The hole size of the pad should be considered in the PCB design

- Nov 03, 2018-

The minimum diameter is designed according to the requirements of the welding pad, which is at least 0.5mm larger than the maximum diameter of the small hole flange of the welding terminal.Test pads must be provided for all nodes as required by ANSI/IPC 2221.A node is an electrical connection point between two or more components.A test pad requires a signal name (node signal name), x-y coordinates associated with the PCB reference point, and the coordinates of the test pad (indicating which side of the PCB the test pad is on).There is a need to provide information on the fixtures for SMT, and there is also a need for the warm fit technology of the printed circuit board assembly layout to promote testability in the circuits with the help of the "circuit test fixture" or commonly referred to as the "nail bed fixture". To achieve this goal, the following steps are required:

1) the diameter of the test pad used for detection shall be no less than 0.9mm.

2) the space around the test pad should be greater than 0.6mm and less than 5mm.If the height of the component is greater than 6.7mm, the test pad should be placed outside 5mm of the component.

3) do not place any components or test pad within 3mm from the edge of the printed circuit board.

4) the test pad shall be placed in the center of a 2.5mm hole in a grid.If possible, allow the use of standard probes and a more reliable fixation device.

5) do not rely on the edge of the connector pointer for pad testing.Test probes can easily damage gold-plated hands.

6) avoid the probe on both sides of the PCBS.Put the test tip through the hole onto the non-component/welding surface of the printed circuit board.