The initial stage of the wave soldering process is the most important part of the entire wave soldering quality control process. As long as the preparation work in this part is carefully checked and done, the quality of SMT wave soldering can be guaranteed only if the temperature control, transmission speed and inclination angle in the remaining production process are well controlled.
Wave soldering transport tilt angle adjustment
By adjusting the transportation inclination angle during wave soldering of circuit boards, the soldering time between the PCB and the wave crest surface can be regulated, which helps to separate the solder surface from the PCB faster and return it to the tin furnace, reducing the cost of bridging and soldering. Controlling the wave soldering transportation inclination angle can be more conducive to solder joint formation. When the PCB enters the front end of the wave crest, the substrate and the pins are heated, and before leaving the wave crest, the entire PCB is immersed in solder. Due to the wetting force, the solder adheres to the pad. Due to surface tension, it will shrink to the minimum state with the lead as the center. The wettability between the solder and the pad is greater than the solder cohesion between the two pads, which will form a round and full solder joint. The excess solder at the tail of the wave crest will fall back into the tin furnace due to gravity.
The climbing angle of the wave soldering transportation of the circuit board is 3-7°C. It is achieved by adjusting the inclination angle of the wave soldering machine transmission device. When the circuit board is wave soldered, the appropriate climbing angle is conducive to removing the gas generated by the flux remaining around the solder joints and components. Especially when THT and SMD are mixed, the PCB climbing angle should be appropriately increased due to the relatively small number of through holes; the contact time between the PCB and the wave crest can also be adjusted by adjusting the tilt angle; the larger the tilt angle, the shorter the time the solder joint contacts the wave crest, and the shorter the welding time; conversely, the longer the time the solder joint contacts the wave crest, the longer the welding time; appropriately increasing the PCB wave crest welding climbing angle is also conducive to the peeling of the solder joint and the solder wave. When the solder joint leaves the wave crest, if the peeling speed of the solder joint and the solder wave is too slow, it is easy to cause bridging;
Wave soldering wave height adjustment
The height of the wave soldering crest is determined by adjusting the speed of the wave motor through the wave soldering frequency converter. The rear crest can be adjusted to different wave shapes by adjusting the guide plate according to different factors of the circuit board. The adjustment of the wave soldering crest generally refers to the adjustment of the wave height of the wave soldering. The crest height refers to the height of the tinning of the PCB in the wave soldering. The crest height should be stable, and the crest height should be 1/2 to 2/3 of the thickness of the circuit board. If the crest height is too high, it will cause the solder joints to pull, and if the tin is too much, it will also cause the tin to overflow the component surface and burn the components. If the wave is too low, it will often cause solder leakage and tin hanging.
Appropriate crest height increases the pressure and flow rate of the solder wave on the solder joint, which is conducive to the solder wetting the metal surface and flowing into the small hole. The crest height is generally controlled at 2/3 of the thickness of the printed circuit board. The front crest of wave soldering uses a fast-moving tin wave to wash away the flux that is trapped behind the mounted components due to the shielding effect, allowing the solder joints to be reliably lubricated. The smooth wave of the rear crest is a step forward in correcting the lubricated but irregularly shaped solder joints to make them perfect.
Post time: Oct-15-2024
