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 When it comes to electronic circuits, we must talk about the electronic components soldered on PCBs. At present, most electronic circuits are composed of surface-mounted components. The mounting method of such electronic components is relatively simple. The conductive pads formed on the surface of the mounting component connect to the pads of the substrates, and the lead-free solder paste is used for soldering. The predecessor of surface mounting technology (SMT) is through-hole technology (THT). THM components usually have leads that can be inserted into specific plated holes on the PCBs and soldered. Although THT has become out of date, it is still used on some occasions, such as the soldering of high-stress connectors. Therefore, we still need to be concerned about the assembly technology of THT components. Dual Inline Package Structure The Dual In-Line Package (DIP) is a common through-hole component. DIP carries out the wire-bonding process on the chip to conn...

 In the solder paste process (SMT), the minimum safe distance between the SMD pads and the inline pads is recommended to be 0.4mm to 1mm. this distance effectively prevents solder paste bridging, component interference, and ensures soldering reliability. For specific applications, refer to IPC-7351 standard and adjust with actual manufacturing capability. Detailed requirements and basis 1. Safety distance norms Basic requirements: The distance between adjacent pad edges should be greater than 0.4mm to prevent tinning or short-circuiting during soldering. The distance between direct insertion pads and SMD pads is recommended to be at least 1.5mm (mixed assembly scenario) to avoid component interference and soldering defects. Special requirements for solder paste process: For pad spacing ≤ 0.5mm, it is necessary to ensure that the solder paste covers 100% of the pads with no offset or bridging. When the pad spacing is 0.65mm~1.25mm, the solder paste offset is allowe...

 Solder Drawbridge Effect: Analysis of the Monumental Phenomenon in Surface Mount Technology I. Definition and Phenomenon Soldering drawbridge effect, also known as Tombstone Effect or Manhattan drawbridge, is a common assembly defect in surface mount technology (SMT). It is characterised by chip passive components (such as resistors, capacitors, inductors) in the reflow soldering process, one end of the PCB pads from the warping, shaped like a tombstone or drawbridge structural abnormalities. II. Causes and Mechanisms 1. Core causes Uneven melting of solder paste: Components at both ends of the solder paste heat melting time is not consistent, resulting in differences in wetting power. One end of the paste melts first, generating surface tension, the other end is not melted or melted slower, resulting in an unbalanced moment. Solder pad design problems: Size asymmetry: pads are too large or inconsistent in size at both ends, causing components to slide. Connectio...

 Solder paste not adhering to the pad is a common problem in electronic soldering, usually caused by oxidation, contamination, insufficient temperature or solder/flux problems. The following are the detailed troubleshooting and solutions: I. Possible causes Oxidation or contamination of the pad surface: The surface of the pad may oxidise due to prolonged exposure to air, forming an insulating layer that prevents the solder from adhering. Pad surface may be stained with dust, oil or other impurities, affecting the adhesion of solder. Improper use of flux: Flux helps to remove oxides and promote the flow of solder, but under-use, over-use, or use of an inappropriate flux may result in the pad not adhering to the solder paste. Improper soldering temperature: Soldering temperatures that are too low and unstable and inconsistent oven temperatures may result in solder that does not adequately melt and adhere to the pads. The surface tension of the melted solder is too h...