Why check BGA chip with X-ray detection equipment?

Date：2021-09-06 15:58:00Views：1434

In the high-tech application scenario of electronic equipment, large-scale integrated circuit packaging has attracted extensive attention. Some large-scale integrated circuit packaging can be connected with hundreds of external connections based on their huge functions. On the chip bottom of several square centimeters to tens of square centimeters, dense connection line nodes are regularly distributed.

The surface mount element with many and dense connecting lines is installed on the PCB board to form an application circuit with corresponding functions. In this case, the nodes of components and PCB board can not be observed by human eyes, that is, visual spot welding can not be performed. However, in the actual production practice, the quality status of different nodes can not be perfect. Each spot welding can have various casting defects (such as bridging, false welding, solder ball, insufficient wetting, etc.), which will seriously affect the stability of the circuit. If there are bridging defects, the circuit will not achieve its design function, or even test operation.

X-ray uses a cathode ray tube to produce high-energy electrons to collide with a metal target. In the process of impact, due to the sudden deceleration of electrons, the lost kinetic energy will be released in the form of X-ray, which has a very short wavelength but high electromagnetic radiation. For the position where the sample cannot be detected by appearance, the contrast effect can be formed by recording the change of light intensity after X-ray penetrates substances with different densities, so as to display the internal structure of the object to be tested, and then observe the problem area inside the object to be tested without damaging the object to be tested.

Based on this invisible to the naked eye, it is powerless to select optical microscope, visual inspection, laser infrared and other detection methods. Therefore, to understand the real situation of this circuit after electric welding, it is necessary to select an X-ray detection method with the ability to penetrate non transparent substances for detection. X-ray has strong penetration. X-ray perspective can clearly show the thickness, shape and quality distribution of spot welding, fully reflect the electric welding quality of spot welding, and make quantitative analysis. To realize the quality inspection of BGA device solder joints, X-rays can not penetrate high-density and thick substances such as tin and lead, so dark images can be formed, while X-rays can easily penetrate low-density and thin substances such as printed boards and plastic packaging, and images will not be formed. This phenomenon can judge the welding quality of BGA from the images.

Common problems mainly include: BGA infiltration defect of spherical array components, internal structure crack, fault, cavity, tin connection, less tin, bad parts in complex precision assembly, displacement, hidden original, open / short circuit of PCB circuit board, electronic component failure, etc.

With X-ray nondestructive testing technology, it can well explain the physical structure characterization, defect detection and analysis, fault analysis and other problems of the internal structure of semiconductor packaging components, meet the testing requirements of high-end electronic equipment manufacturing technology, help to improve production technology and greatly improve the qualification rate.

Since the spot welding of BGA components is completely covered by the component body after electric welding, neither the traditional visual inspection method can be selected to observe and detect the electric welding quality of all spot welding, nor the automatic optical inspection equipment can be used to judge the appearance of spot welding. In order to achieve effective detection, X-ray detection equipment can be selected to detect the spot welding of BGA components.

Spot welding defects mainly include solder bridging, solder beads, holes, displacement, open circuit, loss of solder balls, fracture of welded joints, false welding, etc. This defect hidden in the internal structure has an inestimable impact on the service life and stability of electronic equipment.

With the development of innovative technology, ultra-high resolution and automatic X-ray detection equipment can not only provide time, peace of mind and reliable guarantee for the assembly of BGA components, but also play an important role in the common fault analysis of electronic equipment and improve the detection efficiency of common faults.