Bob,
When I say capped, I mean vias 20 mils or less that the PB substrate is cleaned and tested and SIR testing prior to a dry-film solder mask cap on both sides followed by SMOBC. The same testing is done pre and post HASL.
I have data, but the technet archives also is a good resource.
Dewey
-----Original Message-----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Friday, July 13, 2012 9:51 AM
To: 'TechNet E-Mail Forum'; Whittaker, Dewey (EHCOE)
Subject: RE: [TN] Through hole barrel voids
Dewey,
Do you know of any studies or white papers that cover this?
I have often wondered in capped vias are a good idea as caps can also
interfere with cleaning. But I have zero data to suggest one way or another.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: Friday, July 13, 2012 10:11 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
A via protection strategy (capped, plugged and capped, plugged and
plated-over) is a must to eliminate via failures.
Devoid of humor,
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Friday, July 13, 2012 9:00 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
Hi,
If there are voids with volatile material (probably a flux) how bad is
that? My guess is pretty bad if the vias could contain these voids. On a
board with a lot of vias there are now a lot of opportunity for such
failures. Through hole connector don't scare me as much given the through
hole pin.
Does anyone have any data to indicate that material trapped in via holes
does indeed result in failures? Do plugged via reduce via failures?
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Friday, July 13, 2012 9:41 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
Craig,
The fact that the voids are there wouldn't concern me as much as why...
Some of these pictures appear to show embedded volatile material and Cu in
the voiding areas...
If the PCA was going to go through extreme thermal cycling I might be
concerned about growth of shear cracks around the voiding areas
(j4pin3-4)...
But J4pin3-4 looks like you are over a reasonable voiding limit because of
the amount of unattached pin surface not in contact with the solder...
Paul
Paul Edwards
Process/Quality Engineering
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Craig Sullivan
Sent: Friday, July 13, 2012 5:53 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
Hi Everyone,
I am resurrecting this thread to add some section pictures.
They can be viewed here:
http://ipc-technet.groupsite.com/galleries/show/23706.
I agree some of the larger voids might be cause for concern, but they were
not soldered using a hot plate/pre-heater. Most of the pictures show an end
result of pre-heating the PCB on a hot plate to a top board temp of 100 °C
prior to soldering. Now my dilemma is, I have to convince the customer that
some voiding is normal and will intrinsically occur no matter what. They are
pushing back and requesting 0% voiding.
Any thoughts?
Craig
Subject:
Re: Through hole barrel voids
From:
Craig Sullivan <[log in to unmask]>
Reply-To:
TechNet E-Mail Forum <[log in to unmask]>, Craig Sullivan
<[log in to unmask]>
Date:
Wed, 16 May 2012 15:22:10 -0400
Content-Type:
text/plain
Parts/Attachments:
Parts/Attachments
text/plain (164 lines)
Reply
Reply
Thank you for all of the answers. The connector in question is a d-sub type
and only accessible with an iron from one side. I am waiting for section
results/pictures. As one colleague pointed out, the voids seem to
concentrate on the solder side of the board. Boards are baked and removed
from the oven one at a time as they are hand soldered. These do not see a
wave/selective cycle. I am in the process of setting up the hot plate to run
a few more tests. Surface finish is ImAg and the process is SnPb. The
connector leads are pre-tinned (SnPb) so sayeth the datasheet. As for the
answers regarding the poor barrel plating I am also sectioning these, but as
I mentioned before, initial solderability was fine.
Thank you again,
Craig Sullivan
Manufacturing Engineer
MPL Incorporated
P: 607.266.0480
F: 607.266.0482
[log in to unmask]
P Please consider the environment before printing this e-mail.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Bavaro
Sent: Wednesday, May 16, 2012 2:28 PM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
Let me state the obvious even though I did not see it mentioned.....it is
possible to double side hand solder and trap large voids in the barrel.....I
know because I have seen an engineer attempt this. In his mind, the solder
joints looked great and visually it was compliant.....but I advised him that
the procedure was not authorized and proceeded to xray the connection and
show him the error in his ways.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey
(EHCOE)
Sent: Wednesday, May 16, 2012 10:45 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
To reject, or not to reject, that is the question:
Whether 'tis Nobler in the mind to suffer The Slings and Arrows of
unfortunate outgassing, Or to take X-rays against a Sea of voids, And by
opposing accept them: to die, to pry No more; and say we end the heart-ache,
and the thousand thermal shocks That the assembly is heir to? 'Tis a
consummation Devoutly to be wished for those who don't have a bodkin against
their chest to honor the bottom line.
Barring the chance that I have missed the connection and this was a
metaphorical response to voids or unfulfilled expectations in life and not
the printed board assembly: all other things being equal; I would accept
them (the PTH voids) as-is.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eva J
Sent: Wednesday, May 16, 2012 9:37 AM
To: [log in to unmask]
Subject: Re: [TN] Through hole barrel voids
Craig,
Was this PCB/ connector subjected to wave solder, hand solder and or
intrusive pin/paste solder process?
I have seen touch up soldering to " fill the barrel" on the component side
create voids and contaminant entrapment which may be a reliability issue.
What is the cumulative fill? Solder fill provides the mechanical strength to
withstand its service environment.
Eva
Spec Tech
On Wed, May 16, 2012 at 9:12 AM, David D. Hillman <
[log in to unmask]> wrote:
> Hi Craig! One of the downsides of now having access to Xray inspection
> technology is that we can see many "things" we never could before -
> which now causes the question "is that bad?". There is currently no
> plated thru hole void criteria in the IPC JSTD 001 specification. I
> would recommend that an assessment of the assembly be initiated.
> Pulling and inspecting a number of assemblies that either have been in
> the field or have passed all of the qualification tests will
> demonstrate what level of voids typically exist and if that level of
> voiding is a reliability issue. The presence of voids is not
necessarily an indication of a reliability issue. Good Luck.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
> Craig Sullivan <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 05/16/2012 07:14 AM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to Craig
> Sullivan <[log in to unmask]>
>
>
> To
> <[log in to unmask]>
> cc
>
> Subject
> [TN] Through hole barrel voids
>
>
>
>
>
>
> Hi everyone,
>
>
>
> We have a certain board with several through hole connectors. The
> customer has provided us x ray images showing voiding in the barrels.
> Fillets on both sides are acceptable, and the solderability tests are
> ok. This seems to be isolated to this board because random sampling on
> other boards shows virtually no voiding. The only voiding "criteria" I
> can find is related to BGAs. Is there any published criteria /
> reference material for this type of defect?
>
>
>
> Thank you,
>
> Craig Sullivan
>
> Manufacturing Engineer
>
> MPL Incorporated
>
> P: 607.266.0480
>
> F: 607.266.0482
>
> <mailto:[log in to unmask]> [log in to unmask]
>
> P Please consider the environment before printing this e-mail.
>
>
>
>
>
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