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How does solder joint form by mid frequency welding machine? [DCS10]
Dec 27,2023
There are two main stages in the formation of solder joint in intermediate frequency welder.
First, the solder joints are melted to form the nugget.
The weldments generate resistance heat after electrification. The contact resistance between the electrodes and the weldments also generates heat, but most of it is carried away by water-cooled copper alloy electrodes. Therefore, the contact temperature between the electrode and the weldment is much lower than the contact temperature between the weldments, and the melting temperature can not be reached under normal circumstances.
The metal around the electrode cylinder has low current density and low temperature. The metal near the molten nugget has a higher temperature and reaches a plastic state. Welding occurs under pressure, forming a plastic metal ring, which closely surrounds the molten nugget and does not allow the molten metal to spill out.
Next, to forge the solder joint.
The electrode continues to press the solder joint after the welding current cuts off, which compacts the solder joint. This process is called forging.
After power off, the molten nugget in the closed metal“Shell” starts cool crystallization, where shrinkage is not free. If there is no pressure at this time, solder joints are prone to shrinkage and crack, which affects the strength of solder joints. If the electrode gives pressure, the resulted extrusion deformation causes the nugget to contract freely and become dense. Therefore, the electrode pressure must continue to maintain after the power off and be released until the molten nugget metal all get solidified . Forging duration depends on the thickness of the weld.
The essence of medium frequency welder welding the workpiece is to make two separate metal atoms go close to the lattice distance (0.3-0.5 nm) to form metal bonds, and then make the two metals connect as a whole, to achieve the goal of welding.
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
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