3D Optical Inspection Provides “Eyes” for Process Improvements in Industry 4.0

Automated 3D solder paste inspection (SPI) and 3D automated optical inspection (AOI) systems have become an integral part of the printed circuit board assembly (PCBA) process because they help ensure high-quality production. As today’s board complexity is increasing, inspection technology becomes even more critical.

For example, while talking with Janet Tomor, senior business development manager at Sun- Tronic Inc.—a contract manufacturer with facilities in Richardson and Houston, Texas— I-Connect007 Managing Editor, Nolan Johnson asked, “Streamlining must be something you talk about a lot [at Suntronic].” Tomor replied, “The biggest impact for us has been automat- ing almost everything except for putting your through-hole connector on the board by hand. We’ve automated most of our inspection and have improved quality. We went from 60% yield on our PCBA lines to 98.9% by adding automated 3D inspection from Koh Young.”

Tomor’s team also added 3D SPI equipment, continuing, “I’ll give you an example. We have a solder paste inspection machine on every line. We once put on a stencil, and it wouldn’t pass. The cause was that the stencil was too thick and applied too much solder paste. We would have had parts sliding all over the board because of the excess solder paste. That was a huge discovery and a change we made thanks to our SPI.”

While most manufacturers base quality decisions on a “good-bad” comparison of reference images, these decisions are easily influenced by variables like surface finish, board condition, component proximity, and more. How- ever, data generated from 3D measurement systems provide meaningful insights about the process and helps manufacturers identify and eliminate the root causes of a defect. When manufacturers trust the data from the system, this helps to transform their operations and accurately control and monitor the PCBA pro- cess. What are the requirements of an inspection system to move from inspection to measurement, and ultimately to process control and optimization? Simply stated, the systems must satisfy the three “Rs” for measurement data: reliable, repeatable, and relatable.

When Johnson asked Tomor which equipment they were using to automate inspection, her answer was straightforward: “Koh Young.”

Reliable

Koh Young’s implementation of full 3D coverage monitors performance to detect common defects, such as missing or wrong components and accurately identifies other issues, such as coplanarity and lead bridging. By measuring components and solder joints, and then offering critical height information to the inspection algorithms, contract manufacturers- ers can use reliable measurements to identify errors during the production process. For example, after Suntronic adopted Koh Young 3D inspection solutions, their yields increased into the high 90% range, which has helped to transform their operations. But what’s next? How can they continue to improve?

Tomor further commented, “We also have a post-reflow AOI after the oven tells us if any- thing shifted. It uses true 3D technology, so it can measure if the part is skewed, missing, shifted, tombstoned, etc. Between the Koh Young SPI and AOI solutions, we increased our yield.” When asked what else helps with streamlining the assembly process, Tomor simply stated, “New equipment helps a lot.”

That new equipment solution, though, pays off by prioritizing data over raw throughput. Global competition means that manufacturers place challenging demands on process solutions. Manufacturers want to monitor and adapt the process to achieve zero defects by accessing all of the data anytime, anywhere. Moreover, manufacturers want process optimization. 3D inspection solutions have been instrumental in providing better data in the form of body and lead tip measurement, allow- ing the new equipment to quantify shape, coplanarity, solder amount, etc.

Koh Young 3D inspection solutions, for example, measure the component and solder joint per the IPC-A-610 standard, generating a significant set of reliable measurement data. This data is the foundation for Industry 4.0. Consequently, advanced inspection systems must evolve beyond simply judging “pass/fail” into functioning as highly intuitive, dynamic decision-making systems, which emphasizes the need for reliable data.

Of course, maintaining quality, repeatable measurement data is not enough to realize a smart factory. The system must also instantly analyze the data with relevant indicators, including yield rate, NG (no good) analysis, PPM analysis, gage R&R, offset analysis, and more metrics that allow manufacturers to com- pare board performance and identify process deviations. Artificial intelligence (AI) engines and machine learning can empower systems to help customers analyze and optimize the production process by managing the data from connected SPI and AOI systems.

Relatable

Industry 4.0 is transforming the manufacturing- ing process by improving metrics like first-pass yield and throughput thanks to the application of autonomous process adjustments. Far beyond an automatic line changeover, this line communication is allowing the equipment to automatically adjust production parameters to increase board quality and lower costs by eliminating rework and scrap.

Koh Young facilitates this communication with a software suite called KSMART, which is the foundation for its smart factory optimization. KSMART collects all inspection and measurement data from the equipment in a line or factory, and then provides the data anywhere within the network with an intuitive, web-based user interface.

Repeatable

Koh Young Technology is working with printer and mounter partners as collaborators within the various communication standards to achieve total communication and streamline the surface-mount line for a zero-defect end goal. The connectivity solution exchanges

real-time SPI and AOI measurement data with other machines in the production line, feeding real measurement data, such as offset, volume, height, area, and warnings to other systems. At the same time, it analyzes data to optimize the process and identify trends. For example, when Link@KSMART is installed on the line, the connected inspection systems automatically define correlations between the assembly processes steps.

