Richard,
I concur with Brian. Have seen similar situations arise with high temp
co-fired ceramic packages (although greater gold thickness and higher
temps). Auger analysis indicated nickel on the surface of the gold. Had
the bake been performed in a good nitrogen environment (or stored in a
nitrogen glovebox), the nickel may have diffused to the surface, but ideally
not oxidized.
Could you have used a slightly more activated flux?
Steve
At 11:07 AM 6/21/00 +0300, you wrote:
>Richard
>
>As the gold is somewhat porous, I'd guess that the underlying Ni has
oxidised during 1
>week at 45 deg C (why????).
>
>Brian
>
>Richard Tilbrook wrote:
>
>> NEW MESSAGE:
>>
>> Hi folks,
>> Sorry, I wasn't feeling well yesterday and did not explan myself at all - the
>> reason I asked about baking is that we reflowed one side of a surface
mount board
>> (gold on nickel); we then stored it in a 45'C oven as we were expecting the
>> remaining parts to arrive for this very urgent job. They unexpectedly
took a week.
>> They even more unexpectedly didn't want to reflow properly when we tried
reflowing.
>> I suggested "passivation" as something for the person who brought me the
problem to
>> think about, though I must confess that being an industrial placement
student, I am
>> not best equiped to make that kind of judgement. As I try to follow many
of your TN
>> discussions, and occasionally add when I feel able, I was sure you'd be
able to
>> give better reasons as to the cause and suggestions for either prevention
or cure.
>>
>> Thanks and Regards,
>>
>> Richard Tilbrook
>>
>> PREVIOUS MESSAGE:
>>
>> Hi technetters,
>> I'm hoping to find out a bit more about the effect of baking (at 45 deg.
C) on
>> boards with gold on nickel.
>> I would be grateful for any info on the sibject, including times,
temperatures and
>> effects, such as passivation.
>>
>> Thanks,
>>
>> Richard TIlbrook
>>
>> ##############################################################
>> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>> ##############################################################
>> To subscribe/unsubscribe, send a message to [log in to unmask] with
following text in
>> the body:
>> To subscribe: SUBSCRIBE TECHNET <your full name>
>> To unsubscribe: SIGNOFF TECHNET
>> ##############################################################
>> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
>> information.
>> If you need assistance - contact Keach Sasamori at [log in to unmask] or
>> 847-509-9700 ext.5315
>> ##############################################################
>
>##############################################################
>TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>##############################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in
>the body:
>To subscribe: SUBSCRIBE TECHNET <your full name>
>To unsubscribe: SIGNOFF TECHNET
>##############################################################
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
>information.
>If you need assistance - contact Keach Sasamori at [log in to unmask] or
>847-509-9700 ext.5315
>##############################################################
>
>
##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe: SUBSCRIBE TECHNET <your full name>
To unsubscribe: SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################
|
