Hi again...
I am faced with a decision to make...
We have a need to use a Codec on a design I'm doing and it comes in 2
'flavors' of packaging styles...
One is a MicroStar BGA package with a 5mm chip body and 0.5mm pitch ball
contacts in a 9X9 array....
The other is a 48 pin PQFP with 5.5mm body and 0.5mm pitch gull wing
contacts on 4 sides.
I think we have done the 0.5mm pitch gullwing devices here before. We were
using a Flash memory chip with that pitch... However the smallest pitch we
have done here with a BGA is 0.8mm.
Are there any issues that you have seen with the 0.5mm BGA that would make
you prefer the gull wing leads over it?
I know the via breakout on the 0.8mm pitch BGA was a little difficult and
required very small drilled vias to get the signals out... Will I be forced
to use laser drilled vias to use the 0.5mm pitch BGA?
Any advice is most welcome...
Thanks in advance...
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Brooks,Bill [mailto:[log in to unmask]]
Sent: Tuesday, January 04, 2005 9:35 AM
To: [log in to unmask]
Subject: Re: [DC] Assembly panels
VERY GOOD POINTS CHRIS! (and a nice way to deal with the vendor mistake
issues)
In our case, we have a depanelizing tool, or singulation tool as you would
say, (my spell checker 'hates' both of those words...) and it is important
that the clearance between tie points or web points or singulation points
be sufficient to allow the tool access to cut out the web. IF the board
manufacturer moves them to their preference they can make it near impossible
to use our equipment to de-panel the boards.
I have a 'web detail' on my drawings that specifies the structure of the web
it's tolerances and locations are clearly shown to avoid confusion... Our
old designs had nothing more than a note, "add 2 ties per side" or something
like that and a picture of the rough layout of the panel. Well we have had
one vendor make the panel one way, and on a separate order later from
another vendor they did it a different way, and then a third vendor would do
it their way... too much not specified... So we wrote an ECO to the drawing
and added the details to specify the exact locations and web details to
avoid variances from vendor to vendor and consistent tooling to avoid
additional costs of making new past screens and updating pick and place
programs etc... Fixed In-Circuit-Test fixtures would wreak havoc on us if we
had them on a board panel and had some well meaning board manufacturer shift
the board array pattern on us. I can imagine that some of us have never had
these problems, not all designers have the same criteria to design to, but
those who mass produce and are dealing with product configuration management
issues are really sensitive to these issues because they can cost so much
money when ignored.
Great conversation topic guys...
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Chris Ball [mailto:[log in to unmask]]
Sent: Tuesday, January 04, 2005 5:35 AM
To: [log in to unmask]
Subject: Re: [DC] Assembly panels
Hi Ted-
My $0.02:
If you located the singulation points to avoid stressing components when
separating the individual boards, and they have changed these locations,
you have a problem.
If ICT fixtures, solder paste screens, etc., have been tooled per your
original array drawing, you have a problem.
The fact that they made changes without communicating is a problem, but is
probably not insurmountable, if you are willing to change your
documentation and have their assurance that they won't do this sort of
thing again without you prior approval.
If you submit a complete drawing package with the job, they should submit a
request for change, which can be evaluated and complied with, or not, per
the merits of their request vs. your original intentions.
Happy New Year!
-Chris
P.S. The IPC guideline is just that; a guideline. Variance from it is no
problem if justified.
Ted Tontis
<[log in to unmask]> To:
[log in to unmask]
Sent by: DesignerCouncil cc:
<[log in to unmask]> Subject: [DC]
Assembly panels
12/29/2004 12:17 PM
Please respond to
"(Designers Council
Forum)"; Please respond to
Ted Tontis
The data package that I sent to our assembly house was in a three board
assembly panel. I used the IPC standard for choosing the size of the panel.
It was a panel 260mm x 180mm containing three boards. I talked to the
assembly house yesterday and was notified that the assembly panel size was
changed. There are still three boards in the panel, however the bare board
manufacture decreased the size of the assembly panel. First question I have
is per IPC-2221 5.2.2 Figure 5-1 I picked the correct size for the panel,
optimizing the manufacturing panel? The second question is that in my notes
"no changes where to be made to the board without first receiving written
permission of us." This now leaves me with a question mark over my head
what else was changed without me knowing it. Should I confront the Assembly
house for not following my notes? Have other designers faced similar
problems and what was your course of action?
Regards,
Ted Tontis CID
Engage Networks Inc.
1320 N. Dr. Martin Luther King Drive
River Level
Milwaukee, WI 53212
PH 414-918-4267
FX 414-273-7601
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