What are shorting blocks?

In general, shorting blocks are mechanical devices used to purposely create a short circuit between one or more electrical nodes. They are usually used in testing or troubleshooting to confirm opens really are open.

They may consist of a conductive metal block or plastic with an electrically conductive surface that can be connected to various points in a circuit via a connector, socket or test points. A new ‘short circuit’ is formed by connecting the terminals with a conductor, such as a wire, connector and PCB combination, or through the metal shorting block itself.

Shorting blocks are frequently used in electronic test labs or on-site testing environments, allowing engineers and technicians to swiftly and easily connect or disconnect this test accessory to parts of a circuit and create temporary short circuits useful for testing and diagnostic purposes.

While shorting blocks are useful tools, they should be used with low voltage and low current to avoid creating high current paths that can get hot and cause damage to components or create a burn hazard. It is critical to follow proper safety procedures and to employ shorting blocks only when necessary.

Gold (Au) plated FR4 shorting blocks match thickness of flat pack devices

How are shorting blocks used for verification in test sockets?

In the context of test sockets, shorting blocks are used as part of the verification process to check that the socket is functioning properly. When testing any electronic device or semiconductor package in a test socket, it’s imperative that all of the contacts on the device under test (DUT) make reliable electrical contact with the corresponding pogo pins or elastomer contact in the socket to ensure accurate results.

Shorting blocks can be metal or plastic with an electrically conductive surface

Contaminates like solder residue, airborne debris, and oxides of metal can accumulate on pogo pin tips and other electrical contacts, greatly reducing their contact resistance (CRES) at the DUT. Furthermore, mechanical damage or particulates can get into the internal structure of the pin and cause it to get stuck in the test position. In either case, this can lead to false failures in test results due to artificial “opens” at the test socket level.

To test for this, use shorting blocks to tie all pins to ground (GND) and effectively create a short circuit. Then, using a tool like the MultiTrace which can electrically stimulate individual pins in the socket, run a low voltage signal to each pin to check for continuity. Any ‘open’ pins in the test results indicate a poor or non-existing electrical path at that location which can suggest damaged or contaminated pins.

Overall, shorting blocks can be a valuable tool for ensuring that DUTs make proper contact with all of the necessary test points and confirming the functionality of test sockets and DUT boards. Technicians can help to ensure the accuracy and dependability of their testing operations by routinely cleaning their test sockets and utilizing shorting blocks in this manner.

RTI builds shorting blocks for test sockets

We design and build custom shorting blocks for RTI test sockets and non-RTI test sockets. Contact us for a free quote or download our shorting block infosheet for more information.