BGA and solder point measurement with optical 3D surface measurement technology from FRT

A wide variety of measurement tasks have to be solved in the process-related inspection of BGAs (ball grid arrays) and soldering points as well as printed circuit boards and wafers. On materials that strongly vary in terms of structure and reflectivity, heights, profiles, volumes, roughness as well as flatness and waviness have to be determined.

The investigation of BGAs and soldering points on printed circuit boards requires a measurement method that measures the topography of these structures without contact, quickly and reliable. Highly reflective metal surfaces must be measured just as reliable as reflective lacquer and rough PCB surfaces. The determination of the volume of soldering points requires a system that also detects strongly sloped surfaces. In order to measure the highly structured surface of a BGA, jumps and rapid changes in the surface must also be detected free of artifacts. For process-oriented or integrated control, a machine with high measuring speed is required that enables high throughput.

With optical multi-sensor measuring systems from FRT, all these tasks can be performed in one machine. The system is therefore capable of recording large measuring fields, e. g. for flatness measurement, but also offers the possibility of detecting small surface areas or profiles with high resolution. In this way, volumes of individual soldering points can be determined and roughness and waviness can be determined from profile data as well as from 3D topography measurements. The measurement is fast, non-contact and thus non-destructive. For the process-related control of BGAs and solder point panels, the required individual measuring tasks can be repeatedly executed and logged in an automated measuring sequence. If necessary, image processing can be used to determine the alignment of the measuring objects in order to adjust the position of the previously defined measuring positions to the object position.

Due to the multi-sensor concept we follow, the 3D surface measuring devices of the proven MicroProf® series can be equipped with point and field of view sensors for topography measurement as well as with film thickness sensors. The greatest flexibility is offered by measuring systems that work with point sensors, which scan the surface to be detected line by line. The user can freely set the measuring field size and the number of sampling points within the measuring field. The measurement is based on the chromatic encoding of the measuring range. The basic physical effect, the wavelength dependence of the focal length of a lens, is used for high-resolution surface measurements. The method enables profile and topography measurements to be taken with a height resolution of up to 3 nm at a lateral resolution of 1 to 2 µm. Depending on the requirements, measuring heads with measuring ranges between 300 µm and 3 mm are used. The measuring head operates purely passively without moving or electronic components. This results in a high measuring rate of up to 4 kHz, but also in the robustness of the measuring method, which can be used in rough environmental conditions and works free of wear. If required, additional sensors can be integrated. If an atomic force microscope is integrated, topography measurements with sub-nm resolution can be carried out with the described measuring system. In combination with a high-precision xy-table, as well as powerful analysis software for the acquisition and evaluation of measurement data, you get a measuring system that offers the user a high degree of flexibility and solves the mentioned measurement tasks in BGA and solder point control.

The universally usable surface measuring tool MicroProf® is available in different versions. Depending on the size of the samples to be measured, you can select the system that provides the corresponding sample holder and the travel range. In addition to the MicroProf® 100 desktop unit, there are two larger models, MicroProf® 200 and MicroProf® 300, which are standalone systems.

By adding the thermal unit to the MicroProf®, you can perform measurements of the surface topography of components under controlled thermal load. This is essential because changes in the components due to thermal stress can lead to functional errors or even breakdowns. Fully automatic measurements of the surface topography at different temperatures as well as dwell times at constant temperatures are fully adjustable.

We certainly have a solution for your specific task. Do not hesitate to contact us if you have any questions. Our experts will be glad to take care of your request and develop individual solutions for you.

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