The increasing speed at which semiconductor devices operate has driven the need for higher speed probing capabilities. One approach is to mechanically probe the device while it is mounted directly in a test head. The obvious benefits are:
The TH76 Test Head Prober is constructed around a vibration isolation table. The test head is "docked" beneath a large plate (the vibration table top) that floats on a cushion of compressed N2or C.D.A. A hole is milled into the plate to provide for probing into the device. A micropositioner support platen is mounted on top of the plate. The system has wheels so that it can be positioned above the test head. An assortment of options are available to enhance the probing capabilities of the system, including CAP (Computer Aided Probing) options, lasers, manual or motorized micropositioners, active probes, etc.
The advantages of probing a device while it is mounted directly in a test head are clear, however, there is often the formidable obstacle to overcome of test head induced vibration. Probing small device geometries requires a stable probing environment. Test head vibration sources include air cooling fans, water cooling systems and the test floor itself. Replacing the test head's internal air cooling fans with dynamically balanced fans is sometimes enough to cure the problem.
Another solution is to mechanically decouple the DUT (device under test) from the test head, removing it from the source of vibration. Some test heads have short internal cables that allow the DUT test fixture to be detached and slightly lifted out of direct contact with the test head, while other require the installation of an interface consisting of short (<6" long) signal/ground transmission cables between the DUT and the test head. It is recommended that the vibration characteristics of a particular test head and the solution to the vibration problem be evaluated prior to purchasing a test head probe station. Test head probers are available in standard configurations and can be built on a custom basis for a wide variety of test heads.
Please contact your Signatone sales representative for more information.