Apparatus and system for screen printing of solder paste onto printed circuit boards

A screen printing apparatus for printing onto a surface of a board through a medium of a screen, the apparatus comprising:

• a dispenser including a pair of side walls substantially parallel to, and spaced from, each other in a direction of travel of said dispenser, said dispenser including a front wall fixedly secured to inner surfaces of forward portions of said side walls, said front wall having a lower portion with an inner surface rearwardly inclined and extending transversely to said direction of travel, said dispenser also including a movable rear wall, said movable rear wall being movable toward and away from said front wall on rearward portions of said inner surfaces of said side walls, said movable rear wall having a forwardly extending lower portion with an inner surface rearwardly inclined and substantially parallel to said inner surface of said front wall, said inner surfaces of said front and rear walls defining a slit-like aperture which is closed and opened when said movable rear wall is moved toward and away from said front wall, said front wall, said movable rear wall and said side walls defining a chamber, said dispenser also including a removable lid covering said chamber and a pair of blades extending from said front wall and said movable rear wall and along said slit-like aperture, said blades contacting an upper surface of the screen when said dispenser is moved in said direction of travel;
• actuating means mounted on said dispenser and for closing said slit-like aperture when said dispenser is in a non-printing position and for opening said slit-like dispenser when said dispenser is performing a printing operation, whereby paste contained in said chamber is permitted to be dispensed onto the upper surface of the screen during each pass of said dispenser.

A printing apparatus for printing onto a surface through a screen, the apparatus comprising:

• first guide rails positioned on substantially opposite sides of the surface;
• a carriage slidably mounted on said first guide rails;
• dispenser means mounted on said carriage and for supplying a predetermined amount of paste onto a first side of the screen and onto the surface;
• dispenser movement means for moving said dispenser means toward and away from the screen;
• carriage movement means for moving said carriage and said dispenser means back and forth along said first guide rails;
• second guide rails spaced from said first guide rails;
• first cleaning apparatus movably connected to said second guide rails and positioned on the first side of the screen, said first cleaning apparatus including a transversely extending blade means in contact with the first side of the screen and for removing residue from the first side of the screen;
• first drive means for moving said first cleaning apparatus;
• third guide rails spaced from said first guide rails;
• second cleaning apparatus movably connected to said third guide rails and positioned on a second side of the screen, said second cleaning apparatus including a transversely extending blade means in contact with the second side of the screen and for removing residue from the second side of the screen;
• and
• second drive means for moving said second cleaning apparatus.