In industrial computer systems the backplane is a central element. It sets up the electrical links between the system slots in accordance with the bus architecture employed. To ensure high system performance and reliability, however, not only must the specified design rules be followed but the quality of manufacturing must be high at every stage of production. Schroff's backplanes are produced in the company's special backplane centre and are either custom modifications of standard designs or designed and manufactured from scratch to customer specifications.

In recent years the importance of the backplane in a system has increased drastically. More and more frequently it replaces conventional rear-panel wiring. Backplanes have come to form a central component of integrated, computer-controlled systems such as are most commonly employed in telecommunications, instrumentation and automation technology, medicine, aviation and railway systems. Constantly increasing transfer rates and complexity mean rising demands on backplane development, layout, production, testing, validation and simulation. Whereas only a few years ago high-speed backplanes, for example, were a rare exception, today PCI Express, Gigabit Ethernet and serial rapid I/O are the day-to-day business of backplane developers everywhere. As a consequence, new demands are also being made on manufacture and particularly on design validation. The changeover from parallel buses to packet-orientated serial data-transport mechanisms has also called for a change in approach to certain previous design rules. 3D simulations and a manufacturing process that can guarantee high-precision implementation of the design parameters have become unavoidable. Such simulations and measurements also serve to optimise the performance-to-cost ratio by a potential reduction of the layers required. Schroff's developers and designers have the know-how and experience required to create backplanes for these new technologies. The comprehensive range of standard backplanes (VME, VME64, VME64x, VXS, VPX, CompactPCI, CPCIe, PSB, H.110, PXI, ATCA, MTCA, test adapters, universal bus connectors and power backplanes) form a basis on which custom modifications can be made.

The high demands on development and design naturally extend to the manufacturing process. Here the central issues are manufacturing quality, precision and cost. By continually optimising backplane designs on the basis of measurement results and simulations, together with the savings achieved by new production facilities, it has been possible to cut the list prices of, for example, standard VME, VME64x and CompactPCI backplanes by up to 20 %. Targeted investments in modern manufacturing systems have allowed Schroff not only to reduce costs but also to improve product quality.

At present Schroff is the only backplane manufacturer to apply conformal coating - a special protective fluorescent coating on the board - using special equipment in its own production facility. The result for the customer is both time savings and flexibility and a further cost advantage.

Another example of the efficient use of new manufacturing technology is the new solder paste printer that prints solder paste on the boards for backplanes before the components are pressed into them by high-speed SMD machines and soldered in the reflow system. Previously, the solder paste was applied manually to the boards via stencils using a silk-screen printing process. This method was time-consuming owing to the required manual setting-up, costly because of the different stencils required for each board layout, and grew ever more difficult as the grid pitch became smaller and required higher and higher precision. The new solder-paste printer does not require stencils. It performs some 500 solder points per second, which works out at 1.8 million solder points per hour, precisely and reproducibly.

Despite this high processing speed, however, far fewer errors occur with the solder-paste printer than with conventional screen printing. Less solder paste is required, thus saving costs and improving environmental impact. The printer is so fast that it can serve two placement lines in Schroff's manufacturing facility without difficulty. Its high accuracy means that repairs and post-treatment on the printed boards, such as used to be frequently necessary, are a thing of the past. Product changes can be made simply and at short notice now that stencils are no longer required. Not only is the cost of the stencils eliminated, but so also is the three-day wait for their delivery. With the new solder-paste printer, Schroff's customers thus benefit from considerably greater flexibility in order handling, shorter delivery times and improved product quality.

Following component placement and condensation soldering, each PCB is subjected to an automatic optical inspection (AOI). A system of 15 cameras and 10 light sources, set at various angles, images the boards reproducibly and at a constant grade of quality, to detect placement errors such as missing components, components' polarity, short circuits and dry or poor soldered joints. If errors are detected, the board is sent to a repair station where the fault is corrected by an operator

Next, the connectors are fitted to the backplane using press-in technology. Today, press-in methods with a flexible press-in zone are the state of the art for all types of backplane. The fully automated press-in system uses force/track control. Following the press-in of the connectors and final assembly, the electrical functioning of each individual backplane is tested using automatic backplane testing systems. In addition to standard tests such as for connections and insulation, these high-performance and complex testing systems offer specific test options for electrical components such as resistors, capacitors and diodes. During the automatic "Direct Test", the backplanes are contacted by pneumatic adapters. At the request of the customer, specific additional tests can be performed on individual backplanes such as high-voltage insulation testing and earthing conductor testing. If the backplanes are to be integrated into a system, further tests will be carried out as part of the overall system test, such as optical inspection, a safety test and a function test. Only 100 % tested backplanes and devices leave the Schroff production facility. All tests are documented with internal and external quality documents and may be traced back at any time.

Through its collaboration with leading PCB and connector manufacturers, Schroff creates the conditions necessary for quality products. Schroff's suppliers are obliged to undergo the appropriate audits, and the suppliers thus also become qualified. Schroff itself is certified to ISO 9001 and ISO 14001:2004.

An online configurator for custom backplanes is available on Schroff's website at www.schroff.de/conf. By requesting key data and information, it provides customers with support in configuring their desired backplane. Not only the intended field of application and the quantity and delivery time are required, the configurator also requests information on the required bus specification, the backplane dimensions, number of slots, slot pitch and details on the connectors and power supply. Additional customer requirements may be entered in a separate field. Promptly on receipt of the completed form, the customer is sent a quote. Where there are ambiguities or information is missing, the customer will be consulted by telephone.

From the outset, customers are assigned a dedicated product manager to deal with any issues that may arise. This manager undertakes the entire project management and advises the customer on matters ranging from specification and design through prototype production, testing and inspections to the actual manufacture, including logistics and after-sales service. With a single contact partner for the entire process, from the initial enquiry to delivery and services, communications are greatly simplified.