Abstract:
A method performs test measurements on electrical components. The components are firstly subjected to an aging process before the actual test measurements are performed on them. In order to be able to handle this in a particularly simple manner, the components are firstly disposed on a carrier with a switching matrix. In this case, the switching matrix is configured in such a way that all the components are switched on for the purpose of carrying out the aging process and exclusively the components to be measured—individually or in subgroups—are switched on for the purpose of carrying out the test measurements.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to methods for performing test measurements on electrical components after the components have been subjected to an aging process that is performed simultaneously on all the components. In the past, such methods have been complicated and slow.  
         SUMMARY OF THE INVENTION  
         [0003]    It is accordingly an object of the invention to provide a method for performing test measurements on electrical components that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that can be carried out particularly simply and rapidly.  
           [0004]    With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for performing test measurements on electrical components. The first step of the method involves disposing components on a carrier with a switching matrix and connecting the components to the switching matrix to allow the components to be switched on or off selectively. The next step is driving the switching matrix to switch all of the components on for simultaneously carrying out an aging process on all of the components. The next step is performing the test measurements by exclusively switching on the components to be measured.  
           [0005]    An important advantage of the method according to the invention is that the components are subjected to a predetermined aging process before the actual test measurements are carried out. Those components that already had defects and were faulty during production are primarily the ones that fail during the aging process. After the conclusion of the aging process—also called burn-in process in the case of lasers or light-emitting diodes—all that then remain are the components that are to be regarded as free of defects and that are anticipated to actually reach their expected service life. A further advantage of the method according to the invention is that preferably all the components are subjected to the aging process simultaneously in order to have the effect that the aging process is substantially identical for the components. Carrying out the aging process simultaneously for all the components results in a time saving compared with a sequential aging process in which the components are aged individually or successively. A third advantage of the method according to the invention is to be seen in the use of the switching matrix. Specifically, what is achieved in concrete terms through the use of the switching matrix is that, after the conclusion of the aging process carried out simultaneously on all the components, the components do not have to be contact-connected individually since the components can be switched on or activated individually or in subgroups with the aid of the switching matrix as soon as test measurements are intended to be carried out on them.  
           [0006]    It is regarded as advantageous if a semiconductor material is used as the carrier material. Specifically, a use of semiconductor material advantageously enables the switching matrix to be formed at least partly by semiconductor switches at least partly monolithically integrated in the semiconductor material. The monolithic integration of the semiconductor switches in the semiconductor material makes it possible to achieve considerable cost advantages compared with a discrete construction of switches or semiconductor switches on a carrier.  
           [0007]    With regard to cost considerations, it is regarded as advantageous if silicon is used as the semiconductor material for the carrier.  
           [0008]    The semiconductor switches can advantageously be formed by transistors, in particular by field-effect transistors, in a semiconductor material.  
           [0009]    The method according to the invention can be used in an advantageous manner in the case of light-emitting electrical components, that is to say, in particular, in the case of light-emitting diodes and laser diodes.  
           [0010]    In order in this case to ensure that the light-emitting or laser diodes are not damaged when carrying out the aging process or when carrying out the test measurements, it is regarded as advantageous if a protective diode is in each case connected in parallel with the light-emitting or laser diodes before the aging process is carried out and/or before the test measurements are carried out. A protective diode can be connected to a light-emitting or laser diode for example in such a way that the anode of the protective diode is connected to the cathode of the light-emitting or laser diode and the cathode of the protective diode is connected to the anode of the light-emitting or laser diode.  
           [0011]    Furthermore, it is regarded as advantageous if the method according to the invention is carried out on VCSEL lasers (vertical cavity surface emitting lasers); in this case, the VCSEL lasers are advantageously firstly mounted on a silicon carrier having an electronic switching matrix. The VCSEL lasers are then connected to the switching matrix; in order to carry out the aging process, the switching matrix is then driven in such a way that all the VCSEL lasers age simultaneously. After the conclusion of the aging process, the switching matrix is then changed over in such a way that each VCSEL laser can be measured individually. A very substantial advantage of this method is that the VCSEL lasers can be both aged and measured on the silicon carrier; a “modification” of the measuring device for carrying out the test measurements after the aging process is not necessary, therefore, thereby achieving a significant saving with respect to time and costs.  
