Oxidisation of Seagate & WDC PCBs
in [Storage]
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From: Arno on 14 Apr 2010 19:32 In comp.sys.ibm.pc.hardware.storage Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote: > Sergey Kubushyn wrote: >> In sci.electronics.repair Arno <me(a)privacy.net> wrote: [...] >>> Mine is fine on both sides. However there is a quite a bit of contact >>> area that looks and feels silver-plated to me, most notably areound >>> the screws and on the bottom the contacts to the head assembly. >> >> That makes me wonder why are they silver-plated. It is definitely not the >> best material longevitywise, especially for such low-level signals. It makes >> me even more suspicious and adds to the conspiracy theory. > You know of course that the black silver layer is still conductive > for low level signals?? Silver Silfide is a (bad) conductor? That will help for the R/W signal. However the lines for the moving coil go through the same connector and they need a low resistance path. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
From: Sergey Kubushyn on 14 Apr 2010 19:34 In sci.electronics.repair Arno <me(a)privacy.net> wrote: > In comp.sys.ibm.pc.hardware.storage Sergey Kubushyn <ksi(a)koi8.net> wrote: >> In sci.electronics.repair Arno <me(a)privacy.net> wrote: > [...] >>>> Those 4 were fine on the top of PCB. Black stuff was underneath, on those >>>> pads contacting with springy heads pins. >>> >>> Mine is fine on both sides. However there is a quite a bit of contact >>> area that looks and feels silver-plated to me, most notably areound >>> the screws and on the bottom the contacts to the head assembly. > >> That makes me wonder why are they silver-plated. It is definitely >> not the best material longevitywise, especially for such low-level >> signals. It makes me even more suspicious and adds to the conspiracy >> theory. > > Well, maybe. However I tend to think that "never attribute to > malice what can be adequately explained by stupidity" may apply. I agree but it looks like there is a pattern here... > These contacts should be gold plated with high quality gold. It is > also possible that the HDD vibration (always present with a running > HDD) and thermal variation allows the process to creep between the > contacts and kill them. Maybe a young, inexperienced engineer was > hired to replace an older, experienced (but more expensive one) > and that person made a pretty bad judgement call due to > inexperience, wanting to save a few cents on the design. They did not save anything on that design. Gold plating is a common procedure, it is everywhere, most of card-edge connectors (e.g. PCI) are gold and they even called "gold fingers" by chinese PCB manufacturers. Silver, on the other hand, is almost unheard of and I'm pretty sure PCB makers would charge extra for this if they agree to do it at all. And it is NOT that the entire board is silver-plated; there are gold-plated parts on that same board that makes it have at least 2 different platings so it will be more expensive than simple gold all over. > I have to say that the last time I saw silver plating as contact > protection was in vaccuum tube equipment. Modern electronics > typically uses Gold, or Tin for low insertion cycle contacts. Yep. Silver plating was usually used in microwave equipment, HF coils etc. where skin effect was so profound that current only ran through that silver (that was quite thick, btw.) Silver is also used for HIGH CURRENT relay contacts where the corrosion is removed by mechanical action of closing contacts and burned through with high current. If you look at low current signal relays with stated minimal current capacity _NONE_ of them have silver contacts. It is usually gold, platinum, rhodium, or a mix thereof. I am all pro Occam's Razor but all this looks like deliberate effort to make it fail after some time. It is NOT easier or cheaper to put silver there because it is an _ADDITIONAL_ step and not so common one. --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************
From: Sergey Kubushyn on 14 Apr 2010 19:36 In sci.electronics.repair Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote: > Sergey Kubushyn wrote: >> In sci.electronics.repair Arno <me(a)privacy.net> wrote: >>> In comp.sys.ibm.pc.hardware.storage Sergey Kubushyn <ksi(a)koi8.net> wrote: >>>> In sci.electronics.repair Arno <me(a)privacy.net> wrote: >>>>> In comp.sys.ibm.pc.hardware.storage Sergey Kubushyn <ksi(a)koi8.net> wrote: >>>>> [...] >>>>>>>> That suicide also can happen when some old file that was not accessed for >>>>>>>> ages is read. That attempt triggers the suicide chain. >>>>>>> Yes, that makes sense. However you should do surface scans on >>>>>>> RAIDed disks regularly, e.g. by long SMART selftests. This will >>>>>>> catch weak sectors early and other degradation as well. >>>>>> I know but I simply didn't think all 3 drives can fail... I thought I have >>>>>> enough redundancy because I put not 2 but 3 drives in that RAID1... And I >>>>>> did have something like a test with regular weekly full backup that reads >>>>>> all the files (not the entire disk media but at least all the files on it) >>>>>> and that was that backup that triggered disk suicide. >>>>>> Anyway lesson learned and I'm taking additional measures