During the manufacturing, assembly and usage of circuit boards, various problems may arise, affecting functionality, reliability and even safety. The following are 12 types of high-frequency issues along with their root cause analysis, detection methods and solutions, covering design, process, materials and environmental factors.
1、 Welding process issues
Poor welding, cold welding
Phenomenon
The surface of the solder joints is rough and the electrical connection is unstable.
Reason
The solder paste is either insufficiently active or has expired.
The reflow soldering temperature curve is inappropriate (insufficient preheating or too low peak temperature).
Solution
Replace with high-activity solder paste (such as containing organic acid activator).
Optimize the reflow soldering profile (preheating for 90 to 120 seconds, peak temperature 245 to 250℃).
Tin beads, tin balls
Phenomenon
Tiny tin balls are scattered around the solder joints.
Reason
Solder paste splashing (due to improper design of the steel mesh holes).
Reflow soldering heating rate too fast (> 3℃/s).
Solution
The opening area ratio of the steel mesh is ≥ 1:1.1, and the thickness is 0.1 – 0.15mm.
Control the heating rate (1 – 2℃/s).
2、PCB substrate defects
Open circuits, short circuits
Phenomenon
Line breakage or unexpected connection.
Reason
Insufficient etching (remaining copper) or excessive etching (broken lines).
Drilling offset causes misalignment between layers.
Solution
Strengthen DFM checks (such as minimum line width/spacing ≥ 3 mil).
Use AOI (Automatic Optical Inspection) or flying probe testing.
Layering, board splitting
Phenomenon
Separation or blistering of the inner layers of the PCB.
Reason
The material absorbs moisture (for example, FR4 without pre-baking).
During reflow soldering, the thermal stress exceeds the substrate’s TG value (for instance, a TG 130℃ board can withstand a 260℃ soldering process).
Solution
The humidity of PCB storage is less than 30%, and it should be baked at 105℃ for 4 hours before welding.
Choose high-TG materials (such as TG170℃).
3、Component Issues
Component damage
Phenomenon
IC burned out, capacitor bulged.
Reason
Overvoltage/overcurrent (such as power supply reverse connection).
ESD electrostatic damage (HBM > 2kV).
Solution
Add protection for TVS diodes.
The production line needs to be equipped with anti-static facilities (such as ion blowers, grounding wrist straps).
Reverse polarity connection
Phenomenon
Diodes and electrolytic capacitors are installed in reverse.
Reason
Programming errors in the reflow oven or operational mistakes by humans.
Solution
Strengthen the first-piece inspection.
Use packages with distinct polarity markings (such as thickening the cathode wire for tantalum capacitors).
4、Environmental and Reliability Issues
Corrosion and Oxidation
Phenomenon
The pads or pins have turned black or developed green rust.
Reason
The storage environment has an excessively high humidity level (greater than 60% RH).
There is no protective coating (such as OSP treatment for PCBs exposed to air for more than 72 hours).
Solution
Use anti-corrosion paint (acrylic or polyurethane).
Vacuum package the PCB and complete the soldering within 24 hours after opening.
Thermal stress failure
Phenomenon
BGA solder joints cracked and ceramic capacitors broke.
Reason
CTE mismatch occurs during the temperature cycle (such as between FR4 and ceramic capacitors).
Solution
Optimize the layout (avoid placing large-sized ceramic capacitors close to the edge of the board).
Add flexible glue (such as silicone) to buffer stress.
5、Design Defects
Electromagnetic Interference (EMI)
Phenomenon
Excessive signal noise and interruption of wireless communication.
Reason
The high-frequency signal lines lack shielding or the reference layer is incomplete.
The power ground division is unreasonable.
Solution
Use multi-layer boards (≥ 4 layers) to ensure a complete flat surface.
Key signal lines should be covered with shielding covers or common-mode chokes.
Insufficient heat dissipation
Phenomenon
Chip overheating (> 85℃), shortened lifespan.
Reason
Insufficient copper foil area or no design of heat dissipation holes.
Solution
Add heat dissipation pads and thermal vias.
Apply copper on high-temperature areas and attach heat sinks.
6、Detection and Analysis Methods
Common testing tools
| Question type | Testing tool | Key indicators |
| Cold solder joints, short circuits | X-ray、3D AOI | Solder joint porosity < 25% (IPC-A-610) |
| Signal integrity | Oscilloscope, TDR time domain reflectometer | Signal rise time < 1 ns (high-speed design) |
| Material failure | SEM/EDS composition analysis | Tin whisker growth length < 50 μm (JESD22-A121) |
TORTAI Electronic Testing Service
Failure analysis using X-ray combined with slice-based defect location, providing quick reports.
Environmental testing including temperature and humidity cycling (-40°C to +125°C) and salt spray tests.
EMC testing for radiation emission (RE) and CE certification.
From problem identification to solution, we offer a one-stop solution for circuit board reliability issues!
If you have any questions or need any consultation regarding the circuit board inspection analysis and solutions, please contact us immediately.