What is a Solder Skip on a PCB Board?

When it comes to using soldering for the PCB components, many PCB manufacturing experts use their hands for the soldering. However, it is essential to use specialized machines for the process when it comes to high-level PCB manufacturing. 

Anyone trying to do soldering components for their PCB may have difficulty since the PCB components are becoming compact and smaller daily, leading to an increased risk of soldering problems. One of the major issues that most people go through in PCB manufacturing is Solder Skip. In this article, we will talk about Solder Skip and how to prevent it.

What Exactly Is Solder Skip?

Judging by its name, solder skip can occur when solders are not applied or get spilled over the surface mounting pads. These soldering skips are undesirable since they prevent the connection to the pads or areas of the PCB. The solder skips are similar to the surface mounting joints not soldered onto the printed circuit board.

Moreover, the solder’s quality impacts the PCB’s overall quality. With the soldering, several different printed circuit board components are connected to other electrical components that make PCBs function more efficiently and fulfill their intended.

When manufacturers in PCB manufacturing check for the electrical parts’ quality, one essential factor they keep in mind during the analysis is the soldering quality. 

Solder skips can occur in factories where robots are responsible for soldering the PCB components or the soldering process done by amateurs. It may also happen due to the human operator not concentrating on the process. Moreover, robots can also skip joints. 

When solder skips occur, the circuits are left open, and some or all PCBs are rendered non-functional. You must ensure that you thoroughly check the joints of the PCB.

How Can You Prevent Soldier Skips?

PCB manufacturers must ensure that the solder penetrates the pads sufficiently when soldering the surface to add components to the PCB. Moreover, this process should be lengthy for the solder to get wet. Solder skips can happen when the solder does not wet the interface and fails to form a joint. One of the most efficient ways to resolve this issue is by modifying the design strategies and the machinery.

Soldering issues can occur when the components are wave-soldered to the polymer-printed circuit boards. With fewer chip component problems, active parts formats can be challenging to solder, especially the SOICs and PLCCs.

Molten solder consists of higher surface tensions, making it challenging for solder waves to reach the corners. The soldering surfaces appear somehow when they contact the component. With the wet solder, you can get a better solder surface.

Smooth soldering can lead to bad SM soldering due to no contacts. It happens because the movement cannot penetrate the surface tension of the solder at the pad interface. Similarly, there are cases when close spacing between the SMT parts can occur, which makes it difficult to access the joint.

Manufacturing companies address this issue during the designing process of the PCB. They use the waves with high turbulence levels and the proper attack angle. Solder skips are common and can be addressed by strict preventive methods, as mentioned above.

Essential Precautions and Tips To Keep In Mind During The Soldering Process

The soldering process is not a difficult one. Rather, it can be fun when it comes to creating a solid soldering. The following sections highlight the tips to keep in mind during the soldering process, as well as precautions to practice:

Tips

• During the soldering process, you must ensure the soldering surface is clean. 
• Soldering must be done with great electrical conductivity. 
• Ensure that PCB joints have robust mechanical strength.
• Ensure that there aren’t any loose connections.
• Use a reliable solder during the soldering process. 

Precautions

• Ensure that your soldering gun has a stand.
• A heated solder gun can be dangerous to the skin. Hence, do not touch the gun during soldering.
• When using the soldering gun, ensure your face is positioned at a height. 
• When removing the PCBs’ bridging effect, do not touch the solder. Take out the solder with a gun or use other safe materials.
• Choose a soldering place where people are out of harm’s way.

What Other Soldering Issues Can Occur Other Than Solder Skips?

Other than Solder skip, several other issues can occur, such as:

• Cold Joints

PCBs with cold joints may appear lumpy and dull. Sometimes, they may also look pock-marked. A cold joint may occur when the soldering cannot completely melt. It can lead to a lumpy or rough surface. Many PCB manufacturing companies go through these problems. Hence, these manufacturers try all the essential preventative methods for cold joints. Cold joints can lead to other issues in the PCB as they are unreliable.

Causes of cold joints in PCBs are:

1. Using uneven SMD components during the designing process.
2. Using inappropriate wave height between the PCB and soldering wave.
3. Flux accumulation under the PCB causes the solder to adhere incorrectly.

• Solder Balling

Solder balling occurs when a PCB accumulates moisture due to the water vapor that occurs due to soldering heat. There are many reasons why solder balling can happen. However, it primarily occurs during reflow or wave soldering.

Causes for solder balling are:

1. Not using solder paste printing appropriately.
2. Using oxidized electronic components.
3. Incorrect reflow settings for temperatures.

• Excessive Solder

Another problem issue that manufacturing companies go through is excessive solder. Excessive solder occurs from PCBs having excessive solder in the wave soldering machinery. A significant amount of solder on a PCB can negatively affect the functionality of the PCB.

The causes of excessive solder are:

1. The conveyor belt runs quickly.
2. Using an excessive amount of soldering.

• Overheated Joints

Other than cold joints, there can be overheated joints. Less heat can bring about wonky connections. Significant heat can lead to splitting headaches for you. With the overheated connections, the PCB will not work as effectively. However, burn flux can result from overheated connections, which you can remove with the help of a scraping toothbrush or use isopropyl alcohol.

Causes for overheated joints are:

1. Setting the high temperature on the soldering iron.
2. Not cleaning joints or pads of the PCB.

• Solder Flags

Solder flags are the ideal choice as they ensure that the PCB has a proper connection. However, solder spikes or flags are signs of insufficient and inefficient application. It can lead to flagging or bring other solder issues. There are several reasons for solder flags, such as:

1. Inconsistent flux application.
2. The PCB components’ oxidation is due to bad storage and transportation.
3. The shorts occurrence.
4. Improper solder control drainage coming from the wave.

• Soler Discoloration

Although the PCB may appear cosmetic, it is worth nothing. Because solder discoloration can be frustrating, the manufacturer needs time to discover the root causes. The solder resists on the PCB or the conveyor belt can identify the mask discoloration. It may happen due to:

1. PCB manufacturing companies use different flux materials or higher temperatures during soldering.
2. Longer dwelling times.
3. PCB manufacturing companies mix the batches of PCB in the same processing of the wave soldering.

Conclusion

In conclusion, when working for a high level of PCB manufacturing, it is essential to solder using specialized machines. Solder skips can occur whenever solder spills over some surface mounting pads. Hence, gaining appropriate knowledge about soldering and how to efficiently solder the PCBs is essential.