Making soldering errors is a common occurrence, especially when dealing with many PCBs. As a result, it is possible to encounter various soldering flaws while carrying out such tasks. Even experienced technicians can make mistakes, such as overheating or underheating a pad or applying too much and too much solder. To prevent these mistakes, it is essential to understand how to recognize defective solder joints.
Soldering Troubleshooting
Identifying soldering defects requires a trained eye. A correctly soldered joint should be clean, symmetrical, and have a concave shape compared to the neighboring joints. A defective solder connection will be disorganized and have a physical abnormality, like a swelled shape or a long stem. Here are the 12 Typical soldering mistakes and the resulting problems:
1. Disturbed Joint
One prevalent issue found in columns and rows of soldered connections is the disrupted joint. It is recognizable by its swollen, distorted, and occasionally flakey texture. The main reason for unsettled joints is any form of movement during the soldering process. For instance, if the board is positioned on an irregular surface and vibrates or tilts while the solder is applied, the joint can become disturbed or lose its integrity. Additionally, if the board experiences any movement or vibration while the solder is drying, it can also cause a disturbance in the joint.
Confusing Disrupted joints with cold solder connections is a common mistake. Although they have a Resembling appearance, the causes of these issues are different. In certain situations, reapplying heat to the joint & letting it solidify without any disturbance can fix the problem.
In the coming days, ensure each joint is secure and stable when applying solder.
2. Cold Joint
A common issue observed on a freshly soldered circuit is the presence of icy solder joints. These joints are recognizable by their uneven and sometimes undefined appearance. These joints are typically the result of insufficiently melted solder during the application process. In addition to their unappealing appearance, cold connections are challenging. They do not provide adequate bonding and are prone to developing cracks over time.
Repairing an icy joint is possible by applying heat once again. It can be achieved by using a hot iron. Additionally, if there is an excess volume of solder on the joint, it can be removed by using the pointed end of the hot iron. To avoid cold joints from forming in the future, it is crucial to ensure that the iron is heated to the appropriate temperature before utilizing the solder.
3. Overheated Joint
One of the most noticeable blemishes that can occur on a set of newly soldered joints is the Burnt joint. This type of common forms when too much heat is applied during the soldering process. In contrast to cold joints, which result from Inadequate heat, overheated joints occur(happens) when the iron is excessively preheated before application. These joints have a burnt appearance with a lumpy and misshapen structure.
To rectify the issues caused by overheating during the soldering process, a burnt flux and its surrounding area can be scraped off using the tip of a PCB working tool. If necessary, a solution like an isopropyl alcohol can eliminate a burnt flux. The ideal way to utilize alcohol is by using a small toothbrush.
Overheated joints can be difficult to fix, making it important to avoid them at all expenses. To prevent this issue on typical days, it is crucial to ensure that the iron is heated to the appropriate temperature and to check twice that the connections are clear before starting the soldering process.
4. Insufficient Wetting of the Surface Mount
Failing to heat both the pin and the cushion during a soldering process can result in an inadequate surface mount, where the support elements do not flow on a solder cushion. This issue can be identified easily if irregularities are present across a mount’s row. If different props have correctly streamed on the surface while 1 or 2 extra mounts have retained their actual pin composition, it is likely due to an inadequately wetted place.
To correct an inadequately wetted pad during the mounting process, preheat the iron point to the required temperature and then implement it into a solder pad. Add more solder to the place, allowing it to flow and dissolve into the design with the pin’s solder. To prevent this recurring issue, heat the Pad earlier than heating a pin during future soldering applications.
5. Insufficient Wetting of the Pad
Insufficient wetting of the solder pad in the soldering procedure results in an uneven joint without bonding strength. Typically, in such cases, an ample amount of solder would have moistened the leads, but the pad absences the important bonding power. A common cause of this issue is applying solder to a soiled circuit board, where the dirty circuit board prevents proper bonding. Additionally, if the Pad & pin lack adequate heat during the application, the place may finish with insufficient wetting.
To fix the issue of an improper wetted pad, heat the iron tip to the appropriate temperature or keep it at the base of the joint. Allow the solder to flow onto the surface, ensuring it wets the surface properly. To restrain this issue from happening in the future, ensure that the board is clean before starting the application and preheat the Pad and pin to the required temperature level.
6. Insufficient Wetting of the Pin
If both the pad & pin exhibit poor wetting, it is likely due to insufficient heat treatment of the pin. It commonly occurs when the plug is not getting heat sufficiently, preventing the solder from flowing into place.
