To ensure the welding quality of solder cup terminal pins, it is necessary to strictly control from the preparation before welding, welding process control and post-welding inspection and other aspects, as follows:
Pre – welding Preparation
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Clean the pin and workpiece surfaces: Use special cleaning agents or sandpaper and other tools to thoroughly remove oil stains, oxides, dust and other impurities on the surfaces of the cup – type terminal pin leads and the wires to be welded, ensuring that the welding surfaces are clean and bright, so as to improve the wettability and adhesion of the solder.
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Select appropriate solder and flux: Choose suitable solder according to the material of the pin and workpiece, welding requirements and other factors. Generally speaking, solder wire with 63% tin and 37% lead and added flux core is more commonly used. The flux should have good activity, which can effectively remove the oxides on the welding surface, and at the same time, it should not cause corrosion to the pin and workpiece.
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Ensure the tools and equipment are in good condition: Check whether the power of the soldering iron and other welding tools is appropriate. Generally, a soldering iron with a power of 30W – 60W is suitable for the welding of most cup – type terminal pin leads. Ensure that the shape and size of the soldering iron tip match the weld cup, and the soldering iron tip can heat up normally and the temperature control is accurate. At the same time, prepare auxiliary tools such as tweezers and wire cutters to ensure that the tools are complete and can be used normally.
Welding Process Control
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Insert the pin and wire correctly: Insert the wire to be welded into the weld cup of the cup – type terminal pin lead according to the specified length and direction, ensuring that the wire is in full contact with the inside of the pin and is centered, to avoid the situation where the wire is skewed or not fully inserted.
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Control welding temperature and time: Preheat the soldering iron to a suitable temperature, generally 300℃ – 350℃. Bring the soldering iron tip into contact with the connection between the weld cup and the wire, so that the weld cup and wire are fully heated. When the surface of the weld cup and wire reaches a suitable temperature, send the solder wire to the welding part, so that the solder wire melts under the action of heat and fills evenly in the weld cup, wetting the surfaces of the pin and wire. The welding time is generally controlled within 2 – 5 seconds to avoid over – long welding time causing the pin to overheat and damage or the solder to oxidize excessively, affecting the welding quality.
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Maintain the correct welding angle and force: During the welding process, maintain the soldering iron at a suitable angle with the connection between the weld cup and the wire, generally around 45°, so that the soldering iron tip can fully contact the welding part and ensure uniform heat transfer. At the same time, control the force applied to the soldering iron to avoid excessive force squeezing or shaking the weld cup and wire, so as to avoid loosening the welding part or splashing the solder.
Post – welding Inspection
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Visual inspection: After the welding is completed, first carry out a visual inspection of the welding part to check whether the solder in the weld cup is full and uniform, and whether there are any phenomena such as solder shortage, virtual welding, leakage welding, solder accumulation or splashing. Check whether the surface of the weld is smooth and bright, and whether there are any defects such as pores and cracks.
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Electrical performance test: Use a multimeter and other tools to test the electrical performance of the circuit after welding, and check whether the conductivity between the pin and the wire is good, and whether the resistance value is within the normal range, to ensure that there are no short – circuit, open – circuit and other electrical faults in the welding part.
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Mechanical strength inspection: Gently pull the wire after welding to check the mechanical strength of the welding part, and ensure that the connection between the pin and the wire is firm and will not loosen or fall off due to slight external force. For some applications with higher requirements, more stringent mechanical performance tests such as tensile tests can also be carried out.
