| What are X-rays? |
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X-rays are a highly-energetic form of electromagnetic radiation with a wavelength in the range of 1nm to 1 pms, approximately 1000 to 1,000,000 times smaller than the wavelength of light. Due to their being highly energetic, X-rays are able to pass through materials that absorb ordinary visible light. |
| What is an X-ray image? |
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Part of the X-ray spectrum is absorbed when passing through an object. The more matter the X-rays need to pass through, whether it is thicker or has a higher density, the more X-rays are absorbed and do not pass through the object. The X-rays that manage to pass through the object strike a detector. On the image created on the detector, X-rays appear in different shades of gray according to their intensity. Parts of the object that are thicker or higher in density, as is the case with materials such as iron, copper and lead, are displayed darker than less dense materials such as plastics, paper or even air. |
| How do X-ray inspection systems work ? What are the fields of application? |
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| In general, X-ray inspection systems consist of a radiation safe enclosure, the radiation protection cabinet, containing, in linear alignment, the X-ray tube and the X-ray detector. A remotely controllable manipulating unit allows the user to position the sample within the beam. The final X-ray image is displayed on a monitor for computerized image processing. In addition, the X-ray system may be outfitted with an electronic program control allowing automated sample inspection. The X-ray image shows object features based on differences in material density. Typical applications include the radiographic analysis of solder joints, printed circuit boards, welded seams, castings, mechanical and electronic devices, sensors, spray-castings, technical fabrics and much, much more. |
| What is Computed Tomography? |
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Computed tomography provides a three-dimensional, spatial image of the object under inspection. The CT-image shows different materials as different shades of gray (or as different colors). To generate a three-dimensional image, a large number of two-dimensional X-ray images is taken around a single axis of rotation (360 °). These X-ray images are then reformatted as volumetric representations of structures (3D) using a complex reconstruction algorithm. |
| What are the differences between tomosynthesis/ laminography and CT? |
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| In computed tomography, a three-dimensional image is generated by rotating the object 360 °around a single axis of rotation while taking between 200 and 2000 two-dimensional X-ray images. During this process, the X-ray beam hits the object perpendicular to the axis of rotation. Afterwards, the final three-dimensional image is numerically reconstructed based on the two- dimensional images. The three-dimensional image can be separated into virtual slices enabling analysis of the object at any angle. In digital laminography, an X-ray source and a digital detector move asynchronously on circular orbits around the same axis in such way that only the points in one plane, the focal plane, project to the same position on the detector while the points in all other planes are blurred. The focal plane is what the user is seeing on the detector during this process- an oblique view image, for example at an 45° angle, of always the exact same object detail. This way, between 8 to 30 images are taken at the same angle but from different directions above and below the focal slice and are projected onto different locations on the detector. These images are then superimposed to create cross-sectional images (slices) of the object, perpendicular to the axis of rotation. This process of superimposing cross-sectional images is called tomosynthesis. It is possible to use these images to render three-dimensional data and generate three-dimensional images. These are, however, characterized by strong, image-distorting vertical artefacts, such as pseudo structures which, for example, cause spheres to appear as double-cones and, often, loss of detail In direct comparison, Computed Tomography clearly offers better results than laminography. This is due to the fact that Computed Tomography uses complex mathematical procedures for exact object reconstruction. |
| Can I use high-resolution Computed Tomography to perform simple X-ray inspections? |
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| Our v|tome|x product series was designed for both high-resolution 2D and 3D X-ray inspection. Just use the mouse to select the relevant operating mode. |
| When should I use 2D radiographic imaging (2D) and when Computed Tomography (3D)? |
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| We recommend 2D solutions for the inspection of large batches, since 2D inspection is usually faster and can easily be automated. For failure analysis and quality control, Computed Tomography, possibly in combination with high- resolution 2D inspection solutions, is the method of choice for they provide optimal spatial information at highest possible resolution and contrast. An aspect not to be underestimated is the actual composition and shape of the sample: Compact samples such as sensors and castings are best inspected using Computed Tomography. Nonetheless, finding the perfect X-ray inspection solution depends greatly upon the inspection task at hand. Please contact us- we’ll be happy to find the inspection solution that is best for you. |
| Can I use computed tomography to measure my sample? |
