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The Obvious Trend Is Reflow Soldering Technology
- Jun 22, 2018 -

Circuit board, circuit board, PCB board, pcb welding technology In recent years, the electronic industry process development process, you can notice a very obvious trend is reflow soldering technology. In principle, the conventional inserts can also be subjected to a reflow process, which is commonly referred to as through-hole reflow soldering. The advantage is that it is possible to complete all solder joints at the same time, minimizing production costs. However, temperature-sensitive components have limited the application of reflow soldering, whether it is inserts or SMD. Then people turn their attention to the choice of welding. In most applications, selective soldering can be used after reflow soldering. This will be an economical and effective way to complete the remaining inserts and is fully compatible with future lead-free soldering.

The solderability of the circuit board hole is not good, there will be a virtual soldering defect, affecting the parameters of the components in the circuit, causing the multilayer board components and the inner layer line to conduct unstably and causing the entire circuit to function. The so-called solderability is the property that the metal surface is wetted by the molten solder, that is, the surface of the metal on which the solder is formed forms a relatively uniform, continuous, smooth and adherent film. The factors influencing the solderability of printed circuit boards are: (1) the composition of the solder and the properties of the solder. Solder is an important part of the welding chemical process. It is composed of flux-containing chemical materials. The commonly used low-melting eutectic metal is Sn-Pb or Sn-Pb-Ag. The impurity content must have a certain ratio control. In order to prevent the impurities produced by the oxide dissolved by flux. The function of the flux is to help the solder wet the surface of the circuit of the plate to be welded by transferring heat and removing rust. White rosin and isopropyl alcohol solvents are generally used. (2) The soldering temperature and the cleanness of the metal plate surface also affect the solderability. If the temperature is too high, the diffusion rate of the solder is accelerated. At this time, it has a high activity, which rapidly oxidizes the circuit board and the molten surface of the solder, resulting in welding defects. The surface of the circuit board is contaminated, which also affects the solderability and thus causes defects. Including tin beads, solder balls, open circuits, and poor gloss.