Process and device for generating test patterns when applying solder paste by a screen process on printed circuit boards

Abstract

The invention relates to a method and an apparatus for generating test patterns during the application of solder paste to printed circuit boards by means of the screen-printing process, a structure being optically recorded as a reference pattern in a teach-in method step and this recording being used to generate reference data for the test patterns. It is provided that the printing stencil for the screen-printing process is optically recorded as the structure.

1 . Method of generating test patterns during the application of solder paste to printed circuit boards by means of the screen-printing process, a structure being optically recorded as a reference pattern in a teach-in method step and this recording being used to generate reference data for the test patterns, characterized in that the printing stencil for the screen-printing process is optically recorded as the structure.  
     
     
         2 . Method according to  claim 1 , characterized in that the stencil openings of the printing stencil are recorded with regard to their position (coordinates) and/or their geometry (shape, size).  
     
     
         3 . Method according to one of the preceding claims, characterized in that the side of the printing stencil facing the printed circuit board is optically recorded.  
     
     
         4 . Method according to one of the preceding claims, characterized in that, after the screen-printing process, an optical recording of the solder paste application which has taken place onto the printed circuit board is carried out and that actual data are generated from this recording.  
     
     
         5 . Method according to one of the preceding claims, characterized in that the actual data are evaluated with the reference data taken into consideration.  
     
     
         6 . Apparatus for generating test patterns during the application of solder paste to printed circuit boards by means of the screen-printing process, having a first optoelectronic device for recording a structure as a reference pattern, taking place in a teach-in method step, and having data processing electronics for generating reference data from the reference pattern recording, characterized in that the first optoelectronic device ( 6 ) is arranged in such a way that it records the printing stencil ( 3 ) as the structure.  
     
     
         7 . Apparatus according to  claim 6 , characterized by a displacing device, by which the first optoelectronic device ( 6 ) can be made to enter between the printing stencil ( 3 ) and the printed circuit board ( 5 ) and can be moved there.  
     
     
         8 . Apparatus according to one of the preceding claims, characterized by a second optoelectronic device ( 7 ) for recording the solder paste application on the printed circuit board ( 5 ).  
     
     
         9 . Apparatus according to one of the preceding claims, characterized in that the first and second optoelectronic devices ( 6 ,  7 ) can be moved by means of one and the same displacing device.  
     
     
         10 . Apparatus according to one of the preceding claims, characterized in that the first and second optoelectronic devices ( 6 ,  7 ) are formed by only one optoelectronic apparatus ( 1 ), which can be switched over with regard to the recording direction or has two recording beams.  
     
     
         11 . Apparatus according to one of the preceding claims, characterized in that the optoelectronic apparatus ( 1 ) has a first mirror ( 8 ), which has been made reflective on both sides and one side of which lies in the beam leading to the printing stencil ( 3 ) and the other side of which lies in the beam leading to the printed circuit board ( 5 ).  
     
     
         12 . Apparatus according to one of the preceding claims, characterized in that each side of the first mirror ( 8 ) is assigned a semi-transparent second and third mirror ( 9 ,  10 ), respectively.  
     
     
         13 . Apparatus according to one of the preceding claims, characterized in that the second and third mirrors ( 9 ,  10 ) are in each case assigned first and second optics ( 13 ,  14 ), respectively.  
     
     
         14 . Apparatus according to one of the preceding claims, characterized in that the second and third mirrors ( 9 ,  10 ) are in each case assigned a first and second image recording sensor ( 11 ,  12 ), respectively.  
     
     
         15 . Apparatus according to one of the preceding claims, characterized in that the first optics ( 13 ) lie between the second mirror ( 9 ) and the first image recording sensor ( 11 ) and in that the second optics ( 14 ) lie between the third mirror ( 10 ) and the second image recording sensor ( 12 ).  
     
     
         16 . Apparatus according to one of the preceding claims, characterized in that a first source of illumination ( 15 ) interacts with the second mirror ( 9 ).  
     
     
         17 . Apparatus according to one of the preceding claims, characterized in that a second source of illumination ( 16 ) interacts with the third mirror ( 10 ).  
     
     
         18 . Apparatus according to one of the preceding claims, characterized in that the light of an annular, approximately annular or part-annular third source of illumination ( 19 ) of the optoelectronic apparatus ( 1 ) is directed onto the printed circuit board ( 5 ).  
     
     
         19 . Apparatus according to one of the preceding claims, characterized in that the third source of illumination ( 19 ) surrounds the beam between the first mirror ( 8 ) and the printed circuit board ( 5 ).  
     
     
         20 . Apparatus according to one of the preceding claims, characterized in that the third source of illumination ( 19 ) is formed by a plurality of light-emitting diodes (LEDs).