Those who can’t ramp might lose time-to-market.

The electronics interconnection industry is continually changing. Not only is the technology becoming more complex, the nature of business itself is rapidly evolving. The rise of the EMS segment of the industry, accompanied by the swift demise of vertically integrated OEMs, has pushed printed circuit board design, fabrication, assembly and test expectations of the current suppliers to their technical limits. Today, with reduction of the new product introduction (NPI) cycle time, time-to-market is critical for businesses to remain competitive.

Quickturn and prototype services make up an important segment of the PCB fabrication market and it is imperative that North American suppliers offer this capability. However, today’s requirements go beyond the typical QT feature card designs and now include new dense PCB fabrication with more complexity, higher layer counts and more precise registration than previously required. Regardless of the complexity, fast cycle time has become an expectation, which in turn has led many suppliers to exit the business rather than make the large capital investment required for new, state-of-the-art tools with advanced processing capabilities necessary to stay ahead of the technology curve. Those suppliers that remain have picked up the customers of the departed, but continual capital investment, as well as investment in the technical personnel required to develop new processes capable of running new and advanced materials on state-of-the-art equipment, is required (not to mention expensive).

For the customer, the payback of QT and prototype services is recognized in a significant reduction in process cycle time and process costs, which provides additional capacity and gets products to market faster. Doing so, however, means that the production fabricator must be able to produce the same highly complex product as the quickturn fabricator, lest all the time and effort be wasted. Thus, many end-customers are looking for fabricators capable of providing a rapid turn for the early user hardware or prototypes along with the ability to supply the low volume ramp and volume production quantities of their products. To do this, the QT/prototype line must be a mirror image of the production line with identical processes, chemistries, and techniques implemented, plus a common set of design and data release tools used for both production and QT.

As readers know, defense programs have been a growing and profitable piece of electronics manufacturing over the past several years. In military programs specifically, suppliers have learned that in order to be considered for production work, fabricators must be able to provide quickturn, early user hardware/prototype boards. Customers use these boards to verify the design, and expect their fabricators to offer advice regarding design for performance and manufacturability, along with delivering on time and within budget.

Acceptance criteria for QT and prototype products is another matter to consider, as they may differ from the volume production requirements due to the use and expectations of those products. Furthermore, discussions defining when the clock starts for ultimate delivery of a quickturn order and requirements for accepting design data need to be clearly communicated at the forefront of any project.

Quickturn and prototype services are not only an important differentiator for North American PCB fabricators today, but it is also an essential part of remaining competitive and satisfying customer’s expectations. While there is an upside to providing these services – premium pricing, gaining entry into potentially higher volume production and new customers – huge investment is also required to maintain a competitive edge.

Jeff Knight is vice president of business development at Endicott Interconnect Technologies (eitny.com).

When it comes to understencil cleaning, the devil’s in the details.

Most would consider screen printing a single process: the first step in the assembly line. However, understencil cleaning is a process itself: a screen-printing sub-process. Not only must the production engineer be adept at printing techniques, but cleaning parameters and routines as well.

Understanding software features such as cleaning rates (how often should you clean) and modes (wet, dry, vacuum and their various combinations) is critical and, of course, highly application-dependent. The industry default mode is generally wet/dry/vac – not that it is necessarily the right choice always, but that is what most operators are used to. Aside from determining rates and modes, cleaning materials selection is also tantamount to a robust cleaning process. The understencil fabric and solvents used to remove solder paste from today’s ever-smaller apertures play a large part in the success of the cleaning sub-process, and the overall print process.

As an example, let’s take a look at the fabric. Obviously, the main goal with any cleaning fabric – even those used at home – is to clean the object free of debris at the end of the process. Unfortunately, quite a few understencil cleaning materials don’t do that. Instead, they put lint back onto the stencil, which may in turn block apertures. I’ve heard many engineers debunk the lint effect, arguing a 10 µm thread would have little to no impact. That may have been true five years ago when, by comparison, apertures were fairly big. Today it’s a whole new ballgame.

In fact, during some recent stencil testing using various understencil fabrics, our company discovered lint is, indeed, quite problematic. With 0.3 mm CSPs that required aperture sizes of approximately 180 µm, our AOI results and analysis turned up some strange trends. When we evaluated the stencils in question, we found lint contamination. In most instances, we were finding low paste volumes, which were directly attributable to lint blockage of the apertures. In one case, a lint particle had become drenched in paste, and the inspection system actually viewed it as a bridged deposit. Keep in mind the lint issue is primarily a problem for the dry cycle, but the fabric selection impacts wet and vacuum cycles too.

