Design of X-ray units for inspection applications (review)

Abstract

A review of the structural elements (individual components, printed circuit boards, etc.) of X-ray systems intended for inspection of electronic products is presented. The basic principles of constructing such systems and typical composition of the equipment capable of providing the minimum necessary functionality are considered. Among the main technical characteristics an emphasis is made on the resolution power, which depends on the pixel size and thickness of the scintillator layer of the X-ray detector, as well as on the size of the effective focal spot of the X-ray tube. Comparative analysis of the advantages and shortcomings of clastic (open type) and sealed (closed type) X-ray tubes – one of the main nodes of such systems-is carried out. A structural diagram of a clastic X-ray tube is presented along with and the characteristics of domestic and foreign developments. The main disadvantages of the systems based on clastic tubes are considered. Large dimensions, large weight, relative complexity of the construction, presence of the vacuum-tight collapsible connections, the necessity of using a pumping system providing high vacuum, the necessity of high-voltage training of the tube assemblies after their replacement, and high cost are noted separately. The design of sealed off BS microfocus X-ray tube and radiation sources on their base which can be used in the development of domestic X-ray systems are briefly described. The diameter and length of the metal-glass cylinder tube are 75 and 315 mm, and the diameter and length of the copper anode tube 10 and 100 mm, respectively. A tungsten target is deposited on a beryllium substrate (X-ray tube exit window) with a thickness of 0.2 mm. The minimum focal length during x-ray photography is 0.5 mm. A comparative analysis of the characteristics of a clastic (collapsible) X-ray tube with continuous pumping and an X-ray tube sealed from an exhaust cart revealed the possibility of successful use of sealed tubes in modern X-ray systems used for inspection applications.