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Forum section: electronics / general

author: cleaningOut
author_rank: Contributor
timestamp: June 20, 2017, 03:50:47 pm
content: ...

author: ebclr
author_rank: Super Contributor
timestamp: June 20, 2017, 04:20:31 pm
content: He accept offers also

author: technix
author_rank: Super Contributor
timestamp: June 20, 2017, 04:29:08 pm
content: Seems so. Those are "leftover stock" carrying a 1309 date code, so it is likely that those chips are long past their expiry date and are forced to write off.If you have the right tools for the BGA you can buy some, bake them, and build a DIY experimental board from them. You will need at least some DRAM for it though.

author: technix
author_rank: Super Contributor
timestamp: June 20, 2017, 04:56:20 pm
content: Quote from: cleaningOut on June 20, 2017, 04:31:31 pmThe original company that bought those chips probably dumped them as they wrote them off as expired. Whoever received the dump decided to treat them as NOS and resell them.This is the same reason why there was a time when Xeon E5-2670 and E5-2680 processors was dirt cheap - Facebook and Amazon decommissioned datacenters worth of servers and dumped them to e-waste processors. The e-waste processors treated the processors and memory sticks that are standard products as perfectly resalable second hand and dumped them to the second hand market, causing the street price of the chips to plummet. I grabbed two of them at the cost of 1/3 of a single E5-2620v2 that was used in the same server.

author: andyturk
author_rank: Frequent Contributor
timestamp: June 20, 2017, 08:09:33 pm
content: How would you go about baking these?

author: KE5FX
author_rank: Super Contributor
timestamp: June 20, 2017, 09:54:32 pm
content: Quote from: cleaningOut on June 20, 2017, 09:35:05 pmMeh.

author: technix
author_rank: Super Contributor
timestamp: June 21, 2017, 05:43:36 am
content: Quote from: blueskull on June 21, 2017, 05:33:43 amIt can do 8-, 16-, 18- and 32-bit DDR3. (18-bit DDR3 is 16-bit DDR3 with ECC.)

author: eeviking
author_rank: Regular Contributor
timestamp: June 23, 2017, 02:07:01 pm
content: Hi guys. I am the ebay seller of the Zynqs.As technix have correctly guessed they are legit and were rescued from going to the dump due to expired shelf life.If you want me to change the description I will be happy to do that.They are MSL3 and should be baked before reflow. (The standard says 9h at 125C, 33h at 90C or 13days at 40C <5%RH)I will try to ship air tight with silica gel, but I do not have access to vacuum pack.If anyone have a simple open source board layout for them it would be nice ?

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: June 23, 2017, 02:51:23 pm
content: Quote from: technix on June 20, 2017, 04:56:20 pmExpired? How the hell do chips "expire"?

author: tszaboo
author_rank: Super Contributor
timestamp: June 23, 2017, 02:53:34 pm
content: How many do you have? If it is in the 100s it might be even worth to design something for it. Like couple it with DDR and some flash, route the rest to castellations. Selling that many otherwise might be hard.

author: technix
author_rank: Super Contributor
timestamp: June 23, 2017, 02:56:06 pm
content: Quote from: Sal Ammoniac on June 23, 2017, 02:51:23 pmUnsoldered chips have an expiry date after which the pins may become too oxidized to solder using normal thermal profile, flux and solder paste. Either the chips have to be reballed/reworked or new chips have to be bought. Most company would not bother hiring someone to rework the chips, so they write them off as expired and buy new chips.For us tinkerers the reballing is a price to pay for buying the chips on the cheap, but with an hour or two of our work we can make use of a super expensive chip without actually paying a lot of the money.

author: technix
author_rank: Super Contributor
timestamp: June 23, 2017, 02:58:57 pm
content: Quote from: NANDBlog on June 23, 2017, 02:53:34 pmI would definitely like to buy a few of that. Oh you also need to put the PMIC on the module too.Also you may want to provide an evaluation board for the castellated module so people can get one and start playing with it. For such modules the Raspberry Pi pinout may be a good idea.

