WD HDD PCB Oxidization / corrosion / discolorations you name it


#1

I buy about 4-5 WD harddisk a year and i noticed that weird Oxidization on harddisk PCB in recent years.

below is one on the example:

The copper is Oxidizing to Golden color, blue and gray-dish blue just on new unopened drive still in the plastic bag with silcia gel packet.

And for my new WD1001FALS-00E3A0 after i remove the Oxidization with a rubber and the Oxidization will come back in less then 2 weeks in gray-dish blue and lightly powdered that can be wipe with a dry tissue paper. (happened to ALL of my WD1001FALS and WD6400AAKS harddrives! i fear of mass HDD extinction!)

I have also posted the question in other forms with links to similar topic like tomshardware some time ago. but only get less response.

http://www.tomshardware.com/forum/246067-32-harddisk-discolorations-corrosion

and i see similair corrosion/discolorations on the paper below

Creep Corrosion on PCB

so my concern is, will this affect the reliability of the harddisk? (like the harddisk will die off in 2+ years due to PCB corrosion)

is there anything i can do to preventing the corrosion? (other then putting the slicia gel packs in the computer case.)

And some notes:

I have few 160~200 GB WD hdd running for 4.8 years recorded in SMART and they are still performing well but with some reallocated sectors due to bad motherboard chipset (i put a cooling fan on the old Nforce1 southbridge and later found out that it is affecting the south bridge with EMI and damaging the data). So far with my WD drive test for ALL of the WD harddisk i processes, only one uncorrectable sector was found and 1 old song file affected after running for 4.5 years recorded in SMART plus one dead 250GB drive due to heavy corroded PCB due to heavy humid and overheated environment after using 3+ years. and older 200GB and below harddisk i own does not have the PCB Oxidization problem on visual inspection.

oh yeah, i own 3 seagate drive and 3 of them already out after the second year even after i RMA  it and returned (lasts only 2 months after RMA).


#2

i come across some articke in wikipedia

http://en.wikipedia.org/wiki/Printed_circuit_board

Exposed conductor plating and coating

PCBs[1] are plated with Solder, Tin, or Gold over Nickel as a resist for etching (removal) away the (unneeded after plating) underlying copper.[2] Matte solder is usually fused to provide a better bonding surface or stripped to bare copper. Treatments, such as benzimidazolethiol, prevent surface oxidation of bare copper. The places to which components will be mounted are typically plated, because untreated bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was coated with solder by hot air solder levelling (HASL). This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU and US, which restricts the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3% tin, 0.7% copper, 0.05% nickel, and a nominal of 60ppm germanium.

It is important to use solder compatible with both the PCB and the parts used. An example is Ball Grid Array (BGA) using tin-lead solder balls for connections losing their balls on bare copper traces or using lead-free solder paste.

Other platings used are OSP (organic surface protectant), immersion silver (IAg), immersion tin, electroless nickel with immersion gold coating (ENIG), and direct gold (over nickel). Edge connectors, placed along one edge of some boards, are often nickel plated then gold plated. Another coating consideration is rapid diffusion of coating metal into Tin solder. Tin forms intermetallics such as Cu5Sn6 and Ag3Cu that dissolve into the Tin liquidus or solidus(@50C), stripping surface coating and/or leaving voids.

Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias.[3][4] Silver, zinc, and aluminum are known to grow whiskers under the influence of an electric field. Silver also grows conducting surface paths in the presence of halide and other ions, making it a poor choice for electronics use. Tin will grow “whiskers” due to tension in the plated surface. Tin-Lead or Solder plating also grows whiskers, only reduced by the percentage Tin replaced. Reflow to melt solder or tin plate to relieve surface stress lowers whisker incidence. Another coating issue is tin pest.

http://en.wikipedia.org/wiki/Tin_pest

Modern tin pest since adoption of RoHS

With the adoption of the Restriction of Hazardous Substances Directive (RoHS) regulations in Europe and California banning most uses of lead, and similar regulations elsewhere, the problem of tin pest has come back with some manufacturers using pure tin, who previously used tin/lead alloys. For example, the leads of some electrical and electronic components are plated with pure tin. In cold environments, this can change to α-modification grey tin, which is not electrically conductive, and fall off the leads. After heating back up, it changes back to β-modification white tin, which is electrically conductive, and can cause electrical short circuits and failure of equipment. Such problems can be intermittent as the powdered particles of tin move around. Tin pest can be avoided by alloying with small amounts of electropositive metals soluble in tin’s solid phase e.g. antimony or bismuth, which prevent the decomposition. Silver, indium, and lead have also been used, but lead is not soluble in tin’s solid phase.

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well, i don’t know how cold is cold but my room temp is above 25 and hdd temp is 40± in operation and 24/7 running.


#3

Today i removed one of my WD6400AAKS-00A7B2

smart report it has been run for about 12000 hours

I noticed some “black thing” grow on the pcb’s copper. (Picture attached, let me know if anyone can’t see it)

107iA2A85EE45D463E93

109i2C9D78F58B7C545F

and for my WD1001FALS which are new, i have not yet shut down the computer for maintenance yet. I hope it is not much worst then my WD6400AAKS-00A7B2 since it is just less then 2 months old.


#4

Thanks very much for your research.

It seems that RoHS will be responsible for a lot of reliability issues. It’s no wonder that miltary, medical, and aerospace applications are exempt. That’s ironic when you think about it, ie using unsafe materials in equipment where safety is paramount.

In future you will see problems with corrosion, tin whiskers, and cold solder joints.

Here are two more discussions on related subjects:

Oxidisation of Seagate & WDC PCBs:
http://groups.google.com/group/sci.electronics.repair/browse_thread/thread/2242c6be34042a28/12a896fd389028d4#12a896fd389028d4

Today’s Lead Free Cr*p Solder Stories …
http://groups.google.com/group/sci.electronics.repair/browse_thread/thread/161210aa2275c858/a1e69decdbe741b1#a1e69decdbe741b1


#5

I manage a lot of HDs per week, that “problem” is not only for WD drives.

Also Seagate has same oxidation on the exposed copper parts.

I think it will never effect the performaces…