           [0012]    Other features that are considered as characteristic for the invention are set forth in the appended claims.  
           [0013]    Although the invention is illustrated and described herein as embodied in a method for performing test measurements on electrical components, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
           [0014]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0015]    The FIGURE is a circuit diagram showing an exemplary embodiment of a switching matrix that can be used for carrying out the method according to the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    Referring now to the single FIGURE of the drawing, it is seen that a switching matrix  10  has four terminals, namely a first terminal P 1 , a second terminal P 2 , a third terminal P 3  and a fourth terminal P 4 . The switching matrix  10  is electrically subdivided into columns and rows, which will now be explained with reference to the FIGURE using the terms “columns” and “rows”.  
         [0017]    Between the first and third terminals P 1 , P 3 , column transistors T 11 , T 12 , . . . are connected in series and form a column  20 . Between the second terminal P 2  and the fourth terminal P 4 , further column transistors T 21 , T 22 , . . . are connected in series and form a second column  30 .  
         [0018]    Laser arrays  100 ,  110  and  120  are connected between the two columns  20  and  30 . Each laser array  100 ,  110 , and  120  has 14 laser diodes L in each case, which are in each case connected in series with a switching transistor T 1 , T 2 , . . . , T 14 . The series circuit formed from laser diode L and switching transistor T 1 , T 2 , . . . and T 14 , respectively, is connected to the columns  20  and  30 .  
         [0019]    Electrically connected in parallel with the series circuit formed from laser diode L and switching transistor there is in each case a “row transistor” T 31 , T 32 , . . . per laser array; the row transistors T 31 , T 32 , etc. in each case isolate the laser arrays  100 ,  110 , and  120  from one another in the “row direction”.  
         [0020]    The base terminals of all the row transistors T 31 , T 32 , . . . are electrically interconnected and together form a control terminal T 3  of the switching matrix  10 .  
         [0021]    Moreover, all the base terminals of the switching transistors T 1  are in each case interconnected and thus form a control terminal S 1 . The same applies correspondingly to the switching transistors T 2 , whose base terminals are interconnected and together form a control terminal S 2 . In a corresponding manner, the remaining switching transistors T 3 -T 14  of the laser arrays are interconnected to form control terminals S 3 -S 14 . The control terminals S 3  to S 14  are not illustrated in the FIGURE for the sake of clarity.  
         [0022]    For the protection of the laser diodes L, a protective diode LS—with opposite polarity—is in each case connected in parallel with the laser diodes. The protective diode LS serves to prevent an overvoltage at the laser diode L in the reverse direction.  
         [0023]    The switching matrix  10  of the FIGURE can be used to carry out test measurements on the lasers L, as will now be explained. In this case, the lasers L are intended firstly to be subjected to an aging process. During this aging process, all the components simultaneously are switched on and have current applied to them for a predetermined time.  
         [0024]    After the conclusion of this aging process, also called burn-in process, the individual lasers L are then characterized in each case by themselves by the corresponding test signals being applied to the terminals P 1 -P 4 .  
         [0025]    The text below will now describe how the column transistors and the row transistors in the switching matrix  10  have to be driven in order to enable the burn-in or aging process, on the one hand, and the actual test measurements, on the other hand.  
         [0026]    In order to carry out the burn-in process, current flows through all the laser diodes L simultaneously. In order to achieve this, a positive voltage is applied to the terminals P 1  and P 4 . All the column transistors T 11 , T 12 , . . . of the first column  20  and all the switching transistors T 21 , T 22 , . . . of the second column  30  are switched off simultaneously; the row transistors T 31 , T 32 , . . . , by contrast, are switched on via their control terminal T 3 .  
