THE ETX CPU MODULE
CONCEPT: A STANDARD ASSERTS ITSELF!
WE'VE NOTICED THAT THE DEBATE REGARDING FIELD BUS STANDARDS A FEW YEARS BACK HAS LATELY
WANDERED TO THE PC-BASED AUTOMATION SECTOR.
As yet, however, users themselves are left to decide whether it is really a battle over
the better concept or simply a case of imitators tagging along on the coattails of a
technological innovator. Because "clear" facts are needed for an informed
decision, CODICO has taken a look at them, and we will now try to explain why the ETX
concept "is what it is."
The ETX CPU module concept was introduced in 2000 by JUMPtec AG, a company that has since
merged with Kontron Embedded Modules GmbH. Lately, an increasing number of
competing products have appeared on the market, accompanied by comparisons with the
original ETX technology. This comparison alone, however, does not mean that a new
standard, or form factor, is taking shape. It merely tells us that an alternative product
is available. With this in mind, isn't it about time we looked at the factual evidence
regarding the degree of standardization and technical features?
Processor and Component Alignment
Kontron's ETX CPU building block is sold as a separate module for customer-specific
applications. It is connected to a baseboard via soldered connections (4 x 100 pins),
i.e., without cables. The ETX solution gives designers the freedom of using any x86
processor available on the market.
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Competing products that specify only a
matching alignment position with the various processors do not suffice, however, because
other critical factors such as the construction height of the CPU and the assembly
tolerances of the packages and solder connections (especially for Ball-Grid-Array) should
not be underestimated.
The ETX standard solves all of the above technical factors through the use of a
heatspreader, which effectively eliminates any differences - thermal or mechanical -
between CPUs. The heatspreader additionally serves as a thermal coupling between non-CPU
components, e.g., such as the chipset and video controller. This "all-for-one"
solution ensures that the mechanical design on the OEM side can be uniformly implemented,
and has therefore been standardized. The heatspreader offers an amazingly simple concept
cooling solution, and, by providing a cooling surface of more than 100cm², the time
consuming and costly practice of adding thermal couplers (heat pipes, etc.) can be avoided
altogether. Temperature is instead dissipated via package walls or heat sinks within the
specified operating range. Depending on the CPU used, a passive heat sink will generally
suffice to meet the overall system requirements.
RAM chips - plug-in or solder?
Soldered memory chips tie up capital and restrict maximum upgrade capability. For this
reason, the ETX standard rejects fixed soldering. The advantage is a modular memory
upgrade capability that remains scalable according to individual requirements, and,
furthermore, that memory modules can be added just in time for delivery, which translates
into a cost savings for the user.
A standard must maintain a certain degree of freedom and, at the same time, clearly define
as many features as possible. If there isn't sufficient trade-off between these two
considerations, the economics of scale that a standard must provide cannot be fully
realized. Modern memory sockets, for example, offer adequate shock and vibration
resistance, as millions of laptop owners can attest.
For more details, please don't hesitate to contact:
Egon Brunnhuber, EXT 61
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