Burn-In and Test Socket Manufacturing: Technology, Markets and the Challenges in 2011

By Ron Molnar - [Az Tech Direct LLC]

The requirements, design, and development of burn-in and test sockets continue to expand in complexity in direct relationship with device fabrication and packaging technologies. Over the years, based on corporate directives, it is now common for the Product Development Team - consisting of device, packaging, and test engineers- to design next-generation product based on leading-edge capabilities in these areas. Modeling and simulation are playing an important role in product development, with mechanical, electrical, and thermal considerations taken into account at all levels. Keep in mind the socket is basically an interface between the packaged device on one side and some type of substrate or board on the other, connected to the testing system. This obviously adds to the complexity as socket manufacturers must meet requirements on the board/system side to optimize testing, for that particular device/package type. The impact of heating and cooling on the thermal properties of materials plays an even larger role in design for sockets utilized in hot/cold testing or for burn-in applications, with package geometries and materials also impacted by temperatures during the testing.

The socket supply chain has also grown in complexity, with focus on total cost-of-use or ownership (CoO), versus comparison of the socket selling price alone. Information related to contactor technology, material selection, socket manufacturing, and the customer data on contactor life and yield are all part of the cost model equation. Companies with burn-in and/or test systems, ranging from single facility to multinationals, are going beyond the cost model to define socket supplier relationships. Design and manufacturing locations, technical support and capability for prototype or volume production may be key factors.

To get a snapshot of where the socket industry is and what the next year will bring, executives from some of the world's leading socket manufactures were asked to weigh in with their thoughts in response to three (3) specific questions:

1) What is your competitive advantage?
2) What are the key markets you serve?
3) What are the challenges seen in 2011?

As to be expected, responses to the question about competitive advantage were as varied as the number of companies participating and the range of packages being tested. However, it's interesting to note that while some companies focused on technology features as a competitive advantage - contactor technology, the ability to address fine- and high-pitch features, novel handling features, high performance, high frequency, data requirements etc.; others identified business advantages as their strong suit. For example, lead-time, cost, time-to-market, product and material variety, global presence, turnkey services, were some competitive advantages socket manufactures consider themselves to offer. Key markets being addressed were less varied, making it clear that there are choices out there, and the competition is stiff. Some companies target very specific packages, such as BGAs, CSPs, and custom/oddform packages; while others focus exclusively on specific test processes, such as burn-in, and probe test. Some target the IC and wafer-level test, others work at the board level, still others work at the system level. Some serve specific industries, such as automotive or medical, and then there are those who serve a broader market, filling customer needs for automated test, failure analysis, ATE, system level, failure analysis, the list goes on.

In a general overview of the responses, regardless of the socket technology, responses to the challenges for 2011 were by far the most interesting. For example, one respondent noted that WLP formats are beginning to blur the distinction between wafer probe cards and BGA sockets, driving the performance and reliability needed for wafer probe at a socket price point. The majority of challenges expressed were related to the increases in both the contact point "quantity and density", typically termed as the package lead, pad or ball "count and pitch". Higher performance, higher density, and faster speed at lower cost of ownership and faster time-to-market were an ongoing theme. Additionally, thermal and power challenges, and an increased need for device parallelism were mentioned. Only one company cited concern with the volatility of the semiconductor industry itself. It's interesting how some respondents' competitive advantages were identified as others' challenges.

Figure 1: Interconnect Devices, Inc.'s PoP Socket handles Package-on-Package Devices

The trends in package complexity and miniaturization to improve performance while reducing space requirements is driven by consumer interest and revenue from mobile devices, including cell phones and laptops, as well as the latest e-book readers. Wafer-level, chip scale and 3-D packages are just a few of the topics related to challenges and part of the current and developmental project. For full details of this survey, including the companies polled and their individual responses to the questions pick up a copy of the Jan/Feb 2011 issue of Chip Scale Review magazine at the Chip Scale Review booth in the BiTS EXPO. In it, you'll find a comprehensive International Directory of Test and Burn-in Socket Suppliers.

Ron Molnar is Executive Director of AZ Tech Direct, LLC, an electronics resource network, offering technical and business consulting services to the electronics industry. Ron received his BSEE from UC Berkeley. He is VP of the SMTA Arizona Sonora Chapter and serves on the Editorial Advisory Board for Chip Scale Review.

Figure 3: Multitest's ECT Mercury Test Socket was designed to overcome the physical constraints of standard probe technologies.