Ever tried to breathe through a paper towel? How about a piece of printer paper? I’d argue the former is more beneficial for your oxygen intake. The same theory holds true for the vacuum on the printer’s understencil cleaning system. You’re trying to pull vacuum through the fabric to clean out the apertures and, hopefully, dislodge and then capture all the residual paste into the open weave of the fabric. If the weave is too dense, you are blocking the vacuum, thus compromising its power and your cleaning process. You want a fabric constructed of porous material that permits air flow, yet captures material into the pores of the fabric.

Then, of course, there is the wet bit. The solvent selected can most certainly have an impact on print performance (a topic for another column). Consider the importance of how the fabric wicks the solvent across the exposed area of the material. The solvent breaks down solder paste that remains on the outer edges of and inside the aperture walls, so a fabric that absorbs the solvent uniformly is desired. This must be a stable and highly repeatable process to be effective. The material should be fast and absorbent, and should almost instantly start wicking and create one solid bar across the fabric. What you definitely don’t want is a quick wick that keeps on wicking all the way through the paper because then, when you index the paper along for a dry wipe, it would still be wet. A good solvent process is primarily about the absorption rate of the fabric and also a little bit about the ability of the machine’s solvent bar to dispense the solvent at consistent volumes. If the fabric doesn’t wick properly, a thorough clean is unlikely. This introduces the potential for blocked apertures and, therefore, defects.

The bottom line: Treat the understencil cleaning process with as much rigor and attention as the other parameters of the screen-printing operation. Don’t skimp on the fabric because, in the end, a few more cents for a high quality material will likely save big bucks.

Clive Ashmore is global applied process engineering manager at DEK (dek.com); cashmore@dek.com. His column appears bimonthly.

SIDEBAR

DIY Fabric Tests

Here are three easy, do-it-yourself fabric performance tests:

• Lint: Take a piece of Scotch tape, adhere to fabric, press down and then rip it off. You will quickly see if a so-called “lint-free” material actually lives up to its claim.
• Vacuum: Simply turn the vacuum on and feel the flow to sense the power and volume of the air coming through the weave. More elaborate air-flow measurement mechanisms can be used, but a simple “touch and feel” should do the trick.
• Wicking: Cut a strip of fabric, place a line of solvent across it with a basic dropper and evaluate the speed and uniformity of the wicking. 

For many package subcontractors, the road to recovery won’t be smooth.

Semiconductor industry analysts argue that the worst is behind us. In the second quarter, wafer shipment growth is tracking at over 50% quarter-over-quarter at TSMC, UMC, SMIC and Chartered. ASE, Amkor and SPIL reported positive revenue growth during the period, and are optimistic about the third quarter. Yet, while each quarter may be better than the last, the road to recovery for the backend equipment OEMs and material suppliers may be a bit bumpy.

Advanced packages, comprised of ball grid arrays and chip-scale packages, are the source of much of the unit and revenue growth in the semiconductor packaging and assembly sector. While BGA and CSP shipments will improve quarter-over-quarter, unit volumes will not return to 2008 levels until 2011. Wafer-level packaging seems a bright spot, with many companies favoring use of WLPs instead of some conventional packages because of their smaller form factor and lower profile. With this year’s capital expenditures for the top four IC package subcontract assembly and test operations expected to be less than half the dollar value in 2008, many backend assembly equipment makers may face hard times over the next 18 months (Tabe 1). The key question then is, Are these companies strong enough to survive such a protracted dry spell? Even if they are, can we expect any advances in assembly technology over the next two years? What level of orders will sustain R&D activities for the development of future equipment (and materials)?

Feeling the pinch. What makes up backend assembly equipment infrastructure? A typical assembly line for a wire-bonded package consists of systems for dicing, cleaning, die attach, wire bond, epoxy mold and curing. If the package is a BGA or CSP, equipment for solder ball attach, reflow and cleaning are also needed. If the package is a leadframe, some lead forming and excise equipment will be part of the process. Inspection systems also are used at the final part of the assembly process. If the package has flip chip instead of wire bond, the die attach and wire bond will most likely be replaced by a pick-and-place system for mounting the flip-chip die on the substrate, underfill dispense, and cure system. Test sockets, burn-in ovens, test handlers, and testers are all part of the backend infrastructure, not to mention dicing blades, wire bond capillary tools, bonder heads, nozzles and a host of other components used in the assembly process. While some equipment suppliers are part of large organizations, many of the companies that make up this infrastructure are relatively small in size and revenue, and would feel a prolonged period of slow sales. What does this mean for our industry’s future? As Business Week noted in June, tech companies have seen the deepest cuts in global capital spending, down 28% year-over-year. This much is certain: Even if these companies survive, few will be able to afford to devote resources to R&D for the next generation of packages. In some cases, these companies will merge with larger ones, and the equipment infrastructure will be maintained. For example, ESEC is now a part of BESI, and ESI has purchased the assets of XSiL. In some sad cases, operations will simply cease to exist. Agilent, for instance, announced the closures of its AOI and AXI business units. Is this of concern, or is this just another part of the semiconductor supply chain that will contract?

