Apparatus and method for the visual inspection in particular of concealed soldered joints

A method for checking the quality of the soldered joint between an electric or electronic component disposed on the surface of a printed circuit board or similar including an SMD, BGA, CSP or FC component, and the printed circuit board, the method comprising the steps of:

• using an ocular unit with an apparatus including a lens head, an image transmission unit for transmitting the image received by the lens head to the ocular unit and an illuminating device for illuminating the soldered joints to be tested, in which the lens head comprises a deviating prism for image deviation which extends up to the axially outermost end of the lens head, and in which the illuminating device is disposed in the lens head to cause the exit angle of the light of the illuminating device out of the lens head is substantially equal to the deviation angle of the image deviation and the exit point of the light is disposed next to the deviating prism for image deviation in the area of the axially outer end of the lens head, the component comprising, arranged in rows and gaps after the manner of a matrix, a large number of solder pins, solder balls or solder points which are solderable with a corresponding number of contact points complementary as to shape and function disposed on the printed circuit board;
• visually examining the soldered joints of the outermost row of soldered joints of a first side of the component to be tested with the unit, wherein the component is moved step-wise according to the spacing of the solder joint rows or gaps past the lens head of the apparatus or, conversely, the lens head of the apparatus is moved step-wise past the component;
• rotating of the component or the apparatus through respectively 90 degrees and visually examining the soldered joints of the outermost rows of soldered joints of the further sides of the component with the unit wherein the component is moved step-wise according to the spacing of the solder joints past the lens head of the apparatus or, conversely, the lens head of the apparatus is moved step-wise past the component;
• and
• visually examining the channels formed between the respective gaps or rows for optical visibility.

An apparatus for the visual inspection of soldered joints disposed between an electric or electronic component and a substrate, the apparatus comprising:

• an ocular unit;
• a lens head;
• an image transmission unit for transmitting the image received by said lens head to said ocular unit;
• and
• an illuminating device for illuminating the soldered joints disposed between the electric or electronic component and the substrate, said lens head comprising an image deviation device for changing the direction of the image path from an incoming direction from between the electric or electronic component and the substrate to an outgoing direction, said image deviation device extending up to an axially outermost end of said lens head, said illuminating device having a light exit to provide a light exit direction substantially toward said incoming direction, said light exit of said illuminating device being disposed circumferentially besides said device for image deviation.

A visual inspection apparatus comprising:

• an image transmission unit having a longitudinal axis with first and second ends at opposite longitudinal ends, said image transmission unit transmitting an image from said first end to said second end along said longitudinal axis;
• a head arranged at said first end of said image transmission unit, said head extending a predetermined distance from said first end of said imagine transmission unit;
• an image deviation device arranged in said head and being receivable of an external image at an image axis angularly spaced from said longitudinal axis of said image transmission unit, said image deviation device being feedable of the external image into said first end of said image transmission unit substantially along said longitudinal axis, said image deviation device being receivable of the external image at substantially a farthest longitudinal distance of said head from said transmission device;
• an illuminating device in said head, said illuminating device emitting light substantially parallel to said image axis at a longitudinal position of said image deviation device.