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Transition Automation's self-cleaning squeegee.

The Permalex Paste Manager self-cleaning squeegee is said to eliminate solder paste sticking to squeegees. The squeegee swipes away solder paste after each print stroke, eliminating interruptions to the printing cycle to manage the solder paste inside the printer.

The Permalex Paste Manager "clips" paste from the squeegee in a repeatable and controlled manner, improving the quality and location of paste within the print area.

This system clips paste from the squeegee in a repeatable and controlled manner. In doing so, it improves the quality and location of the solder paste within the print area of the printer. The process also preserves the rheology of the paste and eliminates air bubbles that form due to dried whiskers and drips of solder paste which otherwise frequently form. Since the solder paste remains mostly on the stencil surface, cycle changeovers and cleanup are simplified by not having to remove copious amounts of paste trapped to the squeegees.

In trials, results show that the wiper system produced a significant reduction in solder paste adhesion to the squeegee. While it is desirable to keep as much paste as possible down on the stencil and off the squeegee blade, it is important to review why this is important. It is not so much the amount of solder paste that adheres to the squeegee that is a problem; it is instead how it adheres.

Solder adheres by stretching out and forming a thin blanket hanging off the blade. The large surface area formed by this adhesion is much more detrimental to the quality of the printing operation than is just the weight of solder paste adhesion.

The novel squeegee contains fewer parts than closed head print systems and does not occlude the printing action. Users can view the quality of the printing directly by observing the rolling action of the solder paste. They can therefore ascertain process quality in real-time without having to guess what might be occurring internally, as happens with closed print systems. It reportedly costs up to 40% less than competitive systems.

Most stencil printing operations have an assortment of putty knife style tools and scrapers to help manipulate and reposition solder paste in and around the printer. It takes dexterous human hands and arms to effectively clean a printer either at the end of a production run, or to switch over from one production run to another. The new device introduces a minimum amount of surface area into the paste, and it moves, creating fluid cutting paths, with nothing to "grab." Essentially, a thin wire is integrated into a squeegee blade holder, and its motion and speed are set to produce the best cleaning action. The motion is set such that the wire slides and pinches the solder paste from the squeegee blade.

Permalux is said to integrate directly into dual squeegee platforms with little or no training or reconfiguration of existing equipment. The unique design uses pivoting paste retainers with a cross-link. By linking the forward and back paste retainers, the system becomes self-powered by the relative motion of the two squeegees.

Available from Transition Automation Inc., transitionautomation.com.