Board-edge connector for MXM standard in automotive applications

Paul Boughton

Yamaichi Electronics' BEC-0.5-230-S9-xF-R-EDC is a board-edge connector for MXM/QSeven applications developed and tested especially for the automotive industry. This 90° SMT connector with 230 contacts and a 0.5mm pitch has outstanding features.

The MXM standard (Mobile PCI EXpress Module) and its associated QSeven norm define an interchangeable graphics card module and its mechanical, electrical and thermal interface properties. This includes both the connector itself and its software.

The board-to-board connector transmits image and video data from the graphics card to the screen. Until now, connections compliant with this standard have been confined to notebooks and PCs in the business world.[Page Break]

But now, the application has moved into embedded applications, eg infotainment systems in vehicles. When designing connectors in this type of application, special circumstances must be taken into consideration. These requirements are:

* Mechanical resistance to vibrations in the vehicle
* Wider temperature range, from -40 °C to +85 °C
* Reliable contact even after vibrations and shock
* Improved EMC connection

Mechanical stability is ensured by the use of larger SMT tabs, which simultaneously serve to connect the shielding. The customer has the option of using pressed-in nuts in the SMT tab area to fasten the plugged module to the connector itself using M2 screws. This provides additional reliability in the position of the module even in the face of strong vibrations and the effects of shock.[Page Break]

A special contact design compensates tolerances of the module fixation angle regardless of the PCB thickness (within a specific range). The contact design continues to ensure continuous contact throughout the lifetime of the connection despite high mechanical and climatic stress.

The design in the insertion area of the BEC connector also permits the use of modules without a chamfer, saving costs for the PCBs used.

The special requirements of the automotive industry have been thoroughly tested and verified in comprehensive long-term testing.

The BEC connector supports the latest graphics standards, like PCIExpress, HDMI, DisplayPort, etc. The plug face is compatible with modules that comply with the MXM1.0 and QSeven standards. The installation height of 7.8mm (plug height of module 5mm) can manage even narrow spaces. A total of 30 plug cycles are guaranteed.

The insulation body is made of LCP and the contacts are phosphor bronze. The contact surfaces are available with gold plating in three different contact layer thicknesses from Au flash to 30 µinches. The connectors are delivered on spools (tape and reel).

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