Three years is a long time in the electronics industry. Three years is an especially long time when you consider the advances in IC technology. High-end microprocessors for PCs were barely breaching the 100-MHz level three years ago. Back then, IC designers were just inching their way, so to speak, into the realm of submicron structures.
In 1995, surface-mount devices (SMDs) were finding their way into hundreds of electronic products and systems. Naturally, as the types of SMDs mushroomed, so did the myriad of package styles and configurations needed to encase them.
This scenario was the backdrop for our feature and comparison chart on IC handlers in the May 1995 issue of EE. We showcased gravity-fed handlers from a number of familiar names in the business, including Aetrium, Aseco, Daymarc, Exatron, and MCT. Not to be outdone, pick-and-place handlers received equal billing as we featured models from Advantest America, Aetrium, Aseco, Delta Design, Data I/O, MCT, and Optical Associates.
In 1995, key issues facing handler manufacturers were the need to increase throughput and minimize changeover times. In many companies, floor space for testing operations was shrinking. Some handler manufacturers already were addressing this issue: combining several functions—lead inspection, device marking, and programming—into one handler to help optimize test-floor space.
Reducing the Cost of Test
Fast forward to today. What issues are handler companies grappling with? Actually, they are not much different from those in 1995.
Here’s what Kevin Brennan, Enterprise program manager at Daymarc, had to say. “Reducing the cost of test is a significant driving force for semiconductor manufacturers. Shrinking profit margins for ICs and the lack of funds for expansion are driving the development of handling technologies that will enable IC manufacturers to increase productivity within the same physical facility.”
Echoing this position was Roger Gower, president and CEO at MCT. “The economic issues mainly center around the cost of test which has steadily grown as a percent of total IC cost. This has occurred because of the significant effort and success of automation in the fab or front end and the lack of it in assembly and test or the back end,” he added.
Advantest America, a vendor of handlers as well as testers, is in a position to appreciate the back-end issues. According to Katsumoto Hayashi, product marketing manager at the company, “You can’t really view the handler market as independent from the semiconductor test market. Together, they represent the most expensive capital equipment investment in the back end, and the same economic and technological pressures are bearing on the handler market as on the tester market.”
In trying to contain the cost of test, ATE companies and handler manufacturers are facing some difficult challenges. The playing field is not level; they are continually trying to shoot at moving targets. Consider the fact that device speeds are escalating almost monthly. Microprocessor speeds today are four times what they were in 1995 and soon will be at 0.5 GHz.
Couple the requirements of testing devices at these speeds with the proliferation of package configurations and you get an inkling of the back-end testing challenges. “On the technological front, the major changes in device packages are having a dramatic impact on testers and handlers. The move to flip-chip and chip scale packages (CSPs) will require a revolution in handler equipment to achieve the throughput and yield expectations of the customer,” noted MCT’s Mr. Gower.
“High-speed test and CSPs are the key technological trends affecting handlers today and in the future,” added Mr. Hayashi of Advantest America. One current challenge is how to handle CSPs of 32 in parallel. Currently, DRAMs, SRAMs, and flash memory often are tested in parallel, typically in groups of 32. In the near future, it may be necessary to test these devices with 64 in parallel, he continued.
For logic devices, multiple test-site handlers can help hold down the cost of test. “We are seeing continuing trends in multiple test-site handlers,” said Dan Koch, vice president of Worldwide Sales at Aetrium. Aetrium currently offers quad test sites for the Model 7900Q pick-and-place handler.
Index time—the time from the end of one test to the start of the next—is still a major issue with most handler vendors. Obviously, the goal is to make it as fast as possible. Aetrium uses index wheels which shorten the distance from the input to the temperature chamber to the test site.
A key component in performing high-speed testing is the handler contactor. Electrical integrity and reliability of the contactor are of upmost importance. Mr. Brennan at Daymarc noted that contacting performance is critical to the successful testing of a growing number of devices.
Handlers must integrate the new contactor technologies and work in conjunction with the testers to maximize yields. Plunge-to-board and high- performance handler-tester interfaces will be essential to meet the need for speed, he added.
The Need for Integration
Semiconductor manufacturers are investigating a number of methodologies to reduce the cost of test. Integrating several processes so they can be performed on one piece of equipment is gaining popularity. Instead of the handler just presenting the device to the tester, it can add value by performing other functions, such as lead inspection or device marking.
There is an increased emphasis on integrating and automating the processes in the back end, said Mr. Brennan. This will impact handlers in several ways. Over the next three to five years, handlers will have to conform to a variety of standards that will be developed in areas such as communications with factory networks and automation of material transfer to and from the test cells.
Handler companies are already responding with equipment that addresses the integration requirement. Kent Blumenshine, product marketing manager at Delta Design, said integration is particularly effective for manufacturing flows that have a single test insertion.
The company’s response to integration is the addition of lead inspection to its DeltaFlex™ test handler. Taking integration one step further, Aetrium has added tape-and-reel output, laser marking, and vision inspection to a couple of their new handlers.
What About Memory-Module Handlers?
The memory-module market is undergoing some major transformations. Cecil Ho, president of CST, aptly summed up the situation by saying the industry is at a crossroad of changes. Conventional Fast Page Mode and Enhanced Data Output memories are being replaced by SDRAMs. According to an industry prediction, 60% of all memory modules produced by the end of 1998 will be SDRAMs.
Furthermore, noted Mr. Ho, conventional 72-pin SIMM modules are being replaced by 168-pin DIMM modules. Memory capacity also is going up—today’s 16 Mb is giving way to 64 Mb.
“In the SIMM/DIMM market, pad count continues to increase upward to 300 pads, with pad spacing decreasing to 0.65 mm,” added Victor Morse, worldwide sales manager at Exatron. More importantly, memory-module test speeds have rapidly passed the 100-MHz level and are already reaching 200 MHz.
The increase in memory-module test speeds presents particularly difficult test-contactor challenges for automated SIMM/DIMM handler manufacturers. Exatron’s patented Particle Interconnect™ contactor technology offers a handler interface that has been tested to 500 MHz, noted Mr. Morse.
What does this mean for the memory module handler manufacturer? With thinner, longer, and taller memories, new handlers are needed to process the modules, added CST’s Mr. Ho. Along with new promising technologies coming into the forefront, such as Synchronous Double Data Rate (SDDR), Direct Rambus, and Synchronous Link DRAM (SLDRAM), a handler could be obsolete in just one year. As a result, the industry is looking for the lowest cost handler that can pay for itself in a year.
Stay Tuned
Three years ago, customers were demanding handlers that provided high throughput and had fast changeover times. The situation isn’t much different today. These still are important issues in 1998. There are, however, more package configurations than before, and device speeds are increasing at phenomenal rates. It will be interesting to see how the industry responds.
To provide you with the latest specifications of handlers currently available on the market, we have compiled a comparison chart listing both pick-and-place and gravity-fed equipment. For more information on any handler, please circle the appropriate number on the Reader Service Card accompanying this issue, or visit our web site at www.nelsonpub.com/ee/ and click on ProductLink.
Copyright 1999 Nelson Publishing Inc.
May 1998
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