1. Defective solder bridge solder joints
In the process, solder bridging is mostly associated with smaller, more compact components. This problem occurs due to unnecessary connections between two or more joints. This can cause a short circuit that can eventually damage components.
This problem is particularly challenging because bridges can be too small to be noticed. However, if a bridge can be found, the problem can be solved quickly. All you need to do is melt the solder in the middle with a soldering iron and remove the excess solder with a solder cup.
2. Excessive welding
Beginners can quickly apply as much solder as possible to the pins. This is a common mistake that can lead to excessive buildup on the nail and cause solder bridges.
Another side effect of over-soldering is that it prevents proper wetting of pins and pads. The best way to avoid this problem is to apply enough solder to wet the pads and pins during the soldering process.
3. Solder ball
Solder balls are a common problem during circuit board soldering. As the name suggests, solder balls are balls of solder that stick to a circuit board.
Soldering usually occurs during reflow when you choose the wrong reflow temperature. This can also happen when there is moisture in some components. You must use proper welding procedures to avoid this common mistake.
4. Cold seam
A cold junction simply indicates a poor connection between the component and the PCB. This common situation happens when the soldering temperature is too low if you don't allow the soldering iron to heat up properly. If left unattended, it will crack and eventually the entire element will fail.
5. Overheating of the joint
Conversely, overheated joints are created when the PCB solder temperature is too high or the solder does not flow. It also causes the entire element to fail; therefore, it should be avoided.
6. Tombstone phenomenon
Tombstones are a common problem in PCB soldering. This happens when one end of a passive component, such as a resistor, is partially lifted off the pad. This problem occurs when the solder pads have not completed the wetting process. To avoid this problem, you should make sure to check the size of the pads and use a better PCB coating.
One way to avoid this is to check the size of the pad. When one dimension of the pad is larger than the other, it will complete the wetting process faster since the excess copper acts as a heat sink.
7. Insufficient moisturizing
Wetting is an ideal situation where the solder applied to the board has reached a liquid state, allowing it to properly adhere to the pad or component. If this process is not sufficient, the solder will not bond properly to the component or pad, resulting in weaker solder joints.
Engineers cause this when they don't apply enough heat to the pen and pad, or don't give the solder enough time to flow. Cleaning the PCB and heating the pads and pins will both help prevent this problem.
Eight, welding funnel
Solder containers are surface mount headers that do not require soldering. This happens when solder jumps over a surface mount pad causing the area or pad to break. As a general rule of thumb, placing unevenly sized pads on SMD components should be avoided.
9. Raised pads
As the name suggests, pad lift occurs when a component's pad is lifted off the board. This usually happens when you try to remove a wrongly soldered part. Higher soldering temperatures or excessive force on either joint can also cause the pads to lift.
These problems make the pad difficult to use as the pad becomes brittle. Certain boards are prone to this problem, especially those designed with thin copper layers.
10. No solder joints
No solder joints are solder joints with insufficient solder, resulting in a lack of reliable electrical contact at the solder joints. Occurs when lead heats insufficiently.
Although this joint can still perform its function, it has the disadvantage of being a weaker joint. Over time, stress cracks can develop, causing the joint to fail. You have to reheat the connector to fix this.
11. Welding spatter
Applying excess flux or improper preheating can cause solder spatter. Solder spatter can cause solder fragments to adhere to the solder mask in the form of spatters. In general, make sure the surface of the PCB is clean before soldering. This behavior will help you prevent weld spatter.
12. Pin holes and air holes
These problems usually arise during wave soldering and are easy to spot because they show up as holes in the solder joints. These holes form when excess moisture that has built up on the board tries to escape through the thin layer of copper.
You can avoid this problem by preheating the board, as this will ensure that the moisture contained in the board escapes as steam.
13. Welding mark
Solder indications appear when the solder in the wave soldering machine is discharged too slowly. This problem is generally considered to be an abnormal height of solder on the board. You should try to avoid applying inconsistent flux during PCB soldering to avoid solder marks.
14. Tin Ball
Solder balls are balls of solder that have been separated from the body that forms the solder joint. It is caused by too much oxide in the solder paste.
Solder balls form when air or water vapor trapped in the solder paste escapes and becomes liquid. When this process occurs rapidly, a small amount of liquid solder will be absorbed from the joint; therefore, solder balls will form upon cooling. As a rule of thumb, avoid balls larger than 0.13mm in diameter.
You should also avoid storing the PCB in a humid environment, as this will ensure that the PCB does not contain water. In general, all PCBs should be dried before soldering or assembly and avoid applying too much flux to the solder paste.
15. Solder discoloration
This problem is usually not caused by the engineer, but by the manufacturer. Usually produced by manufacturers using different flux materials. Higher temperatures during wave soldering can also cause this.
English
Chinese