TechArchive

Original article date: September 1998

by Hans-Jurgen Wochian, Product Manager, Non-Portable Systems, Kontron Elektronik

While the development of software and electronics made enormous progress, the mechanics of the PC remained largely unchanged, even up to the present day. The interior of a PC still contains screws and metal plates. A fan blows air through a more or less empty case, with guiding plates influencing thermal currents.

This is where the new E-PAC (Electronic Packaging and Assembly Concept) internal design comes into play. In this system, all parts of the PC such as hard disks, power supplies etc. are no longer screwed into the case, but embedded in foam parts which hold them in place with positive locking. In order to fulfil industry requirements for robustness, temperature resistance and ease of servicing, Kontron Elektronik is the first company in the industrial computer market to produce a new 19in rack computer using E-PAC.

One effect of production using E-PAC is the increased lifespan of the equipment. This stems from the excellent cooling of components. Air flow within the case can now be controlled, because ventilation channels are incorporated in the foam, which directs cool air to the hot parts. In Kontron Elektronik’s IR KPR III rack-mounted computer, for example, about 30% of the ventilation airflow is channelled directly to the disk drives, which give off a great deal of heat when operating normally. The system not only provides cooling for heat-producing parts, it also protects heat-sensitive components.

The air flows through the foam from the hard disk to the CD ROM and floppy disk drives, protecting these components from overheating. And this is the point: the cooler the interior, the longer the life of all components. This allows the lifespan of the IR KPR III to be improved with higher MTBF (Mean Time Between Failures).

A weak point in classic construction methods is processor fans, which are not available on the market in an industry-compatible form, and therefore represent a particular risk factor. Kontron Elektronik has successfully done away with these fans, since even here, temperatures can be kept constant using directed air flows. E-PAC will allow today’s processors, and those of the future with even higher clock speeds, to be kept at non-critical temperatures without CPU fans.

A further significant consequence of production using E-PAC is the reduction in purchasing costs for customers. When high industry specifications are required, the mechanical effort involved in the old Oplate and screwsO method is very high, and correspondingly expensive. E-PAC allows the number and complexity of parts required for the construction of a computer to be reduced. The assembly time for the IR KPR III has been halved.

The EPP (expanded polypropylene) foam used for E-PAC brings great advantages in terms of the shock and vibration resistance of equipment. The sensitive parts of the computer are well protected, without increased expenditure. This property of the foam makes E-PAC design far superior to the conventional process.

A further aspect which reduces costs for users is the equipment development time. If E-PAC is used for internal design, a prototype can be assembled very quickly. The foam parts are cut from a plain block of foam and can quickly be made available for prototype tests and equipment certification. The tools for series production of the foam parts will then be produced only when all the foam parts meet the requirements fully. Instead of 12 months development time for a single case, the IR KPR III was ready for mass production after only 5 months.

In the long term, we can expect to see a changeover from the old mechanical principles used in all industrial computers, and even in office and home computers. Processor clock speeds are continually increasing, and heating problems are becoming ever greater. In addition to temperature problems, EMC problems also occur. Radiation will become more and more difficult to deal with. Here too the the fewer metal parts used, the less perturbing radiation occurs.

• Kontron Electronik
• Marilyn Comrie
• 01923 412345

September 1998