POWER MODULE BOX MOULDED FROM DUPONT CRASTIN RESIN
11 December 2002 - Distrupol

The combination of the accurate materials specification and rapid supply service provided by polymer distributor Distrupol with the one-stop-shop, rapid tooling and technical moulding skills of Dudley Associates enabled the power management division of Semelab, the designer and manufacturer of semiconductor components, to receive prototype parts of a power module box in production materials within two weeks of supplying computerised drawings.

The power module box lips onto a metal base plate to house the electronics that control the lifting gear of an advanced European passenger aircraft. After the electronics are in position they are encapsulated in epoxy resin, so it is vital that there are no leaks from the box.

Designed as a replacement for an all-metal component, the power module box is fitted within the wings of the aircraft. Therefore, it must have extreme environmental reliability, including the ability to withstand temperatures from -55C up to +125C and wide variations in humidity. The one-piece box, which measures 13cm x 11cm, with a depth of 3cm, is moulded in a 30% glass reinforced, low warpage grade of DuPont’s Crastin PBT. The material was initially specified by John Brenchley, one of the polymer engineers at Distrupol, and is proving to be 100% successful in the customer’s product evaluation trials.

Dudley Associates has been handling many of Semelab’s prototyping and low volume production requirements for injection moulded parts for the last two years. They rapid manufacture and mould high grade aluminium tools that are capable of moulding 50,000 parts, or more.

Distrupol is regularly a partner in projects being undertaken by Dudley Associates and is the company’s preferred materials supplier of engineering thermoplastics.

“Other prototype techniques could not fulfil our need for quality assured parts in finished engineering materials for environmental testing and to support low-to-medium volume supply,” says Rick Alliwell, Semelab’s power division engineer. “Distrupol’s response and involvement with Dudley Associates and our project allowed the correct material to be identified and supplied for sampling in perfect harmony with Dudley’s scheduled trials.”

Development of the Crastin PBT power module box is part of a programme being undertaken by a multinational aeronautical company to replace metal components with high quality engineering thermoplastics for a new generation of ‘More Electric’ passenger aircraft. The aim of the programme is to reduce costs and accelerate lead-times in the adoption of extremely reliable, encapsulated, electronic controls to replace hydraulic systems.

The prototype parts for the power module box were moulded by Dudley Associates on a Boy machine with 50 tonne clamp force. They were sent directly to the aeronautical company’s qualification department, where they are meeting all test criteria. One of the key requirements in the specification of Crastin was to ensure it was an extremely stable and robust polymer with high electrical and flame retardant properties. This ensures there is no distortion when encapsulating the electronics and that the assembled component is unaffected by the wide variation in environmental conditions when in service.

Based in Lutterworth, Leicestershire, Dudley Associates was formed in 1995 as a one-stop-shop to specifically meet the demand for high quality, technical injection moulded parts on the shortest possible lead times. It has comprehensive design, tooling and moulding facilities, and its use of special aluminium alloys for the tooling allows production of components in engineering thermoplastics to very high tolerances. Customers are mainly blue chip, first- and second-tier suppliers to the medical, automotive, defence, electronics and telecommunications industries.

The semiconductor business of Semelab plc is also based in Lutterworth, where it has five operating divisions. The power management division provides complete solutions for power supply and control applications through a range of integrated power management circuits, discrete power devices and modules. Other Semelab activities include a wafer fabrication plant in Genrothes, Scotland, and, through its EV Technology subsidiary, the import and distribution of electric vehicles.

Since their collaboration on the power module box, Semelab and Dudley Associates have worked on other projects using the same technological principles. A major attraction of the collaboration is that Dudley is able to quickly undertake any necessary tool modification, while Semelab receives high quality parts in medium volume, production quantities within a fast, prototyping timescale.

http://www.distrupol.com, www.dudleyassociates.com

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