Reliability Test Method for PCB Circuit Board

PCB circuit board plays an important role in today's life. It is the basis of electronic components and highway. In this regard, the quality of PCB is critical.

To check the quality of PCB, many reliability tests must be carried out. The following paragraph is an introduction to testing.

1. Ion contamination test

OBJECTIVE: To check the number of ions on the surface of PCB to determine whether the cleanliness of PCB is qualified.

METHODS: The surface of the sample was cleaned with 75% propanol. Ions can dissolve into propanol, thus changing its conductivity. The change of conductivity was recorded to determine the ion concentration.

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

2. Chemical Resistance Test of Welding Resistance Film

OBJECTIVE: To examine the chemical resistance of welding resistance film.

METHODS: Qs (quantum satisfactory) dichloromethane was dripped onto the surface of the sample. Later, wipe dichloromethane with white cotton. Check cotton dyeing and solder mask dissolution.

Standard: No dye or dissolution.

3. Hardness Testing of Welding Resistance Layer

OBJECTIVE: To examine the hardness of welding resistance film.

Method:

1. Place the circuit board on a flat surface.
2. Use a standard pen to scrape a certain range of hardness on board until there is no scratch.
3. Record the minimum hardness of the pencil.

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

4. Stripping Strength Test

OBJECTIVE: To examine the force that can strip copper wires from circuit boards.

Equipment: Peeling Strength Tester

Method:

1. Strip copper wire at least 10 mm from one side of the substrate.
2. Place the sample board on the tester.
3. Use vertical force to strip the remaining copper wire.
4. Record strength.

Standard: Force should exceed 1.1N/mm.

5. Weldability testing

OBJECTIVE: To check the solderability of pads and through holes on plates.

Equipment: soldering machine, oven and timer.

Method:

1. Bake the board in an oven at 105 C for 1 hour.
2. Soldering flux.
3. Flatly put the board to the solder machine at 235 C, and take out after 3 seconds, the inspected area of the pad should be tin dipped.
4. Place the plate vertically in a soldering machine at 235 C and take it out after 3 seconds to check whether the through hole is leached with tin.

Standard: Area percentage should be greater than 95. All through holes should be leached with tin.

6. Voltage test

OBJECTIVE: To test the voltage withstanding ability of circuit boards.

Equipment: Voltage withstanding tester

Method:

1. Clean and dry the sample.
2. Connect the circuit board to the tester.
3. Increase the voltage to 500V DC (direct current) at a speed not higher than 100V/s.
4. Keep it at 500V DC for 30 seconds.

Standard: There should be no fault in the circuit.

7. Glass Transition Temperature Test

OBJECTIVE: To investigate the glass transition temperature of the inspection plate.

Equipment: DSC (Differential Scanning Calorimeter) tester, oven, dryer, electronic scale.

Method:

1. Samples should be prepared with a weight of 15-25 mg.
2. The samples were baked in an oven at 105 C for 2 hours and then cooled to room temperature in a dryer.
3. The sample is put on the sample table of DSC tester, and the heating rate is set to 20 C/min.
4. Tg was recorded after 2 scans.

Standard: Tg should be higher than 150 C.

8. CTE (coefficient of thermal expansion) test

Objectives: CTE of evaluation board.

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

Method:

1. Samples with sizes of 6.35 * 6.35 mm are prepared.
2. The samples were baked in an oven at 105 C for 2 hours and then cooled to room temperature in a dryer.
3. Place the sample on the sample table of TMA tester, set the heating rate to 10 C/min, and set the final temperature to 250 C.
4. CTE was recorded.

9. Heat Resistance Test

Objective: To evaluate the heat resistance of the plate.

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

Method:

1. Samples with sizes of 6.35 * 6.35 mm are prepared.
2. The samples were baked in an oven at 105 C for 2 hours and then cooled to room temperature in a dryer.
3. The samples were put on the sample table of TMA tester and the heating rate was set at 10 C/min.
4. The sample temperature was raised to 260 C.