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SMT reflow oven soldering process specific requirements

  • Time:2019-12-28
  • Visits:355

SMT reflow oven soldering process specific requirements

To achieve ideal soldering results, proper control of the SMT reflow oven soldering process is crucial. The advantage of the process is that the temperature is easy to control, oxidation can be avoided during the soldering process, and manufacturing costs are also easier to control.

1. What are the specific requirements for SMT reflow oven soldering process

(1) To set a reasonable SMT reflow oven soldering temperature curve and regularly conduct real-time testing of the temperature curve.

(2) soldering should be carried out according to the soldering direction specified in the PCB design.

(3) Strictly prevent vibration of the conveyor belt during the soldering process.

(4) The soldering effect of the first printed circuit board must be checked.

(5) Whether the soldering is sufficient, whether the surface of the solder joint is smooth, whether the shape of the solder joint is half moon shaped, the situation of solder balls and residues, and the situation of continuous soldering and virtual soldering. Also, check for color changes on the surface of the PCB. Adjust the temperature curve based on the inspection results. During the entire production process, soldering quality should be regularly checked.

2. What are the factors that affect the process

(1) Usually, PLCC and QFP have a larger heat capacity compared to a discrete sheet metal component, making it more difficult to weld large-area components than small ones.

(2) In the SMT reflow oven soldering furnace, the conveyor belt not only performs SMT reflow oven soldering on the conveyed products, but also becomes a heat dissipation system. In addition, the heat dissipation conditions at the edges and centers of the heating part are different, and the temperature at the edges is generally lower. In addition to different temperature requirements in each temperature zone, the temperature on the same loading surface also varies in the furnace.

(3) The impact of different product loading capacities. The adjustment of the temperature curve for SMT reflow oven soldering should consider achieving good repeatability under no-load, load, and different load factors. The load factor is defined as: LF=L/(L+S); Where L=length of assembled substrate, S=spacing of assembled substrate. The greater the load factor, the more difficult it is to achieve good repeatability in SMT reflow oven soldering process. The maximum load factor of a SMT reflow oven soldering furnace typically ranges from 0.5~0.9. This depends on the product situation (component soldering density, different substrates) and the different models of the reflow furnace. To achieve good soldering results and repeatability, practical experience is crucial.