With the rapid development of new component packaging such as BGA and CPS packaging, the packaging volume of IC devices is getting smaller, the thickness is getting thinner, the density of the lead out ends is getting higher, and the lead out ends are also moving from the periphery of the device to the bottom of the device. Nowadays, printed circuit board components (PCBAs) contain a large number of surface mount devices such as BGA and CPS packaging. Traditional detection technologies such as manual visual inspection and automatic optical inspection are almost powerless to detect the welding quality of the bottom lead out end of such surface mount devices, indicating that X-ray detection methods are particularly important.
Principles of X-ray Testing
X-rays are electromagnetic waves with extremely short wavelengths and high energy, and have strong penetration ability. When X-rays irradiate a sample, their transmission intensity is not only related to the energy of the X-rays, but also to the material density and thickness of the sample material. The lower the material density and the thinner the thickness, the easier it is for X-rays to pass through.
X-ray testing methods
Firstly, by adjusting the voltage, power, and contrast parameters of the X-ray detector reasonably, the PCBA imaging quality can be adjusted to the optimal state. The entire detection process is mainly divided into four steps. (1) Conduct a global inspection of PCBA, mainly including PCB and components; (2) Enlarge the image for local inspection to identify defects or suspected defects; (3) Identify, analyze, and confirm suspected defects through re magnification and oblique imaging; (4) Perform oblique imaging on all BGA packaging devices to preliminarily check for any solder defects.
The X-ray inspection scheme can identify common welding defects in PCBA and guide PCB design and welding process improvement.
