You mean at half an atmosphere. No one has invented a gravity machine yet - that I know of. :)
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stadem, Richard
Sent: August 30, 2005 9:27 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking &
Solderability
I do not know the answer to that, but it sounds like a good idea. I do
know that back in the 70's a major military OEM used to regularly bake
pwb's at 150 F (note F, not C) at a 1/2 gravity vacuum, and they claimed
the moisture was not removed if they did not have the 1/2 gravity
vacuum.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Creswick, Steven
Sent: Tuesday, August 30, 2005 8:24 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking &
Solderability
Richard,
Is it an approved/acceptable process to place the PWB's into a vacuum
chamber at room temp?
I would not hazard a guess as to how great of a vacuum for what
duration, however. Just curious if it is done in the surface mount
industry.
Nothing gets any more simple than a dessicantor box though!
Steve Creswick - Gentex Corp
-----Original Message-----
From: Stadem, Richard [mailto:[log in to unmask]]
Sent: Tuesday, August 30, 2005 9:05 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG/ Immersion Gold Plating and Pre-baking &
Solderability
Baking of ENIG plated boards may be a requirement in order to drive out
moisture even though it can exacerbate a nickel oxide formation that is
already started. But there are other options for moisture removal,
including lower bake temperatures at longer times. You could even lease
a precision scale and see at what length of time is required for simply
putting the PWB into a drybox (a dessicator box such as McDry, not a
nitrogen box) and allowing it to dry at room temperature for a period
long enough to reduce the moisture content by 90% or more. J-STD-030
does state that the bake times and temperatures they list for components
and pwbs are guidelines. If you can prove your bake process or
dessication process is removing the moisture, then you are qualifying a
lower temp and longer time. You will need to use a number of pwbs in
order to do this, as there is some variation in weights caused by resin
content, etc. But you should be able to show a reduction in the average
of weights (mean weight).
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Schaefer
Sent: Friday, August 26, 2005 10:10 AM
To: [log in to unmask]
Subject: [TN] ENIG/ Immersion Gold Plating and Pre-baking &
Solderability
Does baking these types of plating affect solderability? If so what
factors play a part (i.e. baking temperature, plating thickness, baking
time, etc...). I know that if baked it can cause the Nickel Oxide layer
to become less solderable if the plating process is Poor (thanks Richard
S.). Is there is a factual study that proves that baking any type of
gold plated boards in any way shape or form reduces the solderability
and/ or reliablity of the joints/ product? I am trying to gather data to
prove to management that baking is a bad decision with this type of
plating and should never be performed. Also if a Gold Plated board of
any type is suspect for high level moisture content - how do you remove
the moisture "IF" baking is not acceptable?
Chris Schaefer
Suntron Corporation
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