Abstract:
A stencil foil assembly includes a stencil foil, having a stencil pattern thereon, of a planar configuration secured to a rigid frame with an upstanding wall and a support flange emanating inwardly from the upstanding wall. The stencil foil resides on the support flange with the bottom surface of the periphery of the stencil foil being in communication with the top surface of said support flange. The outer edge of the stencil foil is positioned adjacent to the inner surface of said upstanding wall. The periphery of the stencil foil is secured to the rigid frame. The stencil foil assembly protects a user from injury by preventing contact with the sharp outer edges of the stencil foil. The assembly protects the stencil foil portion from damage and greatly facilitates handling thereof.
Abstract:
Mechanism is disclosed for wiping solder paste onto a printed circuit board through a stencil superposed on the board, including a first squeeges for wiping solder paste onto the stencil, a second squeegee for depositing solder paste at a location for engagement by the first squeeges and a tray, alternatively engagable with both squeeges to cooperate with the squeeges to deposit solder paste at the beginning of a wiping stroke and to pick up excess solder paste at the end of a wiping stroke.
Abstract:
A cleaning apparatus for cleaning solder paste off the bottom side of a printed circuit board stencil includes a container of cleaning solution therein and a blade holder that is movable between a wiping position and the container of cleaning solution. A wiping blade is mounted in the blade holder. The blade holder, with the blade mounted thereon, is reciprocated back and forth when in communication with a stencil to be cleaned. The blade is moved from the wiping position in communication with the stencil into the cleaning solution in the container. A pneumatic piston and rotary actuator provides controlled movement of the wiping blade. The wiping blade may be vibrated during wiping to improve removal of solder paste from the stencil and the cleaning solution may be ultrasonically vibrated to improve removal of solder paste from the wiping blade. The wiping blade may also be pulsed into a sponge to remove excess cleaning solution prior to the next cleaning cycle. After cleaning, the cleaning solution may be filtered and reused in a closed loop method.
Abstract:
This invention improves a machine that has a squeegee-like blade that wipes across an apertured mask to apply to a printed circuit board solder paste or other conductive mounting material. The apparatus and method of the invention involve reciprocating the blade back and forth transverse to the direction of blade sweep across the mask, during the material-applying sweep of the blade across the mask. The reciprocating movement of the blade, combined with the sweep movement, deposits material onto the printed circuit board with high fidelity and with minimal voids.
Abstract:
A method is provided for improving the wiping capabilities of a windshield wiper by causing the windshield wiper blade to vibrate or oscillate in a direction parallel to the longitudinal centerline of the blade during a windshield wiper sweep. The vibrating mode causes less wear on the blade due to windshield abrasion since the blade edge does not contact the same eroded point on the windshield all the time. Secondly, any debris that is caught underneath the blade is quickly ejected due to the vibrating action. In one embodiment, an electromechanical vibrating unit is secured at one or more positions to the blade, with the actuator being driven by a 12-volt source and provided with a quickie disconnect at the center of the blade support structure. The vibrating actuator may be an electromechanically drive off-centered weight, a vibrating linear actuator, an ultrasonic vibrator, or a vibrator in the form of a piezoelectric crystal, with the primary mode of oscillation translating the blade along its centerline. The result is that debris underneath the blade is thrown out, including leaf stems, leaves and particulate matter, with the periodic translation of the blade providing more uniform water removal during the wiping operation to provide clearer visibility through the windshield regardless of the amount of water on the windshield, whether it be from a sporadic sprinkle or a torrential downpour. Wiper life is extended since the blade edge's position on the windshield is constantly varied during wiper sweeps.
Abstract:
Pin supported printed circuit boards are provided with torsion spring locking assemblies in which torsion springs surround the pins and are captured at one end and have free ends that are deflected, causing a tight grip onto the pins. The result is a pin locking mechanism that is inexpensive and robust due to the elongated contact of the spring with the pin that firmly locks the pin in place, with the extended spring contact protecting the pins against abrading and scoring while providing exceptional locking force.
Abstract:
A cleaning apparatus for cleaning solder paste off the bottom side of a printed circuit board stencil includes a container of cleaning solution therein and a blade holder that is movable between a wiping position and the container of cleaning solution. A wiping blade is mounted in the blade holder. The blade holder, with the blade mounted thereon, is reciprocated back and forth when in communication With a stencil to be cleaned. The blade is moved from the wiping position in communication with the stencil into the cleaning solution in the container. A pneumatic piston and rotary actuator provides controlled movement of the wiping blade. The wiping blade may be vibrated during wiping to improve removal of solder paste from the stencil and the cleaning solution may be ultrasonically vibrated to improve removal of solder paste from the wiping blade. The wiping blade may also be pulsed into a sponge to remove excess cleaning solution prior to the next cleaning cycle. After cleaning, the cleaning solution may be filtered and reused in a closed loop method.