Siemens Electronic Manufacturing (EM) production unit produces PCB assemblies and other products for industrial automation — for both its own business unit and for the world market. Products are assembled on six SMT lines, in three-shift operations running five days a week.
|Grid-Lok from Ovation provides PCB support for all aspects of placement and printing processes. |
Last year, as part of the company's efforts to further improve quality, a decision was made to procure PCB support systems for SMT production. With standard widths of 160 to 210mm, double-sided mounting and high densities, the circuit boards in production were somewhat prone to vibrations, especially when assembled by modern high-speed pick-and-place systems. While magnetic support systems are available as standard equipment from the SMT machines in use at the plant, those systems did not meet Siemens' stringent requirements — and an alternative had to be found.
Siemens' Michael Wohrle and Markus Pasurka, both from the assembly production engineering area, began a search for a suitable support system.
Magnetic Supports Inadequate
The company had already gained experience with PCB support systems, since its sophisticated production equipment already included various types of support technologies. The existing systems were the magnetic support type pins integrated into the host machines. In such systems, individual pins provide selective support for the undersides of circuit boards. The disadvantage is that the pins have to be readjusted when production machinery is retooled for different products. In discussing the challenges this presents,
Markus Pasurka explained: "Because of the large sizes of our circuit boards, and because we use double-sided mounting, positioning the pins proved to be an extremely tricky task. We have a number of `pin-in-paste' processes, and in those processes there was always a possibility for a support pin to come into contact with the solder paste and then track paste onto other components. Just one wrong position would lead to defects. With large circuit boards, it is especially difficult to find a golden mean that would allow absolutely precise pin placement throughout a broad range; any wrong position can have pretty disastrous consequences."
Michael Wohrle evaluated a number of common support systems that met the applicable requirements. "We looked at three fully automatic systems and two brushcard systems in light of our benchmark," explained Wohrle. "We soon discovered that Ovation Products' Grid-Lok system, which is supported by local German distributor Ben-Technologies, was a perfect fit for our production needs. The fully automatic Grid-Lok support system was able to accommodate large, densely populated circuit boards across their entire surface areas. And, it was able to do so in areas where magnetic pins just wouldn't have worked. In addition to having the best price/performance ratio, Grid-Lok also provided a solution for our "pin-in-paste" process." There were other factors to consider as well, such as
electrostatically sensitive areas. Every system in the manufacturing line must incorporate ESD protection. This proved to be another area in which the Grid-Lok support system performs perfectly; upon contact with components, it can carry out gentle electrical discharges that do not damage components in any way.
These advantages really do the job in a production operation with six SMT lines, running on a three-shift basis, with about eight to ten actual product changes per shift and line. "Our lot sizes range from 200 to 1,500 units, meaning that the automatic Grid-Lok support systems has a great potential to reduce our costs," said Wohrle. After an initial evaluation period, Siemens ultimately secured a total of 21 Grid-Lok systems, comprising 62 modules.
Contact: Ovation Products, 3864 Courtney St., Suite 240, Bethlehem, PA 18017 484-893-1028 Web: http://www.ovation-products.com