Wire bonding is a key process in semiconductor production. Extremely fine wires with diameters of 15 to 75 µm are used to create tiny electrical connections between a semiconductor chip and other components. The distances between the bond wires are often less than 100 µm. Any deviation, however small, can lead to connection errors. Therefore, wire bonding requires the highest precision and forms the basis for the production of high-performance electronics that are used in many different applications.

F&S Bondtec Semiconductor from Braunau, Austria, relies on image-processing technology with industrial cameras from IDS Imaging Development Systems for precisely determining wire positions and for quality assurance.

F&S Bondtec covers the desktop bonder and tester segment worldwide, offering a wide range of production and test equipment. It extends to the desktop microfactory, which combines all wire-bonding processes and test methods in one machine base. Since the company was founded in 1994, several thousand wire bonders and bond testers have left the factory and are in use in many laboratories, development departments, pilot production lines, and production facilities around the world.

Application

Wire bonders are available with various degrees of automation. With manual devices, each bond wire must be positioned manually before the corresponding connections can be made. Semi-automatic machines position the wire after the first bond to create a wire bridge. Fully automatic machines use a structure-recognition system to determine the position of the chips. Here, all wire bridge production is completely automatic. The operator only has to change the wire or tool on the bonder occasionally, and take care of loading and unloading.

F&S Bondtec uses image processing with IDS industrial cameras for various tasks in the production process, especially in the semi-automatic machines of the 56i series and the automatic wire bonders of the 86 series. “Our wire bonds connect previously placed microchips or other components with different contact points on printed circuit boards and breathe life into the chips,” says Johann Enthammer, managing director and CTO at F&S Bondtec. “However, positional inaccuracies of the components can occur during the upstream processes. Our machines have to determine these positional inaccuracies using the IDS camera image and our own image recognition software, and update the wire bond positions accordingly.”

Image processing is used by the semi-automatic 56i series wire bonders.

For each bonding process, parameters such as ultrasonic amplitude, force, time, or the movement sequence for setting up the bonding bridges must be programmed in advance. The camera’s image feed is also used when creating these programs. For example, you can drag a wire in the live image and change its position. The axes can also be adjusted by clicking on the image.

On the software side, the Austrian company relies on a specially developed image recognition library that works with position/pixel mapping, grayscale recognition, and edge detection.

Visual assessments of bond connections

Once the bonding process is complete, the camera is used again. “After welding, the wire bonds are visually checked by the operator via the camera image,” says Enthammer. “Among other things, the position and shape of the bond bridges are assessed. The camera image therefore has more than just one function during the bonding process.”

From one to seven industrial cameras are used per system. Depending on the type, these can be the particularly compact and cost-effective uEye XCP models. At just 29 x 29 x 17 mm, they are the smallest housed IDS cameras with C-mounts and have a completely enclosed die-cast zinc housing. Their screw-type USB micro-B connection and compatibility with the vision standard (U3V/GenICam) simplify integration.

F&S Bondtec also uses uEye CP cameras. These tiny powerhouses offer maximum functionality with extensive pixel preprocessing and are also perfect for multicamera systems, thanks to the internal 120 MB image memory for buffering image sequences. Users can choose from a large number of modern CMOS sensors. Another feature is a compact housing that measures just 29 x 29 x 29 mm.

Camera F&S Bondtec uses various uEye industrial cameras. The Eye XCP is the industry’s smallest housing camera with C-mount. Bondtec used model U3-3680XCP Rev.1.2. The uEye CP is fast, powerful, and future-proof. Bondtec used model U3-3040CP Rev.2.2.

Camera selection

The small design of the models and the large number of different sensors were important criteria when selecting the camera, as was the low thermal expansion. However, the free IDS peak software development kit, with all the programming interfaces and software tools required for operating and programming the cameras, was also crucial. Easy-to-understand functions ensure an intuitive programming experience, and quick and simple commissioning of the industrial cameras.

“The driver shows very stable runtime behavior,” says Enthammer. “The easy-to-program API and the plug-and-play functions with running software convinced us. This is because there are many different use cases for our systems that can be implemented with the API without any problems. Our machines can be equipped with up to seven different bond heads. A different IDS camera can be integrated in each one.”

Outlook

The wire bonders from F&S Bondtec ensure stable connections in semiconductor production. With the help of integrated image processing, the manufacturing quality and productivity of the systems can be further increased and rejects avoided. At the same time, the cameras make work easier for the operators.

In addition to standard products, the company develops special machines and customized software solutions that use AI models. “We definitely see a lot of potential for the use of artificial intelligence in our applications in the future,” says Enthammer.

Image processing opens up new potential, especially in conjunction with AI,  in terms of efficiency, precision, and quality. And thanks to IDS’ broad portfolio, the right “eye” can be found for every application for micrometer-precise results.