Soldering temperature standard for electric soldering iron_Analysis of soldering principle of electric soldering iron
1. Principle of manual welding
The common manual welding process is to transfer heat from the soldering iron tip and melt the solder to connect the welding parts (electronic components, etc.) and the pads (the parts to be welded).
Manual welding elements: power supply (soldering station or soldering iron), heating element (heating core), soldering iron tip, solder, welding parts, etc.;
2. Lead-free soldering knowledge
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, regulations such as ROHS prohibit it from being used in electronic products. So alternative lead-free solders have emerged.
Lead-free solder versus lead-based solder:
The melting point increases by about 34-44 degrees; 2. The tin content in the solder increases; 3. The tin-applying ability is poor (poor solderability). The solder diffusion of lead-free solder is poor, and the diffusion area is almost 1/3 of the eutectic solder.
3. Manual welding temperature formula
The most suitable temperature for soldering operations is the melting point of the solder used +50 degrees. The set temperature of the soldering iron tip depends on the size of the welding part, the power and performance of the soldering iron, the type and line type of solder, and it is appropriate to add X degrees (usually 100) to the above temperature.
That is: soldering iron tip temperature = solder melting point + 50 + X (loss). For example: the common soldering temperature of lead solder 63/37 is about 183+50+100=333, and the lead-free tin copper is: 227+50+100=377 degrees.
Due to the influence of different product solder joint sizes, different soldering tins, different environments and operating habits, X changes greatly here, so the soldering temperature ranges from 350-450.
4. Principle of soldering iron tip loss
The tip structure of the soldering iron tip is roughly: copper-iron plating layer-tin plating layer. When soldering, when heated, a physical and chemical reaction will occur between the iron plating layer and the tin in the solder, causing the iron to be dissolved and corroded, and this The process accelerates as the temperature increases.
Therefore, during lead-free soldering, the soldering temperature generally increases and the tin content in the solder also increases significantly, so the life of the soldering iron tip is drastically reduced.
5. Frequently asked questions about lead-free manual soldering
1) When using high temperatures, components may be easily damaged;
2) If the thermal recovery of the soldering iron or soldering station is not good, false soldering will easily occur, and the defective 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 (itself plated with lead-free tin, and the iron plating layer is appropriately thickened to delay corrosion and extend life without affecting thermal conductivity);
2) Use a special lead-free soldering station (high power, rapid temperature recovery, making the temperature more stable, and able to use low temperature for soldering);
7. Lead-free soldering station knowledge
It can be seen from the welding principle that the welding process is completed by the transfer of heat. Therefore, lead-free soldering requires the heating body to have better heating efficiency, which requires the soldering station or soldering iron to have greater power and faster thermal recovery.
