Table of Contents
Electrical Testing (E-Test) is a vital part of the quality control process since it ensures that each PCB works exactly as specified before assembly. By identifying problems early on, E-Test avoids costly failures, rework, and warranty claims, ensuring that your boards meet industry standards and customer expectations.
In this article, we’ll explain what PCB E-Test is, why it’s important, how it works, the common testing methods, and how it’s used in specific applications like PCB Rogowski coils.
What is PCB Electrical Testing?
PCB Electrical Testing is the process of verifying the electrical integrity of a printed circuit board. The goal is to ensure that:
- No unintended connections (shorts)
- All required connections are present and working (continuity)
E-Test is a final quality control step before a PCB moves to the assembly or delivery process.
Why is PCB E-Test Necessary?
Even the smallest fault in a circuit can lead to device failure, malfunction, or even safety issues. But PCBs are increasingly complicated with multiple layers, high-density components, and fine traces, visual inspections or other tests are often not enough.
E-Testing detects issues such as:
- Opens – Missing or broken connections
- Shorts – Unwanted electrical connections
- Impedance deviations – Critical in high-speed or RF designs
- Insulation weaknesses – Potential leakage or breakdown
When internal layers of PCB aren’t visible and can’t be visually inspected, electronic testing is the only way to find the hidden defects.
Benefits of E-Test in PCB Manufacturing
E-Test offers a lot of advantages to both the PCB manufacturer and the end user:
- Improved product quality: The electrical integrity of the PCB is pretty effective in reducing the possibility of defects.
- Lower Failure Rates: E-test ensures faults are detected at a very early stage of manufacturing processes, avoiding failures that might cost when it comes to the finished products. The field failure rate of PCBs also tends to go down, coupled with costs for repair, rework, and warranty claims.
- Increased Reliability: E-Testing ensures the reliability of PCBs, wherein they should work exactly in a real-world environment as expected.
Also, recent systems of E-Test add software that creates and helps analyze maps for results generated during the testing to rapidly identify errors and appropriately record this for quality control purposes.
How does E-Test Work on PCB?
E-Test is performed through special tools that assess the electrical attributes of the PCB.
E-Testing generally includes the following core test types:
1. Conductivity Test
- This test is performed to check the PCB for breaks or shorts in lines, whether the electrical connection is according to design requirements or not.
2. Insulation Resistance Test
- Verify the insulation performance between different conductors to prevent leakage or short circuit.
3. Dielectric Withstand Test
- Apply a specified high voltage to ensure that the PCB’s insulation can resist it without electrical failure. This is especially relevant for high-voltage circuit boards and safety-critical applications.
4. Impedance Test
- It detects whether the characteristic impedance of a PCB meets the design value, which is very important in high frequency or high speed digital circuits.
In addition to these core tests, two specialized electrical testing methods are widely used in PCB manufacturing:
5. Flying Probe Test (FPT)
- It is no fixture e-test of PCB where the manufacturers uses flying probe for PCB testing. The probe test the signal on each traces as command by the specified application program.Capability: It checks the open and short circuits on bare board while it validates the values of capacitance, resistance and inductance on populated board.Advantages: Flexible, low setup cost, ideal for prototypes and low-volume production.
5. Bed of Nails Test (Fixture Method)
- Each type of PCB will have one test template, and then uses a custom-made fixture with spring-loaded pins (“nails”) that press against the PCB’s contact points to test multiple circuits simultaneously.Advantages: Very fast and accurate, making it ideal for high-volume production.Considerations: It is time-consuming to align the fixture and the individual set up is costly.
Flying Probe vs Bed-of-Nails Test Comparison Table
| Feature | Flying Probe Test | Bed-of-Nails Test |
| Fixture Required | ❌ No | ✅ Yes |
| Setup Cost | Low | High |
| Test Speed | Slow (1 PCB at a time) | Very Fast (Many points at once) |
| Accuracy | High | Very High |
| Flexibility | Very Flexible | Limited (One fixture per PCB) |
How to Take a PCB Electrical Testing?
Standards for PCB Electrical Testing
Industry standards define the E-Testing requirements that would guarantee quality and consistency in the manufacturing of PCBs. One widely recognized standard is the IPC-9252, which includes procedures and requirements applying to the electrical testing of PCBs.
This standard defines:
- The test data, test analyzers, and test parameters for continuity and isolation
- The acceptance criteria for helping to identify open and short circuits
- Guidelines for testing multi-layer and high-density PCBs
Step-by-Step PCB E-Test Process
1. Data Preparation: Load the PCB netlist or Gerber data into the tester.
2. Test Setup: Choose Flying Probe or Bed-of-Nails depending on volume.
3. Continuity Test: Check for opens and shorts.
4. Insulation Resistance Test: Measure resistance between conductors.
5. Dielectric Withstand
6. Test: Apply high voltage to ensure breakdown resistance.
7. Impedance Test: Verify controlled impedance in high-frequency designs.
8. Result Recording: Store data for quality control and traceability.
Example: Electronic Test for PCB Rogowski Coils
PCB E-test is an indispensable means to guarantee the performance of electronic components or devices. Rogowski coils are used for current measurement in power systems, especially in high-frequency and high-current applications.
Applications in E-Test:
- Manufacturing Verification: Ensure winding and connections are correct.
- Performance Evaluation: Measure mutual inductance coefficient and frequency response.
Design Improvements with E-Test Feedback:
- Symmetrical Structure Coils: Reduce interference for better accuracy.
- Differential Structure Coils: Maximize mutual inductance for higher sensitivity.
Conclusion
Assuring electrical integrity, reliability, and quality in printed circuit boards makes E-test the crucial process in PCB manufacturing.
E-Test technologies are advancing to support the growing complexity and density that have raised the bar for PCB manufacturing. E-Test is a basic aspect of the quality control of PCB manufacturing, whether in the Flying Probe or Bed-of-Nails methods. More reliability will be guaranteed as long as products meet the requirements based on IPC-9252 or better.
Ready to ensure 100% quality for your PCBs?
Check out ELEPCB’s quality control page to find the better choice!
References
[1] Yue, X.; Zhu, G.; Wang, J.V.; Deng, X.; Wang, Q. PCB Rogowski Coils for Capacitors Current Measurement in System Stability Enhancement. Electronics 2023, 12, 1099. https://doi.org/10.3390/electronics12051099
[2] A. P. Nurmansah and S. Hidayat, “Design and testing PCB Rogowski-coil current sensor for high current application,” 2017 International Conference on High Voltage Engineering and Power Systems (ICHVEPS), Denpasar, Indonesia, 2017, pp. 493-497, doi: 10.1109/ICHVEPS.2017.8225897.
CONTACT US
English 
Italian 
Hungarian