6 Common Soldering Problems and How to Fix Them

August 9, 2023

Printed circuit boards (PCBs) are at the heart of nearly every electronic device, mechanically supporting and electrically connecting different components. However, before they become central parts of various electrical devices, PCBs must undergo a rigorous assembly process, and certain parts of that process are more integral than others. 

One of the most crucial parts of the PCB assembly process is soldering. This is very important, not only because it is the first step in PCB assembly, but soldering flaws can cause a device to malfunction or underperform, making soldering a key element in the effectiveness of a given device. 

Without soldering, it would not be possible to attach various electrical components to a PCB. Depending on the type of PCB being made and the scale of production, different types of soldering methods may be used to attach these electrical components.

What are the most common soldering problems, and how can you resolve them?

Although the technicians who do the soldering during PCB assembly are often highly trained, mistakes can still happen. However, understanding the most common soldering problems and knowing how to avoid them will make it much easier to conduct flawless soldering on PCBs of all types. 

The following are some of the most common PCB soldering problems, along with ways to resolve these issues:

1. A disturbed joint

A common problem often found among the columns and rows of soldered connections on a PCB is a disturbed joint, which can be recognized by its swollen, distorted, or flakey appearance. The main reason solder joints can become disturbed is due to some movement that occurs during the soldering process.

You can avoid disturbed joints by ensuring that you do not position your board on an irregular surface or a surface that could potentially vibrate or tilt during the soldering process. 

If you notice a disturbed joint, it is typically possible to fix it by reapplying heat to the joint and then allowing it to solidify without any disturbance.

2. An icy joint

Another common issue is an icy solder joint, which will have an uneven or undefined appearance and cause inadequate bonding, often leading to cracks. Icy joints result from insufficiently melting your solder while applying it to the joint. It is essential to ensure that your soldering iron is always heated to an appropriate temperature before using it to prevent icy joints. 

If you notice an icy joint on your board, you can fix it by heating it up with a hot iron. If there is an excess amount of solder on the joint, use the pointed end of the iron for this purpose.

3. An overheated joint

Problems can also arise if a joint is overheated during the soldering process. A burnt joint can be identified by a lumpy or misshapen appearance, and is commonly the result of excessively preheating a soldering iron before use. Always ensure your iron is heated to an appropriate temperature to sidestep this issue.

Although it is challenging to rectify a burnt solder joint, it may be possible to scrape off a burnt flux and its surrounding area with the tip of a PCB working tool or by applying isopropyl alcohol with a small toothbrush.

4. A solder-starved joint

When an insufficient amount of solder is applied to a joint during the soldering process, this joint can be referred to as “solder starved”. It can result in board failure if left uncorrected, as solder-starved joints are not strong enough to perform their intended function. Sometimes, solder-starved joints may still exhibit good conductivity, but boards with such joints are unsafe to use. 

A solder-starved joint can be corrected by reheating the joint with an iron tip and adding solder to a spot as an original application. This should strengthen the joint and make it as reliable as the others on the board.

5. An over-soldered joint

Adding too much solder to a joint during the soldering process can be just as significant of an issue as underapplying solder. A joint with too much solder can be identified by its round, bulging, bubble-like appearance. An over-soldered joint could lead to inadequate electrical conductivity and prevent the joint from performing as intended.

Fortunately, you can resolve this problem by removing excess solder and reshaping the joint until it is concave as it should be. Just heat the endpoint of the iron and carefully trim the excess solder or try using a solder sucker for this purpose.

6. Untrimmed leads

One of the most hazardous errors to encounter is untrimmed leads, which are easily identifiable since they protrude like horns. Unlike the concave shape of properly trimmed leads, these extend upwards and can tilt to the side. If two of these untrimmed leads touch one another, a short circuit can occur. 

It is quite easy to fix untrimmed leads, as they just need to be cut down to the proper size and shape. This is typically done with wire cutters or side cutters.

How Circuits Central Can Help You With Soldering Problems

To avoid dealing with the issues mentioned above while soldering a circuit board, consider hiring professional PCB assembly technicians like those at Circuits Central. Our team of experts in electronics manufacturing and PCB assembly can handle all aspects of the production process, from material management and prototyping to PCB assembly, which, of course, includes all of the necessary soldering.

We have over 25 years of experience working on all kinds of PCBs ranging in terms of their complexity. Thus, we are incredibly familiar with the potential obstacles that can be faced during assembly and know exactly how to counter these issues so that our PCBs are always of the highest quality.

If you have already completed the PCB assembly process and are uncertain about whether your PCBs have any issues stemming from soldering problems or other matters, we also offer post-manufacturing testing services. 

Whether through x-ray testing, automated optical inspection, functional testing, environmental stress testing, or any of our other many testing types, we can identify potential issues with your PCB and let you know the best way to correct them.

For more information about how Circuits Central can help prevent or resolve soldering issues in your PCBs, or to learn more about our other PCB assembly and manufacturing services, call us at 1 (888) 602-7264 or contact us here.

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