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RoHS type alternatives

  1. Aug 19, 2008 #1
    Restriction of Hazardous Substances Directive...

    As most of you know, there is a list of restricted hazards which are to be avoided when possible during manufacturing, designing, etc...

    The list for the ROHS via a recent search through wikipedia.org list the following:
    1. Lead
    2. Mercury
    3. Cadmium
    4. Hexavalent chromium (Cr6+)
    5. Polybrominated biphenyls (PBB)
    6. Polybrominated diphenyl ether (PBDE)

    What alternative substances and processes exist which help during the design / manufacturing phase for electronic components? Purchase Orders are starting to impose restrictions stating that RoHS substances may not be used. One problem with that is there may not be a suitable alternative to keep the physical integrity of the part from diminishing due to using a sub-standard alternative.

    If anyone has any experiences that they would be willing to share, I am sure many of us could benefit. I am getting ready to enter into this problem, and will report any failures / successes that I come across.

    Best to all....
     
  2. jcsd
  3. Aug 20, 2008 #2

    berkeman

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    We went through this at my company over the past couple of years. In general, the RoHS parts require higher temperature soldering processes (less/no lead), and that is the biggest re-qualification issue. If folks have specific questions, post them here, and we'll try to help out in answering them.
     
  4. Aug 20, 2008 #3
    Within the coming months, I am definitely going to have some questions. Is there an issue with allowing a thread to go on for a while without any replies, then post a reply a couple weeks or a month later?

    I was reading a thread where someone pointed out that old threads should not be reinitialized.

    thanks,
     
  5. Aug 20, 2008 #4

    berkeman

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    No worries. That's why I stickied it. I'll try to find a good reference or two, and post the links for general info as well.
     
  6. Aug 22, 2008 #5

    MATLABdude

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    Does anybody have any good suggestions / experience with brands and/or compositions of lead-free (reduced?) solder for manual soldering? I did some stuff with silver solder years and years ago which I found nearly impossible to work with, and I remember popping a number of pads on the (home etched) PCB I was using at the time. I was just starting out at the time, so I imagine that probably had a hand in things, as well.
     
  7. Aug 22, 2008 #6

    berkeman

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    No suggestions on brands, but I'd stongly suggest investing in a Metcal soldering iron. They're a bit more expensive than the traditional Curie point temp-control soldering irons, but they are amazing at how well they control the tip temperature, and how they handle such a wide range of soldering (fine SMT all the way up to big lugs and things). They use RF heating of the tips.

    http://www.okinternational.com/
     
  8. Oct 23, 2008 #7
    Falling in line with the RoHS topic, when you do in fact have an item, say solder, and you need to get a lab to do the inspection to find out what the composition of the solder is, who do you use?

    Going through one of those wonderful quality audits and it has been mentioned that we need a third party inspection of our solder to match the spec sheets the vendor provides. Any suggestions, and any guesses on how much that costs.
     
  9. Oct 23, 2008 #8

    berkeman

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    I ran this by our RoHS specialist, and here is his response:

     
  10. Oct 23, 2008 #9
    you may want to add beryllium to your list. the oxide is used as a thermal conductor sometimes and is extremely toxic.
     
  11. Oct 24, 2008 #10

    berkeman

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    Sorry, I didn't understand your post. Do you mean that the RoHS initiative has added beryllium to their list and we should be aware of it, or do you mean it's something that we should think about independently of the RoHS initiative? I honestly am not that up on it all myself, and use our in-house expert for this stuff.
     
  12. Oct 24, 2008 #11
    i'm not familiar with RoHS, just mentioning another hazard some may run into. probably rare and only seen by defense applications and such. sorry if this goes outside the scope of this thread.
     
  13. Nov 7, 2008 #12
    Something that I realized a little while ago, but forgot to post, is that some contracts have a specific requirement RoHS components are not to be used. The reasoning for this is the TIN whiskers which can form on the leads of components causing them to break.

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

    Certain jobs allow you to be exempt from the RoHS stuff, so beware of that. A real pain in the butt is that some vendors have switched to RoHS compliant parts, but don't tell everyone that they have, kept the same part numbers.....so an inventory nightmare potential.....
     
  14. Nov 11, 2008 #13
    What is your industry, customer type, and customer location? There are exemptions that you may be entitled to follow if you use BGA packages, press-fit connectors, or other devices where lead is still required for proper assembly and long term reliability.

    You will still face supply chain issues as vendors change to tin-only interfaces with the same part numbers. For the critical parts many have chosen to change their part number because they understand the danger of mixed stock.
     
  15. Nov 27, 2008 #14
    I noted that you specifically mentioned "electronic components" rather than assemblies - in light of that, almost all electronic component manufacturers have been offering RoHS compliant parts for some years now; some haven't changed manufacturing part numbers - can be a nightmare in this respect. There is a general consensus that they don't last as long as traditionally made lead-based components, but it also depends on your application. Medical devices and military applications are exempt (category 8 and 9) - there are more, but hey. The directive mainly concerns itself with the broad umbrella of consumer products.

    If you meant electronic assemblies, we have had excellent results using SAC 305 (96.5 Sn/3.0 Ag/0.5 Cu). It takes some getting used to, but reliability is good as long as the process of heating, soldering and cleaning is followed.

    Hope that helps somewhat.
     
  16. May 7, 2009 #15
    Re: RoHS type alternatives...Tin Whiskers

    I've been working very closely with Microsoft and Motorola and since the advent of ROHS more manufacturers are going back to the use of tin. Tin in leaded solder does not pose a problem, but whith the deletion of lead we were seeing some odd things happening, namely Tin whiskers . We were surprised to find how fast these crystalline structures grew and obviously it posses a serious threat, for thay are conductive. We have even reported crystalline growth in lead free solder, needless to say about a recall we had with hard drives that had tin in the outer covers that when the structures grew on the inside of the drive, well need i say more! The problem has been serious enough that NASA had to pull all 52 of the flight computers out of the shuttle because of this, some whiskers were up to 18mm long! So sometimes the cure is worse then the illness. http://nepp.nasa.gov/whisker/
     
    Last edited: May 7, 2009
  17. May 27, 2009 #16

    berkeman

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    I haven't been able to get an update from my RoHS PE (we're both hammered at work, sorry), so I'll unstick this thread until there is new info.
     
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