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PCB (printed circuit board) reliability test method

2019-07-25 18:22:48 404

PCB (printed circuit board) reliability test method

PCB (printed circuit board) plays an important role in today's life. It is the foundation of electronic components and highways. In this regard, the quality of the PCB is critical.


To check the quality of the PCB, a number of reliability tests must be performed. The following paragraphs are an introduction to testing.


Ion contamination test


Purpose: Check the number of ions on the surface of the board to determine if the board is clean.


Method: The surface of the sample was cleaned with 75% strength propanol. Ions can be dissolved in propanol to change its conductivity. The change in conductivity is recorded to determine the ion concentration.

Standard: Less than or equal to 6.45ug.NaCl / sq.in


2. Chemical resistance test of solder mask


Purpose: To check the chemical resistance of the solder mask


method:

Qs (quantum satisfactorily) dichloromethane was added dropwise to the surface of the sample.

After a while, wipe the methylene chloride with white cotton.

Check if the cotton is dyed and the solder mask is dissolved.

Standard: no dye or dissolved.


3. Solder mask hardness test


Purpose: Check the hardness of the solder mask


method:

Place the board on a flat surface.

Use a standard test pen to scratch a range of hardness on the boat until there are no scratches.

Record the minimum hardness of the pencil.

Standard: The minimum hardness should be higher than 6H.


4. Stripping strength test


Purpose: Check the force that can strip the copper wire on the board


Equipment: Peel strength tester


method:

Strip the copper wire from at least 10 mm from one side of the substrate.

Place the sample plate on the tester.

Use the vertical force to strip the remaining copper wire.

Record strength.

Standard: The force should exceed 1.1 N / mm.


5. Solderability test


Purpose: To check the solderability of the pads and vias on the board.


Equipment: soldering machine, oven and timer.


method:

The panels were baked in an oven at 105 ° C for 1 hour.

Dip soldering agent.

The plate was slashed to the solder machine at 235 ° C and taken out after 3 seconds, the area of the pad was inspected for immersion tin.

The plate was placed vertically in a 235 ° C soldering machine, and after 3 seconds, it was taken out to check whether the through holes were immersed in tin.

Standard: The area percentage should be greater than 95. All through holes should be immersed in tin.


6. Withstand voltage test


Purpose: To test the withstand voltage capability of the board.


Equipment: pressure tester


method:

Clean and dry the sample.

Connect the board to the tester.

Increase the voltage to 500V DC (DC) at a speed no higher than 100V / s.

Hold it at 500V DC for 30 seconds.

Standard: There should be no faults on the circuit.


7. Glass transition temperature test


Purpose: Check the glass transition temperature of the plate.


Equipment: DSC (differential scanning calorimeter) tester, oven, dryer, electronic scale.


method:

Prepare the sample and its weight should be 15-25mg.

The sample was baked in an oven at 105 ° C for 2 hours and then placed in a desiccator to cool to room temperature.

The sample was placed on a sample stage of a DSC tester and the rate of temperature increase was set to 20 ° C / min.

Scan 2 times and record Tg.

Standard: Tg should be above 150 °C.


8. CTE (coefficient of thermal expansion) test


Objective: Evaluate the CTE of the board.


Equipment: TMA (thermomechanical analysis) tester, oven, dryer.


method:

Prepare a sample with a size of 6.35 * 6.35mm.

The sample was baked in an oven at 105 ° C for 2 hours and then placed in a desiccator to cool to room temperature.

Place the sample on the sample stage of the TMA tester, set the heating rate to 10 °C / min, and set the final temperature to 250 °C.

Record the CTE.


9. Heat resistance test


Purpose: To evaluate the heat resistance of the board.


Equipment: TMA (thermomechanical analysis) tester, oven, dryer.


method:

Prepare a sample with a size of 6.35 * 6.35mm.

The sample was baked in an oven at 105 ° C for 2 hours and then placed in a desiccator to cool to room temperature.

Place the sample on the sample stage of the TMA tester and set the heating rate to 10 °C / min.

The sample temperature was raised to 260 °C.