/What are the most common problems in PCB assembly?
As a member of the PCB assembly factory, according to experience, we summarize some of the most problematic packaging and problems (according to the difficulty) as follows:
(1) QFN: The most common adverse phenomena are bridging and virtual welding (open welding).
(2) Close-footed components: such as SOP QFP below 0.65 mm, the most likely adverse phenomena are bridging and virtual welding (open welding).
(3) Large spacing and large size BGA: The most common adverse phenomenon is the stress fracture of solder joints.
(4) Small spacing BGA: The most common adverse phenomena are bridging and virtual welding (open welding).
(5) Long fine spacing meter sticking connector: the most likely adverse phenomenon is bridge connection and virtual welding (open welding).
(6) Micro-switches and sockets: The most common adverse phenomenon is the internal rosin.
(7) Transformers, etc.: The most common bad phenomenon is open welding.
The main causes of common problems are:
(1) The bridging of micro-spacing components is mainly caused by poor solder paste printing.
(2) The cracking of large size BGA solder joints is mainly caused by moisture.
(3) The bridging and virtual welding of BGA with small spacing are mainly caused by poor printing of solder paste.
(4) The poor coplanarity of the pins of the components is the main reason for the open welding of transformers and other components.
(5) Bridge connection and open welding of long fine gauge table-mounted connectors are largely due to the different welding deformation of PCB and the layout direction of sockets.
(6) The internal rosin of micro-switch and socket is mainly caused by the capillary effect formed by the structural design of these components.
1.Snpb Hot Air Leveling craft. The Snpb Hot Air Leveling craft is a traditional PCB pad coating method. The specific craft process is immersed in the molten Snpb alloy after the PCB circuit is etched, and then slowly lifted and coated with a Snpb alloy layer under the action of hot air, which is ...
The width of the printed conductor depends on the current carrying capacity of the conductor and the allowable temperature rise. The thickness of the copper foil plated copper foil is generally 0.02 to 0.05 mm. The different widths printed conductors have different cross-sectional areas too. The ...
After the position and shape of the components on the PCB board are determined, the wiring can be performed according to the position of the components. The following are the basic requirements for the circuit board: The low frequency wires are placed close to the edge of the printed circuit boar...