TECHNET Archives

1995

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Date:
Thu, 14 Sep 95 17:19:18 EST
Content-Type:
text/plain
Parts/Attachments:
text/plain (83 lines)
Help! I have a question concerning the use of anode baskets in place of 
anode bars. What are the advantages and disadvantages of using anode 
baskets? Which shape of basket is better, round or rectangular? Does any 
one out there have any technical data available?

You can reach me at Details Inc. (714)-630-4077 

Paul Walker
Sr. Process Eng.      


Paul:

    We've been using anode baskets for acid copper plating for over 10
    years here.
    Converting to anode baskets vs solid bars can result in a significant
    cost savings as a result of not having to send "useable" copper out to
    a reclaimer. The delta between the cost of new anodes and the salvage
    value of the "scrap" copper is this savings. This savings can often pay
    back the capital expenditure for the baskets in a reasonable (12-18
    months?) period.
    In my opinion, the round baskets offer more flexibility for anode
    location as well as anode area. I think it's easier to "fine tune"
    anode placement and anode area with the round vs the rectangular
    anodes.
    There are several "caveats" to be aware of when converting to baskets
    from bars.
    Be careful of the design of the baskets. I've found that they are
    available made from either expanded metal mesh or perforated metal. The
    expanded metal mesh baskets are often much lower cost than the
    perforated metal but are also more easily damaged unless they are well
    reinforced with solid titanium rings and vertical ribs.
    Be careful of the guage thickness of the titanium used. Lower cost
    baskets will have a thinner guage titanium. The strength and
    conductivity of the basket may suffer as a result. Compare different
    suppliers for this.
    Depending on how deep your tanks are and how long your baskets have to
    be, you may find a top-to-bottom plating thickness variation due to the
    lower conductivity of the titanium vs solid copper.  The design and
    thickness of the titanium impacts this also.
    One of the big problems with baskets is "bridging". As the copper
    anode chunks corrode, a "bridge" may form somewhere down in the basket
    which doesn't allow the fresher chunks on top to fall down in the
    basket. The anode material below the bridge corrodes away over time and
    a void results below the "bridge". Your anode area then changes and
    your plating distribution becomes a problem (potentially overplating an
    underplating within the same plating load.) People try to avoid this by
    shaking the baskets or poking them with a rod before topping them off
    with fresh anode material. The round "ball" anode material is an
    attempt to avoid this; however, it is common to pay a premium for the
    "balls" over the "chunks". We have also found that we can still get
    bridging with "balls".
    Another "problem" is how to "top off" the baskets with fresh material
    and when to do this. You want to "top off" the baskets often enough so
    that your anode area stays reasonably constant. The other problem
    depends on access to the baskets: i.e., whether you are dealing with a
    small "hand" tank or a wide automatic plating line. No matter how
    carefully the anodes are topped off, some material seems to find its
    way to the tank bottom. Over time, this accumulates and you find you
    need to empty your plating tank to remove it.
    I've also found that periodically it is worthwhile to remove the
    baskets, empty them, replace the anode bags and refill them with fresh
    anode material. Otherwise, you never know the condition of the bags,
    baskets, sludge build up, etc.

    Hope this helps. Contact me if you need any more information. Good luck
    with your decision.


                                   John Monaghan
                                   Chem. Eng. Mgr.
                                   Hadco Corp. - Derry Division

                                   [log in to unmask]



    The net of it all is that baskets can yield a cost savings but they
    still require some "maintenance" other than just "fill 'em and forget
    'em".



ATOM RSS1 RSS2