Soldering Techniques Illustrated Guide to Basic Soldering Hand Methods Five-Step Method of Soldering Technology

As a training method for beginners to master manual soldering skills, the five-step method is highly effective and deserves separate discussion.  

  Soldering Posture and Hygiene 

The chemical substances volatilized when the flux is heated are harmful to the human body. If the nose is too close to the soldering iron tip during operation, harmful gases can easily be inhaled. Generally, the soldering iron should be kept at least 30 cm away from the nose, with 40 cm being the recommended distance.  

There are three ways to hold a soldering iron, as shown in Figure 1. The reverse grip method provides stable movement and is less fatiguing for prolonged use, making it suitable for high-power soldering irons. The forward grip method is suitable for medium-power soldering irons or those with a bent tip. The pencil grip method is commonly used when soldering printed circuit boards on a workbench.  

There are generally two ways to hold solder wire, as shown in Figure 2. Since solder contains a certain proportion of lead, which is a harmful heavy metal, it is important to wear gloves during operation or wash hands afterward to avoid ingestion.  

When using a soldering iron, a soldering iron stand should be provided. It is typically placed on the front right side of the workbench. After use, the soldering iron must be securely placed on the stand, ensuring that wires or other objects do not touch the tip.  

As a training method for beginners to master manual soldering skills, the five-step method is highly effective and deserves separate discussion.  

Many electronics enthusiasts commonly use a soldering method where the soldering iron tip is first coated with solder, and then the iron is placed on the solder joint to wait for heating and solder wetting.  

This method is not the correct technique. Although it may join the components, it does not guarantee quality. This can be easily understood from the soldering mechanism.  

As shown in Figure 3, when solder is melted onto the soldering iron tip, the flux in the solder wire adheres to the surface of the solder. Since the soldering iron tip temperature typically ranges from 250°C to 350°C or higher, the rosin flux will continuously volatilize before the iron is placed on the solder joint. When the soldering iron is placed on the joint, the component temperature is low, and heating takes time. During this period, most or all of the flux may volatilize, leading to poor wetting due to insufficient flux. At the same time, the significant temperature difference between the solder and the component makes it difficult to form a reliable bond, increasing the risk of cold solder joints. Moreover, with the loss of the protective effect of the flux, the solder is prone to oxidation, inevitably compromising quality.  

  The Five-Step Method of Soldering 

The five-step soldering method is a commonly used basic soldering technique suitable for workpieces with large heat capacities, as shown in the figure below:  

(1)   Preparation for Soldering   

Prepare the solder wire and soldering iron, ensuring all pre-soldering preparations are complete. It is especially important to emphasize that the soldering iron tip must remain clean, meaning it should be coated with solder (commonly referred to as "tinning").  

(2)   Heating the Workpiece  

Place the soldering iron on the solder joint. First, ensure all parts of the workpiece (such as leads and pads on the printed circuit board) are heated. Second, ensure the flat part (larger area) of the soldering iron tip contacts the part of the workpiece with a larger heat capacity, while the side or edge of the tip contacts the part with a smaller heat capacity to ensure even heating of the workpiece.  

(3)   Melting the Solder  

Once the workpiece is heated to a temperature that can melt the solder, place the solder wire on the joint. The solder will begin to melt and wet the joint.  

(4)  Removing the Solder    

After a sufficient amount of solder has melted, remove the solder wire.  

(5)   Removing the Soldering Iron  

Once the solder has fully wetted the joint, remove the soldering iron. Note that the direction of removal should be approximately 45 degrees.  

For workpieces with smaller heat capacities, the process can be simplified into a two-step method: prepare for soldering, place both the soldering iron and solder wire on the joint simultaneously, then remove the solder wire and soldering iron at the same time.  

For most solder joints, the above process takes about two to three seconds. For solder joints with smaller heat capacities, such as small pads on printed circuit boards, a three-step method is sometimes used, combining steps 2 and 3 into one and steps 4 and 5 into another. In reality, the distinction is still based on the five steps.  

Thus, the five-step method is universal and serves as the foundational approach for mastering manual soldering. In particular, the timing between each step is crucial for ensuring soldering quality, and mastery can only be achieved through practice.