BGA patch welding plant
Bga patch welding detection methods mainly include visual method, infrared detection method, online detection method, etc. In these methods, the development of model patch is economical,R & D model patchThe visualization method is commonly used, which is economical, simple and feasible. Several other options require active device support.
1 visual method
Visually relying on the human eye to observe the soldering condition of the solder joint surface indirectly, it can check the soldering defects such as poor wettability, inappropriate solder volume, scattered pads, bridging, small solder ball spatter, dull solder joints and missing soldering. The simplest is a magnifying glass, which is usually used with 510 times the light of a solid magnifying glass. It is completely suitable for the inspection of low-density circuit board welding. The disadvantage of this thing is that it is easy for the inspector to sit up. A better visual inspection instrument is the camera screen performance inspection instrument, which can be enlarged and adjustable up to 80-90 times. It displays the welding part of the board on the screen through ccd, so that people can watch the screen like watching TV. Senior inspectors can take the initiative to move the circuit board welding in two directions, and can also take the initiative to locate and realize the detection of key parts of the pcba. Equipped with a video recorder to record the inspection results.
2 infrared detection
The infrared detection method is the radiant heat from the infrared beam to the solder joints on the board, and then detects whether the heat conduction curve of the solder joints can be normal, so as to identify whether there are cavities inside the solder joints, and achieve the purpose of indirect detection of welding quality. This detection method is suitable for large quantities , Active welding, and the consistency of the pad is good, the component volume is not much different. In addition, other factors have too much influence on the cooling characteristics of the solder joint. Because the conditions of this detection method are more qualified, there are differences in the size of solder joints for any kind of circuit board soldering. Therefore, it is less used in electronic product testing
X-ray method: The talent of X-ray to pass through solder does not pass through copper, silicon, FR 14 and other materials, showing the characteristics of strong dispersion of welding thickness, shape and mass density.This detection is actually used for invisible welded joints (ie, hidden welding joints). Soldering) It places the circuit board to be tested in the X-ray channel. On the performance screen, the solder joints can be seen to block the X-rays through the solder joint surface.
4 online test
The online test method is implemented by an online tester, which connects the test points on the soldering parts of the circuit board to the tester through a signal connection component called a "bed of needles" on the tester. It can check the circuit board welding open circuit, short circuit and faulty components, and can also check the function of the components, such as the resistance and capacitance value and the polarity of the transistor. Using the integrated circuit floating foot test method, the virtual solder foot of the integrated circuit can be detected. If the component density of the circuit board is large, the test points required for poor configuration can deceive the boundary scan technology, and these test points pass the planned test circuit acquisition board The edge bridge of the weld allows the online tester to measure the desired point position.
The online test of the R&D sample patch is a kind of electrical signal test. It can check the welding form of the circuit board welding. This inspection is very close to the actual situation. Generally, the installation and application can be carried out at the end of the online test of the circuit board welding, but It cannot give the quality of the welding results, and there is no intuitive solder joint safety.