Inspection

Has 3-D X-ray PCB assembly inspection finally become a mainstream, inline production tool? The answer ranges from "it has been for some time" to "almost" and clearly depends on whom you ask.

Thermal management becomes more critical as higher electronics performance is designed into smaller packages. As a result, heat removal mechanisms need to become more efficient to prevent overheating and failure. Recently, there has been increased attention to the details of heat sinks, heat spreaders, and heat removal methods in military, medical, and other sectors of electronics manufacturing.

For many years, increases in machine vision speed came almost automatically with increasing microprocessor speeds. However, this no longer is true with multicore PC architectures, which require major software design changes to take advantage of the parallel processing capabilities.

Automated optical inspection (AOI) and automated X-ray inspection (AXI) have been around for some time in various configurations and both have played a role in improving the quality of circuit boards. While some companies opt for one technology over the other, each form of inspection contributes its own unique benefit to the manufacturing process.

Machine vision applications involve widely varying degrees of difficulty. Some are straightforward and easily handled by one of the so-called smart cameras. Smart cameras have sufficient built-in processing capabilities to perform basic image analysis tasks. Vision sensors are similar but more limited in the kinds of applications they address. Both types may provide a complete solution by integrating lighting, a camera, image processing, and camera-to-host I/O.

Manufacturers of advanced PCB assemblies know that simultaneously producing cost-competitive products and meeting the quality expectations of customers are vital to their success. Driven by advancing board complexities and the desire to improve yields by effectively using real-time process information, manufacturers are increasing their adoption of automated test and inspection technologies.

On any given day, a certain percentage of the plastic-encapsulated components passing through an assembly line is defective in some way. The defect is less likely to be a chip-level electrical flaw that would already have been caught by testing and more likely to be an internal structural packaging flaw, which can be much harder to detect.

One of the major changes to affect automatic optical inspection (AOI) equipment used during PCB assembly and inspection is the greatly reduced size of the latest components. As stated in an October 2007 press release from Hitachi High-Technologies, "In recent years, the size of resistors, capacitors, and other electronic parts has generally fallen from 0402 (1.0 mm x 0.5 mm) to 0201 (0.6 mm x 0.3 mm) with the need to cope with size 01005 parts (0.4 mm x 0.2 mm) on the horizon." After describing how component sizes have decreased, the Hitachi press release announced the development of the GXH-3 Component Mounter capable of processing 95,000 chips/h.

For best results, IR camera users must think carefully about the type of measurements they need to make and then be proactive in the camera's calibration process. The first step is selecting a camera with the appropriate features and software for the application. And, an understand-ing of the differences between thermographic and radiometric measurements is very helpful in this regard.

The characteristics of nanomaterials can be very different from those of large-scale versions of the same substance. Some of this behavior relates to unique structures, such as carbon nanotubes that exhibit very low resistance and semiconductor effects. In other cases, the large surface area-to-volume ratio of a nanomaterial makes the action of atomic-level forces more pronounced. An example is the greatly increased activity of nanocatalysts used to facilitate chemical reactions.

Machine vision certainly is not new, but for first-time users, the wide range of unfamiliar products and technologies can be daunting. One way that vision system vendors have addressed the problems of component selection and integration has been to develop complete off-the-shelf vision solutions.

Consumer demand for products that incorporate camera modules such as cell phones, automobiles, and even toys continues to grow rapidly. Sales of camera phones reached 295 million units worldwide in 2005 and will rise by 26% annually over the next four years according to Gartner Dataquest as reported in November 2005.

Engineers setting up a new surface-mount assembly line or modifying an existing line generally try to create a sequence of production processes that will successfully assemble the components while ensuring the end product will experience the fewest possible field failures. Both in the development stage and the pilot production stage, engineers try to eliminate any process variation that could result in electrical failure.

Conventonal bar codes such as Universal Product Codes (UPCs) have gained wide acceptance in applications ranging from checkout and inventory control in retail sales to tracking PCB serial numbers in electronics manufacturing. To increase the character content and store the information in smaller spaces, companies have developed 2-D alternatives.

PCI Express (PCIe) is the next-generation peripheral bus for industrial computing. It provides a scaleable, high-bandwidth, point-to-point pathway between peripheral cards and the computing core while retaining application software compatibility with previous generations. For machine-vision systems, the capabilities of PCIe already are yielding increased frame rates and simplifying the implementation of multichannel capability.

Machine vision systems have been used for years to automate processes. Applications can range from checking the amount of fluid in bottles on production lines to inspecting the number and alignment of pins on a microchip or detecting flaws in fruit before it is packaged for shipping.

All dressed up with 680 MB/s of image data? PCIe gives it somewhere to go.

Location, location, location may be the real estate salesman's motto, but in digital I/O, it's bandwidth, bandwidth, bandwidth. Because of the ever-constant demand for more I/O speed, it's easy to understand the attention that PCI Express (PCIe) has received by significantly improving on PCI's performance.

AXI is an effective technology for finding manufacturing defects in electronics assembly operations.

Manufacturers of advanced electronics products know that simultaneously producing a cost-competitive product and meeting or exceeding their customers' quality expectations are vital to success. For these manufacturers, automated X-ray inspection (AXI) is becoming increasingly popular because, like its counterpart automated optical inspection (AOI), AXI is a noninvasive inspection solution.

When infrared technology wasn't enough, pulsed ultrasound found the cause of leaky MEMS tubes.

An early and critical step in microelectromechanical system (MEMS) production is the bonding of two silicon wafers. The success of later processing steps usually is heavily dependent on the quality of the bond between the two wafers. When yield begins to decline for unknown reasons, the root cause may lie in the wafer bonding operation.

To address today's image analysis tasks, you need a judicious mix of old methods and new techniques.

The purpose of analysis is to determine whether the results obtained from an operation are accurate, logical, and true. Engineers use analysis tools to monitor a given process. In machine vision, this process of monitoring is performed using image analysis tools. Thanks to faster CPUs, these tools have become more robust and more powerful, allowing machine vision to perform in more complex applications than ever before.