SMD components repair process
Release time:
2022-12-15
【Summary Description】 The repair process can be divided into flux coating method, solder bridging method and solder surrounding method according to the material; according to the size of the component removal force, it can be divided into surface tension method, tweezers method and vacuum method. The first step in the repair process is non-destructive welding. Tables 2 to 6 show the Welding tools and processes for repairing SMD components, QFP, BGA, LCCC and other major surface mount components, respectively. After successful removal, the liner needs to be cleaned. The preparation of the substrate pads is very important before reassembling the components on the old pads. During this process, care was taken to avoid thermal and mechanical damage to the liner. Pad preparation includes: (1) Removal of old solder. Can use soldering iron, tin absorption soldering iron, copper braid, special soldering iron, etc. (2) Clean the pad surface. It is mainly to remove flux residue, as well as alcohol, brushes, etc. can be used; (3) Add new solder. This step can also be regarded as the step of mounting components, mainly pre-plating solder on the pads. The method may use a soldering iron, a welding wire, and a solder paste. 37 shows a process comparison for removing old solder when repaired with a copper braid. Table 7 shows several common pad cleaning methods. Table 8 lists several common methods of soldering and surface tinning. After the surface of the backing plate is cleaned and leveled, it can be repaired and assembled according to the component assembly process described herein. It is worth noting that when QFP is repaired and disassembled, if there is no special repair table, you can also refer to the soldering iron repair process shown in Figure 38, but it will cause great damage to the pins of the components and is generally not recommended. When repairing BGA, it is necessary to simulate the BGA welding process, dry the PCBA, remove the moisture that may invade, prevent pitting or delamination, and set the preheating melting curve. Notably, some fine-pitch elements are easily bridged during the repair process. Soldering iron common removal methods are drag and diffusion method. The mechanism is that the attraction of the solder head to the solder must be greater than the attraction of the pin to the solder. The temperature of the drag soldering iron is generally 280°C, and the temperature of the diffusion soldering iron is generally 315°C. Table 9 shows the method and procedure for bridging the airfoil pin and the J-pin.
The repair process can be divided into flux coating method, solder bridging method and solder surrounding method according to the material; according to the size of the component removal force, it can be divided into surface tension method, tweezers method and vacuum method. The first step in the repair process is non-destructive welding. Tables 2 to 6 show the Welding tools and processes for repairing SMD components, QFP, BGA, LCCC and other major surface mount components, respectively.
After successful removal, the liner needs to be cleaned. The preparation of the substrate pads is very important before reassembling the components on the old pads. During this process, care was taken to avoid thermal and mechanical damage to the liner. Pad preparation includes:
(1) Removal of old solder. Can use soldering iron, tin absorption soldering iron, copper braid, special soldering iron, etc.
(2) Clean the pad surface. It is mainly to remove flux residue, as well as alcohol, brushes, etc. can be used;
(3) Add new solder. This step can also be regarded as the step of mounting components, mainly pre-plating solder on the pads. The method may use a soldering iron, a welding wire, and a solder paste. 37 shows a process comparison for removing old solder when repaired with a copper braid. Table 7 shows several common pad cleaning methods. Table 8 lists several common methods of soldering and surface tinning.
After the surface of the backing plate is cleaned and leveled, it can be repaired and assembled according to the component assembly process described herein. It is worth noting that when QFP is repaired and disassembled, if there is no special repair table, you can also refer to the soldering iron repair process shown in Figure 38, but it will cause great damage to the pins of the components and is generally not recommended. When repairing BGA, it is necessary to simulate the BGA welding process, dry the PCBA, remove the moisture that may invade, prevent pitting or delamination, and set the preheating melting curve.
Notably, some fine-pitch elements are easily bridged during the repair process. Soldering iron common removal methods are drag and diffusion method. The mechanism is that the attraction of the solder head to the solder must be greater than the attraction of the pin to the solder. The temperature of the drag soldering iron is generally 280°C, and the temperature of the diffusion soldering iron is generally 315°C. Table 9 shows the method and procedure for bridging the airfoil pin and the J-pin.
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