Printing Equipment & Stencils
December 31, 1969 |Estimated reading time: 4 minutes
Selector Roundup Printing Equipment & Stencils
In SMT assembly, the screen/stencil printing step is critical. Studies have shown that many printed circuit board (PCB) defects can be traced back to poor solder printing performance. Printing equipment can range from small, stand-alone machines to large, fully automated, in-line systems. When printer maintenance is required, replacement squeegee blades and holders are available. SMT presents the following Printing Equipment and Stencils Selector Roundup, spotlighting an assortment of available products.
Machine Performance UpgradeProFlow DirEKt Imaging reportedly averages about six times faster than screen printing with squeegees but still can use conventional stencils and solder pastes. The upgrade is a clean process, eliminating "tramlining" because it is sealed against the stencil. Paste cannot escape the sides of the transfer head so none can remain on the stencil top surface. Paste is replaced via cartridge replacement, reducing the time to around two minutes. All major solder paste suppliers now offer their products in ProFlow cassettes. Each case holds about 1 kg (2.2 lb) of material, so replenishment is not frequent. Additionally, switching to different paste formulae is easy. The operator switches to a second ProFlow transfer head. The first canister is put into a refrigerator for storage, creating a changeover time of about five minutes. ProFlow can be used for printing microBGA spheres and for wafer bumping applications. DEK Printing Machines Ltd., Weymouth, Dorset, United Kingdom.
High-volume SMT Screen PrinterThe Siplace SP-500 screen printer was designed to integrate SMT production lines with Siplace placement machines. The printer reportedly has been developed to meet the demands of high-volume production. With printing speeds up to 150 mm per second, the printer is said to be well suited for applying solder paste in placement tasks requiring high throughput and maximum accuracy. The printer requires an area of 1.5 x 1.3 m, and has a multitude of features ensuring print results and high process stability. Siemens Production and Logistics Systems AG, Nuremberg, Germany.
Large Panel PCB PrintersThe 2444AV and 2444AVL printing machines incorporate advances in large format SMT PCB printing technology. Said to be designed to handle solder paste printing on large panels (backpanel, backplane, telecom PCBs), the systems offer a standard print of 24 x 44", with up to 24 x 52" available. With programmable vertical lift, dual PCB flatteners to offset PCB warpage, as well as on-board 2,000-file storage capacity, the unique printer reportedly can process all types of large panel, ordinary size and small PCBs. Surface Mount Techniques, Laguna Hills, Calif.
Stencil Printer with 2-D VerificationUltraprint 1500 stencil printer reportedly combines a base platform with several options and product improvements that are configured easily to process both SMT and non-SMT boards. Offering product flexibility, the printer is said to be capable of printing boards up to 22 x 20". Standard features include automatic board-to-stencil alignment, a self-leveling squeegee print head, programmable hard board stops and a Microsoft Windows NT operating system. Additionally, the printer features a 2-D print verification system, aligning automatic verification of print quality on freshly printed boards. Speedline MPM, Franklin, Mass.
Automatic Vision Alignment PrinterAn automatic screen and stencil printer, SP200 also is said to be applicable for fine-pitch printing. The system automatically aligns the PCB so that the operator only has to place the substrate onto the slider and start the printing process. Two cameras detect the taught fiducial marks on the PCB and the computer calculates the actual position. The universal, magnetic PCB fixation reportedly is adjustable to any PCB's outer dimensions up to 500 x 500 mm, as well as single- or double-sided PCBs. Stencil and print are parallel separated after printing (important to fine-pitch printing). ESSEMTEC AG, Aesch, Switzerland.
Solder Paste PrinterPanasert SPF solder paste printing machine delivers printing speed and cycle times as low as 8 seconds per board. It uses an open-type, high-speed squeegee head designed to maximize squeegee speed up to 220 mm per second and improve solder paste printing time. The unit also is equipped with a real-time pressure feedback system, which monitors squeegee pressure and adjusts the print stroke 50 times per second for highly accurate print. A multi-stage screen separation ensures accurate printing, while a high-speed vacuum removes solder paste on the underside of the screen mask, preventing clogs. Panasonic Factory Automation Co., Franklin Park, Ill.
Stencil Printer Cycles The AP-SpeedMax features a cycle time less than six seconds. Its high-speed option is said to enhance cycle time, accuracy and repeatability. Three major features combine to reduce board transport and alignment times: board staging duplicates a triple track conveyor system on a single-track; center-nest hard stop provides maximum transport speeds; and the rear-rail camera parks behind the rear transport to minimize travel distance. The standard balanced control print head reportedly provides accurate and repeatable pressure control for precise paste deposition. Speedline Technologies Asia, Singapore.
Screen Printing Mesh TechnologyThe PCF Sectionally Pre-coated Mesh reportedly allows screen printers to go from stretching directly into exposing. The mesh is a monofilament polyester of high quality, engineered with a sectionally pre-coated emulsion that allows for high-tension value, low-tension loss and dimensional stability. The technology is said to eliminate numerous steps in the stencil production process, providing reduced production cost as well as improved consistency. The mesh is coated with a storage-resistant emulsion and protected by a sturdy foil. Sefar America Inc., Briarcliff Manor, N.Y.
Stencil Verification SystemScanSTENCIL/LMA is a stencil verification system that is said to bring process control capability to the smallest of apertures. For incoming stencils, verification can be done after stencil fabrication and reportedly validates acceptable wear on production stencils in minutes. Able to identify poor quality or damaged stencils is a benefit of this system because it allows replacements to be in-house prior to the next production run, thus eliminating additional delays or poor quality production. The system uses Windows-based, proprietary software coupled with an industry standard, calibrated, high-resolution flat bed scanner. ScanCAD International Inc., Morrison, Colo.