Semiconductor Test Contactors/Sockets

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Contactors/Sockets - Page 2 of 3

The motion of the contact element as it comes into contact with the lead is another factor in selecting a good contactor. Old contactor designs simply push the contact elements against the leads to make the contact. New contactor designs give the contact elements a ‘wiping’ action, so that contaminants, oxides, and residues on the DUT lead will first be removed before the final contact is made.

Fig. 2. More examples of contactors

Ease of maintaining, replacing, or configuring a contactor is another consideration when looking for a good contactor. Contact elements degrade with usage, and should therefore be monitored and maintained regularly. It should be promptly replaced once it has exhausted its useful life, since poor contact caused by worn-out contact elements can result in a lot of test issues. Well-designed contactors should be able to do several hundreds of thousands of contact cycles within its lifetime.

The electrical characteristics of the contactor is also critical in ensuring the integrity of the test process. Contact resistance, stray capacitance, and stray inductance, as well as capacitive and inductive coupling must all be minimized. The dimensions, shapes, and material of the various features of a contactor as well as the contact area and tip topography of the contact element all affect the electrical performance of a contactor.

Fig. 3. Examples of sockets

The term 'contactor' is also used to refer to sockets employed to get convenient electrical access to the DUT, especially if the DUT is a fine-pitch, high-pin count complex device. Sockets are often used for hand-testing DUT's or in failure analysis. The fine-pitched device is simply inserted into the socket, which has leads that correspond to those of the device but more widely-spaced for convenient electrical access. In some cases, the contactor used in the contactor block may also serve as a socket on its own.

Examples of manufacturers of contactors are Johnstech International, Dimensions Consulting Inc. (DCI) and Kulicke and Soffa (K&S).

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