         [0027]    With this circuitry of the row and column transistors, a current flow is produced as follows: firstly the current flows from the first contact P 1  via the first laser array  100  to the second column  30 . Because the topmost transistor T 21  of the second column  30  in the FIGURE is then turned off, the current flows from the second column  30  via the row transistor T 31  back to the first column  20 , from where it passes via the second laser array  110 , i.e. via all the switching transistors T 1 -T 14  and the associated laser diodes L of the second laser array  110 , to the second column  30  again.  
         [0028]    Because the column transistor T 22  of the second column  30  is in turn switched off, the current must flow from the second column  30  via the row transistor T 32  to the first column  20  again, from where it flows back to the second column  30  via the laser array  120 . To summarize, then, the current flows in each case from the first column  20  to the second column  30  via a laser array and from the second column  30  back to the first column  20  again via a row transistor; what is achieved in this way is that the current flows through all the laser arrays.  
         [0029]    In this case, the current flow through the laser arrays is carried out for as long as is necessitated by the predetermined aging process. After the conclusion of this aging process, the laser diodes are then characterized individually. This requires a corresponding driving of the column and row transistors, which has to be effected as follows.  
         [0030]    By way of example, if the intention is to measure the first laser diode of the first laser array  100 , then voltage is applied to the first control terminal S 1 , which leads to an activation of all the switching transistors T 1 . The remaining switching transistors T 2  to T 14  and also the column transistors T 11 , T 12 , . . . of the first column  20  are switched off, thereby preventing a current flow through these transistors. The column transistors T 21 , T 22 , . . . of the second column  30 , by contrast, are switched on in order to enable a current flow through these transistors. The row transistors T 31 , T 32 , . . . are switched off in their entirety via their control terminal T 3 .  
         [0031]    Due to this driving of the column and row transistors, a measurement current will flow from the first terminal P 1  via the activated transistor T 1  and also via the assigned laser diode L to the second column  30 , from where the current flows away via the activated column transistors T 21 , T 22 , . . . of the second column  30  to the fourth terminal P 4  of the switching matrix  10 .  
         [0032]    The remaining transistors T 2 -T 14  of the first laser array  100  can be measured in a corresponding manner by activation of the corresponding switching transistors T 2 -T 14 .  
         [0033]    The remaining laser diodes L of the remaining laser arrays can also be driven in a corresponding manner. By way of example, if the intention is to measure the first laser diode L of the second laser array  110 , then voltage has to be applied to the first control terminal S 1 , which leads to an activation of all the switching transistors T 1 . The first column transistor T 11  of the first column  20  is additionally activated.  
         [0034]    The remaining switching transistors T 2  to T 14  and also the remaining column transistors T 12 , . . . of the first column  20  have to be switched off. Of the column transistors of the second column  30 , the topmost column transistor T 21  in the FIGURE has to be switched off, whereas the remaining column transistors T 22 , T 23 , etc. have to be switched on. What is thereby achieved is that a measurement current can flow from the first terminal P 1  via the activated column transistor T 11  and the switching transistor T 1  through the first laser diode L of the second laser array  110  and reach the second column  30  of the switching matrix, from where the measurement or test current then passes to the fourth terminal P 4  of the switching matrix  10 .  
         [0035]    Finally, an explanation will now also be given with respect to how, for example, the fourteenth laser diode of the second laser array  110  can be measured. For this purpose, firstly all the switching transistors T 14  of the laser arrays are switched on via their common control terminal S 14 , which is not illustrated in the FIGURE for the sake of clarity. The remaining switching transistors T 1 , T 2 , . . . , T 13  have to be switched off. The rest of the circuitry of the column and row transistors is exactly like that described in connection with the measurement at the first transistor of the second laser array  110 .  
         [0036]    What can thus be achieved with the switching matrix  10  in accordance with the FIGURE is that each laser L of each laser array can be driven individually.  
         [0037]    It is possible, in addition, to drive the switching matrix  10  in such a way that current can be applied to all the laser diodes L simultaneously for an aging process or burn-in process.