Actually most aluminium corrosion on IC die is due to excessive phosphorus
in the glass passivation/getter layer that protects surface metallization
from damage. Chlorine has a nasty habit of being mobile and causing
threshold voltage shift on individual transistors on the chip typically
causing long term reliability problems. All very ugly.
John Maxwell
At 01:05 PM 1/18/02 -0500, you wrote:
>Genny, FYI, Mostek (if anyone remembers them) years ago had a problem that
>arose from marking bad dice on wafers with a red marker. The ink contained
>chlorine, some of which migrated to good dice, leading to corrosion of the
>aluminium metallization while in operation. Lou Hart
>
>-----Original Message-----
>From: Genny Gibbard [SMTP:[log in to unmask]]
>Sent: Friday, January 18, 2002 12:39 PM
>To: [log in to unmask]
>Subject: [TN] Silver component contamination
>
>Happy Friday! (tappity, tappity - doing the Friday dance)
>We have ceramic resonators with silver coating on several products. We
>started handling those OEM boards with gloves during our test processes
>because the customer expressed concern with skin oil contamination.
>At times these components have been marked in house, for various reasons,
>with a standard sharpie marker. In fact, at an early point in the
>production schedule, the CM we were using at the time was marking them on
>their own, because the resonators are so close in size they were having
>trouble telling them apart and getting them installed in the right
>locations
>(due to tight time requirements, we got a shipment of bulk parts that were
>being placed by hand). The marks looked like they were marker applied and
>used a variety of dot and line patterns in various colours. We have never
>noticed any harmful effect on their response, although build quantities
>were
>low.
>Now someone on our production floor is asking whether the ink may be a
>contamination that we should avoid. We have easily cleaned this marker off
>of other surfaces with board wash. They wanted to know if they should
>clean
>the components with board wash. I think that if the marker is already on
>there and a contaminant, don't compound it by rubbing board wash on it.
> >From what I can tell, from the MSDS on the marker website, the ink is
>primarily propanol/butanol/alcohol based. The board wash is alcohol based.
>Chemistry is my weak subject. Is alcohol - related substances on silver
>coated components a concern?
>
>Genny Gibbard (mailto:[log in to unmask])
>Product Transition and Support
>Wavecom Electronics Inc.
>202 Cardinal Crescent
>Saskatoon, SK, Canada
>ph: (306) 955-7075 ext. 229
>fax: (306)384-0086
>
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