Ceramic Substrate Interconnection Technology – 2000
René E. Coté, Unicorn Consulting, Inc., 4600 Boulder Run, Fort Worth, TX 76109-3216, cotere@dfw.net
A small group of dedicated people accepted a July, 1997, challenge to undertake the task of roadmapping the various interconnection technologies on ceramic substrates. The group, made up of members of the Ceramic Interconnect Initiative (CII) of the Microelectronics Marketing Research Council (MMRC) of IMAPS, came together in a hotel conference room at the Chicago O’Hare Airport Hilton and began the work that has resulted in a fourth iteration of the roadmap, which has just been submitted to the National Electronics Manufacturing Initiative (NEMI). The 1997 roadmap was published as part of the IPC roadmap. Shortly after, NEMI invited the IMAPS group to become part of its National Roadmap effort and we responded with a chapter in the 1998 NEMI Roadmap. We updated our chapter for the 1999 IPC Roadmap and now have just completed the work on a total update of the 2000 NEMI Roadmap.
This IMAPS initiative covers bare substrates; thick film; thin film; low-temperature cofired ceramic (LTCC); high-temperature cofired ceramic (HTCC); and pure copper metallizations on ceramic. The current Interconnection Substrates – Ceramic chapter is approximately 40 pages long and looks at the attributes of each technology in 2001, 2003, 2005 and 2011. The tables included here are representative of the material that can be found in the roadmap. Tables 1-3 are samples of the substance of the roadmap. Table 4 shows the critical and paradigm shifts needed for bare substrates. Table 5 shows the same for thick film technology. Table 6 gives the general and specific needs of copper metallization technologies and Table 7 lists the gaps and potential show stoppers related to the NEMI product sector needs.
The NEMI process uses “Sector Champions” to present the needs of OEMs in the Low-Cost, Hand-Held, Cost-Performance, High-Performance and Harsh Environment industry sectors. The Sector Champions develop and present “emulators” that are used by the different Technical Working Groups (TWGs) as the basis for developing their roadmap projections. The aim of NEMI is to expose gaps between industry needs and technology capabilities that should be addressed and funded by various agencies such as the National Science Foundation (NSF), the Defense Advanced Research Projects Agency (DARPA), the National Institute of Science and Technology (NIST) and others. It also gives suppliers an understanding of where R&D should be directed to meet industry needs of the future. For selected projects, NEMI assigns Technical Implementation Groups (TIGs) to oversee the programs. A couple of examples where NEMI TIGs have been involved are a Microvia for organic substrates program and recently a no lead solder program.
Following is the Executive Summary of the latest IMAPS CII chapter:
Executive Summary
Ceramic substrate interconnection and packaging technologies have been used for many years, in many different types of applications, and they offer circuit and device packaging solutions that are cost effective and completely applicable for today’s needs. This is especially true for the wireless hand-held and harsh environment automotive and military segments. Nevertheless, most system and design engineers do not have the knowledge of ceramic interconnections readily available to consider these technologies. There is a perception that ceramic is exotic and expensive. This chapter attempts to define this knowledge gap.
The major gaps that exist for ceramic interconnection substrates are application and design education, design tools, infrastructure, a perception of a lack of standards and the issues of real and perceived cost. In addition, there is the perception of a significant gap between production cycle times and vendor promises, particularly in LTCC. Device designs must be turned in two weeks or less, however, the perception appears to be six to ten weeks.
There is a need to publicize the capabilities and benefits of these technologies using a variety of educational tools. Packaging and system designers have limited awareness of the capabilities and benefits of the technologies. In addition, there has been a shrinking and consolidation of producers in the U.S. The producers who remain are very capable of supplying current needs and adding to the infrastructure is neither difficult nor overly expensive. However, in an effort to differentiate themselves from their competition, suppliers give the impression that each has distinct, proprietary technology. This marketing strategy is counterproductive since it gives potential customers the perception that no standards or second sources exist thus making ceramic interconnection technology options seem risky. This is certainly not the case.
The issue of cost is difficult to address because it is nearly impossible to make a meaningful comparison of a ceramic substrate technology to alternative technology such as organic substrates like FR-4, PTFE (polytetrafluoroethylene, Teflon®) or the like. The user is well advised to consider all aspects of cost when making any comparison. There is no way to give a simple cost per unit area for ceramic substrate technology due to the difference in layer count and the inclusion of integrated components and the value in use that they represent when evaluated at the functional unit level.
NEMI could help in the ceramic area by organizing a TIG to develop a large area alumina substrate. The most straightforward way to address cost is to use larger substrates and process multiple circuits at the same time. The largest, commercially available, standard size for alumina substrate is 5” X 7”. Priority should be given to developing 96% alumina substrates a minimum of 10” X 10” in size. The TIG should also address the availability of processing equipment suitable for the larger formats.
