The requirement is in J-STD-001 paragraph 9.2.5.  At Lockheed Martin Space,
we further interpret this picture to be 75% filled, counting solder
recession from the top and the bottom. (See illustration below).  In
addition, we do not allow for the unfilled options of Figure 9-2 F, except
in the case of vias, which are too small to fill.  For this instance, the
designer will choose a via protection design option.  These requirements
correspond with MIL-2000A, paragraph 5.3.2.3.

So if you have a via that you want it filled conductively, I would submit
that the pictures in Figure 9-2 would apply in this case.







-----Original Message-----
From: John Perry [mailto:[log in to unmask]]
Sent: Thursday, January 02, 2003 9:33 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Conductive Via Fill Requirements

Colleagues,

IPC has a task group (D-33D) charged with developing a set of requirements
for via protection (plug, fill, tent, etc) that will ultimately find a home
in the IPC-2221 and IPC-6012 documents.  At present, there is a strawman
document for this effort, available through the IPC Committee Home Page
located at http://members.ipc.org/commreg/default.asp

There is an industry request within the 6012 task group for conductive via
fill information, based on what now appears in 3.6.2.15 of the IPC-6012A
document.  Given that a D-33d Strawman draft does exist, is there any
additional information that can currently be provided to this question:

1. Are there any IPC specifications or specific Customer specifications that
define the requirements for conductive via fill? For example, Amount of
minimum fill, the surface flatness, etc.

Note: IPC 6012 paragraph 3.6.2.15 "Resin Fill of Blind and Buried Vias"
states that resin fill in buried via shall be at least 60% but there is no
mention of Conductive Fill requirements.


The D-33d Hole Protection Strawman can be downloaded through the
above-mentioned website.  Select the "D-30 Rigid Printed Board Committee"
and then use the "+" symbols to the left of each link to expand out to the
D-33 Subcommittee and then subsequently the D-33D task group.  From here you
will then be able to select "Drafts" on the right-hand side of the web page
and access the strawman document in .pdf format.

Regards,

John Perry
IPC