As a model of small devices BGA in recent years, the equipment is widely used in electronic equipment QFP package devices or PLCC compared with the package devices, BGA the device has a large number of pins, small inductance and capacitance between pins, pin coplanar strong, good electrical performance, good heat dissipation performance and other advantages. All the same. BGA equipment has many advantages, but there are still unchangeable disadvantages: that is, after the completion of BGA welding, because all spot welding is below the abdomen of the device itself, the traditional estimation method can not observe and detect the welding quality of all spot welding, nor can AOI (automatic optical detection) equipment be used to evaluate the quality of spot welding appearance. At present, common methods are adopted. X-RAY inspection equipment to BGA inspection equipment spot welding physical structure.
X-RAY detection principle
X-RAY detection equipment is based on the X-ray image principle, the X-ray generator will be transmitted to the detected printing plate group and printing plate group BGA the device for direct exposure. X-rays cannot produce dark images through dense and thick substances such as tin and lead, but they will randomly produce images through small and thin substances such as printing plates and plastic packaging to complete the welding spot welding quality inspection of BGA devices.
Solder joint defect type
1. Solder bridge connection
Because the solder bridge connection results in an electrical short circuit, there should be no solder bridge between the adjacent solder balls after welding of the BGA equipment. This defect is used in use. It's very obvious when you X-RAY the device.
2. Solder bead
Welding bead is one of the main defects in the process of surface mounting. There are many reasons for welding bead. The flaw lies in the flaw. The X-RAY image area is also easy to identify, the application area is also easy to identify, X-RAY observation and measurement of solder beads, should pay attention to its specifications and position requirements, do not violate the minimum electrical clearance requirements.
3. Air welding
Generally speaking, air welding is caused by insufficient reflux welding process. In the process of reflow welding, the solder ball and solder paste did not form a good fusion, and could not produce a well-wetted co-crystal. Air welding is a kind of defect which can not be ignored. It is easy to cause the equipment to fall off and affect the electrical performance of the equipment. Air welding defects also need to be inspected through the Angle of rotation ray, and then effective measures should be taken to prevent their occurrence.
It is a cost-effective method to use X-RAY inspection equipment to check the welding quality of BGA equipment. With the development of new technology, ultra-high resolution, intelligent X-RAY is not only inspection equipment BAG equipment assembly to provide time-saving, labor-saving, reliable guarantee, also can play an important role in electronic equipment fault analysis, improve the troubleshooting efficiency.
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