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Method for detecting BGA welding

Method for detecting BGA welding


For the BGA is concerned because the chip is welded, it is difficult to judge the welding quality. In the

absence of inspection equipment, the first visual observation of the BGA the most outside of the solder

joint situation (as shown in Figure 2), then the chip to the light, if each column can be determined by the

light can not be determined, and sometimes the size of a large point can also be seen. However, this

method can not be used to determine whether there are other defects in the solder joints or whether

there is a hole in the solder joint. To better judge the quality of the solder joint, the X light spot inspection

instrument is used.


Traditional two-dimensional X-ray direct photographic equipment is cheaper, but the disadvantage is in

two sides of the PCB board all the solder joints are also in a photo developing. For components on two

sides of the same position, the formation of these solder shadows will overlap points not clear which is

the surface of the component, if defective, it is not clear which layer. This can not meet the requirements

for accurate determination of welding defects.


In addition a 5DX HP circuit board inspection instrument is specifically designed to check the solder joints

of X ray tomography inspection equipment. Of course, it is not only able to check the BGA, the circuit

board all the solder joints which can be checked. Although it was previously thought that this device was

too expensive for solder joints inspection cost was too high but with the application of BGA devices more

and more people have been able to accept this expensive equipment. 5DX HP is a X ray tomography,

which can be used to produce the effect of the film layer. The images of X ray tomography can automatically

analyze the solder joints according to the original design data and the user settings. The CAD can be used

to perform a precise comparative analysis of all the components of the PCB. Why is there a very high effect

of X - ray radiography in tomography? This is determined by the principle of its work.


The HP system of the 5DX X system is generated by a X ray tube at the upper end of the device. At work,

the voltage must be raised from 160KV to 200V, and the current is 100mA. An electron beam produced

under high voltage will produce a X ray on the metal tungsten. This a bunch of X-ray diagonal shot down

to 7.6 (Rev / sec speed high-speed rotation, also in the following is not a scintillator platform with the

same speed and X-ray synchronous rotation. The flash device is actually a receiver for X light sensitive.

Generally speaking, metal tin, lead and other heavy metal X light will not through, will form a dark scene

and the general material is X light penetrate what can not see. X light in a position between the light

source and the platform of the flashing device to appear a gathering plane, the aggregation of objects

or images on the platform to form a clear image, but not on the aggregation level of objects or images

on the flash platform is eliminated only a shadow. The principle of X ray tomography is shown in Figure 3.

As a result of the high degree of PCB on different joints of the fault, you want to check a layer of welding

conditions as long as the layer will be adjusted to the location of the plane will be very clear to show the

results of the scan.



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