Online pcb manufacturing component incoming inspection

The performance and appearance quality of online pcb manufacturing components have a direct impact on the reliability of surface mount components. The incoming materials inspection must first check the components according to relevant standards and specifications. And pay special attention to whether the performance, specifications, packaging, etc. of the components meet the order requirement sand product performance indicators, whether it meets the assembly process and the production requirements of the assembly equipment, and whether it meets the storage requirements.

(1) Component solderability test

The solderability of component leads or electrode terminals is the main factor affecting the reliability of SMA soldering. The main reason for the solderability of online pcb manufacturing is the surface oxidation of the component leads, which is easy to occur oxidation. To keep soldering reliability, on the one hand, measures should be taken to prevent components from being exposed to the air for a long time before welding, and to avoid long-term storage; on the other hand, it is necessary to pay attention to solderability test before welding, and to find problems and solve problems. The most primitive method for processing the solderability test is visual evaluation. The basic test procedure is: immerse the sample in the flux, remove the excess flux, and then immerse in the molten solder bath. When the immersion time is about twice the actual production welding time, take it out. For visual evaluation, this test is usually carried out by using a dipping tester, which can precisely control the sample dipping depth, speed and dipping residence time.

(2) Component pin coplanarity detection

Surface-mounting technology is to mount components on the surface of the PCB. Therefore, there is a strict requirement for the pin coplanarity of the online PCB manufacturing device. Generally, the specification must be within the tolerance zone of 0.1 mm. This tolerance zone consists of two planes, one is the pad plane of the PCB, and the other is the plane where the component leads are located. If the three lowest points of all the pins of the component are in the same plane parallel to the solder plane of the PCB, and the distance between each pin and the plane does not exceed the tolerance range, mounting and soldering may be performed, otherwise it may occur solder faults such as pins virtual welding, missed welding and the pins are not coplanar, as shown in Figure 8-1.

There are many methods for detecting the coplanarity of component leads. The easiest way is to place the components on the optical plane and use a microscope to measure the distance between the non-planar pins and the optical plane. At present, the high-precision patch system generally has a self-contained mechanical vision system, which can automatically detect the coplanarity of the components before the patch, and eliminate the components that do not meet the requirements.