PCB News - Adding principles and size selection of PCB test points

Next, we will continue to ask our big coffee to explain the principle of adding PCB test points and size selection.

In fact, some friends may have realized it. Speaking of this, the main work of our PCB design is actually coming to an end, and the rest of the work is basically to clean the "battlefield".

But don't be careless, the rest of the work is also extremely important. All links are also "dangerous", and you will "step on thunder" if you are not careful.

Test points on the PCB board

(1) The principle of adding test points for PCB circuit boards

Selection of test points:

1) The test points should be evenly distributed on the entire PCBA board.

2) The lead-out pins of the device, test pads, connector lead-out pins and via holes can all be used as the test points of the PCB circuit board, but it is better not to use the via holes as the test points of the board.

3) It is better to use test pads as test points for SMD components.

4) A test point should be added to each network line when wiring, and the test point should be as far away from the device as possible. Two tests

The spacing of the dots should not be too close, and the center spacing should be 2.54mm; if there is already a PAD or Via on a network line, there is no need to add additional test pads.

5) The pads of SMD components on the bottom layer cannot be used as test points.

6) There should be more than 10 test points for the power supply and the ground, and these test points should be evenly distributed on the entire PCBA board to reduce the influence of the reverse drive current on the potential of the entire PCBA board during the test. Equipotential on PCBA board.

7) When testing the PCBA board with battery, jumper wires should be used to prevent the short circuit around the battery from being undetectable.

8) When adding test points, the additional line should be as short as possible.