Explanation of 7 common PCBA circuit board performance test methods

PCBA circuit board performance test is a necessary test to ensure the stability of product performance after PCBA processing is completed. According to the actual use environment and purpose of the product, it is generally divided into voltage resistance test, insulation test, salt spray test, impedance test, vibration test, high temperature and high humidity test, welding strength thrust test, etc. Below we will introduce these 7 PCBA circuit board performance tests in detail.

1. Voltage resistance test

The purpose of the voltage resistance test is to detect the voltage resistance of the circuit board, and the equipment needed is the "voltage resistance tester".

Test method: Connect the PCBA circuit board to be tested to the tester, increase the voltage to 500V DS (direct current) at a speed not higher than 100V/S, and keep it for more than 30 seconds. If there is no fault in the circuit, it means that the test has passed.

2. Leakage current test

The purpose of the leakage current test is to check whether the leakage current of the circuit board is within the requirements. The equipment needed is the "leakage current tester".

Test method: Simulate the leakage current between the part of the product that can be contacted to the two poles of the power supply under normal working conditions and normal temperature conditions of the circuit board. If the current is less than the design standard, it means that the test has passed.

3. Salt spray test

The purpose of the salt spray test is to check the corrosion resistance of the circuit board. The equipment needed is a "salt spray test machine"

Test method: First, we need to prepare a salt solution. The preparation method is: use chemically pure sodium chloride and distilled water or deionized water with a resistivity of not less than 5000 ohms*CM, and use 5% sodium chloride and 95% water. After sufficient mixing, make a salt solution with a sodium chloride content of 5±1%. After the salt solution is prepared, spray it continuously for 48 hours in a test site at a temperature of 35℃. The average spray volume per hour must reach 80CM square/10CM. After 48 hours, if the product functions normally, and the appearance and structure are normal, it means that the test has passed.

4. Impedance test

The purpose of the impedance test is to check whether the circuit board circuit can operate normally. The equipment needed is an "ohmmeter"

Test method: Connect the transmission line of the circuit board to the battery. If we measure the impedance in a shorter time than the transmission line reflection, we get the "surge" impedance or characteristic impedance. However, if the waiting time is long enough until the energy is reflected back and received, the impedance changes after measurement. Generally speaking, the impedance value will reach a stable limit value after bouncing up and down. If the limit value is within the specified range, it means that the test has passed.

5. Vibration test

The purpose of the vibration test is to detect whether the circuit board can pass the random vibration test of different levels. The equipment needed is a "vibrator"

Test method: Fix the circuit board or the packaged circuit board on the test bench, set the frequency to 20Hz, axial direction: X, Y, Z three axial directions, and last for one hour in each direction, for a total of three hours. After the test, the circuit board functions normally, the appearance and structure are normal, and there is no loose soldering of components, cracking and other abnormalities, which means that the test has passed.

6. High temperature and high humidity test

The purpose of high temperature and high humidity test is to check the applicability of the circuit board under the harsh conditions of high temperature and high humidity. The equipment needed is "constant temperature and humidity test chamber".

Test method: The PCBA circuit board is placed in the test chamber in a working posture under the working state of multiple rated voltage conduction and rated load to simulate the temperature and humidity conditions during actual work. If the actual working temperature and humidity are not clear, the temperature can be set to 70±2℃ and the humidity can be set between 90-95%. It can be continuously worked for 8 hours. If the basic functions of the PCBA circuit board are normal, the appearance and structure are normal, it means that the test has passed.

7. Welding strength thrust test

The purpose of welding strength thrust test is to test whether the welding strength of components meets the requirements. The equipment needed is "thrust gauge"

Test method: Place the welded PCBA circuit board on the thrust gauge. Components of different specifications have different passing requirements. Generally, we will eliminate other components on the edge of the target component, then reset the instrument to zero, and perform thrust test at an angle of ≤30 degrees to check whether the components are desoldered and record the value of component desoldering.

The thrust standards for commonly used components are: 0.65Kgf for 0402 components, 1.20Kgf for 0603 components, 2.30Kgf for 0805 components, and 3.00Kgf for 1206 components.

The above are 7 common PCBA circuit board performance test methods. You can choose different test methods according to the actual situation of your product.