in-car (passenger) electronic device use: resonance vibration natural frequency

[kellogs]

Hi,

I have this smallish gadget that I want to use inside my diesel engine car. It is mostly going to sit somewhere inside the car for the most part, and I am considering vibrations.

The PCB is under 100 g / 4 oz and about 45 x 50 mm / 1.8 x 2 in. From what I read this makes for a low mass, and also in a low frequency vibrations environment, which may not be so well. Further I have read and seen the standard solution to this problem: raising the natural resonance frequency of such systems by staking the bulkier / heavier parts with epoxy adhesive. But, there is also the solution of lowering the resonating frequency, hence my question below. I must say that I do not know what the vibration / shock frequencies would be in this environment; I guess a couple of Hertz for the diesel engine ? Maybe tens of Hertz for otto engines ?

To the question:

Would there be any advantage over the industry's standard solution if I mounted my PCB through layers of double adhesive tape, a layer of 6 mm latex foam and some additional weight to bring the whole thing at around 0.5 kilograms or over - thus achieving lower natural resonating frequency ?

 

[Alec_t]

Would there be any advantage over the industry's standard solution if I mounted my PCB through layers of double adhesive tape, a layer of 6 mm latex foam and some additional weight to bring the whole thing at around 0.5 kilograms or over - thus achieving lower natural resonating frequency ?

I would think that will increase the risk of damage to the pcb, not reduce it. Consider what will happen if you brake sharply or the car hits something. All that extra weight will have considerable kinetic energy, some (much?) of which will be dissipated in the pcb and its components.
What enclosure will the pcb be mounted in and how will that enclosure be supported/mounted?

 

[kellogs]

I would think that will increase the risk of damage to the pcb, not reduce it. Consider what will happen if you brake sharply or the car hits something. All that extra weight will have considerable kinetic energy, some (much?) of which will be dissipated in the pcb and its components.
What enclosure will the pcb be mounted in and how will that enclosure be supported/mounted?

You have got a point there; if it rolls over -> not good. And since the enclosure won't be mounted in any way.. I guess I'll take the standard route with epoxy staking and screw mounting (PCB <-> enclosure).
My biggest part is going to be a finger press button. And maybe a bent led. I am wondering if I should stake these and some small caps at all...