Electrons remain important in electronics test

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Test engineers are struggling to optimize printed-circuit board (PCB) test and inspection strategies as board complexity increases and manufacturing gets outsourced. Finding the right mix of test and inspection technologies was the topic of the Test and Inspection Summit panel held April 3 at the APEX show in Las Vegas (see "Test, inspection technologies target PCB quality").

In the panel discussion, which I moderated, Chad Hankinson, president of Everett Charles Technologies' fixture services group, addressed outsourcing, noting that in many parts of Asia sufficient talent isn't available to support the growth rate of manufacturing. “Consequently, when we do a fixturing program for the China market, Everett Charles personnel have to install the system, run the first lot of boards, and provide ongoing support to ensure success.”

John VanNewkirk, president and CEO of CheckSum, echoed that point, saying, “You have to buy equipment that is extremely stable so that the fixturing program you set up in your NPI [new product introduction] center is going to run the same at your production facility.”

Steve Case, chairman and founder of CyberOptics, commented on process control's role in producing high-quality products. You have to make sure all steps of the assembly process—such as solder-paste deposition—are done correctly, he said, noting that increased connectivity between pieces of equipment will become increasingly important.

Deciding what equipment to deploy—from automated optical inspection (AOI) systems to device programmers—is key. Jack Rozwat, a GM at Agilent Technologies, summed up the problem this way: “The good news is there are a lot more technologies to choose from. The bad news is that you've got to make some tough choices.” He noted that what people want is a program that employs process and yield simulations and fault spectrum information and determines a test strategy. Unfortunately, he said, he doesn't have such a program to sell.

Glenn Woppman, president and CEO of Asset InterTech, commented, “No one is going back to DIP packaging technology.” Instead, he said engineers will increasingly face what he calls SIP, PIP, POP issues—ones dealing with system-in-package, package-in-package, and package-on-package devices—as designers cram more functions into silicon. These devices, he said, look like PCBs, with interconnects between die, but the only way to access the interconnect may be through boundary-scan's JTAG port. But boundary scan won't soon displace other test techniques. Said VanNewkirk, “In the late '80s, a lot of people thought that boundary scan was going to take over for in-circuit, but now most people realize that these are complementary technologies.”

Don Miller, president of YesTech, agreed that a balanced approach is necessary. “The fault spectrum that AOI and x-ray address is huge,” he said, noting that AOI in particular can find defects early in the production process so they can be corrected. But, he added, “At the end of the day, there is still place for electrical test.” Or as VanNewkirk put it, “You can learn a lot about a pizza by looking at it, but there is no substitute for taking a bite. Electrons are a very important part of electronics.”