solderable SD card - Page 1
Forum section: electronics / projects

author: lincoln
author_rank: Regular Contributor
timestamp: April 01, 2016, 10:17:08 pm
content: Hello,I am building a box that will have an arm processor as its main micro controller. Well hardly a micro controller if you can boot linux.... any way, not the point.Well currently we are using SD cards as the non volatile storage which is great for development. Easy to image, convent to swap, huge sizes, ect. Fast access. For production this is a non starter. The board are going to get conformaly coated and have to stand up to shock and vibration.We can use serial connected flash but this limits out storage size. The code will have to go on a diet to fit. Probably not a bad thing over all but this will take time. There is also a matter of figuring out how to switching things over.In the interim do you know of a SD card compatible chip / module that can be reflow soldered? My search results have tuned up hacks to solder pins to a SD card rather than a properly made module.There has to be some thing in the embedded systems space to do this. I expect it isn't going to be cheap ether compared to commodity SD card. But with some sort of bom I can show how much "leaving things as- is" would really cost us vs transitioning to a serial flash.What do you think?Thanks

author: wraper
author_rank: Unknown
timestamp: April 01, 2016, 11:23:22 pm
content: eMMC

author: Nerull
author_rank: Frequent Contributor
timestamp: April 01, 2016, 11:23:51 pm
content: eMMC is SD compatible, in chip form factor.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 02, 2016, 03:29:32 am
content: Maybe you could consider soldering down the card?http://goughlui.com/2015/04/05/teardown-optimization-comsol-8gb-usb-flash-stick-au6989sn-gt-sdtnrcama-008g/

author: technix
author_rank: Super Contributor
timestamp: April 02, 2016, 04:33:48 am
content: Or you can just put a microSD card with a basic card holder inside your board and glue the card in place?

author: abyrvalg
author_rank: Frequent Contributor
timestamp: April 02, 2016, 10:09:50 am
content: Embedded SD:http://www.sandisk.com/Assets/Categories/OEM/SanDisk_iNAND_0108.pdfBut they are quite uncommon. eMMCs are much easier to get (they are used in all modern smartphones, excluding Apples), but they are NOT fully SD compatible. Although they have compatible electrical interface, low level protocol and full Linux support, there are differences in command set critical for early boot stage. You need to check does your CPU supports booting from MMC. Last but not least: both eSDs and eMMCs are in BGA 0.5 (somebody have got a "cool" idea to reserve pins for a builtin SDRAM, so a 14 pin eMMC device ended up in BGA-153 package).

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 02, 2016, 03:04:43 pm
content: Quote from: abyrvalg on April 02, 2016, 10:09:50 amThe latest standard is UFS, basically embedded SATA. I recall that Samsung started using it in the S6.

author: technix
author_rank: Super Contributor
timestamp: April 04, 2016, 09:12:58 am
content: Quote from: abyrvalg on April 02, 2016, 10:09:50 amApple used straight DDR NAND chips in A8 and older with NAND controller built into the main processor. For A9 they want with straight NVMe (and moved the camera and audio subsystem to PCIe since they already have a PCIe root complex, and the graphics subsystem to eDP)

author: Raj
author_rank: Frequent Contributor
timestamp: May 13, 2016, 07:25:54 am
content: how about soldering an micro sd to sd adaptor?

author: lincoln
author_rank: Regular Contributor
timestamp: May 14, 2016, 04:30:04 pm
content: Hello Raj,Thank you for the suggestion but this is a product so..... thats not going to work. The plan is to use a micro sd card in a holder with a zip tie for the first run and solve it in rev 2.

author: Raj
author_rank: Frequent Contributor
timestamp: May 14, 2016, 05:16:29 pm
content: glue it permanently....the apple inc. way

author: Smokey
author_rank: Super Contributor
timestamp: March 28, 2023, 12:45:43 am
content: Saw this today:https://www.adafruit.com/product/4899https://cdn-shop.adafruit.com/product-files/4899/2005251034_XTX-XTSD04GLGEAG_C558839%282%29.pdfLCSC only

author: Haenk
author_rank: Super Contributor
timestamp: March 28, 2023, 04:59:12 am
content: Most modern SD cards are monolithic, i.e. compact and sealed like a microSD card. You could easily crack the case open and extract the module, usually half the size of the case. Glue it down and directly solder it. No one will recognize it as a SD card...When sourcing, I'd suggest using A2 class.