October, 2024 Continued from previous page


high speed of movement (neces- sary to keep the test time within acceptable limits). Contacting the solder joints


of the components means sub- jecting the device to the force of impact of the probe, which increases as the contact speed increases. Usually, the complete testing of the board requires con- tacting the same points several times. This may wear out the pins of the components and, in the case of miniaturized compo- nents, even break them.


Motion Control For the testing of high-den-


sity boards, it is then necessary to use a tester capable of control- ling the probing motion profile, to reduce the force of impact without affecting the test time. The effective control of the


probing force mainly depends on the motion technology in use. If we consider the two technologies typically used — linear motors and stepper motors — we need to know that only the first one can provide good results at the high- est speed, since the movement profile is controlled in real time by linear optical encoders and closed-loop controllers. This technology allows the


probes to perform an “S-curve” movement, combining maximum speed with a zero-energy landing profile. With a less than 0.1 µm resolution, they guarantee a positioning accuracy and relia- bility that is about ten times higher than systems based on rotational encoders — typically used on systems with ball screw motion — and more than twenty times that of systems based on planar motors, that typically do not use any encoder. SPEA flying probe testers


are then able to overcome anoth- er accessibility limit: the height of components. Their operative systems can automatically con- sider the possible areas that can- not be overflown, optimizing the probe movement to avoid any possible collision.


Mitigating Risk Traditionally, the expecta-


tion for an in-circuit tester is that it must be able to contact, and test through a parametric verification, all the components that are assembled on a board. As mentioned earlier, this capa- bility cannot be fully reached by the bed-of-nails systems, due to their lack of accessibility when dealing with miniaturized, high- density assemblies, while SPEA flying probe testers include the suitable technology to reliably probe targets of a few microme- ters.


But what about their capa-


bility of testing? In terms of elec- trical testing, the flying probe


See at electronica, Hall A3, Booth 365 WX3000™ M


www.us-tech.com What Flying Probe Testers Can Test Today...


technology has evolved, bringing these testers from being “flying ohm-meters,” able to perform as MDA systems, to match the capabilities of an in-circuit tester. Some of them, like SPEA flying probe testers, include the same test instru- mentation designed for in-cir- cuit test platforms, therefore offering the same measure- ment capabilities. It is not only a matter of


parametric test, but it is about adapting to the increasing integration of functionality that characterizes today’s


printed circuit boards. More and more functions are integrated on a printed circuit board and their


correct functioning can be veri- fied with other test techniques, such as AOI, laser test, and RF test, which can be performed by a flying probe tester with- out affecting the costs of a test fixture. In alternative or in addi-


tion to the electrical probes, SPEA flying axes can mount specific tools such as robotic force actuators, light meters and spectrometers, laser meters, optical cameras, ther- mal cameras, and even sound meters.


SPEA 4080 flying probe tester. Continued on page 53


Page 51


WX3000™ Metrology and I ev


ology and Inspection Systems for Wafafer-Level and Advanced Packaging


Seriously Fast. tio


dvanc Copper Pillar


Micro Bump


Flip Chip (c4) Powered by


Multi-Reflection Suppression® (MRS®) Technology


BGA Ball


2-3X Faster with High Resolution and High Accuracy WX3000 3D and 2D metrology and inspection system provides the ultimate combination of high speed, high resolution and high accuracy for wafer-level and advanced packaging applications to improve yields and processes.


Powered by Multi-Reflection Suppression (MRS) Sensor Technology The 3-micron NanoResolution (X/Y resolution of 3 micron, Z resolution of 50 nanometer) MRS sensor enables metrology grade accuracy with superior 100% 3D and 2D measurement performance for features as small as 25-micron.


Ideal for wafer bump metrology, solder on wafer metrology and for measuring photoresist and plating uniformity to improve the plating process.


100% 3D and 2D metrology and inspection can be completed simultaneously at high speed (25 300mm wafers/hour and 55 200mm wafers/hour) as compared to a slow method that requires two separate scans for 2D and 3D, and only a sampling process.


nordson.com/testinspect | +1 760.918.8471 Copyright © Nordson Corporation. All rights reserved.


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