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Why do we need a conveyor angle during wave soldering?
I don’t know if you have noticed a phenomenon, that is, during wave soldering, the chain that conveys the circuit board will be inclined at an angle, and the circuit board will be slowly sent up from the bottom, and this inclination angle is generally called conveyor angle. That’s right, the wave soldering chain is slightly inclined at an angle to facilitate the desoldering of solder joints.
In fact, we can think of the molten tin pool as a basin of water. Imagine that you are holding a piece of wood to dip it in water, and then pick it up horizontally. There is a high probability that you will find that the water droplets are almost concentrated in the middle of the board. The speed will also be slower, and the behavior of the board in the tin pool is similar, so it is easy to cause a large number of tin connections and short circuits in the middle of the board, especially the plug-in parts.
Therefore, we need to incline the plane of the board and the tin pool at an angle, and then use gravity to let the tin liquid drip down along the inclination angle of the board and flow into the wave solder pool to achieve the purpose of controlling the amount of tin in the solder joint.
Generally speaking, this “tilt angle” will be set at about 3~7°.
The smaller the detinning angle, the fuller the solder joints, but bridging short circuits may also occur
If the de-soldering angle is smaller, that is, the more horizontal, the solder joint will be larger and fuller. If it is a multi-pin part, when the pin direction is parallel to the wave soldering, the tin of the last solder joint will be broken after drawing. The stronger the rebound force, the easier it is to form a short circuit with the adjacent front pin, and when the pin direction is perpendicular to the wave soldering, the bridging short circuit phenomenon is more likely to occur.
The larger the desoldering angle, the smaller the solder joint.
Conversely, if the de-soldering angle is larger, the solder on the solder joint will be smaller, and sometimes there will even be less tin, or worsen the shadow effect and cause the problem of empty soldering.
In addition, the larger the de-tinning angle may also cause the solder that falls back from the PCB to the tin pool to splash the tin liquid and splash on the PCB to form tin beads.