Park Air Systems, members of the Northrop Gummam Corporation based in Market Deeping Cambridgeshire, are the world's leading designers and manufacturers of air traffic control systems. The company's Communication, Navigation and Surveillance (CNS) technologies provide integrated air traffic solutions for Air Space Management and are to be found in 167 countries throughout the world.
Like many companies in the electronics sector, they use copper alloys for a number of applications including connectors, heat sinks etc, but one application that demonstrates the versatility and cost-effectiveness of brass (an alloy of copper and zinc) is detailed below.
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Why Park Air Systems chose brass:
- Brass's high electrical conductivity, combined with its other physical properties, ductility, malleability, and ease of soldering, make it an ideal material for RF shielding.
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One of the company's products includes a receiver module, which sits in a transceiver unit, and is used for ground-to-air radio communication. A tremendous amount of radio and electrical interference is generated by the everyday activities that go on at an airport and it is of the utmost importance that this interference does not interrupt or interfere with radio communications between the airport and the aircraft. It is therefore essential to screen the receiver module against this interference and Park Air Systems' simple but efficient solution is to use brass as the RF shielding material.
The screen takes the form of a number of rectangular cells, in which sit the various electronic components. These cells are produced by soldering together, at right angles, lengths of brass strip. Brass surfaces rapidly oxidise when exposed to air, forming a protective film which prevents further oxidation (corrosion/rusting). Brass is readily soldered but, to achieve a successful soldered joint on oxidized surfaces, it is necessary to use a halide based flux which can be corrosive if not fully removed, usually by washing, after soldering. To overcome this problem and allow the use of a non-corrosive rosin flux, the company electro-tin the brass surfaces prior to soldering.
The company has been using this method of shielding for at least the last 15 years and claims that brass gives them a cost-effective, tried and tested solution on which they can depend.
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