To address the problem of an incompletely wetted pin, heat the iron trading point to the required temperature and apply additional solder. It is important to touch the Pad and the hook with the iron tip during the reapplication process to condition these elements for the appropriate application. To avoid this problem in the coming days, ensure that the pin and the Pad are heated to the right level during soldering.
7. Solder Starved
A joint that has an insufficient amount of solder is a solder-starved joint. Such a joint lacks the strength to perform its intended function and can lead to board failure if not addressed. Even though an insufficient solder joint may exhibit good conductivity, the board would still not be safe to use until the issue is resolved by adding more solder to the affected joint.
To fix a solder-starved joint, heat the joint (connection) with the iron tip to the correct temperature and add solder to a spot as an original application. This process should make the joint stronger & reliable, similar to the other joints on the circuit board. Once completed, the joint should withstand stress & make the circuit safe for computer equipment.
8. Too Much Solder
An overabundance of solder presents another significant issue. These joints are easily identifiable on a circuit board as they appear round and bulging, resembling a bubble. In contrast, a properly formed joint with the correct solder amount will have a concave shape. Excess solder coverage can result in inadequate electrical conductivity, rendering the joint incapable of fulfilling its intended function. Although it may not be prone to stress fractures, it will not serve its purpose.
If you encounter an excessively soldered joint, the solution involves removing excess solder and reshaping the joint to achieve the desired concave shape. So to accomplish this, you can heat the endpoint of the soldering iron & carefully trim away the excess solder until the connection no longer appears inflated or round. The solder-sucker may prove helpful in removing the excess solder more easily.
9. Untrimmed Leads
The presence of untrimmed leads on joints is one of the most hazardous errors. These leads protrude like horns. They are easily identifiable with the naked eye. Unlike properly trimmed tips with a concave shape, these leads extend higher and may tilt slightly sideways. When two untrimmed charges make contact, a short board/circuit may occur. Additionally, even when the leads become upright, they can bend over time & make contact.
Correcting untrimmed leads is a straightforward process that involves cutting them to the proper size for the common joint. You can use the same equipment for solder cutting and bring a joint down to a similar height as others on the circuit board.
10. Solder Bridge
When an excessive quantity of solder liquefies between nearby joints on the circuit board, a solder bridge may form. The joints on PCBs are intentionally separate, and unintentionally creating a connection between two joints during soldering can render the board unusable. Therefore, it is crucial to rectify the issue immediately to avoid further problems.
These are the steps you can follow to separate the accidentally connected points by removing the additional solder:
Make your soldering iron hot and use its tip to cut the extra solder that connects the two points from underneath. It will create a canal. Widen the channel until the joints are at the proper distance from each other. After removing the extra solder, you can use the soldering iron to fix the connection shape if they look wrong. To avoid this issue recurring, it’s essential to use only the right value of solder during all applications, as excessive solder can melt sideways & collide with nearby joints.
11. Lifted Pad
In addition to joint-related issues, you may encounter instances where a solder cushion separates from the board. Overworking a joint or repeatedly applying heat to the solder can result in a lifted pad, generally due to excess stress on the board. For instance, when removing a solder short/bridging with the iron and scaling the lateral crosstalk away from a joint, you may accidentally lift much & dislodge the joint from aboard. The problem is more prevalent on boards with thin copper layers and no through-plating.
Repairing the lifted Pad can be a challenging task, but it is possible. The most useful method involves folding the solder and bonding it to the unbroken copper pathway. If there is a solder mask covering the trace, you will need to eradicate it to reveal a copper.
12. Stray Solder
During the soldering process, it’s possible to end up with random bits of solder on the board due to messy oversights. These bits are not with the copper trace. They are with a flux residue. If these bits are not on the circuit board, it’s important to eradicate them before putting the circuit to use. If left unresolved, these solder bits can cause short circuitry in a PCB.
To eliminate solder from the PCB, you can use a sharp printed circuit board tool, like a small knife. Use the tool point to scrape off the solder bits from the board’s surface. It’s important to check the circuit twice to ensure that no extra solder parts are present before using it.
Conclusion
So, you have found this guide to be informative and helpful. If you find that you have made any of these common soldering flaws, do not discourage yourself. Becoming a specialist at soldering can take time & practice, and making mistakes is a normal part of the learning process.
While there is no guaranteed way to achieve perfect soldering, these tips may be helpful to follow:
Before soldering, inspect and become familiar with the printed circuit board.
- Ensure that the joints & pads are clean and contaminants free and prepared for soldering.
- Maintain the soldering iron in excellent condition, paying close attention to the tip.
- Take the time and avoid rushing.
- Practice frequently to improve your skills.
