1. Field of the Invention
The present invention generally relates to test systems for testing circuit units to be tested and relates, in particular, to automatic test devices (ATE, Automatic Test Equipment) which are used to ensure product quality in the semiconductor industry, in particular.
2. Description of the Prior Art
In the semiconductor industry, an automatic test unit (ATE, Automatic Test Equipment) is normally used to ensure product quality of the semiconductor apparatuses which have been produced and of the circuit units to be tested (DUT, Device Under Test). Although the quality, for example the operating behaviour, is continually being improved as regards the processing speed of the automatic test unit, it is often necessary to use an external verification device, for example an oscilloscope, to analyse and verify the waveform and the time response of different signals which are sent to the circuit unit to be tested or are sent by the latter to the tester unit. In order to analyse such signals using an oscilloscope as a verification unit, it is necessary to connect the oscilloscope or the probe head of the oscilloscope to the circuit unit to be tested (DUT) as closely as possible and with as little interference as possible. In an inexpedient manner, the circuit unit to be tested and the connection pins of the latter cannot be accessed or can be accessed only with difficulty after said circuit unit has been inserted into a test receptacle.
It is often not possible at all to reach contact-making units (connection pins) of the circuit unit to be tested if the latter is mechanically clamped to a receptacle device of the test system. In the case of mechanical clamping, it is not possible to access such connection balls or connection pins with the probe head of the oscilloscope.
The prior art has proposed numerous test apparatuses and methods in order to solve this problem. The problem of probing different contact-making units of a circuit unit to be tested is therefore dealt with in various ways because the circuit unit to be tested often has to be tested by verifying, by means of an external (additional) verification device, for example an oscilloscope, the signals which enter the circuit unit to be tested and are output from the circuit unit to be tested during testing using a test system.
Another disadvantage of the conventional test apparatus shown in
It is also inexpedient that the test apparatus shown in
In order to also be able to use conventional methods to test circuit units DUT which are to be tested and have ball grid arrays, the prior art has proposed the test apparatus which is shown in
In a disadvantageous manner, a signal cannot be measured close to a contact-making unit K of the circuit unit to be tested DUT. In this way, it is uncertain whether the signal which reaches the circuit unit to be tested or the signal which is output from the circuit unit to be tested DUT is the same as that which is measured via the verification channel L2. It is also inexpedient that crosstalk, reflections and other interference can occur in the event of the verification channel L2 branching off from the tester channel L1 which comprises a plurality of lines.
It is an object of the present invention to provide a test apparatus for testing a circuit unit to be tested, in the case of which apparatus it is possible for verification signals to be tapped off in a reliable and interference-free manner during testing of the circuit unit to be tested.
The object is achieved in accordance with the invention by means of a test apparatus for testing a circuit unit to be tested, comprising:
The object is also achieved in accordance with the invention by means of a test method for testing a circuit unit to be tested, comprising the steps of:
A fundamental concept of the invention involves providing, in the receptacle unit, a signal output unit for outputting verification signals when testing the circuit unit to be tested, said signal output unit being arranged between the circuit unit to be tested and connection pins for connecting the circuit unit to be tested.
The advantage of the inventive test apparatus resides in the fact that it is possible to tap off verification signals in a safe and reliable manner without interfering reflections. In this way, certain signals which are supplied to the circuit unit to be tested or are output from the circuit unit to be tested can be verified in an efficient and reliable manner and with high contact stability.
It is also an advantage that only slight changes have to be made in comparison with the conventional receptacle arrangement.
The signal output unit which is arranged in the receptacle unit between the circuit unit to be tested and the connection pins for connecting the circuit unit to be tested may be in the form of a signal decoupling layer. The signal decoupling layer preferably has the same area as the circuit unit to be tested.
The verification signals which are output, using the signal output unit, when testing the circuit unit to be tested can be verified in a verification device. The verification apparatus may be expediently formed by an oscilloscope. The verification signals which are output, using the signal output unit, when testing the circuit unit to be tested are verified in a verification device. The verification device may automatically be connected to the signal output unit using a plug connection. In this manner, the present invention makes it possible for verification signals to be output in a reliable and efficient manner by means of a verification channel when testing circuit units to be tested.
Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.
In the figures, identical reference symbols denote identical or functionally identical components or steps.
After the test system 201 has been electrically connected to the connection pins 104 which are fitted in the receptacle unit 102 and are intended to connect the circuit unit 101 to be tested, desired data 203 and actual data 204 may be interchanged by the test system 201 and the circuit unit 101 to be tested via the tester channel 202 which comprises a plurality of lines.
In this case, the desired data 203 are generated using the test system 201 and are output to the circuit unit 101 to be tested. The actual data 204 which are output from the circuit unit 101 to be tested on the basis of the desired data 203 supplied to the latter are also analysed in the test system 201.
Such a signal decoupling layer will be explained in more detail below with reference to
In order to avoid signal reflections on lines which are not connected, such lines should be terminated with a 50 Ω resistor. The screen of the signal cable which forms the verification channel 302 to the verification device 301 should be connected to the earth connections 402 of the signal output unit 401 and/or to the corresponding earth contact-making units 103b of the circuit unit to be tested.
The inventive test apparatus with the provision of a signal output unit 401 has the advantage, in particular, that only slight changes in the operating behaviour are expected as a result of the conventional receptacle being modified. Measurements using all standard receptacle units are advantageously possible without making relatively great changes to the test apparatus. Another advantage resides in the fact that, in comparison with probe measurements, numerous signals can be simultaneously output because decoupling is effected directly in the path between the signal output unit 401 and the verification channel 302. In principle, all signals, that is to say desired data 203 which are supplied to the circuit unit 101 to be tested and actual data 204 which are output from the circuit unit 101 to be tested, can be simultaneously tested in the verification device 301.
It is also possible for voltage supply lines which are connected to the signal output unit 401 to be monitored in order to detect, for example, voltage drops under normal operating conditions. The measurements can be carried out at high or low temperatures, it being possible to heat or cool the apparatus in a temperature chamber.
The electrical connections between the tester channel 202 (which comprises a plurality of lines) and the circuit unit 101 to be tested, on the one hand, and between the verification channel 302 and the circuit unit 101 to be tested, on the other hand, are reliably retained since thermal expansion exerts a smaller influence on the contact-making process than test apparatuses according to the prior art.
It shall be pointed out that the signal decoupling unit 401 may be permanently introduced into the receptacle unit 102 in order to connect the tester channel 202 which comprises a plurality of lines to the circuit unit 101 to be tested. It is also possible for the signal output unit 401 to be fitted in the receptacle unit 102 such that said signal output unit can be removed and for the latter to be introduced into the receptacle unit 102 only when verification signals 303 are to be discharged to a verification device 301 via the verification channel 302.
Reference is made to the introduction to the description as regards the conventional test apparatus which is illustrated in
Although the present invention was described above with reference to preferred exemplary embodiments, it is not restricted thereto but rather can be multifariously modified.
Moreover, the invention is not restricted to the application possibilities mentioned.
Number | Date | Country | Kind |
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102005007103.1 | Feb 2005 | DE | national |