author: NorthGuy
author_rank: Super Contributor
timestamp: June 23, 2017, 03:13:20 pm
content: Quote from: eeviking on June 23, 2017, 02:07:01 pmIt's about $500, if not more, to print a minimum amount of 6-layer ENIG boards with 4mil traces (5mil might be Ok though) and 8mil drills. This will kill all the savings from buying your chips.

author: technix
author_rank: Super Contributor
timestamp: June 23, 2017, 03:24:49 pm
content: Quote from: eeviking on June 23, 2017, 02:07:01 pmFor now store them in a dry hot room with bags of rice surrounding them. The rice grains are very hydrophilic and can pull the moisture out of the chips.Quote from: eeviking on June 23, 2017, 02:07:01 pmIs there anything else you have rescued from the dumpster? I do like to stock up some FPGA in QFP packages. (hand soldering does not mind the moisture level, and I can use some sand paper to quickly dispatch the corrosion.)

author: eeviking
author_rank: Regular Contributor
timestamp: June 23, 2017, 03:59:24 pm
content: Quote from: NANDBlog on June 23, 2017, 02:53:34 pmI only have about 50 left.

author: eeviking
author_rank: Regular Contributor
timestamp: June 23, 2017, 04:01:35 pm
content: Quote from: technix on June 23, 2017, 02:56:06 pmI don't think the solderability will be a problem, they have been stored at <5%RHThe expiration date is set to ensure 100% yield witch is important if you produce stuff like offshore electronics and you don't want to take any risks. For hobby/prototype use it's not a problem.They are stored in sealed bag with silica gel packs. I think they are better than rice

author: technix
author_rank: Super Contributor
timestamp: June 23, 2017, 04:02:48 pm
content: Quote from: eeviking on June 23, 2017, 04:01:35 pmIt is the oxygen in the air that killed the solderability, not the humidity.Big bags of rice would work much better than a small packet of silica gel.

author: eeviking
author_rank: Regular Contributor
timestamp: June 23, 2017, 04:09:20 pm
content: Quote from: technix on June 23, 2017, 04:02:48 pmYes, but high temperature and humidity will accelerate the oxidation.I use big bags

author: technix
author_rank: Super Contributor
timestamp: June 23, 2017, 04:57:55 pm
content: Quote from: eeviking on June 23, 2017, 04:09:20 pmEven in cool dry air the oxidation will ha;pen, albeit much slower. But those chips have been sitting on a shelf for more than 4 years...Have you rescued other chips from the dumpster?

author: KE5FX
author_rank: Super Contributor
timestamp: June 23, 2017, 06:36:51 pm
content: Quote from: technix on June 23, 2017, 04:57:55 pmThis kind of thing matters in ISO-compliant processes where procedures must be documented in detail and perfectly reproducible, where the difference between five-sigma quality and six-sigma matters. Or if you're sending hardware to the Kuiper Belt. For every other application, from prototyping to limited production runs, they'll be OK.

author: Koen
author_rank: Frequent Contributor
timestamp: June 23, 2017, 08:17:02 pm
content: AllPCB have a special on leaded HASL 6-layers at 70 USD for 10 boards of 100x100.

author: NorthGuy
author_rank: Super Contributor
timestamp: June 23, 2017, 09:22:04 pm
content: Quote from: Koen on June 23, 2017, 08:17:02 pmYou cannot really fan it out with 6mil wires and 12mil holes. They don't publish a separate "hole to copper" specs, but assuming it's the same as with annular ring: 12mil hole + 2*6mil annular ring + 2*6mil gaps + 6mil trace = 42mil, but the distance between ball centers is only 31 mil. So you only will be able to do the outer row of balls (perhaps the second row if you undersize ball pads). I don't think HASL would work neither.

author: eeviking
author_rank: Regular Contributor
timestamp: October 23, 2017, 12:07:02 am
content: Did anyone get boards made with these?Any problems with solderability?I still have some left I plan to dump for a good price in the buy/sell section.

