Alex,
The spacing of BGA balls after reflow will vary significantly this will be
due to how the balls collapse and the co planarity of the BGA site. Another
words some joints may form columns if there are co planarity issues and on
the flip side some of the balls will collapse more than desired due to co
planarity. Minimum spacing is very difficult to gauge because of this.
Generally BGA's are not used in high voltage aplications (as far as I know)
so.... If the ball are not shorted together than you have done your job.
There should be no problems with different potentials jumping around Good
luck.
Best regards,
Shawn C. Murphy
Process Engineer
6640 185th Ave NE
Redmond, WA 98052-5038
[log in to unmask]
Tel: (425) 885-0107 Ext. 678
Fax: (425)867-5600
-----Original Message-----
From: Alex L Chan [mailto:[log in to unmask]]
Sent: Tuesday, April 17, 2001 5:32 AM
To: [log in to unmask]
Subject: Re: [TN] Minimum spacing between two BGA solder joints?
Hi Steve,
Sorry if I didn't present the question clearly. The question I am asking is
refer to the
spacing (gap) between two solder joints not the pitch of a BGA component.
For example, in a
1.27mm (50 mil) pitch BGA, a solder joint is roughly 35 mil after reflow,
that leave the
theoretical spacing between the solder joints become 15 mil. However for
some reason the
package that used may have balls that off the true position which may result
the two solder
joints come very close together after reflow.
What would be the minimum allowable spacing between the two joints?
Thanks,
Alex
"Stephen R. Gregory" wrote:
> Hi Alex!
>
> Do you really mean .005"? Sounds pretty 'friggen tight to me. Here's a
page
> that talks about ball pitch on uBga packages and chip scale packages:
>
> http://www.ednmag.com/ednmag/reg/1995/052595/11df1.htm
>
> No where are they getting that tight...I just want to say, I see you're
from
> Alcatel, so you're in the packaging business, have a heart on us assembly
> guys, you may design a package that works, but then leave it up to
> "floor-rats" like us to figure out how to put these things together. A BGA
> package that goes down to .005" spacing is asking too friggen' much!!! I
> don't think I'm alone in that observation....I could be wrong...(it hasn't
> been the first time)
>
> Geeze, you designers need to get down on the manufacturing floor...don't
mean
> that badly, just a necessary requirement before you push the limits...
>
> -Steve Gregory-
>
> << Hi,
>
> Do anyone have any literature referring to what is the minimum spacing
> between two BGA solder joints? From talking to many people, 0.005" seem
>
> to be the most commonly use number. Do people agree with this number?
> Why?
>
> Thanks,
> Alex >>
>
>
----------------------------------------------------------------------------
-----
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send the following message: SET
Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information, or 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 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET
Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or 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 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