In addition to the recommended TIG activity to develop large area substrates, NIST has a group addressing the needs of the LTCC community to develop test specifications and methods aimed specifically at high frequency applications and to develop models and measurement techniques to correlate green to fired properties of ceramics. These activities are aimed at the fastest growing electronic segment ever in history, wireless applications. Ceramic technologies seem to be ideally suited for telecom and wireless applications and this has caused a resurgence of energy in the ceramic community.
The roadmap effort has been important in many ways. Obviously, roadmapping of technology in itself is important to the industry; however, some other benefits were derived. The fact that a group of competitors and users came together, shared mutual experiences and frustrations and developed a unified sense of purpose was very important. Members of the CII were energized to promote their technologies. It was realized that organic technologies were not “the enemy.” As a matter of fact, Dieter Bergman of the IPC was very instrumental in facilitating the organization of our roadmapping effort and participated actively at the initial meeting. The fact is that as we approach this new area of need, ceramic and organic technologies are as complementary now as they have ever been. The best and most cost effective solutions are reached not by excluding, but rather by including all approaches and combinations of approaches. That is a major lesson that has been learned as we have moved forward.
It turns out that many of the gaps facing producers of ceramic substrate interconnection solutions are the same as those facing their organic counterparts. Lack of adequate design and modeling tools, integrating passive elements as buried components, etc., are shared problems. Cost is a shared issue as well.
A very large area of concern is overcoming the custom or practice of cost analysis by using a cost/unit area metric. This metric originated in the printed wiring board marketplace and has spilled over into all substrate technologies. It is totally misleading when one incorporates passive elements and functions. How does one compare a simple FR-4 printed circuit board containing a low number of layers and conventional copper conductor patterns to a Microvia board or more poignantly a multilayer ceramic substrate, HTCC or LTCC package with integrated close tolerance resistors and capacitors using this overly simplified cost-per-square-inch metric? This is meaningless, misleading and not representative of current or future trends.
It is unfair and meaningless to more than the substrate/circuit manufacturer. It is unfair to the system designer/producer as well. Decisions are made at one level of the supply chain that impacts the others. One may save pennies at the substrate level only to have to spend dollars at the assembly area to add components or to have to deal with thermal management issues by having to add heat sinks or fans. The industry has to develop a better comparative metric and that is the challenge.
People with access to the IMAPS website www.imaps.org can sign in to the CII area and download a copy of the latest roadmap. Comments and upgrades are always welcomed. Many people have generously given of their time to make this product as good and as useful as it is, however, the process is evergreen. A roadmap of this type is never finished and never as good as the next input will make it. All who access the roadmap should feel absolutely comfortable to make any comments and suggestions as they wish. These should be sent to cotere@dfw.net and you can be assured that they will be considered and incorporated as deemed appropriate.
This has been a very rewarding experience for most of the people involved in it. The work product has improved with age, just like fine wine. Many people have contributed, however, there are a few people who deserve special mention. They are: Dan Amey, DuPont; Peter Barnwell, Heraeus; Don Brown, IWPC; Steve Capp, Laserage; Herb Dwyer, Sam Horowitz, DuPont; Dick Kramer, CTS; Jim Lawson, C-MAC; Andy London, Heraeus; John Paxson, CoorsTek; D.H.R. Sarma, Delphi-Delco Electronics; Rick Sigliano, Zecal; Dave Wilcox, Motorola; and Chris Wolf, Cirqon. All of these people took leadership roles and championed the different sections of the roadmap. I do not wish to minimize the efforts of all members of the roadmap TWG, it is just that the people mentioned went well above the call to assure that we would end up with a very good work-product.
| For reference, here is the index of the current roadmap: |
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Interconnection Substrates – Ceramic
Executive Summary
Introduction
Situation Analysis
Substrates
Thick Film Technology
Summary
High and Low Temperature Cofired Ceramic Technology
Current Status
Technology Trends
Cost Model
Paradigm Shifts
LTCC Measurement Needs
Needs Assessment
Potential Solutions
Thin Film Technology
Thin Film Multilayer Technology
Pure Copper Metallization on Ceramic
Characteristics of Pure Copper
Metallization on Ceramic
Plated and Bonded Copper (PBC)
Substrates
Thick Film
High and Low Temperature Cofired Ceramic Technology
Thin Film and Thin Film Multilayers
Pure Copper Metallization on Ceramic
RF and High Frequency Applications
Technology Needs
Gaps and Show Stoppers
Recommendations on Priorities and Alternative Technologies
Glossary
Contributors
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