Transmissive 2-D x-rays speed PCB inspection
By Rick Nelson, Chief Editor -- Test & Measurement World, 2/1/2008
Building high-speed, low-cost automated x-ray inspection systems that are easy to program is the goal of MatriX Technologies, according to managing director Eckhard Sperschneider. In an interview at Productronica 2007, he said the company also works to link automated optical inspection (AOI) and automated x-ray inspection (AXI) data to find defects and correct their causes in real time. Sperschneider said the German company, founded in 2004, targets OEMs serving the automotive, telecom, and other industries where maintaining high production throughput is critical.
To build systems that achieve high speeds at low cost while performing x-ray inspection of double-sided printed-circuit boards (PCBs), MatriX avoids using expensive, slow tomosynthesis techniques, according to Sperschneider. Instead, the company employs its Slice Filter Technique (SFT) to augment standard, high-speed transmissive 2-D x-ray analysis. At Productronica, MatriX introduced the X2.5 addition to its AXI product line, which adds a 0 to 45° angle-shot capability that Sperschneider said can work with SFT to guarantee 100% test coverage of double-sided PCBs.
SFT, which in conjunction with the X2.5’s new angle capability discerns hidden or overlapped joints, employs a proprietary algorithm to separate image data for each side of a double-sided PCB without requiring the use of 3-D laminography techniques. Sperschneider explained that SFT combines software with a knowledge of the x-ray dynamic-absorption characteristics of specific PCB materials to acquire top-side and dual-side images and then derive a bottom-side image (figure).
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The proprietary Slice Filter Technique (SFT) supports the inspection of solder joints on double-sided assemblies: (left) the top side of a PCB before assembly of the bottom-side components; (middle) an x-ray of the fully assembled double-sided PCB; (right) the bottom-side solder joints after SFT-based image reconstruction. Courtesy of MatriX Technologies. |
To implement the AOI-AXI link, MatriX uses its MIPS_Process software, which in its latest release includes a module that can correlate different inspection points in the SMT line—for example, on encountering a solder defect, the software can call up paste-inspection results and initiate corrective measures.
MIPS_Process can also be used as a Web interface tool. Sperschneider said that MIPS_Process acquires results from AOI systems from companies such as Viscom with the goal of locating problems such as joints with insufficient solder and locating the process step that results in the defect. “Finding defects is one thing,” he said, but the goal is to eliminate them.