Enter advanced process control   (APC)— a proven control and optimization technology that delivers measurable and sustainable improvements in production yield. Most engineers will agree that stabilizing control loops with underutilized or ineffective process time and strong process interactions are exceedingly difficult. APC helps create those stable controls. For example, APC can collect and analyze solder and component location data from an inspection system, and then send recommendations across the line to printers or mounters for automatic implementation (Figure 1).

An enhanced APC solution, formed of interlinking software modules, can actively optimize the printing process by combining real-time printing information with SPI measurement data. More advanced software automatically performs the design of the experiment (DOE) intended to complete a detailed SPI result analysis using advanced diagnostic algorithms and noise filtering models, and then recommends the ideal print parameters.

Using advanced communication, the Koh Young AOI systems feed corrected mounting position values to mounters, which ensures the pick-and-place machines mount the components in the correct position. This feature improves process repeatability by automatically adjusting placements and identifying trends to make further positional corrections.

Creating the Real-time Feedback Loop

Connecting mounters and AOI provides obvious benefits, but when integrated with APC, it can improve yields, especially in high-density boards. To do this, mounters use the data received from inspection to update the placement program, ensuring the components are placed onto the solder deposits rather than onto the substrate pads. This approach to placing components on the printed solder can increase production yields and reduce defects. Connecting inspection systems with mount- ers can help achieve complete line communication and further enhance the value of the inspection process. For example, M2M connectivity optimizes the process by exchanging real-time measurement data between printers, SPI, mounters, and AOI systems. The systems feed offset and warning data to other systems while analyzing trends for process optimization and traceability. Combined, this process provides unsurpassed performance power.

Figure 2: Post-refiow defect reduction effects with adaptive process control.

Communication between equipment will improve pro- cess repeatability by automatically adjusting component placement to the solder deposit rather than to the pad location. This advanced process further improves microchip mounting reliability. Figure 2 charts dramatic improvement across five different defect types when a manufacturer uses advanced process control in production compared to a conventional placement approach with no communication between systems.   Networked intelligent systems that allow real-time results to be correlated, calculated, and visualized will become even more essential in the smart factory.

Freeing up the Front Office

Understanding the increasing importance of networked intelligent systems in the smart factory, Koh Young has been continuously testing its modular platforms with its KSMART partners. Thus, Koh Young designed the modular platform for future growth and expansion. When Koh Young releases new software modules, a manufacturer can implement the upgrades as needed. Harnessing the power of the Koh Young Intelligent Platform (IP), KSMART extends beyond automated adjustment toward a comprehensive infrastructure for autonomous process optimization. Indeed, a smart factory is within reach of any manufacturer.

Back at Suntronic, the question is posed to Janet Tomor, as to what their priorities are for further streamlining their process and workflow. Tomor responds, “Working with the customer to produce a manufacturable board with well-supported components.” With inspection systems optimized, and with a path toward the real-time adjustments that CFX, M2M communication, and advancements in AI and knowledge modeling from companies like Koh Young, Tomor’s attention isn’t focused on the data from the shop floor; it’s focused on the customer’s supplied data.

Jenny Yuh is marketing assistant at Koh Young Technology

Brent Fischthal is senior marketing manager at Koh Young America.

Gesture Recognition Using Ultrasound

A research team at the Fraunhofer Institute for Photonic Microsystems (IPMS) have used a new class of ultrasonic transducers to reliably detect distance changes, movement patterns, and gestures in ranges of up to half a meter.

For this development, researchers are implementing electrostatic microelectromechanical bending actuators that have been continuously advanced for generating sound in micro-loudspeakers and micropumps since 2016. The Fraunhofer IPMS proprietary nano-e-drive (NED) principle utilizes the high forces of electrostatic fields in nano- meter-sized electrode gaps to allow for the mechanical movements with displacements in ranges of several microns. The chip surface, as well as the complete component volume, is used for sound generation.

Group leader Sandro Koch explains, “Using the entire chip volume for sound generation enables us to produce very small components. Because hundreds of such devices can fit on a single wafer—and multiple wafers can be simultaneously processed in single process steps—the cost of manufacturing large volumes is potentially low.”

Fraunhofer researchers expect that high air volume flows that have been converted into high sound pressure will support further development to provide an increased signal-to-noise ratio for low-frequency ultrasonic transducers. The resonance frequency and thus the detection range and spatial resolution can then be defined by the geometry of the NED bending actuators.

The tiny components are inexpensive to produce, allow for high sound pressure, and provide a flexible frequency design for an optimal balance of distance and sensitivity. Possible fields of applications include uses in automation, safety, and medical technology as well as the automotive, entertainment, and household electronics industries.