Sanmina-SCI's electronics assembly facility in Gunzenhausen, Germany, has reported a 63 percent reduction in paste wastage by fitting one of its stencil printers with a paste-level sensor from DEK International GmbH (Flemington, NJ). The company will now upgrade its remaining three ProFlow printers to maximize paste savings on all lines.
With a conventional stencil printer, the solder paste is applied directly on the stencil, and a squeegee is used to pass the paste across the stencil and onto the circuit board. With the ProFlow printer, the paste is contained in an enclosed printhead. As the printhead moves across the stencil, it forces paste through the apertures. Because the paste is not exposed to the air, it does not become dry and unusable. This reduces print defects.
The printhead comes in lengths of 150 to 500 millimeters. Two types of printhead are available. One accepts disposable cassettes containing 800 grams of solder paste. The other is refilled manually. A sensor inside the printhead alerts operators when the cassette is nearly empty.
However, early versions of the sensor were not always accurate. In some cases, 40 to 50 grams of printable paste could be left in the cassette when the sensor called for replenishment. The new sensor solved the problem.
The sensor took little time to install. Fitting is completed within 4 hours, including replacement of the paste pressure cylinder. It is compatible with all machines fitted with software-controlled and manually regulated printheads, including rechargeable and cassette types. The sensor is also clean room compatible.
Sanmina anticipates each machine will repay the initial investment within 2.9 months, and will go on to save 1,080 euros per month at the Gunzenhausen site.
For more information on ProFlow, call 908-782-4140 or visit www.dek.com.