Collection! Analysis of Common Defect Causes in PCB Manufacturing

January 5, 2026

PC-ESD-2020

PCB manufacturing is a complex process. Throughout the series of production steps in PCB fabrication, there are many points where alignment and matching are crucial. A slight misstep can lead to board defects, as a single issue can affect the entire process. Consequently, PCB quality problems can emerge one after another. Common examples include shorts, opens, and more!

Common Defect Causes in PCB Manufacturing

1.Shorts

(1) Improper pad design. We can change circular pads to oval ones, increasing the distance between points to prevent shorts.
(2) Improper component orientation design on the PCB. For instance, if the leads of an SOIC package are parallel to the solder wave, it can cause shorts. Therefore, we can appropriately modify the component orientation to make it perpendicular to the solder wave.
(3) Bent leads from automatic insertion can also cause PCB shorts. As IPC standards specify lead lengths below 2mm, and there is concern about components falling off if the bend angle is too large, shorts can easily occur. Therefore, solder joints should be kept more than 2mm away from the circuit traces.

Besides the above three points, some other reasons can cause short circuit issues on PCBs, such as oversized substrate holes, too low solder pot temperature, poor board solderability, solder mask failure, board surface contamination, etc. Engineers can conduct a series of fault investigations targeting these reasons.

2.Opens

Opens occur when a trace is broken, or when solder is only on the pad and not on the component lead. This is because there is no adhesion or connection between the component and the PCB. Like shorts, these can occur during production, soldering, or other operations. Vibrating or flexing the board, dropping it, or other mechanical deformation factors can damage traces or solder joints. Chemicals or moisture can cause wear on the solder or metal parts, leading to broken component leads.

3.Dark and Granular Joints Appearing on the PCB

This type of problem on the PCB is mostly due to contaminated solder or excessive oxides mixed into the molten solder, resulting in a brittle solder joint structure. It's important not to confuse this with the dark color caused by using solder with low tin content. Another cause of this problem is changes in the composition of the solder used during the manufacturing process, with excessive impurity content. Adding pure tin or replacing the solder is needed.

Blistering is a physical change in the glass fiber laminate, such as separation between layers. However, this is not a solder joint defect but rather the substrate being overheated. Reducing preheat and soldering temperatures or increasing the board travel speed can help.

4.PCB Solder Joints Turning Golden Yellow

Normally, PCB solder presents a silver-gray color, but occasionally golden-yellow solder joints appear. The main cause of this problem is excessive temperature. Simply lowering the solder pot temperature is the solution.

5.Environmental Impact

Under extreme or fluctuating temperatures, excessive humidity, high-intensity vibration, and other harsh environmental conditions, PCB damage is very likely. For example, changes in ambient temperature can cause board deformation, which can then damage solder joints, warp the board, or cause breaks in the copper traces on the PCB. Moisture in the air can lead to oxidation, corrosion, and rust on metal surfaces. Exposed copper traces, solder joints, pads, and component leads can be affected. The accumulation of dirt, dust, or debris on components and the PCB surface can reduce airflow and cooling, leading to PCB overheating and performance degradation. Vibration, drops, impacts, or bending of the PCB can deform it or cause cracks, while high current or overvoltage can lead to PCB breakdown or rapid aging of components and pathways.