John:
We routinely use 27X27, 37.5X37.5 and 41x41 BGA's. We use solder paste,
no glue, in the process without problems, and the BGA's are machine
placed. When profiling, we had to drill a small hole in the center of
the BGA pattern on the board and attached a thermocouple by coming in
from the backside of the board. The balls count from 352 up to 600+ in
this manner. By the way, all BGA's have, by definition, balls (BGA=Ball
Grid Array).
> Bill Davis, Ph.D.
> Diamond Multimedia Systems
> Senior Scientist
> Tel. 408.325.7868
> Cell. 408.888.5650
> e-mail: [log in to unmask]
>
>
-----Original Message-----
From: John Chandler [mailto:[log in to unmask]]
Sent: Wednesday, January 13, 1999 6:50 AM
To: [log in to unmask]
Subject: [TN] BGA and profiling
We are getting into doing BGA's. Just a 27 by 27 overall dimension
component, with pitch of 1.27 with 20 rows & columns, with balls. Not a
complex part by any means. Our IC placement machine picks up, recognizes
and places great. Been told that since the part is spec'ed out to be
with
balls, that it is either a hand place deal with a special machine or use
glue dots on the masking of the PCB, to hold the component in place
during
reflow. No solder paste using a screen printer required.
My questions are does anyone use solder paste and a screen to place
BGA's
with or without balls? Where should the thermocouples be placed to get
the proper reflow profile?
Thanks in advanced.
John Chandler
ITRON
2818 N. Sullivan Road
P.O. Box 15288
Spokane, WA 99215
[log in to unmask]
Voice (509) 891-3343
Fax (509) 891-3355
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