Thank you all very much... I appreciate your input - it's good to know there is a source for good information out here.
-----Original Message-----
From: Joe Russeau [mailto:[log in to unmask]]
Sent: Wednesday, August 10, 2005 10:53 AM
To: TechNet E-Mail Forum; Schaefer, Chris
Subject: Re: [TN] PCB Storage
Hi Chris,
You have a number of issues that need to be addressed. I'm not sure,
especially if your company is unwilling to do anything about them, that any
resolution will come from this group, but I will kick in my few cents. Take
it for what it is worth.
The issues that you are having with your board vendor are not uncommon. I
have worked with numerous companies that have had issues with board
suppliers. They like to cut corners to save money. If your board supplier
is not willing to meet the standards set forth by your company, then maybe
it is time to find a new supplier. This is of course assuming that you have
made an effort to enforce your standards. Using desperation as a
justification for continuing to accept inferior quality ( as defined by your
standards) is a poor excuse, especially from a Class III manufacturer. What
do you folks manufacture again? I would suggest (if you have not already
done so) entering into some discussion with your board supplier. If you
have done that and nothing has changed, then find someone who is willing to
make, test and package the boards as you require. As a manufacturer, I
would not take the chance of producing poor quality Class III product. As a
consumer, well... that is a different soap box.
As far as storage is concerned, their have been many good comments since
yesterday about storing PCB's. However, the impression you leave is that
your company doesn't regard this as an important issue. Mind sets will need
to change if you expect to address the issues you are having. Baking the
boards is band-aid over a gapping wound. With the type of humidity you have
in your area (50-85%) and an uncontrolled environment, then you are going to
oxidize metal, period. Baking the boards may drive off moisture, but will
not change oxidation. Baking can make oxidation worse.
Removing oxidation form the boards can be done with saponifier depending on
the thickness of the oxidation layer. It may be that a more concentrated
solution of saponifier is needed. Since you are using Kyzen material, I
would recommend talking with them before making such a change. You may have
oxidized to the point that no saponifier is not going to be effective.
Best of luck!
Joe Russeau
Precision Analytical Laboratory, Inc.
----- Original Message -----
From: "Schaefer, Chris" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 10, 2005 8:51 AM
Subject: Re: [TN] PCB Storage
> Hello All,
> Hope you are all having just a wonderful day in the land of Milk and
Honey!
>
> HELP PLEASE...
> We are currently in a situation in which we have little to no control of
the humidity or temperature within our facility, and probably never will. We
also do not have complete compliance to our procedures from the board
vendors - so we do not receive the boards as we would like them (MBBag,
appropriate desiccant and volume of desiccant, HICard, solderability test
results, and ionic or other cleanliness test results from each lot/ date
code set). This will not change in the near future either due to the fact
that we need the boards so desperately we accept almost anything. Internally
we have little if any discipline when storing/ handling the boards so we are
constantly baking boards and performing solderability tests (especially
during the summer months). We try to keep all board packaged in an MBB with
HICard with a maximum of 20 boards per bag (zip-lock), but still have
humidity failures (We are in Kansas - currently 50-85%RH depending on the
day). How should this be done properly? Most of the boards are Class 3
products and we are required to use 2% no-clean flux with most product, so
it is difficult to solder anyways.
>
> My first question is: Can you clean the tin/ lead HASL plating with a type
of chemical to remove oxides so that we do not have to send the boards back
to the vendor for cleaning or re-plating? If so what is the chemical? We
have tried using A4512P (Kyzen product), but this does not work well. I have
been told to get something with MEK in the mixture, but I don't know for
sure.
>
> My second question is: When I have Gold Immersion plated boards and they
are found in the packaging to have a failed HICard, how do you remove the
moisture in the board? I have read that baking this type of plating actually
reduces the solderability of the board. Is this true?
>
> Please HELP...
>
> I appreciate any support I can get. Thank You.
>
> Chris Schaefer
> Suntron Corporation
> Process Engineer
> 540 N. Rogers Road
> Olathe, Kansas 66062
> 913.393.5878
> [log in to unmask]
>
> NOTICE:
>
> This message is intended for the use of the individual entity to which it
is addressed and may contain information that is privileged, confidential
and exempt from disclosure under applicable law. If the reader of this
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>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Joe Russeau
> Sent: Tuesday, August 09, 2005 3:14 PM
> To: [log in to unmask]
> Subject: Re: [TN] PCB Storage
>
>
> Hi Paul,
>
> This is one of those "It Depends" questions.
>
> Most of the studies I have read with respect to storage of tin-lead HASL
> boards suggests a shelf life of up to twelve months. I have not seen any
> studies for boards with that surface finish being stored for that extended
> period of time (2 years). In my opinion, the ideal situation would be to
> purchase the boards as you need them and eliminate the issues surrounding
> extended storage. But since you already have the boards that is not an
> option.
>
> My 2 cents are to make sure that if you plan on storing them, that you
> package for the long term (2 years) and not for the short term (6mos). I
> would suggest vacuum packaging them in a clean, moisture and debris
> resistant container (e.g. Kapak heat-sealable bag). Depending on how many
> boards you have to store and their dimensions, it may be advisable to
store
> them in a dessicated environment after vacuum sealing them. Controlling
the
> humidity is going to be key to reducing the oxidation rate. Unless you use
a
> nitrogen blanket to store the boards, you will not eliminate oxidation,
but
> by controlling the humidity, you should be able to slow the process a bit.
>
> It is hard to say what will happen after long term storage, but I would
> suggest checking a few boards (provided you have extra) for solderability.
> If the boards solder as you expect, then you may be safe to continue to
> assembly. If you have problems, you may want to consider a mild saponified
> wash to remove any oxidation or debris that has accumulated from storage
and
> repeat the solderability. Best of luck!
>
> Joe Russeau
> Process Analyst
>
> Precision Analytical Laboratory, Inc.
> 4106 Cartwright Dr. Ste. A
> Kokomo, IN 46902
>
> P: 765-455-1993
> F: 765-455-1996
> E: [log in to unmask]
> ----- Original Message -----
> From: "Black, Paul" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, August 09, 2005 2:31 PM
> Subject: [TN] PCB Storage
>
>
> > Hi All,
> >
> > I have some bare PC boards that may be built up in the future, but not
in
> the near future. I would like to put them into storage until needed
> (anywhere from 6 months to 2 years). The boards are .062" FR-4 HASL
boards.
> What would you recommend for protection, assuming that the storage
> conditions are typical of an office environment? Would I have to do
anything
> special to them when they are removed from storage? Any suggestions would
be
> greatly appreciated.
> >
> > Thank you,
> > Paul Black
> > Manufacturing Engineer
> > Kronos
> > E-mail: [log in to unmask]
> >
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