Detecting the welding quality of electronic components by Xray

Date：2021-09-07 11:26:00Views：1402

Welding is an important process in the assembly process of electronic products. The core functions of electronic products represented by smart phones come from the circuit board containing large and small electronic components. These components usually need to use manipulator equipment to accurately place them in different positions of the circuit board and complete welding. With the continuous development of technology, the circuit board is filled with smaller and smaller components. It depends on the robot to weld and needs to be tested to ensure the normal operation of the circuit board. When we can't detect the welding problem by naked eye, we need to use X-ray real-time testing equipment.

The welding of electronic components is divided into three categories: fusion welding, pressure welding and brazing. Now commonly used tin welding belongs to soft soldering in brazing (the melting point of solder is lower than 450 ℃), which is called tin welding because lead tin solder is used for welding. Fusion welding and pressure welding are generally used for high-power electronic components and equipment with special requirements. Through X-ray, the solder joints of electronic components can be imaged with high resolution on the computer. The principle is to use the characteristics of X-ray penetrating non-metallic substances to check whether the lower parts of components such as BGA are well welded and whether there is short circuit. Simple software settings are made to determine welding defects, and the following devices with welding problems are selected. At the same time, X-ray electronic component testing equipment can be added to the production line to further improve the testing efficiency.

1. Continuous welding: the solder between adjacent solder joints is connected together

2. False soldering: component pins are not wetted by solder, and solder pads are not wetted by solder

3. Empty soldering: all insertion holes of base materials and components are exposed, and the component pins and pads are not wetted by solder

4. Semi soldering: component pins and pads have been wetted, but some insertion holes are still exposed

5. Multi tin: the solder at the pin bend contacts the element body or sealing end

6. Package welding: too much solder makes it impossible to see the component feet, or even the edges and corners of the component feet

7. Tin beads and slag: the slag with too large diameter and length is stuck on the surface of the bottom plate

8. Less tin and thin tin: the solder does not completely wet the metal holes of the double-sided plate

9. Tin tip: the lead head of components or the tin layer of circuit board is pulled out in a sharp shape

10. Tin crack: there is crack between solder joint and pin, or there is crack between pad and solder joint or solder joint itself

11. Pinhole, cavity and air hole: there are pinholes or holes of different sizes in the solder joint

12. Pad warping: the separation between conductor, pad and substrate is greater than the thickness of pad

13. Broken copper foil: the copper foil is disconnected on the circuit board

14. Cold welding: the surface of the welding spot is not smooth, burr or granular

Conclusion: the above is the whole content of "testing the welding quality of electronic components by Xray". The welding quality directly affects the working performance of electronic circuits and electronic devices. Excellent welding quality can provide good stability and reliability for the circuit. Poor welding methods will cause damage to components, bring great difficulties to the test, and sometimes leave hidden dangers, affecting the reliability of electronic equipment.