What is PCB Backplane Testing?

A backplane is an electronic system which contains slots and sockets to interconnect various PCB assemblies or devices in parallel to each other. It acts like a ‘Backbone’ for an electronic system and distributes low-voltage power to each slot.

Backplane testing evaluates the working of backplanes and passive electronic components such as resistors, capacitors, and diodes. The backplane provides the physical and electrical connections between system components, it is essential that it is operating within its prescribed parameters. In order to ensure the smooth working of a backplane, some tests are performed. The process of identifying the major faults in the backplane by using test processes is called backplane testing.

Key Specifications of backplane testing include test points, test resistance, maximum current and maximum voltage.

Backplane Testing Consists of the following types of tests:

Visual Inspection: In this test, components on the backplane are checked individually for correct placement. It also includes checking solder joints and component orientation. It can be done manually or through Automated Optical Inspection (AOI).

Electrical Tests: These test checks the connections by sending an electrical current through the pins and traces on the board. It has two major areas to test:

• Continuity or open circuit which means there is a connection between the pins.
• Isolation or short which means there is a space between the pins to make sure that there is no connection.

The electrical test provides confirmation in two terms, i.e, ‘Continuity’ if a connection exists between the test points and ‘Short’ if doesn’t. This test is important since a connection which is not required can cause interference on the board and lead to malfunctions.

Functional Test: This test is done to check how the circuitry will work after integrating with the final device or application intended.

Signal Integrity Analysis and Simulation: As higher speed signals are constituted within the backplanes. In order to analyze such signals, network analyzers are used for the time domain and frequency domain measurements.