AOI and SPI: Can Inspection Equipment Makers Successfully Do Both?

Estimated reading time: 4 minutes

 — Several inspection companies debuted new models at productronica 2009 in Munich, Germany, with traditionally solder paste inspection (SPI) companies entering the automated optical inspection (AOI) market, and vice versa. While inspection companies have steadily pushed for optical inspection earlier in the SMT assembly line (pre-reflow), this move was markedly widespread, with Koh Young, Mirtec, Marantz, Viscom, and others looking to capture market share outside of their core inspection sector.

Henk Biemans, GM of business electronics, Marantz Europe, put it bluntly: AOI and SPI have little to do with each other. Why then are so many companies jumping the line and seeking market share in both inspection markets? Kwangill Koh, Ph.D., CEO, Koh Young Technology, explains that their high-end SPI customers are upgrading AOI simultaneously. Investing in an AOI system with the same brand behind it reassures them of ease of use and quality of inspection. Another reason is simply that solder paste inspection is an increasingly required step in SMT assembly, as rework and scrap rates are intolerable in a lean, waste-free manufacturing climate. AOI companies may be banking on manufacturers gleaning a strong return on investment for their SPI equipment. No two AOI companies entering SPI are doing it with the same technology under the hood, with pure optics, lasers, Shadow Moire, interferometry, 2D/3D combinations, and other

Viscom debuted the S3088VPI, a high-reliability 3D SPI system. The inspection system makes completely vertical measurements instead of projecting grids. The interferometry approach enables high speeds while inspecting orthogonal edges, such as drill holes, or gaps in paste bricks. Viscom sees customers’ batch size diversity increasing, noting that a batch size of 1 is not difficult to program in and inspect. The company also noted that computer speeds are catching up with mechanical speeds, enabling inspection systems that perform a great deal of processing to now match the speeds of primarily robotic systems like printers and pick-and-place machines.

Marantz also entered the solder paste inspection market, with the PowerSpector S1, a collaborative introduction with DJTECH of Japan. This system uses 3D volume measurements with 2D area inspection for defect detection. This 2D inspection helps detect and compensate for warpage, measure from the 0 level, at the copper, and show differences in materials. For 3D, the system uses 4 lasers, in 2 colors, with 64× oversampling for repeatability. The companies’ sensor technology allows the system to maintain line speeds.

Mirtec, which offers an array of desktop and in-line AOI systems, uses dual-probe Shadow Moire SPI technology in its new MS11. The system’s algorithms enable 01005 paste-print inspection while its robotics are the same as those used for Mirtec’s AOI systems. Designers are increasingly incorporating 01005s into boards, says Brian D’Amico, Mirtec, adding that manufacturers investing in inspection have to add this capability or risk becoming obsolete. The MS11’s system shines light through a grid at 45° angles, casting light over the inspection area 4× in one direction and 4× in the other, compiling these 8 images to make a map of the solder paste. 

CyberOptics expanded its SE500 product line to include the SE500X model for larger circuit boards, such as for server, military, and other panelized PCBs, noted Parito Lee, global marketing manager for the Inspection Systems Business. The company’s calibration-free sensing technology uses on-the-fly image acquisition. For cost and time-to-market reasons, the company has moved its system R&D and manufacturing operations to Singapore, maintaining a sensor R&D team in the U.S. “We are an inspection technology integrator,” explained Kitty Iverson, president and CEO, adding that the SIM image acquisition technology can be integrated into AOI, SPI, in-printer SPI, and in-Mounter AOI applications. The company has a series of new AOI product platforms in the pipeline, which will become available in 2010.

With a pendulum swing in the opposite direction, Koh Young stepped out of its traditional SPI arena, introducing the Zenith 3D AOI system to the European market at productronica. The company made its first AOI sale, installing a Zenith for a consumer electronics OEM. With a leap into a new market, you want even more customer feedback and testing, says Koh, noting that the company has beta systems operating in Europe, Asia, and the U.S., inspecting PCBs destined for diverse end-products. “We are targeting the same customer segment as we have for the Koh Young SPI systems, but at the end of the line,” he notes, meaning high-end high-reliability manufacturers. Short programming times and a graphical interface are part of this uniformity between inspection systems. Per field of view (FOV), the Zenith gathers 32 3D and 9 grayscale images. This combination is designed to limit operator interpretation and guesswork, making tombstones and other defects clear. The system’s component library is based on IPC610 tolerances, but users can also define their own tolerances. For more on the system, see our coverage from APEX: Test and Inspection Products and Test and Inspection ROI

After Agilent exited the AOI sector in early 2009, some speculation circulated about further consolidation. While this is still possible, the majority of AOI system fabricators seem to be exploring new inspection areas, working out of the post-reflow niche and seeking to gain footprint in higher reliability SMT lines. To expand from AOI to SPI or SPI to AOI, a company must be clearly focused on what it is good at and what customer segment buys its inspection products. There are too many companies in the inspection arena for every player to be every thing to every user. However, if a customer attaches real value to an inspection company at one place in the line, they seem willing to add that inspection brand in other places. As more installations take place, we’ll see how this AOI/SPI venture fares, whether approached from an inspection integrator standpoint, a collaboration with another inspection company, or other IP investment.

Meredith Courtemanche, executive editor, SMT, may be contacted at mcourtemanche@pennwell.com