An automatic tin feeding laser welding method

Abstract

The invention relates to the field of laser welding, in particular to an automatic tin feeding laser welding method. A laser outputs laser to pre-heat welded workpieces by adopting a positive defocus way; tin wires are then output to a laser focus part, are melted to form tin balls, and are downwards moved to the part of the welded workpieces; the tin balls soak welding points through continuous laser irradiation; the tin wires are finally moved upwards to the initial position. According to the automatic tin feeding laser welding method, the stability in tin wire discharge can be ensured, the tin wires can be quickly melted after being in contact with the welding points, the focus of the laser is not in direct contact with the welding points, and thermosensitive elements surrounding a welding pad are prevented from being influenced by high temperature during welding.

Description

technical field [0001] The invention relates to the field of laser welding, in particular to an automatic tin-feeding laser welding method. Background technique [0002] The traditional automatic tin-feeding laser welding method is completed by controlling the laser and the tin-feeding mechanism. It can complete the welding of 3C electronic products, and is also capable of welding heat-sensitive components with low temperature requirements. [0003] Such as figure 2 Shown is the flow of the traditional welding method, which is divided into the following steps: ⑴ move the workpiece to be welded to the predetermined welding position; ⑵ the laser emits laser light with a predetermined current or energy to irradiate the welding point; ⑶ set a sender The wire feeding delay of the tin mechanism enables the laser to fully preheat the solder joints; (4) The tin feeding mechanism sends the tin wire to the solder joint, and the tin wire melts and infiltrates the pad under the action ...

AI Technical Summary

Problems solved by technology

[0004] In the traditional method, the tin wire comes out directly at the welding point, and the tin wire is easily hindered by the welding point, causing the tin wire to bend, block the wire, and change the position of the starting point of the tin wire before and after welding. This series of factors lead to the failure of the tin wire The state is uncontrollable, resulting in an uncontrollable amount of tin. If the amount of tin is small, the heat of the pad will still be excessive, causing the pad to burn. If the amount of tin is too much, the heat of the pad will not be enough, causing the tin to form balls after melting without infiltrating the pad. , forming virtual welding

In addition, since the tin wire absorbs heat and the pad absorbs heat, the lead wire on the pad will also absorb heat. In addition to the stable and controllable heat dissipation of the tin wire, the heat dissipation of the solder pad and the lead wire varies greatly. To make the tin wire It can melt smoothly without causing damage to pads and components. This series of factors further increases the difficulty of reasonably controlling the state of tin wire

In addition, the laser focus is directly irradiating the solder joint during welding, which has great potential damage to heat-sensitive components.

In the existing situation, it is difficult to achieve continuous welding by avoiding the laser focus on the pad for a long time and solving the uncontrollable state of the tin wire.

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