Circuit board burn-in test method and general tutorial

　　The concept of PCB aging

　　The PCB aging we usually say is that after the circuit board is energized and worked for a certain period of time under certain conditions, some component parameters on the circuit board will change. This change is related to the time the circuit board is used. This is for some special purposes. Circuit boards are absolutely not allowed, so many circuit boards will be treated with anti-aging treatment before they leave the factory to stabilize the circuit before use. In this way, reliability and safety can be greatly improved.

　　PCB aging test method

　　In general industrial refrigerators, a single piece of non-welded parts is used in a fixed manner, and the temperature generally changes alternately between -40°C and +55°C. During this process, the lower temperature must be maintained for 1 hour, and then Slowly return to room temperature, keep it for 4 hours if it is not at room temperature, then slowly increase the temperature after 4 hours, and rise to the highest set temperature. This state should also be maintained for 2 hours, and then slowly fall to room temperature. 2 hours, take it out, check the smallest line and cut the health condition with vias. This process requires two cycles to be more assured.

　　Double-sided bonding circuit board

　　General Rules for Aging of Instrumentation Circuit Boards

　　Here is a general procedure for the aging of instrumentation circuit boards. We need to divide this procedure into several covers. These aspects include:

　　1. Subject content and scope of application

　　2, definition

　　3. Purpose

　　4, test environmental conditions

　　5. Requirements before aging

　　6. Aging equipment

　　7, aging

　　8. Recovery

　　9, final inspection

　　Let’s talk about these nine points separately.

　　Subject content and scope of application

　　This standard specifies the basic content and requirements for the aging screening of instrumentation function circuit boards. This standard applies to the aging screening of various single-loop regulators and functional circuit boards of various digital instruments in the instrumentation industry.

　　definition

　　instrumentation function circuit board (hereinafter referred to as the function board) refers to a printed circuit board that has installed components or components in the instrumentation and can complete a certain function.

　　Purpose

　　Make the functional board in a thermal aging equipment with temperature change, and withstand the change of air temperature. Through the combined effects of high temperature, low temperature, high and low temperature changes and electric power, the defects of the functional board are exposed, such as poor welding, component parameter mismatch, and temperature. The faults caused during drift and debugging can be eliminated, which will stabilize the parameters of the non-defective function board.

　　Detect environmental conditions

　　The test should be carried out under the following environmental conditions: Temperature: 15~35℃ Relative humidity: 45%~75% Atmospheric pressure: 86~106Kpa

　　Requirements before aging

　　There are also two requirements for the old circuit board. The two requirements are:

　　1. Electrical parameter testing All functional boards to be aging need to be tested for electrical parameters, and functional boards whose parameters do not meet the requirements should be eliminated.

　　2. Visual inspection is required for all functional boards to be aging in appearance inspection. For functional boards with obvious defects, such as short circuit, open circuit, component installation error, missing parts, and other defective functional boards should be eliminated.

　　Aging equipment

　　Any point in the working space of the heat aging equipment should meet the following requirements:

　　1. It can maintain the low temperature required for thermal aging.

　　2. It can maintain the high temperature required for thermal aging.

　　3. The change process from high temperature to low temperature or from low temperature to high temperature can be carried out according to the temperature change rate required for aging.

　　Function board installation and support

　　1. The function board should be installed on the bracket in the normal use position.

　　2. The support of the functional board should be insulated to ensure that there is no leakage between the tested functional board and the support.

　　3. The heat conduction of the support of the functional board should be low, so that the functional board and the support are actually insulated.

　　Electric power aging equipment

　　1. Electrical power aging equipment should ensure that it should not be shut down midway due to aging equipment during the aging process.

　　2. The electrical power aging equipment should ensure that it provides the voltage and current required by the aging function board, and can provide a variable input signal, and can detect each functional partner at any time.

　　Ageing

　　heat aging conditions

　　1. The heat aging time is at least 72h.

　　2. If there are no other regulations, the temperature cycle range should be: 0~60℃ or ~10~60℃, which can be selected by yourself.

　　3. Temperature change rate (average value during the change from low temperature to high temperature or from high temperature to low temperature) 1±0.5°C/min.

　　Double-sided binding PCB board

　　Aging method

　　The aging method is generally divided into seven steps. The seven steps are:

　　1. Put the functional board at the ambient temperature into the heat aging equipment at the same temperature.

　　2, the function board is running.

　　3. Then the temperature in the equipment should be reduced to room temperature at a prescribed rate.

　　4. Then the temperature in the equipment should rise to the specified temperature at a specified rate.

　　5. Then the temperature in the equipment should be reduced to the specified temperature value at a specified rate.

　　6. After the temperature in the equipment reaches a stable level, the functional board should be exposed to high temperature for 2h.

　　7. After the temperature in the equipment reaches a stable level, the functional board should be exposed to low temperature for 2h.

　　8, repeat 3 to 7 consecutively. Until the specified aging time, and according to the specified aging time, the function board is measured and recorded once.

　　9. The function board should be taken out of the box after the temperature in the equipment reaches room temperature and is stable.

　　recover

　　After taking out the functional board, it should be placed under the specified conditions and allowed to reach a stable temperature. The recovery time is at least 1h.

　　final inspection

　　Perform electrical parameter testing on the function board under specified conditions, and reject those that do not meet the requirements.

　　Through the above nine steps, under normal circumstances, it is possible to do a good job of detecting the aging of the circuit board, but some special cases still need to be excluded, so everyone must learn to learn and apply.

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