Soldering iron welding temperature standard_Principle analysis of electric soldering iron welding
1. The principle of manual welding
The common manual soldering process is to transfer heat through the tip of the soldering iron and melt the solder to connect the welded parts (electronic components, etc.) to the pads (welded parts).
Manual welding elements: power supply (soldering station or soldering iron), heating body (heating core), soldering iron tip, solder, welding parts, etc.;
2. Knowledge of lead-free soldering
The previous solder was a tin-lead alloy, such as 63/37 (63% tin, 37% lead), with a melting point of 183 degrees. Due to the toxicity of lead to the environment, ROHS and other regulations stipulate that it is prohibited in electronic products. So there is an alternative lead-free solder.
Lead-free solder relative to lead solder:
1. The melting point rises by about 34-44 degrees; 2. The tin content in the solder increases; 3. The tinning ability is poor (poor solderability), and the solder diffusion of lead-free solder is poor, and the diffusion area is almost 1/ of that of eutectic solder 3.
3. Manual soldering temperature formula
The most suitable temperature for soldering is the melting point of the solder used + 50 degrees. The set temperature of the soldering iron tip, due to the size of the soldering part, the power and performance of the electric soldering iron, the type of solder and the type of wire, it is advisable to add X degrees (usually 100) to the above temperature.
That is: soldering iron tip temperature = solder melting point + 50 + X (loss). Such as: lead solder 63/37 common soldering temperature: about 183+50+100=333, lead-free tin copper: 227+50+100=377 degrees.
The size of solder joints of different products, different solders, different environments and operating habits, etc., here X changes greatly, so the soldering temperature is used from 350-450.
4. Principle of soldering iron head loss
The structure of the tip of the soldering iron tip is roughly: copper-iron plating layer-tin plating layer. When soldering and heating, a physical and chemical reaction will occur between the iron plating layer and the tin in the solder, so that the iron is dissolved and corroded, and this The process accelerates with increasing temperature.
Therefore, during lead-free soldering, because the soldering temperature generally increases, the tin content in the solder also increases significantly, so the life of the soldering iron tip decreases sharply.
5. Common problems of lead-free manual soldering
1. When using high temperature, it is easy to damage components;
2. If the thermal recovery of the soldering iron or soldering station is not good, it is easy to have false welding and false welding, and the defect rate will increase;
3. The oxidation loss of the soldering iron tip increases;
6. Common countermeasures for lead-free manual soldering
1. Use a special lead-free soldering iron tip (it is plated with lead-free tin, and the iron plating layer is appropriately thickened to delay corrosion and prolong life without affecting heat conduction);
2. Use a dedicated lead-free soldering station (high power, fast temperature recovery, making the temperature more stable, and can use low temperature for welding);
7. Knowledge of lead-free soldering station
It can be seen from the welding principle that the welding process is completed by the transfer of heat. Therefore, the heating body needs to have better heat supply efficiency during lead-free soldering, which requires a soldering station or soldering iron to have greater power and faster heat recovery.
The power of lead-free soldering stations commonly used in the market is above 90W. Compared with the previous 60W soldering station or single soldering iron, the thermal efficiency and thermal recovery have increased a lot, so when soldering the same product, the required soldering temperature will be lower. Up to 10-30 degrees, and more stable.
