Also, check your incoming air pressure! If you don't have the right supply,
no matter how hot the nozzle temp settings, nothing will happen.
-----Original Message-----
From: Ryan Grant [mailto:[log in to unmask]]
Sent: Thursday, July 13, 2000 11:53 AM
To: [log in to unmask]
Subject: Re: [TN] BGA Reflow Problems
Jason,
Contact your Conceptronic rep for help with that machine. Although
we don't have one, we did bring one in on evaluation and it worked great.
Also, don't be fooled by the high air temperature used. Check to
see what the actual part temperature is. Even with an SRT where the nozzle
encloses the part, I have measured a 20 degree delta from the top of the
part to the bottom.
It is true that you do not have air flow underneath the component,
(even when it is set up properly). However, I doubt that there is any real
"air flow" under the component in the reflow oven. Air movement from under
the part likely follows the more powerful force of a pressure gradient
caused by the density difference of different air temperatures. This will
draw cool air out from under the component and replace it with the more
active hot air from around the side of the component. Unless the
Conceptronics can't get a curtain of air around the component (too small of
nozzle maybe?), the air flow under the part will likely be similar to the
SRT.
Thanks
Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]
> -----Original Message-----
> From: Jason Gregory [SMTP:[log in to unmask]]
> Sent: Wednesday, July 12, 2000 3:18 PM
> To: [log in to unmask]
> Subject: [TN] BGA Reflow Problems
>
> Hello technetters,
>
> I'm having a strange problem at my new digs. We have an outer-arrayed 256
> pin BGA going on a 6 layer FR-4 board. Everything is standard. The problem
> is the rework. We have a Conceptronic station and the nozzle we are using
> does not fully encapsulate the component. It always stays about 1/8" off
> the
> board. Therefore, I am not getting full underside airflow. The techs are
> using extremely high temperatures to get the component to reflow. I am
> wondering this: if I run a standard profile (using previous BGA reflow
> experience) and the part won't even begin to reflow, can I chalk it up to
> the airflow problem. I am guessing that the reason that using abnormally
> high temps is reflowing the part, then it's only happening by conduction
> through the part, not proper heat getting under it. Also, in this regard,
> if
> I'm only reflowing by conduction through the part, then what's happening
> to
> the integrity of the part? Please help.
>
> Jason Gregory
> ACT Manufacturing-Production Supervisor
> Corinth, MS.
> (662)287-3771 x470
> [log in to unmask]
>
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