micro SD card holder in vibration environment (bistable push in/in type)  - Page 1
Forum section: electronics / projects

author: glenenglish
author_rank: Frequent Contributor
timestamp: August 07, 2024, 12:30:19 am
content: Does anyone have any real experience with microSD card holders in an automotive environment, bolted to the chassis.The type of card holder that has a spring-loaded bistable behaviour IE push in (holds). Push in again (ejects)Not the slide in, friction holding type.Does the hold-in system prevent the card moving (and thus not wearing the contacts)?thanksglen.

author: thm_w
author_rank: Super Contributor
timestamp: August 07, 2024, 12:41:46 am
content: It locks the card with spring force but does not completely immobilize it due to tolerances. Though I would think the weight of the card is low enough its not going to be shaking around wearing down the contacts.- If it doesn't have to be removed: silicone glue in place.- If it does have to be removed: can place a screw in block or cover behind it, to prevent it from ever coming out.Maybe relevant:https://service.tesla.com/docs/ModelS/ServiceManual/en-us/GUID-FEBA625B-4D8E-4328-A4F3-614E753AB444.html

author: darkspr1te
author_rank: Frequent Contributor
timestamp: August 07, 2024, 08:00:11 am
content: There is a type of sdcard holder that works the same way as sim holders do, you place the card contacts down then clamp a frame over that. might be what you looking for, they are used often in head-units and car systems.darkspr1te

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 07, 2024, 08:28:26 am
content: We have a device with a small PC104 board and this type of SD slot, cards kept failing until we placed a blob of hard a silicone we use to fix large capacitors in place, covering part of the slot so it sticks to the SD card thought the holes, and in the back, gluing the protuding part to the pcb.Will remove easily with an exacto knife.Soft RTV meant for sealing was too soft, cards kept failing, you need something hard.

author: glenenglish
author_rank: Frequent Contributor
timestamp: August 07, 2024, 08:35:52 am
content: good point. I'll probably need to stick to side entry though. hmm maybe it'll work.a few optionspush and push, push pin , with and without card present detection switch.https://www.we-online.com/en/components/products/CRD_SD_MICRO_PUSH_AND_PULL_8_PINShinge:https://www.we-online.com/en/components/products/CRD_SD_MICRO_HINGEL_8_PINShinge clamp looks good, but maybe more likely for people to damage.dunno.

author: wraper
author_rank: Unknown
timestamp: August 07, 2024, 09:42:34 am
content: I'd rather suggest non latching type as they're tighter fit and much more robust IME, and fixing the card in place with a few specks of some compound if it will be permanent.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 07, 2024, 10:04:21 am
content: I'd use something that's not easy to remove, but not permanent either, SD cards can wear out and fail.I tried a 2mm blob of epoxy in a corner with burned board & card, not good, it tore apart the resist layer of both pcb and card when removing it.Better a hard, rubbery compount you can easily cut.If this is meant to be definitive (Unless maybe a mainteinance routine), then why the fear of breaking it, when people is not supposed to access it?I like hinge slots quite a bit, to me they're actually more robust unless you break it when handling, easy to replace when broken...The latching type can fail more easily, they're more prone to have issues with dirt / flux / contamination, and I found out that lots of these don't actually hold the card, you can simply pull the card out with tweezers.This was the problem we had with these PC104 boards, the slots were still "clicked in" but the cards were falling off.You could solder the card directly into the board, though not funny if needing replacing:https://hackaday.com/2015/08/18/reflow-solder-your-micro-sd-to-ensure-it-doesnt-go-anywhere/I'd put a small pad nearby and solder the hinge to lock it in place.Make the pad part of ground plane (Solid) or it will lift easily, small so it holds just enough solder to lock the hinge in place (About 2-3mm / 80-120th seems reasonable), and make sure it doesn't go under the SD slot or it will be hard to clean.

author: glenenglish
author_rank: Frequent Contributor
timestamp: August 07, 2024, 08:17:45 pm
content: Thanks all for the comments