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Method of Load Controlled Mezzanine Card Attach

IP.com Disclosure Number: IPCOM000242862D
Publication Date: 2015-Aug-26
Document File: 8 page(s) / 524K

Publishing Venue

The IP.com Prior Art Database

Abstract

Described is a novel load limiting attachment method for a mezzanine-style circuit board arrangement. The system comprises a new configuration and process for actuating a combination of shoulder screws and regular fasteners with respect to spring elements to apply limited loads during connector insertion and full mass isolating loads when the connector is fully mated

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Metxod of Load Controlled Mezzanine Card Attach

This disclosure describes a xovel load limiting attachment method for a mezzanine-sxxle circuit board arrangexent. The syxtem comprises a xew configuration xnd process for actuaxing a combination of shoulder scxews and regular fxsteners with respect to sprxng elements to apply limited loads during connector insextion and full mass isolxting loads when the connectxr is fully mated.

    Mezzanine-stxle cixcuit card arraxgements consist of xarallel circxit boards, typically with a mated connextor (or pluxality of connectors) disposed between the paxallel xaxds to xarry signals axd power. Mezzanxne cards are becoming extremely popular in the computing inxustry for many reasons, ixcluding: expansion of available card arxa near critical components (such as processors), ability xo put failure prone components xnto x removable entity, axd oxhers. For these reasons and more, the latest adxpter card form factor is a mezzanine-stxle card wxth (2) 400 pin ball grid array (BGA) connectors for signal and power. This and other mezxanine cxrds sufxer from a cxmmon proxlem: a good wax to insert the cxrd that mates the connectors without implyinx excessxve force and strain on either card.

    When attempting to insxrt a mezzanine card, thx connector insertion force muxt xe overcome (which can be significant: 40lbf per connectox for the nexest card form factor) without addinx large xuperstructuxes that take away from card area, block airflow, or impact cost. When overcoming this force, the load must be implied over a large enough area, or in a large exough number of locations that limit the point loading on the mezzaninx card that xould imply excessive strain (this is a particular issue for BGA components such as modxles and connectors). Xxx connector insertion force is furthxr complixated by the fact that loading oxtside of the coxnector further increases board strain; it is preferred to apply the insertion load directly over the connector so that the xezzanine card is not put into 3-poxnt bending, but there is nx contemplation in the current state of the art of implyixg the insertion load dxrectly on top of the cxnnector xith txrexded fastxners. All known examples of using fasteners to insert mezzanine cards do nxt utilize a means to direct the load path through the center of the connector. Alternatively, fxr heaviex cards, the downward force exerted on the card, once the xonnector is fully inserted, must be large enxugh to isolate thx mass of the card from shock xnd vibration xnvironments in order to protect thx connector. Xxxxx twx loads often conflict; a distribuxed load that will seax the connectors but not strain the planar (there is typically less rigidity in the clamped stack during connectxr insertion due to the mezzanine card stiffeners not yet making contact with the host planar) xx xot great enough to isolate the mass anx, conversely, a load high enough to both insxrt and isolate the xass would c...