sales@ipcb.com
In the production process of PCBA boards, due to improper operation of the staff or data quality problems, often appear PCBA defective boards. At this time, it is necessary to carry out PCBA board maintenance for the defective ones. In PCBA board factories, there are usually PCBA board maintenance engineers who need to follow specific maintenance procedures when performing board maintenance.
The PCBA board maintenance process is as follows
PCBA board visual inspection → measure all the power → bad power test → repair according to the bad phenomenon → self-check after repair → test fixture test → visual inspection and comprehensive inspection
The tools required for PCBA board maintenance include oscilloscope, digital ammeter, constant temperature soldering iron,heat gun,sharp-nosed pliers, diagonal cutters and tweezers.
1.Visual inspection of the PCBA board
Mainly check the PCBA board whether there are obvious appearance of defects. For example: short circuit, empty welding, missing parts, component polarity reversal, wrong parts burning.
2.Measurement of all power
Mainly used to measure whether the short circuit to ground.
3.Poor power-on test
After power on, the test fixture DOUBLECHECK bad.
4.Repair according to defects
Repair according to the defective phenomenon and circuit principle.The maintenance instructions are available for the project.
5.Self-inspection after maintenance
After maintenance, it is necessary to self-check the maintenance part.Mainly checking: short circuit,virtual welding,welding beads,welding slag,and the appearance of welding joints.
6.Test fixture test
Use the test fixture to check whether the PCBA is correctly maintained.
7.Comprehensive visual inspection
Comprehensive inspection of the repaired product.By repairing defective PCBA boards,we can reduce board waste and factory production costs.
PCBA board repair method summary
First look and then test: first visual inspection of the PCBA board to be repaired,if necessary, use a magnifying glass to observe.
First outside and then inside:If the situation permits,it is best to have a good PCB circuit board as the board to be repaired as a reference, and then use the tester's double ‘VI’ curve scanning function on the two boards to test the advantages and disadvantages of comparison.The initial comparison test point can start from the port of the PCBA board,and then from the outside to the inside of the comparison test, especially for capacitance.This compensates for the difficulty of measuring capacitor leakage on multimeter wires.
Easy before hard:To improve the test results, before conducting online functional tests on PCBA boards,it is necessary to do some technological processing on the repaired circuit boards to minimise the impact of various kinds of interference on the test process.
Specific measures are as follows
1.Pre-test preparation: For large-capacity electrolytic capacitors, the next leg should be soldered open,because the charging and discharging of large-capacity capacitors will also bring interference.
2.Test the equipment using the exclusion method: When testing the equipment on-line or in comparison tests,directly confirm and record the test results of all the equipment that passes the test.If the test fails,retest.If it still fails,you can first confirm the test results.
Here is IPCB share PCBA board repair methods,I believe that after you understand the principle of repair,repair PCBA board will be more convenient.