The invention relates to an apparatus for making contact between a T/R module and a test device. In this case, T/R module is short for transmit-receive modules, such as those used in particular in active antennas in the RF range.
According to the prior art, contact can be made with T/R modules (unit under test) by fitting them in special measurement holders. In these holders, the RF connection to the test environment is made by coaxial plugs and the RF connection to the unit under test is made by adaptors with bonded wires and/or ribbons. The DC supply and the connection for the control signals are provided in a similar manner. Although the bonded connections are removed after a test has been carried out, residues of the connection and visible traces remain on the connecting pads of the units under test.
Instead of using this mechanically complex process of making contact with units under test, which leaves traces and residue can, the testing can be carried out with the aid of needle adaptors for low-frequency operations and the DC supply. For this purpose, the radio-frequency signals are supplied with special coaxial test probes (RF probes). Even when contact is made in this way, both the needles and the test probes leave traces (scratches) on the connecting pads when contact is made, which can adversely affect the further processing of the modules (installation in the system by bonded connection). Furthermore, the connecting pads are kept very small, for space reasons and because of the RF technical requirements. In order to ensure reliable contact with the modules for the measurement, both the unit under test and the test probes must therefore be manually visually aligned with one another, independently of one another, with the assistance of a microscope. This quite complex procedure is the only way to ensure that the individual mechanical tolerances of the units under test do not have a disturbing effect on the electrical characteristics of the modules. It should also be noted that the quality of the contact that is made directly affects the quality of the measurement results, and that high-quality contacts can be achieved only by experienced operating personnel.
When contact is made in this way, the individual test probes must be aligned individually, typically using optical methods with a microscope, and this is very time-consuming. Furthermore, the quality of the contact made is highly dependent on the capabilities of the operating personnel.
German patent document DE 41 07 248 A1 describes a measurement apparatus for a planar circuit, in which the planar circuit is moved with respect to the contact elements of a contact-making unit using a shifting device which has a plurality of inclined planes.
Exemplary embodiment of the present invention provide an apparatus for making contact with T/R modules, which overcomes the disadvantages of the contact-making methods described above, in particular with the aim of achieving a high-quality contact, which can be handled easily and can be reproduced well.
An exemplary apparatus for making contact between a transmit-receive (T/R) module and a test device for transmission of RF signals, includes a mechanically guided contact-making unit in the form of a frame and having a plurality of contact elements for making contact with the T/R module. A line substrate is arranged rigidly on a side of the contact-making unit facing away from the T/R module. The line substrate is electrically connected to the T/R module, the line substrate is a triplate line, and the RF signals are passed to the test device via the line substrate. One or more register pins for defined alignment of the T/R module with respect to the contact-making unit and a fixing unit for mechanical fixing of the T/R module are also provided. A shifting device with a plurality of inclined planes that convert a shifting movement of the shifting device to a movement of the contact-making unit toward the T/R module at right angles to the shifting direction. When the contact-making unit reaches a defined final position the contact is made with the T/R module via the contact elements in one process.
According to the invention, the optical alignment of the unit under test is replaced by mechanical guidance of a contact-making unit, which makes contact with the T/R module to be tested, after reaching a defined final position. The mechanical guidance is provided using a shifting device which has a plurality of inclined planes, wherein the inclined planes convert a shifting movement of the shifting device to a movement of the contact-making unit at right angles to the shifting direction toward the T/R module. The T/R module to be tested is aligned using register pins. A line substrate which is arranged on the contact-making unit makes the connection for the connecting ports of the test device. This line substrate is in the form of a triplate line. The contact-making unit has contact elements (for example spring contact pins) and therefore connects the line substrate to the corresponding contact pads on the T/R module.
When contact is made according to the invention, there is no need to individually align the test probes with the unit under test in order to make a secure and reliable connection with the T/R modules. Likewise, there is no need for viewing through a microscope, as required for this purpose.
All the required contacts, that is to say not only the radio-frequency signals but also the low-frequency signals or DC signals, can be made securely and at the same time in one process.
The apparatus according to the invention means that the quality of the contact made is largely independent of the capabilities of the operating personnel. This ensures that the characteristics of the units under test are reproduced without corruption.
A further advantage is also that the connecting elements (for example spring contact pins) themselves leave neither residues nor visible traces on the contact-making surfaces of the module, even after contact has been made with the same unit under test a number of times. In addition, the spring contact pins can be subjected to a large number of contact-making cycles before any evidence of wear can be found on the contacts.
A further advantage is that the test station can be calibrated very easily, using the same contact-making principle. The calibration elements that are purpose-made for this purpose have the same design as the line substrate and have triplate lines of different length, which are mounted on a metal mount. The metal mount has an external contour which is approximately the same as that of the unit under test, with the same geometry of the connections as the unit under test. The calibration elements can therefore be inserted into the test holder, just as easily, with contact being made in the same way as with the T/R modules. No additional effort is required for adjustment and alignment, for this purpose. Even the sequence of insertion can be preset by the operator, using the control program.
The way in which contact is made according to the invention can be applied without problems to automatic placement and therefore also to automatic testing of relatively large quantities in the course of large-scale manufacture of T/R modules.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.