As the melting temperature of lead-free solder increases, the working temperature also increases, leading to a greatly accelerated corrosion of the soldering iron tip and a shorter service life. This is a reasonable explanation. When lead-free soldering, the required soldering temperature is much higher than ordinary soldering, which is a main reason for shortening the life of the soldering iron tip. The higher the temperature, the faster the oxidation rate. After applying lead-free soldering, why is the tip life shortened?
The general tip structure is mainly made of copper, and the outside is plated with iron (iron plated layer), and the front part of the iron plated layer is plated with tin (tin plated layer), and the rear end is plated with anti-oxidation chromium. Since tin and iron are also highly active metals, they can easily be combined into mixed metals, especially at high temperatures. And the flux used in soldering is also a catalyst to accelerate their mixed metal reaction. The production speed of mixed metals will vary with different welding temperatures. The higher the temperature, the faster the generation speed, especially at 400 ℃ or above.
When welding, tin and iron will continue to produce a mixed reaction, and because the resulting mixed metal will peel off from the surface of the tip coating, the tip coating will gradually be eroded away, and then tin will quickly attack the copper in the tip In the end, it will cause the welding tip to penetrate the hole in a short time.
Solders with different compositions will have different erosion rates on the tip. The figure above shows that tin +0.7 copper has the fastest erosion rate to the tip, then tin +3.5 silver +0.75 copper, tin +2 silver +0.75 copper +3 bismuth, and finally tin +37 lead. Compared with traditional eutectic solder (67/37 solder), at a soldering temperature of 400 ℃, lead-free solder: tin + 3.5 silver + 0.7 copper, the erosion rate of the nozzle is 3 times faster, and tin + 0.7 copper 4 times faster.
■ Method to extend the life of lead-free soldering iron tip
1. When using lead-free solder for soldering operations, due to the heat resistance of the parts and the consideration of safe operation, the setting temperature of the soldering iron tip is generally expected to be below 350 degrees to 370 degrees;
2. According to the different welding operations of the electric soldering iron, it is very important to choose the most suitable soldering iron tip. A suitable soldering iron tip can reduce the temperature of the soldering iron tip and increase the efficiency of the operation.
3. Unlike ordinary water-containing sponges, a metal wire that needs to be impregnated with an auxiliary agent does not reduce the temperature of the soldering iron tip, but also plays a cleaning role, and can also remove the oxide on the surface of the soldering iron tip. Set the low temperature of the soldering iron tip as much as possible.
4. When not using for more than 10 minutes, the power of the electric iron should be cut off.
5. When the tip of the soldering iron becomes black, first remove the oxide with the solder of the flux. If it cannot be removed, use dip first.
6. The wire cleaner of the penetration aid removes the oxide on the surface and then coats with new solder.
In addition to erosion accidents, lead-free soldering also accelerates tip oxidation. Although the temperature required for the formation of lead-free solder joints is higher than that of SnPb solder joints, as far as the industry's usual production capacity requirements are concerned, it is not necessary to increase the temperature of the soldering iron to achieve lead-free soldering; Temperature overshoot improves the heat transfer efficiency of the solder joint and reduces the idle temperature of the soldering iron. In addition, the shape of the soldering iron tip must also be matched to avoid excessive temperatures, otherwise the soldering iron tip will accelerate corrosion, thereby increasing the replacement cost and downtime of the soldering iron tip.
The soldering iron tip produced by BEE Jimei has reached the advanced level of the introduction of Germany in electroplating technology, and the quality has been improved by leaps and bounds. The crystal structure of our iron layer is fine and dense, and the total plating time is more than 48 hours. The lead-free soldering iron nozzle has the advantages of high temperature resistance, oxidation resistance, corrosion resistance, long life and fast soldering. The service life is more than 60,000 solder joints, and the use time is more than one week.