PC board anchoring for Aircraft Vibration 1

[DHambley]

I have a small, approx 1.25" x 2.5" PC board (called a daughter board) which I need to connect to a larger board. In our box there is only enough room to either, 1. Attached the smaller board at a 90d angle to the mother board with a 90d connector or, 2. Bolt the daughter board several inches away and run a ribbon cable between the two boards. I'm worried about the cable idea due to picking up noise from nearby noisy parts.
Our vibration level is category U (Helicopter). Our mechanical engineer is concerned about vibration if the small board is left at the 90d angle.
I'm looking for ideas from anyone about anchoring the small board with some kind of bracket or something in addition to the 90d connector to allow it to be stable under these high vibration levels. Have you found a method to solve a similar problem?

Thanks in advance.
- Darrell


Darrell Hambley P.E.
SENTEK Engineering, LLC

 

[drawoh]

DHambley,

In a vibrating environment, cantilevering a board off a connector has to be a bad idea. Can you add a support bracket to each end of the board?

Can you use a shielded cable?

--
JHG

 

[SwinnyGG]

I have a great deal of experience in mechanical design of housings to make electronics survive harsh exposure, and would agree that a board cantilevered from a connector is a bad idea.

Even if you anchor the board at both ends (connector on one side, bracket on the other) you still have to worry about the mode shapes of the daughter board under free vibration- they can and will impart significant forces in the connector.

Is the daughter board single-sided? The quickest method to make a PCB assembly robust in vibration is to use single-sided population, and then attach the full back side of the board to the housing using PSA or thermal interface material.

 

[DHambley]

jgKRI, The attached single-sided board just might work. Are you thinking of flush headers or something to connect the two boards?

Darrell Hambley P.E.
SENTEK Engineering, LLC

 

[SwinnyGG]

Flush headers or ribbon cable, headers obviously would be more robust.