Fewer material choices? Materials such as substrates, leadframes, bonding wire, mold compounds, underfill materials, dielectrics, plating solutions, solder balls, thermal interface materials, and a variety of other products are also part of the infrastructure. The materials sector has already seen consolidation (Henkel’s acquisition of National Starch's Ablestik and Emerson & Cuming business; Dow Chemical’s acquisition of Rohm and Haas.) In Taiwan, substrate suppliers PPT and Unimicron will merge. Will this result in few choices of suppliers, and shortages? In Taiwan, Chipbond reports the LCD driver IC backend assembly business is experiencing a shortage of substrates (tape in the form of chip-on-flex). Will prices rise over time? Will material suppliers be healthier in the future and therefore able to invest resources in materials to meet future industry needs? These questions remain.

Future shock. Semicon West this year had fewer companies for the semiconductor backend assembly sector, and part of the reason certainly was the downturn. The question remains, after the recovery, will these companies return, or will empty halls echo with the sounds of ghosts from our industry’s past?

E. Jan Vardaman is president of TechSearch International, (techsearchinc.com); jan@techsearch
inc.com. Her column appears bimonthly.

Jim McElroy is about the last person who would want to be profiled in an industry magazine, which is probably why the iNEMI chief executive has been so effective over the past 13 years.

Indeed, he has made his mark in the background. To McElroy, running the consortium is not so much about leading, but “leadership facilitation.” Or, as the low-key, longtime New Hampshire resident describes it, “leading from the rear.”

Association management tends to be intramural, attracting candidates from other associations, rather from industry. But one of the secrets to McElroy’s success has been the more than two decades he spent as an engineer and business manager for the likes of RCA, Digital Equipment Corp. and MMS, where he eventually rose to vice president of international operations. Such background and experience cannot help but inform a person about how difficult a task it is to conceive, design and build quality electronics products, and how in an industry that changes at light speed, nothing can be taken lightly or for granted.

These notes resounded in an interview McElroy conducted with Circuits Assembly on July 6, the day he announced his retirement. (For the full transcript, visit circuitsassembly.com/cms/component/content/article/5-current-columns/8560-leading-from-the-rear.)

Asking what type of person it takes to succeed in his job elicits a laugh from McElroy, who admits he’s “probably biased.” Still, he elaborates in a way that’s refreshingly candid, especially given the tech industry's penchant for secrecy. “The biggest part is leadership ability. It’s different from leadership ability in a public company, where in a sense, you’re in charge of your own destiny; you can do what you have to do. That’s not the way it works in this job. The leadership has to be subtler. Our role is more one of leadership facilitation, forging direction and making things happen. The most successful things we do are driven by industry leaders with the passion to drive it to timely completion.

“[And you] have to be able to interact at a number of different levels. Our project [staff] might be working at the engineering level or the first level of management. But if we’re driving a new initiative, we have to get the attention of senior-level people. Executives approach technology gaps in a different way than technologists do. We need to be able to speak the language that each understands so that we can connect with them and gain their support.”
When McElroy took over, iNEMI primarily was a vehicle for roadmapping activity. Name recognition was limited. On his watch, the organization has grown both in scope and stature. It expanded overseas, where it now has a pair of outstanding engineers, experienced handling operations in Europe and China, respectively. It took a lead role in facilitating the lead-free transition, helping to settle on a SAC alloy from which the industry could start baselining solutions, and publishing extensive research on the subsequent tests. And McElroy was perhaps the only person capable of sorting out the longstanding battle between various trade groups and companies over the competingdata transfer formats – a conflict about as lengthy and arcane as the Middle East's.

Although it lacks a dedicated research facility, it is the closest undertaking to Sematech insofar as being a forum where the best and brightest engineers share ideas, resources and work out problems. (The roadmaps, which iNEMI has steadily published every two years, have become, in McElroy’s words, “self-fulfilling prophecies,” pointing to the targets and setting the industry in motion toward them.)

As is his style, McElroy didn’t spend much time discussing his legacy, preferring to note the work ahead. As the supply chain becomes more segmented, the layers add to the complexity of the problems – and solutions. “We still have to orchestrate across that supply chain in order to drive the technology,” he says. “When companies were integrated, it was easier to do. We’re doing tech initiatives across a number of different companies and cultures, and in an environment when many companies have limited margins. So folks have limited funds to invest in R&D. The question is, How do we do this in a positive way that has the biggest impact?”

It’s someone else’s turn to address that issue. Now 64, McElroy is looking for a change, citing the opportunity to spend more time with family and give back to the community. The electronics community should be grateful, for among his peers managing associations, McElroy is head and shoulders above the crowd. For iNEMI, it’s been a lucky 13 years.