For PCBA, performance tests after manufacturing is necessary. According to the actual environment and purpose of the product, the tests are generally divided into withstand voltage test, insulation test, salt spray test, impedance test, vibration test, high temperature and high humidity test, welding strength thrust test, etc. Here, let's talk about 7 common performance tests that check if the product is good.

1. Withstand voltage test

The withstand voltage test detects the withstand voltage capability of the circuit board. And the equipment is withstand voltage tester. How is it done? Connect the PCBA to the tester. Increase the voltage to 500V direct current at a speed not higher than 100V/S. Keep it for more than 30 seconds. If there is no fault in the circuit, the product passes the test.

2. Leakage current test

The leakage current test checks whether the leakage current of the circuit board is within the requirements. And the equipment called "leakage current tester" comes into use. You know how to test it? Simulate the leakage current between the contactable part of the product and the two poles of the power supply under the normal working condition and the normal temperature. If the current is less than the design standard, the PCBA passes the test.

3. Salt spray test

The salt spray test checks the corrosion resistance of PCBA. We use the equipment called "salt spray test machine"

First of all, we need to configure the salt solution. How to do that? Prepare chemically pure sodium chloride and distilled water or deionized water with a resistivity of not less than 5000 Ω*cm. 5% sodium chloride and 95% water are also what we need.

After thorough mixing, make a salt solution with a sodium chloride content of 5±1%. After the salt solution is prepared, spray continuously for 48 hours in a test site with a temperature of 35°C. The average spray volume per hour should meet the requirement. After 48 hours, if all functions of the product are normal, and the appearance and structure are normal, the product is good.

4. Impedance test

This impedance test checks whether the circuit board works well. Ohmmeter does that job.

Connect the transmission line 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 we wait for a while until the energy is reflected, it can be found that the impedance has changed through measurement.

Generally speaking, the impedance reaches a stable limit value after bouncing up and down. If the limit value is within the specified range, it means that the PCBA is good.

5. Vibration test

The vibration test detects whether the circuit board passes the random vibration test of different levels. The equipment needed is the "vibration meter".

Fix the circuit board or the packaged circuit board on the test bench. Set the frequency to 20Hz. There are three axes, X, Y, Z. The duration is one hour in each direction, a total of three hours.

After testing, if the function of the circuit board is normal, the appearance and structure are normal, and there is no loose welding of components, cracks and other abnormalities, it means that the PCBA is good.

6. High temperature and high humidity test

The high temperature and high humidity test checks the applicability of the circuit board under the harsh conditions of high temperature and high humidity. The equipment is a "constant temperature and humidity test chamber".

The PCBA is in the double rated voltage conduction, under the working state of rated load. Put it into the test chamber with a working attitude, and simulate the temperature and humidity during actual work. If you don’t know the temperature and humidity, you can set the temperature to 70±2°C, and the humidity is between 90-95%. Let it continue to work for 8 hours. If the basic functions of the component are normal, and the appearance and structure are normal, it means that the component can work well.

7. Welding strength thrust test

The welding strength thrust test checks whether the welding strength of the components meets the requirements, and the equipment that needs to be used is a "thrust meter".

Place the soldered PCBA on the thrust gauge. Components of different specifications have different passing requirements. Generally, we eliminate other components on the edge of the target component. Then reset the instrument to ≤ 30 degrees. Carry out a thrust test at the corner to check whether the components are desoldered. Next, record the desoldered value of the components.

Those are 7 important performance tests of printed circuit board assembly. You can choose different test methods according to the actual situation of your products.