PCB Inspection Process Fflow and Notes
PCB inspection process includes the following steps:
Appearance Inspection: Mainly check the surface of the PCB circuit board to see if there is any obvious damage, loose joints or broken solder joints and other problems. In addition, attention should also be paid to the PCB circuit board pads, solder joints and pins connected to the device to see if there are any quality problems such as false soldering, excessive soldering and short circuits.
Component Inspection: PCB circuit board components for inspection, special attention should be paid to checking the circuit board components whether there is inserted reverse, inserted loose and whether the quality of the components are qualified and other issues.
Electrical Inspection: Use test equipment to measure the electrical characteristics of the PCB circuit board, check whether the connection between the components on the circuit board is normal, whether the line is smooth, and whether the working state of the circuit board meets the requirements.
Functionality Check: Test the board by simulating the normal working condition to check whether the board can work normally. Function check needs to be based on different types of circuit boards and functions to set up the appropriate test program.
Check After Power On: After power on, first observe the circuit with or without abnormal phenomena, such as smoke phenomenon, there is no abnormal odor, hand touch the outer package of the integrated circuit is hot. If there are abnormal phenomena, you should immediately turn off the power supply, to be eliminated after the fault and then power on the check.
Static Ttest: Check the level state step by step to see if the level state is as expected, and gradually restore the welding 0Ω resistor. Sub-circuit debugging order is generally carried out according to the signal flow, the previous debugged circuit output signal as the latter level of input signals, to create conditions for the final unification.
Dynamic Testing: Gradually add external input and output signals to debug the various parts of the system. This step needs to be combined with the software for joint debugging.
In the testing process, carefully observe and analyze the experimental phenomena and make records to ensure that the experimental data are complete and reliable.
When using the test instrument, the meter pen or probe should not be short-circuited between the IC pins due to sliding. It is best to measure on the peripheral printed circuits that are directly connected to the pins.
When testing the PCB board, pay attention to the power integrated circuit heat dissipation, power integrated circuits should be good heat dissipation, not allowed to work without a heat sink and in a high-power state.
When testing the PCB board, to ensure the quality of welding. Soldering does weld firmly, the buildup of solder, air holes can easily cause false soldering. Has been welded integrated circuits should be carefully viewed, it is best to use an ohmmeter to measure whether there is a short circuit between the pins, to confirm that there is no solder sticking phenomenon before turning on the power.
In the debugging process, we should carefully observe and analyze the experimental phenomena, make a good record to ensure that the experimental data is complete and reliable.
In the testing process, special attention should be paid to voltage measurement or waveform testing with an oscilloscope probe, the pen or probe do not slide and cause short-circuiting between the pins of the integrated circuit. It is best to measure on the peripheral printed circuit directly connected to the pins.
Test PCB board test meter internal resistance should be large. Measurement of integrated circuit pin DC voltage, should be used in the head of the internal resistance greater than 20KΩ / V multimeter, otherwise there will be a large measurement error on some pin voltage.
When conducting functional testing, it is necessary to combine the software for joint debugging. In addition, care should be taken to deal with the ground terminal between the audio amplifier IC and the preamplifier circuit.
In the whole testing process, attention should be paid to safety issues, such as avoiding the use of sharp tools, avoiding the circuit board falling, etc.. Attention should also be paid to environmental protection issues, and appropriate measures should be taken to deal with waste products such as exhaust gas and waste liquid.
In order to ensure the quality and reliability of PCB, the following key pointsshould be noted during the testing process:
Accurate Measurement: Ensure the accuracy and stability of the test instrument to avoid misjudgment due to measurement error.
Detailed Observation: During the appearance inspection and function test, special attention should be paid to the details, such as the size and color of the solder joints, and whether the pins are loose.
Standardized Operation: Ensure the consistency and standardization of the testing process to avoid human error.
Safety First: In the testing process, special attention should be paid to safety issues, such as avoiding the use of sharp tools, avoiding circuit boards falling, etc.
Environmental Protection Treatment: In the testing process, corresponding measures should be taken to deal with waste such as waste gas and waste liquid to ensure environmental protection and safety in the production process.
Record and Traceability: The data and phenomena in the testing process are recorded in detail to facilitate problem tracing and subsequent analysis.
Feedback and Improvement:Provide timely feedback on problems based on test results and take corresponding improvement measures to improve the quality and reliability of PCB.
Regular Training: Regular training and skill enhancement for testing personnel to ensure that they can accurately and efficiently carry out PCB testing.
Equipment Maintenance: Regular maintenance and calibration of testing equipment to ensure the stability and accuracy of the equipment.
Preventive Maintenance: Preventive maintenance and upkeep of testing equipment to reduce the probability of equipment failure.
Result determination and classification: determine the quality level of PCB according to the test results, and carry out classification to ensure that non-conforming products are dealt with in time.
Synergy With Other Links: Maintain close communication and synergy with other links of PCB production to ensure quality control from the source.
Test Document Management: Establish a perfect test document management system to ensure the long-term preservation of test data and results.
Test Environment Control: Ensure that the test environment meets the requirements, such as temperature, humidity, etc., to avoid the impact of environmental factors on the test results.
Follow Industry Standards and Norms: In PCB testing, should follow the relevant industry standards and norms to ensure the accuracy and reliability of test results.
In general, PCB testing is a rigorous process that requires strict adherence to operating procedures, attention to detail, to ensure that each link is effectively controlled and managed. Only in this way can we ensure that the final PCB product meets the requirements and improve the reliability and stability of the product.
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