages for everyone involved: it helps EMS companies satisfy their shareholders' desire for never-ending growth and allows them to set aside enough money to invest in new technologies. It gives OEMs a chance to get rid of unprofitable manufacturing operations and convert them into ready cash for their stockholders. And those who purchase the end products profit from an optimum price/performance ratio for products of superior technical quality.
However, a large number of smaller manufacturers and service providers are getting involved at the global level, as well. They include a number of specialised companies that will often accept tasks which are too complicated for 'large-scale' operations. For example, a job may entail investing in state-of-the-art technologies that an OEM feels are still too risky or that involve manufacturing processes which are not yet reliable enough for a global EMS. Smaller service providers, on the other hand, are certainly in a position to serve these niche markets with consistency and know-how - even under global market conditions.
If we assume that the process of change described here has already reached the phase of commercial acceptance and increasing use, it comes as little surprise that - given the importance of the relationship between an OEM and an EMS - many companies have intensified the search for strategies and are falling back on outside help in the process. After all, OEMs must first learn to do what EMSs have been practicing for years. There will always be plenty of consulting companies who analyse existing relationships in enterprises and offer assistance when it come to making decisions. Furthermore, if it is good for the entire electronics-manufacturing sector, equipment manufacturers and material suppliers will learn to deal with these developments, as well.
A breath of fresh air is beginning to characterise relationships between suppliers and users. Technical solutions are no longer the only important factor. Instead, EMSs are dictating future criteria for more efficiency in production, for machine availability and for process-capable materials. Just as large and medium-size global and regional service providers must use the most modern software and information technology available if they want to remain competitive, companies must keep their eyes open for global production locations. In the future, they must make information available to their users around the world - and use Internet service structures that provide assistance and service.
Information from Productronica 99. For further information about the trade fair contact the Southern African-German Department of Trade & Industry, (011) 486 2775.
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