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CSTM R&D Solutions has developed a series of enclosures for Foxcom’s flagship product: the “Platinum” – communication equipment for distributing satellite signals using optical fibers.
Among the enclosures realized during the project, a multi-assembly enclosure for a 19″ rack, stood out. This enclosure was required to contain 25 different configurations of sub- assemblies for various purposes, in addition to the power supply and controller cards.
The enclosure project was considered large scale, since it related to thousands of items and covered numerous design details.
CSTM was required as follows:
• to consider electromechanical means of decreasing EMI\RFI problems
• to have the design comply with a given thermal regime
• to solve the electro-mechanical interface problems between circuits
• to adapt a suitable sub-enclosure to each of the sub-assembly configurations
• to relate to various connector types (fiber optic, control, power)
• to carry a pre-layout mechanical design for all the PCBs
At the end of the concept stage, it was decided to converge upon a solution of 5HP/10HP wide sub-assemblies packed side by side in a sub-rack enclosure.
Additional requirements
CSTM was requested to meet the following :
A. Cost reduction
In order to reduce production costs, the developers sought to reduce the amount of parts and to increase the part-to-part uniformity.
Each sub enclosure consisted of four elements:
– Base circuit
– Cover circuit
– Front Panel
– Back cover
• Base – The design converged upon a uniform single shape circuit base (for all the sub- assemblies) which had 5 standoff configurations.
• Cover – Each base had a matching cover, thus 5 such configurations were realized.
• Front panel – created in 8 different variations
• Back cover – was manufactured in 20 variations of the I/O ports
Consequently it was possible to reduce the number of parts from 100 to 38, some of them being identical in the metal work and differ only in their assembly standoffs
B. High reliability
All sub enclosures were connected to a “backplane assembly” containing twelve 55-pin Eurocard connectors. The pins were delicate, and the designers faced a problem to prevent any pin bending during assembly and reassembly. This required a sophisticated tolerance analysis based solution.
C. Regulatory Compliance
The design was reviewed by engineers of a regulation Institute which often came up with essential requirements to which CSTM converged so as to meet the UL60950 standard.
Eventually, mainly due to good tolerancing , the manufacture and integration stages where carried out smoothly: the enclosure chassis with all its parts have been proved successful at the first round, without any need to carry any further amendments. |
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