PCB Shock & Vibration - Page 1
Forum section: electronics / beginners

author: Leptir
author_rank: Newbie
timestamp: July 22, 2023, 11:56:48 pm
content: Electronics neophyte here, need some basic help.I want to replace the hard drive in an automotive device (navigation/entertainment unit) with an SSD. The hard drive is a Toshiba model designed for automotive applications. I’ll be replacing it with a Swissbit industrial SSD designed for extreme temperature and shock/vibration. So, no problem there.The problem is that I need to use an IDE to M.2 SATA adapter to make it work… and that part is not industrial-grade. In fact, it’s cheap Chinese junk. (Picture attached.) I’m afraid of what might happen to it when subjected to years of shocks and vibration inside the car.I’ve come to the idea of using Loctite Red 271 on the two capacitors, the voltage regulator, and the other surface-mounted components to help protect against shock/vibration. Is this a good idea? And if not, is there anything else I can do?

author: Benta
author_rank: Super Contributor
timestamp: July 23, 2023, 12:23:59 am
content: It's a lousy idea and you're overthinking this completely.When did you last open an ECU? Did you see any goo there?None, huh?It's fine as it is.

author: Leptir
author_rank: Newbie
timestamp: July 23, 2023, 03:11:33 am
content: The idea of this thing vibrating for years makes me uneasy, but you are probably right, I'm overthinking it. It'll leave it be (and I have a spare just in case). Thank you Benta.

author: Manul
author_rank: Super Contributor
timestamp: July 23, 2023, 08:39:16 am
content: Well, yes, inside industrial environments such issue exist and generally it should be taken seriously. What helps most is proper mounting. You can often estimate that just by “feel”. If PCB is fixed by screws at many points and nothing is particularly flexing when pushed with a finger and does not feel like “ringing” when taped and there are no heavy components, most likely it will be ok. To do proper vibrational analysis is much more demanding task. In some cases, if PCB seems “ringing” you can add dampening material like a little sponge at some specific place to stop it from resonating.

author: tszaboo
author_rank: Super Contributor
timestamp: July 23, 2023, 09:38:35 am
content: If you have silicone sealant, that's usually the stuff to use this. For a production line, you should use the good stuff. For a one-off project, you an use the same thing you use for the bathroom and kitchen.

author: AndyC_772
author_rank: Super Contributor
timestamp: July 23, 2023, 10:21:56 am
content: Nothing on that board is heavy enough to really be an issue.Make sure the PCB is properly secured, use shake proof washers on any machine screws, and leave it at that. It's only the entertainment system, not the airbag controller.

author: tooki
author_rank: Super Contributor
timestamp: July 23, 2023, 11:53:56 am
content: Quote from: tszaboo on July 23, 2023, 09:38:35 amMake sure it’s not a type that cures with acetic acid. Look for “neutral cure” or similar description.

author: tszaboo
author_rank: Super Contributor
timestamp: July 23, 2023, 12:50:12 pm
content: Quote from: tooki on July 23, 2023, 11:53:56 amYou are absolutely right.

author: Leptir
author_rank: Newbie
timestamp: July 23, 2023, 08:30:03 pm
content: Thank you guys, this is all very informative. I will pay attention when mounting this thing.

author: EPAIII
author_rank: Super Contributor
timestamp: July 24, 2023, 11:19:10 am
content: Despite it being cheap Chinese junk, that PCB looks as solid as a tank to me - perhaps much more so than some tanks. Unless you plan to do off-road, cross country racing with that car, EVERY DAY, then I wouldn't worry about it.In over 45 years I have only once seen capacitors come apart from a PCB and that was on a rotating assembly that constantly spun at about 1800 RPM. And they were the very heavy, tantalum capacitors. None of the other parts on the board showed any signs of the slightest movement. Your board will be just fine.PS: Automotive electronics is built to one and only one spec: CHEAP!Oh, and it is not the mounting of the board that you need to worry about. It is the cables hanging off of it on the super cheap connectors that the computer industry uses. Be sure to clamp those wires and cables down to the same part of the car that the board is mounted on. And place those clamps very close to the board, like one inch or so. Don't let them flap around with every bump. That is one thing that auto makers DO do.

author: wraper
author_rank: Unknown
timestamp: July 24, 2023, 11:48:22 am
content: Quote from: Leptir on July 22, 2023, 11:56:48 pmThread lock does not work like that. It needs to be squeezed between metal surfaces to harden. Not to say it's likely somewhat conductive, blue 243 certainly is. For better robustness you can fix those capacitors with neutral RTV silicone or replace them with tantalum or aluminum polymer capacitors in rectangular package.

author: tooki
author_rank: Super Contributor
timestamp: July 24, 2023, 11:52:18 am
content: Quote from: EPAIII on July 24, 2023, 11:19:10 amThat statement is complete and utter nonsense of the highest degree.While the auto industry is indeed extremely cost-sensitive, that is most decidedly not the SOLE criterion. Weight is another one.But what sets automotive electronics apart from ordinary consumer electronics is one big thing: reliability. Because so many automotive electronics systems are safety-critical, they must meet reliability standards set out by regulators as well as the automakers’ own legal departments, who assess liability. The end result is that they must design most of the electronics to be extremely reliable. Moreover, even non-safety-critical electronics, like audio systems, need to be reliable enough to avoid damage to the company’s reputation. (And if a non-critical device, like the audio system, gets used for safety-critical or regulated purposes, like using the audio system to play the turn indicator clicks and warning chimes, then the audio system’s reliability has to meet the reliability requirements of the critical systems.)Furthermore, the automotive environment is a quite hostile one. Automotive electronics must handle temperature extremes (ca. -40C to 110C), humidity extremes (0% to 100%), constant vibration, g-forces, dust and water ingress, and in at least some cases, chemical fumes (like fuel vapors). The automotiveelectricalenvironment is notoriously rough, too, with tons of noise from the ignition system, ground loops (because the chassis is normally the ground), plus significant variations in voltage.The result of the need for high reliability in a hostile environment is that automotive electronics are designed carefully and tested rigorously. They employ all kinds of methods rarely used in consumer products, like conformal coatings and sealed connectors, as well as solderless through-hole connectors (press-fit into plated holes) because they handle vibration much better.Will they try to shave off cost wherever possible? Of course, and why shouldn’t they? But they also know very well that they need to meet their reliability requirements at the end of the day.

author: Smokey
author_rank: Super Contributor
timestamp: August 25, 2023, 08:39:20 am
content: These guys claim common loctite for electrical connections is a really bad idea.https://www.emcstandards.co.uk/never-use-liquid-threadlockers-on-any-electricaI wonder what the consequences would be for a pre-torqued bolt that needed to conduct like 50A. I would image that the torqueing of the bolt while the loctite was uncured would make all the mechanical connection it was ever going to make, and it would be a lot.