Key points of soldering operation for electronic circuit boards

1) Manual welding

① Before welding, the insulation material should be checked in advance, and there should be no signs of scalding, burning, deformation, cracks, etc. During welding, it is not allowed to scald or damage components.

② The welding temperature should generally be controlled at around 260 ℃, and should not be too high or too low, otherwise it will affect the welding quality.

③ The welding time is generally controlled within 3 seconds. For welding components with high heat capacity such as multi-layer boards, the entire welding process can be controlled within 5 seconds; For the soldering of integrated circuits and thermal sensitive components, the entire process should not exceed 2 seconds. If the soldering is not completed within the specified time, it should be re soldered after the solder joint has cooled down, and the quality standard for re soldering should be the same as that of the solder joint during the first soldering. Obviously, due to factors such as differences in soldering iron power and solder joint heat capacity, there is no fixed rule to grasp the welding temperature in practice, and it is necessary to treat the conditions in detail.

④ During welding, it is necessary to prevent nearby components, printed boards, etc. from being affected by overheating, and necessary heat dissipation measures should be taken for thermal sensitive components.

⑤ Before the solder cools and solidifies, it is necessary to securely fix the welded area without swinging or shaking. The solder joint should cool naturally, and if necessary, heat dissipation methods can be used to accelerate cooling.

2) Wave soldering

① It is necessary to apply soldering flux to ensure that the surface of the board and leads are quickly and thoroughly wetted by solder. Generally, rosin type flux or water-soluble flux with a relative density of 0.81-0.87 is selected.

② The circuit board coated with flux should be preheated and generally controlled at 90-110 ℃. Grasping the preheating temperature can reduce or prevent the occurrence of sharp and rounded solder joints.

③ In the welding process, the temperature of the solder should generally be controlled within the range of 250 ℃± 5 ℃, and its suitability directly affects the welding quality; The inclination angle of the welding fixture entering the wave crest should be adjusted to 6. about; The welding line speed should be controlled between 1-1.6 n/min; The peak height of the solder surface in the solder bath is about 10mm, and the peak is generally controlled at 1/2 to 213 of the thickness of the circuit board. If it is too high, it will cause molten solder to flow onto the surface of the circuit board, forming a "bridge".

④ It is necessary to perform appropriate strong wind cooling on the circuit board after wave soldering.

⑤ The cooled circuit board needs to have its component leads cut off.

3) Reflow soldering

① Before welding, it is necessary to clean the solder and the surface of the workpiece, otherwise it will directly affect the welding quality.

② Being able to control the amount of solder applied in the previous process reduces welding defects such as virtual soldering and bridging, resulting in good welding quality and high reliability.

③ Partial heating heat sources can be selected, so different welding methods can be used for welding on the same substrate.

④ The solder used for reflow soldering is a solder paste that ensures the correct composition and generally does not contain impurities.

(4) Board cleaning

After welding is completed, it is necessary to thoroughly clean the surface of the board in a timely manner to remove residual solder, oil, dust and other contaminants. The detailed cleaning process should be carried out according to the process requirements.

Article source: PCB manufacturerhttp://www.yonghongpcb.com/