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High-quality CT-systems provide distortion-free, three-dimensional images with calibratable scale. Using a special surface extraction module by phoenix|x-ray, the object surface can be extracted based on these three-dimensional volume data sets and saved as a standardized file format. By means of a customary software such as „Polyworks“, these data sets can be compared against CAD-data. Furthermore, the phoenix|x-ray software allows the user to measure the outside and inside of the object and, as opposed to conventional and mechanical measuring instruments, even complex interior surfaces- by fitting ruled geometries, radiuses, planes, and other object features can be measured. |
| Is there a difference in lifetime between open and sealed X-ray tubes? |
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| Sealed X-ray tubes are sealed, evacuated glass tubes containing all components necessary for producing X-rays. This type of tube is maintenance-free, but has a shorter lifetime than open tubes and will need replacing at some point. Open X-ray tubes use vacuum systems to create a vacuum inside the X-ray tube. Due to the fact that the tube’s steel enclosure can be opened to replace consumable parts (Filament, target), this type of tube offers almost unlimited lifetime. Open microfocus and nanofocus™ X-ray tubes can be operated at considerably higher voltages and tube currents, and offer therefore considerably higher resolutions, magnifications and overall image quality than comparable sealed tubes. phoenix|x-ray offers both types in a wide range of variations to meet all of our customers’ technical and economical needs and provide each customer with an optimum solution! |
| What kind of solder joints can be inspected automatically? |
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| phoenix|x-rays offers evaluation algorithms for all common types of SMT solder joints: BGA, CSP, QFP, Gullwing, J-Lead, QFN, MLF, chip components and, using phoenix|x-ray’s oblique view imaging technique, even thru-hole solder joints such as PTH and THT- Type solder joints. Also the percentage of voiding in solder joints, an particularly crucial factor when examining assemblies, can be determined according to different criteria. For atypical solder joints and new evaluation criteria, the user may create new evaluation routines using the phoenix|x-ray’s Xe² (X-ray image Evaluation Environment). |
| What are the determining factors for image quality? |
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| Image quality is determined by two variables: image resolution and image contrast. Image resolution describes the detail an image holds. It quantifies how close lines can be to each other and still be visibly resolved. It is defined in terms of periodically recurring lines, the “horizontal lines of resolution”, which is the number of alternating lines that can be reproduced in an X-ray image and all be seen distinctly. For high magnifications, such as 100x or higher, resolution equals focal spot diameter divided by two. (Feature recognition, that means the size of the smallest, visibly resolved object, is defined as one third of the focal spot diameter). For lower magnifications (< 10 times), the detector’s effective pixel width is the decisive factor. The image contrast is dependant on the tube current and, above all, the signal-to-noise ratio on the detector output screen. For highest image quality, choose an X-ray system that is supplied with an X-ray tube offering a focal spot that is as small as possible (nanofocus®) while, at the same time, having enough power to ensure a low detector signal-to- noise ratio. The “high-power nanofocus®”- tube by phoenix|x-ray meets all these requirements. The detector, just as the digital ones used by phoenix|x-ray, should have little intrinsic noise but a high dynamic range- ideally, 16-bit with 65,536 gray scales. |
| What does “easy and intuitive use” mean? |
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| To provide outstanding ease of use and to make operation as easy and intuitive as possible, we center our designs around the following: Ergonomics phoenix|x-ray systems can be operated in either sitting or standing position. The large window ensures that the sample will remain in sight of the operator at all times. Other user-friendly features are the tilting, height-adjustable control panel and the inclined door for easy introduction of the sample. Intuitive manipulation with “Easy View Configuration” phoenix-ray systems are equipped with “Easy View Configuration”. This means that the object is displayed on the 21“ TFT-monitor in exactly the same way the operator sees it through the viewing window. This holds true for oblique views, too. A laser crosshair on the sample indicates the center of the field of view. Whenever the manipulator is used to move the actual sample inside the X-ray system, the image on the monitor changes accordingly. When tilting or rotating the sample or changing magnification, both X and Y axis move synchroneously so that the center of the field of vision remains constant. Example: The operator moves a solder joint into the centre of the X-ray image. This solder joint will remain in that exact same position regardless of changes in magnification or orientation made to the actual sample, thus making the inspection process as user-friendly as possible. With the novel “Easy View Configuration”, phoenix|x-ray offers an intuitive sample manipulation tool that makes X-ray inspection easy- even for beginners. A variety of operating modes to choose from X-ray systems by phoenix|x-ray offer a number of operating modes to suit most preferences and technical requirements. Users may select one or a combination of the following:
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| What does “operator-friendly” programming mean? |
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For automated or semi-automated inspection, our systems may be programmed for various levels of complexity via intuitive user interfaces (GUI):
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| When does it make sense to use a 2-megapixel or 4-megapixel camera? |
