Smooth Operation for microSD Connectors

MicroSD cards are the smallest memory cards commercially available and are used in a host of devices such as mobile phones, tablet PCs, digital audio players, digital cameras and other electronic devices. At 15mm x 11mm x 1mm, these tiny cards are holding ever-increasing amounts of data at ever-decreasing cost to the consumer.

A range of card connectors are available in formats that best suit the application.  Push-pull, push-push and hinged sockets all require a different mode of operation and a user’s experience with these connectors can be a significant contribution to the overall experience of the complete device. That’s why connector makers have to get it right when it comes to smooth operation of microSD connectors!

Push-pull and hinge-type connectors have a relatively simple construction, and both insertion and withdrawal of the memory card are more within the control of the user themselves.  In the case of a push-push connector, the extraction of the card in particular is very much dependent on the design of a quite complex spring-ejector mechanism.  This mechanism has a number of components, each with its own function: a coil spring creates the extraction force; a cam and follower pin controls the inward and outward stroke of the card; a slider mechanism with integrated hook holds the card in place during movement.

The real trick in a great design is getting that mechanism to balance the two main problems with push-push connectors – card sticking and card fly-out. Connector makers must optimize the variables in that “sticking versus fly-out” equation and produce a socket with the smoothest possible action, over large temperature ranges and over thousands of operating cycles.  The challenge for manufacturers is compounded further by the huge variety of cards on the market today from a growing number of sources, not all of which are within the SD Association specification limits on size and surface-roughness.

Molex continues to rise to this challenge and pushes the form-factor envelope on microSD card connectors.  Molex offers a full range of connectors in push-pull, hinge and push-push styles in various profile heights.  Molex’s ultra-low-profile (height 1.28mm, 503398 series) push-push connector is a great example of a smooth operator in today’s microSD card connector market.

What’s your opinion on the sticking versus fly-out balance?  Which is the lesser of the two evils? Are connector makers getting it right?