/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.
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