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| phoenix|x-ray systems are outfitted with an image intensifier. The resolution of the X-ray image is only limited by the size of the X-rays tube’s focal spot and the loss of magnification that can be attributed to the detector is only minimal. In order to avoid unnecessary losses of resolution, it is crucial to at least use a 2-megapixel high-resolution camera. To meet highest demands, phoenix|x-ray also provides 4-megapixel cameras. For a 2-megapixel camera to reach its full potential, it is necessary to use it together with a high-resolution X-ray tube and high-quality image intensifier. Typical applications include: bond wires, flip-chip solder joints, detection of cracks, etc. |
| What is a digital image chain? |
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A digital image chain is an image chain that is equipped with a digital detector instead of an analogue one. The digital detector converts X-ray signals into digital images for display on a monitor and digital image processing. Unlike conventional image intensifier chains, digital image chains provide better signal-noise ratios and higher image contrast while eliminating image artefacts and distortions. |
| What is a CNC-control and what does it do? |
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CNC stands for Computer Numerical Control, meaning that both manipulator and axes are controlled by the computer for precise and automated sample positioning by means of semi-automated and automated (AXI) inspection programs. CNC-controlled inspection allows the user to set up reproducible routines making inspection easier and faster. |
| What is the highest possible feature recognition/detail detectability? |
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| The obtainable feature recognition depends greatly upon the X-ray tube used. Tubes by phoenix|x-ray provide the following feature recognitions: x|s 240d (high-performance tube, 240 kV, 320 W) Feature recognition: <2 µm x|s 180t submicron (transmission tube, 180 kV, 20 W) Feature recognition: <1 µm x|s high-power nanofocus™ (transmission tube, 180 kV, 15 W) Feature recognition: 200 – 300 nm (0.2-0.3 µm) |
| Is there a risk of my sample being damaged due to collision or exposure to radiation? |
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| No. phoenix|x-ray systems are equipped with a variety of safety precautions and devices to prevent sample damage: Collision protection: phoenix|x-ray’s X-ray inspection systems provide active collision protection. As soon as the sample gets to close to the tube, the manipulator automatically stops. Unlike with merely mechanical safety devices, the authorized user may temporarily defeat the active collision protection mechanism to move the sample as close to the tube as possible to obtain the maximum magnification. Merely mechanical collision protection mechanism do not provide this option, thus decreasing magnification by 10 to 100 times. Reduced dose of radiation: High doses of radiation can potentially damage semiconductor components. The radiation dose typically used in X-ray inspection is only a thousandth of the dose rate that would cause damage to semiconductor components. phoenix|x-ray provides the user with a variety of options for controlling and adjusting the dose rate when dealing with very sensitive samples.
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| What are the benefits of using a higher tube voltage? |
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| The higher the tube voltage, the faster, and therefore more energetic, the X-ray photons, the greater their ability to pass through matter. Detectors require a certain minimal photon intensity to generate a high-quality X-ray image. When inspecting particularly thick or dense objects, it is crucial to set a higher tube voltage to obtain a high- contrast, low-noise X-ray image. Application examples: Tin or lead trough-holes, welded seams in denser steel parts. Please Note: In order to obtain artefact-free results with Computed Tomography, higher tube currents are necessary than in regular 2D X-ray imaging. |
| What are the benefits of “ovhm” - oblique views at highest magnification? |
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| Oblique views provide three-dimensional views of the object under inspection or reveal object details that would not be visible otherwise, a typical example being the inspection of BGA solder joints: Oblique views reveal the vertical contours of the solder joint, void and pad wetting distribution. phoenix|x-ray’s ovhm-option offers oblique views without any loss of magnification. |
| When is it beneficial to use 70°-oblique view? |
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In most cases, it is helpful to inspect the sample from as many angles as possible. But especially with flat components, this does not always make sense. Starting at 65° to 70° and up, even solder joints with a greater pitch begin to overlap in the image, which makes inspection harder not easier. Moreover, material density increases by 1/cos (radiation angle). This means that, with wide samples and a radiation angle of 90°, material density is arbitrarily big resulting in a very low-contrast image. |
| Is it possible to integrate the X-ray inspection system into the production line? |
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Integrating an X-ray inspection system into the production line is possible, provided that:
Example: A cycle time of 20 seconds is sufficient to thoroughly inspect the solder joints on a PBGA. However, if all of the 3000 solder joints on a component are to inspected in 40 seconds, only a superficial inspection is possible. Alternatively, there is always the option to set up an X-ray inspection system in proximity to the production line, but not as part of the production line. This option is recommend for the inspection of random samples or smaller batches consisting of very diverse products. Automatic feed-in of samples is still possible. This way, phoenix|x-ray systems can be integrated into the production cycle for the automated (AXI), high-resolution inspection of random samples. |