Why Solder Does Not Stick?

Cases where solder does not stick create difficulties in forming strong connections in solder joints. So why does this happen? Let’s explore some essential information in the article below!

One of the Reasons Why Solder Does Not Stick

Dirty or Oxidized Surface

During the soldering process, dust, grease, or tiny particles can accumulate on the surface of the material, components, or PCB. These contaminants create a barrier, making it difficult for solder to adhere firmly to the surface.

Regarding oxidation, most components and circuit boards are made of metal. When exposed to air, metal tends to oxidize, forming a thick oxide layer. This layer prevents proper soldering and weakens the bond between materials.

Using Low-Quality Solder

There are various types of solder on the market, with different price ranges and qualities. The most common types include leaded and lead-free solder. The quality of solder significantly affects the soldering process.

Some low-quality solder contains too many impurities, making it difficult to melt and preventing adhesion to materials, components, or circuit boards. Additionally, using incompatible solder can also lead to adhesion problems.

Incorrect Soldering Technique

Besides the quality of the solder, soldering technique plays a crucial role in determining the strength of the solder joint. If done incorrectly, solder may not melt or adhere properly.

This process is typically carried out by professional soldering technicians, or beginners should be supervised to avoid errors during soldering.

Insufficient Soldering Iron Temperature

A soldering iron transfers heat to melt the solder. If the iron’s temperature is too low, the solder may not fully melt. When solder does not melt completely, it cannot penetrate the surface properly, leading to poor solder joints.

On the other hand, if the soldering iron temperature is too high, it may burn the PCB or damage electronic components.

Not Using Flux or Rosin

Flux or rosin is essential for cleaning the surface and improving solder adhesion. Without these materials, solder struggles to stick to metal surfaces, resulting in poor-quality solder joints.

Unsuitable Soldering Environment

The soldering environment also plays a significant role. High humidity or low temperatures can cause problems. Excessive moisture can create a thin water layer on the material’s surface, while low temperatures can prevent the soldering iron from reaching the required heat.

Thus, ensuring the right working conditions is crucial for successful soldering.

Improper Maintenance of Soldering Equipment

Soldering tools require proper maintenance to ensure optimal performance. If the soldering iron is dirty, it can negatively impact the soldering process and result in poor-quality joints.

How to Fix Solder Not Sticking?

Cleaning Dirty or Oxidized Surfaces

• Use isopropyl alcohol or specialized cleaning solutions to remove dust, grease, and contaminants. This step enhances solder adhesion.
• For oxidized surfaces, remove the oxidation layer using fine sandpaper or specialized cleaning solutions before soldering.

Using High-Quality Solder

To avoid issues caused by low-quality solder, invest in better solder options. Choose a reputable supplier to prevent purchasing counterfeit products.

Correct Soldering Technique

• Maintain the correct soldering angle and apply the right amount of solder.
• Hold the soldering iron on the joint for about 2-3 seconds before applying solder.
• Keep the iron at a 45-degree angle to ensure even melting and proper penetration.

Ensuring Proper Soldering Iron Temperature

• For leaded solder, maintain a temperature of 180-250°C.
• For lead-free solder, use a higher temperature of 220-300°C.
• Using an adjustable soldering iron allows for better control over different solder types.

Using Flux or Rosin

Many modern solder options already contain flux. However, if the solder lacks flux, apply additional flux or rosin before soldering. This step removes oxides and impurities, improving solder adhesion.

View more: What is solder wire? Overview of solder wire to know

Maintaining Soldering Equipment

• Clean the soldering iron tip after each use to remove grease and residue.
• Use fine sandpaper or a cleaning solution to remove oxidation.
• Regularly maintain the soldering iron; if it becomes too worn out, consider replacing it to ensure high-quality solder joints.

There are many reasons why solder does not stick. Observing and assessing the situation will help you find the right solution. Ensuring a safe soldering process and achieving high-quality solder joints is essential.