It’s essential to ensure that solder joints are made correctly in any electronics construction. Poor and dry soldering cause equipment not to work once. Or there is a possibility that the solder joint could fail. In this blog, we will introduce why dry soldering occurs and how to solve it.
What is Meant by Dry Soldering?
Dry soldering refers to a poor solder joint that lacks proper electrical connectivity on a PCB assembly product. This issue occurs when the solder does not properly melt and bond to the components, leading to weak connections. These joints are often brittle and prone to failure, which can result in intermittent or complete loss of electrical connectivity.
Why Dry Solder Joint Causes?
Dry solder joints occur due to several reasons, each impacting the quality of the solder connection. First of all, the solder paste reflow process is only a small area, which is easier to harden than the solder paste in the solder paste can. At this time, the solder paste will not melt, and the flux cannot cover the solder joint, resulting in poor welding of the solder joint. Meanwhile, the solder paste is easier to heat transfer, and the high temperature actually makes the solder paste not easy to melt, so we can slightly adjust the reflow welding temperature curve to solve the problem, or welding in a nitrogen environment is basically a good way to solve this problem.
Secondly, the solder paste does not melt because its own composition contains a very volatile flux, which is also the reason why the solder paste is easy to harden. Among them, the flux with the largest content of solder paste is rosin, rosin contains a lot of rosin acid, rosin acid is easy to lose activity at too high temperature. Therefore, the temperature of the welding process should be controlled to ensure that the temperature is about 200 ° C, which is not suitable for too high or too low. At the same time, the quality of thixotropic agent will also lead to the solder paste is easy to dry, the quality of thixotropic agent is not good will affect the viscosity of the solder paste, the viscosity of the solder paste is easy to dry. Therefore, the choice of high-quality solder paste can fundamentally solve the problem that the solder paste is easy to harden.
In addition, the use of solder paste scene, humidity, temperature and other external factors will also affect the solder paste in the use of hard non-melting phenomenon. So these external factors should be paid attention to. I hope these solutions can solve your problems.
How Do You Fix Dry Solder?
Solder paste is one of the very important materials in the electronics industry, and it has an important impact on the production quality of the entire component. Here are some tips that can help to fix the dry solder paste.
1.Add flux
Usually, if the solder paste is too dry, you can try to add some water to the right amount of flux, stir well and add it to the solder paste. This can play a certain role in alleviating drying and improve the fluidity of the solder paste.
2. Take some measurements during management
a. Keep the ambient temperature moderate during storage;
b. Stir well before use;
c. Cover the solder paste in time after welding to avoid exposure to the air.
3. Replace it with new one
If the solder paste becomes too dry, adding flux is difficult to restore its original properties, it is recommended to replace the solder paste to avoid affecting the quality of the components.
Therefore, we need to regularly maintain and manage the solder paste to ensure that its quality meets the standard requirements.
What Does a Dry Solder Look Like?
Recognizing a dry solder joint is crucial for proper diagnosis and repair. Unlike a good solder joint, which is shiny and smooth, a dry joint looks matte and rough. The joint might have visible cracks or look brittle. It might not be fully bonded to the component lead or the PCB pad. Identifying these visual cues can help in quickly addressing the issue.
How Do You Prevent Dry Solder?
Preventing dry solder joints is key to maintaining the reliability of your electronic projects. You can try to use these tips to prevent your solder paste become dry.
- Proper heating
- Clean surfaces
- Use quality solder
- Steady hand
- Maintain equipment
- Fast usage and storage
If you want to know more about solutions of dry solder paste, you can read our another post, How to Solve Dry Solder Paste.
How to Tell If Solder is Bad?
Bad solder can lead to dry joints and other issues. So, how can we identify if my solder paste is bad? May you can follow these points. If everything matches up, there’s no doubt that your solder paste is broken.
- Appearance of solder joints
Bad solder joints often appear dull or matte instead of shiny and smooth. They may also show cracks or a brittle texture, indicating poor bonding or excessive heating. These visual signs suggest that the solder did not properly melt or flow.
- Solder flow and coverage
If the solder does not adequately cover the component leads or PCB pads, or if it spreads unevenly, it is likely bad. Proper soldering should result in a well-formed, consistent fillet around the leads, ensuring reliable electrical connections.
- Difficulty in melting
Solder that requires unusually high temperatures or takes a long time to melt may be old or contaminated. Proper solder should melt easily at the recommended temperature and flow smoothly to create a solid joint.
- Contamination indicators
Oxidized or tarnished solder indicates contamination and can affect its performance. Excessive residue or debris also points to poor quality, affecting how well the solder adheres and flows.
Best Technology is a one-stop PCB manufacture and PCBA service provider, our SMT factory is equipped with more than 6 assembly lines. Meanwhile, we have automatic SPI machine and solder paste printing machine, with good management system, we can ensure the good quality of solder paste. In addition, there are many advanced equipment in our workshop, including online dual AOI, X-ray, Nitrogen reflow oven, dry-ice cleaning machine, and so on.
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