-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueBox Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
Boost Your Sales
Every part of your business can be evaluated as a process, including your sales funnel. Optimizing your selling process requires a coordinated effort between marketing and sales. In this issue, industry experts in marketing and sales offer their best advice on how to boost your sales efforts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
Embedded Passives - Stuck in the Chasm?
December 31, 1969 |Estimated reading time: 11 minutes
Every so often, new technologies promising to revolutionize PCB design enter the scene, and possibly the technology-adoption life cycle. It is often stated that the transition from pioneer to early adopter to majority user takes less time than it used to - forcing the industry to adopt new technologies to maintain a competitive edge. This article looks at where embedded passive technology is, as well as its benefits.
null
By Per Viklund
Technologies promising to revolutionize PCB design occasionally enter the scene, possibly the technology-adoption life cycle. It is stated that the transition from pioneer to early adopter to majority users, according to Geoffrey A. Moore’s “Crossing the Chasm” model1, takes less time than it used to - forcing the industry to adopt new technologies quickly to maintain a competitive edge. Although this is true for many new technologies, embedded passive (EP) technology seems to have moved more slowly than expected. This article examines where EP technology stands, what happened to the expected market boom, who uses this technology, and its benefits.
Embedded vs. Discrete Passives
The world market for discrete components, such as resistors and capacitors, is estimated at over $10 billion annually. At the same time, numerous technical issues with discrete parts challenge designers. Embedded passives are seen as a way to combat many issues with discrete parts, including cost, stock and handling, assembly time, assembly yield, solder, and board space.
EP technology is nothing new as some of the materials and methods have been around since the early 1970s. It is an enabling technology that allows companies to design products that otherwise would be too large, too heavy, too expensive, or would suffer from poor performance. It also came with a significant cost at a time when consumer electronics had yet to take off on a large scale. Hence, the market drivers for embedded passives at the time resonated only within military and aerospace technologies. With few products and small production volumes compared to consumer electronics, PCBs were quite complex and large, and in a segment where lower cost was less important than it was for consumer products. However, with the consumer electronics boom came a new set of market drivers for advanced electronics - changing EP market drivers. Suddenly, more advanced, low-cost electronics such as cell phones, camcorders, laptops, and network hardware hit the market. Board volumes for these products were large, and the number of potential buyers was dramatically higher than that of military technology.
With the demand for faster, smaller, lighter, and cheaper products, one would think that embedded passives would experience rapid technology adoption with significant market growth. The reality is that even though it is such a promising technology, EP sees steady, but modest growth, compared to expectations of a few years ago. However, looking at EP material use for specific product areas, there is stronger growth. This is true for cell phones, camcorders, and network equipment.
Why is this the case? A simple answer is that these are products that benefit from all the enablers of embedded passives (size, performance, cost, weight), so there is a need to consider EP as a means to beat the competition. However, this is not the whole story. Many other types of products also benefit from the same technology, such as designs with large, fine-pitch BGAs requiring high-speed signal terminations, or any design being manufactured in large volumes. Yet, designers of these products still have not adopted embedded passive technology on a broader scale, so it is not simply based on need.
Is EP Technology Crossing the Chasm?
The adoption of embedded passive technology, as with other technologies, can be expressed using the chasm model. This model assumes that a technology is first adopted by a few innovators, and is then followed by a larger group of early adopters. Meanwhile, an even larger majority picks up the technology, while a smaller group of laggards remains skeptical, and waits as long as possible (Figure 1). The steepness of the curve shows how fast a technology transitions from adoption by innovators to being used by the majority. The chasm is the slow step where a technology transitions from innovators to the early majority.
Figure 1. Number of adopters vs. time - only when the early majority adopts a technology will the market grow significantly.1
The curve for EP is not as steep as was expected a few years ago, and the electronics industry is still trying to bridge the chasm. But, is this true for everyone? Looking at one industry, for example, the military and aerospace segments - most experts would agree that there are possibly only a few laggards remaining, as these markets widely use embedded passives. In contrast, the consumer product segment - especially the cell phone industry - is further ahead than the electronics industry as a whole.
Will this trend continue? Much is pointing in that direction. For once, the factors that drive this technology are being further accentuated each day. As designers use larger BGA circuits with smaller pin pitches, they are forced to use HDI/microvia technology, and it is becoming more difficult to terminate high-speed signals without embedded passives. Standard surface mount components are located too far from circuit pins.
While some have started looking to embedded passives, others have been shipping large volumes of products that use EP technology. These companies must have seen something that other companies have not yet discovered - or they have found solutions where another company sees problems that prevented them from using this technology.
Is Cost the Issue or the Benefit?
Let’s focus for a moment on what some potential benefits and problems might be. It would be natural to try to stretch known technology as far as it can go, and many are doing that. Step by step, complexity is increasing by stretching known processes in which BGAs have more pins, pin pitches are shrinking at each step, and the size of standard SMT resistors and capacitors are also shrinking. Companies are now looking to use 01005 components. At this level of complexity, companies cannot scale known methods and processes. They need new technology to cope with board miniaturization. If this is the case, EP is a technology that companies must apply to be successful. Companies that have used EP technology typically have also applied many of the aforementioned miniaturization technologies. This is no coincidence. Like most new technologies, embedded passives affect the entire organization - from design planning and board design, to board and parts procurement, to assembly and test. Therefore, it doesn’t help if one group within a company tries to convince the management of the benefits of this technology unless the impact and benefits on the entire organization are clear. This requires an organization that fosters this cross-discipline communication.