author: asmi
author_rank: Super Contributor
timestamp: October 23, 2017, 03:21:07 pm
content: I've been thinking about designing a board for this SoC. Recently I found a fab that quoted me $234 for 10 6-layer boards with 0.1/0.1 mm traces and 0.2 mm drills and CI (and that price includes DHL delivery to my door), but I would like to see them deliver before I can formulate my opinion. If these parts would still be available at the time, I will definitely buy several - don't mind baking them at all.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: October 23, 2017, 05:19:07 pm
content: Quote from: KE5FX on June 23, 2017, 06:36:51 pmNowthatsounds like an interesting kickstarter campaign!

author: asmi
author_rank: Super Contributor
timestamp: November 06, 2017, 02:17:29 pm
content: Quote from: cleaningOut on November 06, 2017, 10:25:20 amIf you don't want to use smaller density ICs with 15 address lines (I personally would've chosen that option), you can tie unused address line high or low (it doesn't really matter either way), but don't let it float! Keep in mind that different density ICs have different refresh times, so make sure you specify correct parameters when setting up DDR3 controller.Also - I would love to see how you managed to breakout DDR3 lines using only 2 layers (as other two will need to be reference planes to maintain signal integrity). DDR3 traces NEED to have UNBROKEN reference plane along their entire length. This is even more so if you want to use DDR3L as it has even smaller margin than regular DDR3. Even with 0.1 mm traces and 0.2 mm drills process that would not be easy as Zynq is in 0.8mm pitch BGA package so you can't fit two traces between balls/vias.

author: asmi
author_rank: Super Contributor
timestamp: November 06, 2017, 04:20:38 pm
content: Quote from: cleaningOut on November 06, 2017, 04:04:43 pmMake sure your 1.5 V rail can provide enough current - DDR3 can have huge transient currents (in the order of few Amps!), and if you PMIC (or power source) isn't quite up to task, you could get hard-to-debug issues caused by 1V5 rail going places. Also Xilinx recommends using termination to Vtt, so you will need tracking regulator for that. Read Ch.5 of UG933 very carefully and do as they say. Unless you are willing to experiment (read - got money to burn on possible board respins) that is.Quote from: cleaningOut on November 06, 2017, 04:04:43 pmI doubt I can make it on the livestream (as my spare time is always sketchy), but would love to watch full-length recording at my own schedule. Don't mind 5+ hrs long YT videos at all.But like I said, I seriously doubt you would be able to make it work on 4 layers. It least I couldn't make even much simpler Artix-7 + DDR3L x8 work on 4 layers without violating DDR3 layout requirements.My first 6-layer boards are now on their way to me - looking forward to get my hands on them

author: ThomasDK
author_rank: Regular Contributor
timestamp: November 06, 2017, 09:12:35 pm
content: Quote from: cleaningOut on November 06, 2017, 10:25:20 amThe Zynq PS only supports 16 and 32 bit databus, so you need at least 16 bits.The address bus is behind the data lines, stretching all the way in to the 7th row(see attached)I doubt it can be fanned out in 4 layers, I would go for 6. This would also allow a 32 bit databus, doubling the memory bandwidth.Thomas

author: Someone
author_rank: Super Contributor
timestamp: November 06, 2017, 10:39:43 pm
content: Quote from: cleaningOut on November 06, 2017, 10:07:55 pmComponents of minimum x8, for a total bus width of 16 or 32 bits.

author: ThomasDK
author_rank: Regular Contributor
timestamp: November 06, 2017, 10:49:43 pm
content: Quote from: cleaningOut on November 06, 2017, 10:07:55 pmhttps://www.xilinx.com/support/documentation/sw_manuals/xilinx14_1/platform_studio/ps_r_gui_zynq_tab.htmQuote

author: eeviking
author_rank: Regular Contributor
timestamp: November 07, 2017, 04:08:24 pm
content: I also have a bunch of DDR3L MT41K128M16JT-125 IT:K FBGA's if anyone is interestedWill they work with the Zynq?

author: asmi
author_rank: Super Contributor
timestamp: November 07, 2017, 06:43:49 pm
content: Quote from: eeviking on November 07, 2017, 04:08:24 pmI've just ordered some of those exact modules from Arrow, as I couldn't find them anywhere else.I don't see any reason why they won't work with Zynq.