Extraction Levers on Circuit Card Assemblies

[AHilditch]

Hi All!

I'm designing a circuit card assembly with a 3U card that utilizes ANSI/VITA specs 46.0, 48.2, and 20.
What I'm running into is that it is possible to design an assembly (includes Printed Circuit Board and a Frame)according the the specifications that does not leave room for mounting an extration lever. As per my design needs, the extraction lever will not fit.
Questions:
1: Is there anywhere in the VITA specs that says you abosolutely have to have an extraction lever or is it optional?
2: Could I use an alternate method of extraction, like a pull tab or something you physically pull on, or does it have to offer mechanical advantage?
3: Are there specs that specify how much clearance is needed between the end of the Circuit card assembly and the door/cover of the CCA chassis/housing?

I've been combing through these specifications and am not finding answers. Has anyone else run into this issue?

Any information at all will be helpful.

Thanks,
Alison

 

[IRstuff]

Surely, you must have similar boards lying around. I would suggest that you attempt to remove such a board from its motherboard connect without risking injury to yourself in close quarters. Fully populated boards often have more than 30 lbf extraction force:

http://www.cbttechnology.com/assets/PDF/CBT Technology Inc VPX HAndle Cycle Test Report.pdf

Tabs, I think, would be useless. On VME boards that didn't have extractors, we would often grab the ICs closest to the outside edge for leverage, which is not a good thing.

TTFN
faq731-376

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[AHilditch]

Unfortunately the single borad I have has a different frame form and component requirements. It has an extraction lever, but the 6U card design has a thicker frame than my current project. I couldn't find in VITA documentation much information specifically on extraction levers (standard placement or design of features to accomodate the lever). This is my first time doing this kind of design so I'm really looking for more knowledge on the subject. I followed the specifications for a 3U card with a mezzanine card and, because the PWB, frame, and mezz (according to diagrams in the spec) stack flush along the one end, that design leaves no room for the lever.

 

[Sparweb]

Perhaps a different extraction strategy is necessary? The choice of extractor affects a lot of things, particularly the interface of board in the header so I won't try to speculate about what alternatives might suit you. I'm just handling my digital camera, plugged into this laptop, and I think there are at least 6 different extraction devices between the two.

STF

 

[MikeHalloran]

I think you need to provide an ejector/extractor,
or a place where you can hook it to a slide hammer.



Mike Halloran
Pembroke Pines, FL, USA

 

[AHilditch]

Hm... I guess what I'm looking into now is extending the frame of the card so that there's enough material for an extraction lever to even be mounted, since that was my original issue. There was no way a lever could be mounted without it interfering with mounting holes, wedgelocks, and PWB. Perhaps my question now is it an acceptable move, especially if I have the clearance in relation to the chassis. I can not really find any recommendation or rule in the VITA specs for convection cooled cards saying not to alter the frame in this direction. Though the diagrams in VITA seem to have the PWB flush with the end of the frame. It's all rather confusing.