It could be argued that this is an expression of the tendency to apply only fully mature technologies, tools, and processes. In reality, companies do need state-of-the-art technologies, tools, and processes to remain competitive in the market. Companies would prefer to be the early- to late-majority adopters in the chasm model, but should be innovators or early adopters.
Companies investigating EP technology for products frequently make two potentially costly mistakes. First, they underestimate the cost benefits by applying a primitive cost model when trying to calculate the net cost of embedded vs. discrete passives. Underestimating the cost benefits typically means that companies do not adopt the technology at all because they cannot see a cost benefit.
While some companies are experiencing success with embedded passives, it is not easy to learn about their results because EP is viewed as a competitive advantage, and results are typically considered classified. However, some have published papers on the size, cost, and performance benefits they have seen in their designs using EP.
Cost modeling for embedded passives is a complex task with many parameters. A large number of parameters appear as a per-component cost, meaning that with a large number of components, even for modest product volumes, the analysis radically fails if these cost items are not correct, or worse, completely left out. However, there are specialists and tools available that can help with these tasks, and if there is one piece of advice for companies wanting to look at EP, then it would be to bring in a specialist for cost analysis.
Understanding a New Technology
The second mistake companies frequently make is underestimating the complexity of adopting EP technology. There are several different technologies available for embedded resistors and capacitors, and each one comes with its own set of rules and considerations. Hence, what is right for one design might not be right for another.
There has been much debate around the two main classes of resistor materials: thin film and thick film. Within each, there are several sub-types - each have slightly different characteristics that make them more or less appropriate for a design. Traditionally, thin film has been considered an expensive technology. However, as board sizes shrink, fitting more boards into a panel, the cost difference is becoming less dominant (Figure 2).
Figure 2. Thin-film resistors can be made small enough to allow parallel terminations inside a BGA pin pattern.
Other parameters differ considerably and can affect whether or not a project saves cost. One factor is tolerance. Thin film typically can be manufactured to closer tolerances before trimming, while thick-film technologies require laser trimming, which is an added cost. Assuming that trimming could be performed to better than 1%, laminating the board to a certain level might ruin that precision. To make matters worse, thick film typically gives a random tolerance drift for each resistor for a finished tolerance around ±5%. Thin film also gives a lamination drift, but in this case, resistors shift in the same direction - making it possible to compensate the effect on the design.
Design Tools
Thick film currently is the most common choice for consumer technology. The problem is that it is not possible to look at a design schematic or part list and decide if it is feasible to use EP, or which material technology gives the best results. There are several parameters that must be applied to design tools so that they can analyze important circuit parameters and material characteristics, and then present a foundation for a decision. The design tools that pioneered embedded passive design are in their third generation, and provide this type of assistance. In one design-planning step, component parameters and material characteristics can be investigated to determine the optimal combination.
Tolerance also plays a role in circuit design. In traditional discrete design, engineers typically pick components from a parts database where all resistors are at 1% tolerance. In EP design, the engineer must specify the actual required tolerance while being aware that a sharp tolerance is more costly than a relaxed one. In technologies in which all resistors are manufactured in the same step, the correlated tolerance between parts on the same board is much better than the individual component’s nominal tolerance. This is important because in most resistor applications, the ratio between two or more components is more important than an individual component’s nominal value.
Having designed the circuit and the board, companies must face another way of thinking. In the past, they sent Gerber/ODB++ files to a board manufacturer and expected the completed boards to match the connectivity in these files. It was also comparably trivial to test that these boards were acceptable. With EP technology, companies outsource a major part of their design - hundreds of components - to the board manufacturer, and expect to receive a correct PCB. This causes some issues.
First, companies must deliver enough manufacturing data to allow the board shop to meet expectations. This includes part data with nominal values, as well as tolerance and power ratings that allow the shop to test these parameters to provide good boards. But using this process creates a more expensive PCB than the un-embedded PCB. Board procurement is an instance that sees longer delivery times and higher costs, so a procurement team must be aware of the difference to allow them to deal with the cost and time difference properly.
Finally, embedded passives have been around for a long time, and companies see a transition from pure EP toward more general embedded technology. This means that they no longer embed only passive parts, such as resistors, capacitors, inductors, ESD components, and dedicated RF planar structures, making them part of the actual board substrate. They also embed active parts and SMT components by laminating them into the PCB.
Conclusion
The EP market is growing, but the rapid growth the industry once expected is only seen within certain product segments. It is a silent revolution - companies deploying EP technology see it as a competitive advantage, but few speak openly about it. As more companies design products that not only benefit from EP, but also require it to meet design objectives, the industry will see the technology become more common and driven to a more general embedded technology. New and improved materials that allow for improved manufactured tolerance and smaller dimensions at lower costs are also being introduced. At this point, companies will cross the chasm. Meanwhile, design tools that pioneered EP technology can provide automation for embedded component design - making design clear and less complicated while mitigating much of the risk that once dominated EP design.
EP technology touches all steps in the design, procurement, manufacturing and test chain, making it vital to communicate effectively within a company, and with suppliers and subcontractors. However, efficient technology adoption requires an organization in which there is sufficient decision-making to accept that some teams will see added costs and longer lead times, but will earn it back later on the bottom line.
REFERENCES
1 Moore, Geoffrey, Crossing the Chasm, New York, HarperCollins Publishers, 2002.
Per Viklund, director, advanced packaging, systems design division, Mentor Graphics Corporation, may be contacted at 46 411 456 11; e-mail: per_viklund@mentor.com.