now. It was not a >>>>>> very good experience loosing some of my work... >>>>> Yes, I can imagine. I have my critical stuff also on a 3 way RAID1, >>>>> but with long SMART selftests every 2 weeks and 3 different drives, >>>>> two from WD and one from Samsung. One additional advantage of the >>>>> long SMART selftest is that with smartd you will get a warning >>>>> email on every failing test, i.e. one every two weeks. For additional >>>>> warning you can also run a daily short test, e.g.. >>>> No matter what you do you can not prevent an occasional disaster :( One >>>> MUST remember that "backup" in not a noun but a verb in imperative. >>> Indeed. >>> >>>>>> BTW, I took a look at brand new WDC WD5000YS-01MPB1 drives, right out of the >>>>>> sealed bags with silica gel and all 4 of those had their contacts already >>>>>> oxidized with a lot of black stuff. That makes me very suspicious that >>>>>> conspiracy theory might be not all that crazy--that oxidation seems to be >>>>>> pre-applied by the manufacturer. >>>>> Urgh. These bags are airtight. No way the problem happened on your >>>>> side then. My two weeks old WD5000AADS-00S9B0 looks fine on the top >>>>> of the PCB. I think I will have a look underneath later. >>>> Those 4 were fine on the top of PCB. Black stuff was underneath, on those >>>> pads contacting with springy heads pins. >>> Mine is fine on both sides. However there is a quite a bit of contact >>> area that looks and feels silver-plated to me, most notably areound >>> the screws and on the bottom the contacts to the head assembly. >> >> That makes me wonder why are they silver-plated. It is definitely not the >> best material longevitywise, especially for such low-level signals. It makes >> me even more suspicious and adds to the conspiracy theory. >> >> --- >> ****************************************************************** >> * KSI(a)home KOI8 Net < > The impossible we do immediately. * >> * Las Vegas NV, USA < > Miracles require 24-hour notice. * >> ****************************************************************** > > You know of course that the black silver layer is still conductive > for low level signals?? It is not. Look at low level signal relays with stated _MINIMAL_ current capacity and think why none of them has silver contacts. --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ******************************************************************
From: Sjouke Burry on 14 Apr 2010 19:48 Sergey Kubushyn wrote: > In sci.electronics.repair Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote: >> Sergey Kubushyn wrote: cut >>>> area that looks and feels silver-plated to me, most notably areound >>>> the screws and on the bottom the contacts to the head assembly. >>> That makes me wonder why are they silver-plated. It is definitely not the >>> best material longevitywise, especially for such low-level signals. It makes >>> me even more suspicious and adds to the conspiracy theory. >>> >>> --- >>> ****************************************************************** >>> * KSI(a)home KOI8 Net < > The impossible we do immediately. * >>> * Las Vegas NV, USA < > Miracles require 24-hour notice. * >>> ****************************************************************** >> You know of course that the black silver layer is still conductive >> for low level signals?? > > It is not. Look at low level signal relays with stated _MINIMAL_ current > capacity and think why none of them has silver contacts. I have done brain wave registration, eye movement detection and skin resistance measurement with silver-chloride electrodes, and they conducted nicely.
From: Sergey Kubushyn on 14 Apr 2010 20:00
In sci.electronics.repair Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote: > Sergey Kubushyn wrote: >> In sci.electronics.repair Sjouke Burry <burrynulnulfour(a)ppllaanneett.nnll> wrote: >>> Sergey Kubushyn wrote: > cut >>>>> area that looks and feels silver-plated to me, most notably areound >>>>> the screws and on the bottom the contacts to the head assembly. >>>> That makes me wonder why are they silver-plated. It is definitely not the >>>> best material longevitywise, especially for such low-level signals. It makes >>>> me even more suspicious and adds to the conspiracy theory. >>>> >>>> --- >>>> ****************************************************************** >>>> * KSI(a)home KOI8 Net < > The impossible we do immediately. * >>>> * Las Vegas NV, USA < > Miracles require 24-hour notice. * >>>> ****************************************************************** >>> You know of course that the black silver layer is still conductive >>> for low level signals?? >> >> It is not. Look at low level signal relays with stated _MINIMAL_ current >> capacity and think why none of them has silver contacts. > > I have done brain wave registration, eye movement detection and > skin resistance measurement with silver-chloride electrodes, > and they conducted nicely. That is totally different application. Yes, silver sulfide is not a perfect dielectric but it is not a good conductor either. And modern HDD heads are magnetoRESISTIVE. --- ****************************************************************** * KSI(a)home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * ****************************************************************** |