1. opps. SUSAN, you are correct. Take out the word "NOT". It should have
read
"Zone B extends 80um beyond the ends of each pad(internal or external). For
defect evaluation, the pad closet to the defective area would be
considered for the zone b boundary."
2. Also, my use of the word "zigzag" for the zone B boundary was
misleading. If you use a line 80 um from the end of each pad extending
vertically half way into the dielectric zone b becomes a "stair step or a
series of vertical lines" and does not have diagonal lines. I will try and
draw it below
The PAD end is last "*" Zone b "!"
****pad layer1******** !
!
!
****pad layer 2** !
!
!
!
!
**pad 3**** !
!
!
I hope that helps.
Mike
-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
Susan Mansilla
Sent: Friday, January 24, 2003 10:14 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Hi Mike and All
My line also zig zagged so your approach appeals to my mind set.
But I don't understand the following suggestion - second sentence after the
comma
"Zone B extends 80um beyond the ends of each pad(internal or external). For
defect evaluation, the pad closet to the defective area would not be
considered in the zone b boundary."
Will you clarify for me? Would not the pad closest to the defect be the one
that determines the point at which Zone B begins for this defect?
Thanks
Susan
-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
Mike Hill
Sent: Thursday, January 23, 2003 4:07 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Susan,
You seem to have stirred up some interest. Discussion is great. here is my
input:
1. Figure 3-5 in 6012 has the note " The thermal zone extends 80um beyond
each land." I have always interpreted laminate cracks and thermal zone from
the pads on either side or closest to the defect excluding any other pads in
the hole (external or internal). The picture in figure 3-5 draws this nice
straight line where zone B starts for a perfectly register hole but in my
world this line is a "zigzag" around each pad end.
2. Furthermore from Para 3.6.2.4 "Laminate Cracks": "Cracks which originate
in Zone A and extend into Zone b ..shall not be in excess of 80um..." In
the case of Susan's photo, the cracks starts in zone A and certainly does
not get to zone B if the external pad is considered. If on the other hand,
Zone B is defined from the adjacent pads it certainly may touch Zone b and
may indeed be over 80um in size, ergo defective.
Specification Suggestions:
1. I would modify note 1, figure 3-5 to read:
"Zone B extends 80um beyond the ends of each pad(internal or external). For
defect evaluation, the pad closet to the defective area would not be
considered in the zone b boundary."
Then change the pictorial in Figure 3-5 to depict the zone b for pads in
different degrees of misregistration. I'm sure the wording could be
improved and I hope you can see where I'm heading. Zone b would then be a
series of boundary lines that start 3 mils from the end of each pad and
extend vertically half way to the adjacent pad.
2. Any crack or laminate void from the hole wall or any where in Zone A
toward a ground plane clearance should be evaluated against minimum
dielectric requirements ((total distance from the two conductive surfaces
minus the crack size) versus the min dielectric).
Mike
-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
Susan Mansilla
Sent: Thursday, January 23, 2003 9:45 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Here is the photo that shows outer lands that are used to determine the Zone
B.
Please note that:
1) The outer lands are larger than the internal lands
2) The voids/cracks almost extend to the ground or power layers.
Thanks for all of you who are thinking about this. I realize that 95% of
the
product we build and evaluate do not have ANY laminate voids or cracks, but
we
need to have the specification clear and appropriate.
Susan
-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
[log in to unmask]
Sent: Wednesday, January 22, 2003 3:33 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Your point about the internal pad would appear reasonable. Send the
picture.
Jim Reed, WWSQE
Dell
Phone: (512) 723-5083
Fax: (512) 728-2790
Pager: (877) 342-0104
Email: [log in to unmask]
-----Original Message-----
From: Susan Mansilla [mailto:[log in to unmask]]
Sent: Wednesday, January 22, 2003 1:12 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
If that "pad edge" is an internal land, then I would agree - the outer lands
are larger than the internals and therefore
can impact that zone criteria much more than a misregistered internal land.
I have a photo that details what I am talking about - I could send it, if
you would like to see.
Susan
-----Original Message-----
From: IPC-600-6012 Mail Forum [mailto:[log in to unmask]]On Behalf Of
[log in to unmask]
Sent: Wednesday, January 22, 2003 10:53 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Susan, I have always used the outer boundary for the thermal zone as the pad
edge. I may have been in error, but it does seem to work well. However, it
will not insure that voids in and around GP or PP clearances will not
violate spacing requirements. Should be make a special case for these
anti-pads?
Jim Reed, WWSQE
Dell
Phone: (512) 723-5083
Fax: (512) 728-2790
Pager: (877) 342-0104
Email: [log in to unmask]
-----Original Message-----
From: Susan Mansilla [mailto:[log in to unmask]]
Sent: Wednesday, January 22, 2003 10:46 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Zone B Concept Clarification
Greetings to All
As those of you who have attended the recent meetings are aware - the Note 1
description of the Zone B (Thermal Zone)
is different in 600 and 6012. The committee is proposing to standardize on
the following:
1. The thermal zone extends 80 µm [3150 µin] beyond the end of the land
extending furthest into the laminate area.
NOW I have the following concerns and would like to have group input so that
perhaps in Tempe and in Long Beach we can
come to some resolution.
A. I do not think surface lands should be included in this determination.
B. If there is gross misregistration of one inner layer that would end up
with the Zone B starting beyond where a ground clearance starts, then that
inner layer should be disregarded.
C. If the laminate void or crack completely extends to where a ground
clearance begins such that the hole wall and
ground plane are for all intent and purpose connected by a void - this would
be considered non-compliant.
As you might have guessed I have been faced with trying to defend the fact
that all of the above would be a real threat
to long term performance and reliability.
So we really need to clarify this Zone concept -
Thanks for your input and help - hopefully we can finally have the documents
agree and be clear.
Susan Mansilla
Technical Director
Robisan Laboratory, Inc
6502 E 21st Street
Indianapolis, IN 46219
317-353-6249 phone
317-917-2379 fax
www.robisan.com
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