Microchips and printed circuit boards, phones and tablets, or batteries for electric vehicles – when it comes to the inspection of planar objects, laminography is the method of choice.
Laminography: combining the benefits of 2D and 3D inspection
Computed laminography is sometimes referred to as “2.5D inspection” because it is a technological intermediate between 2D X-ray radioscopy and 3D computed tomography (CT). Laminography addresses the specific challenges of inspecting flat components, such as printed circuit boards (PCB), microchips (IC), entire cell phones, tablets, laptops, or even scripts on papyrus. While a 2D X-ray inspection provides high resolution but does not give spatial information, 3D CT supplies good spatial information but can lack resolution. A case for laminography: It adds depth information to high-resolution 2D images, so defects can be reliably detected and spatially located in a plane object.
How do laminography and CT create image data differently?
Unlike computed tomography, laminography does not record 360-degree projections to generate spatial information but scans objects from a limited angular range. This limited angle allows moving the X-ray tube much closer to the flat inspection object for higher resolution. The inspection system generates high-resolution slice images in the lateral plane of the object.
Laminography is supported by these Comet Yxlon systems
- Cougar EVO
- Cheetah EVO
- FF85 CT
Electronics: testing printed circuit boards (PCB) with laminography
Laminography is the ideal technology for quality assurance of solder joints, for example on ball grid arrays (BGA) which are reflow-soldered to circuit boards. Inspection of the solder joints ensures that the contact areas are large enough to conduct current or heat as specified, and it determines the existence, size, or distribution of voids. When inspecting densely packed double-sided PCBs, systems such as the Comet Yxlon Cheetah EVO and Cougar EVO use laminography to create layered images of the contact area, free of overlays of components on the other side of the PCB obstructing the view as in a 2D X-ray images. For the final evaluation of the solder joints, software support is provided by the VoidInspect CL inspection workflow.
Semiconductors: quality control of microchips
In ICs and wafers, it’s not the connections between a PCB and a chip that need an inspection, but the connections between different layers within a chip – for example between silicon dies or between silicon dies and a substrate or redistribution layer. Since advanced packaging ICs contain several layers, a 2D radioscopic image is usually insufficient for analysis, because it does not give spatial information and the different internal structures tend to overlap. Systems such as the Comet Yxlon Cheetah EVO and Cougar EVO use laminography to produce high-quality images of the interconnecting plane.
Assembly checks of flat electronic devices
Since critical components in tablets, mobile phones, or laptops are typically arranged in one plane, laminography is a particularly suitable inspection method for these flat electronic devices. During quality assurance and failure analysis, the Comet Yxlon laminography systems reveal whether all parts are assembled and correctly positioned, or whether there are mechanical defects such as breaks in connections, connectors, or circuit boards. With the help of high-resolution laminography, it is also possible to, e.g., detect short circuits between wires or to determine whether the adhesive is where it is supposed to be, for example in cell phone displays.
Non-destructive inspection of EV battery cells and modules
In the fast-developing e-mobility sector, battery configurations for electric cars are changing quickly. To ensure safety and quality in mass production, lithium-ion batteries need to be inspected in large quantities. Inspection during production calls for high throughput in addition to a high resolution compared to the size of the battery. In contrast to classic 2D testing, laminography allows inspecting the internal structures of batteries even more reliably and accurately, by e.g., revealing the geometry of packed electrodes with wall distances and angles, anode overlaps, or inclusions of foreign objects or voids.