What are the round pads on the bottom of a PCB?

These test pads and the test points are probably used in different parts of the manufacturing process. For example,

• The test points may be used for board-level testing and the test pads may be used for system-level testing. These are test pads designed for use with a pogo-pin test fixture, also known as a bed-of-nails test fixture. These fixtures have a specially shaped array of pogo-pins that press down and make contact with the test pads on the board under test.
• Or, perhaps, the test pads are used for programming and/or debugging firmware, when the device under test is clamped into the bed-of-nails fixture.

Read More: Multiple Testing Methods

#PCB Assembly #PCB Testing