TECHNET Archives

November 2001

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Houston, Terri" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 9 Nov 2001 14:46:05 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (69 lines)
Warren, some board shops are able to fill the vias with a conductive paste
and then plate over the top.
This avoids the problem of a partially plugged via while giving you a
surface to probe.
The BGA side could use soldermask to cover the plugged via.

Good luck,
Terri

> ----------
> From:         [log in to unmask][SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.
> Sent:         Friday, November 09, 2001 3:23 PM
> To:   [log in to unmask]
> Subject:      [TN] BGA Via's to tent or cover or not?
>
> I have seen different ways to address masking small vias (<13mils) under
> BGA.
>    cover them with mask prior to HASL top an bottom ( can't we need to ict
> probe
>    bottom)
>    cover top with mask prior to HASL (could cause trapped chemistry in via
> and
>    will not allow solder thru, we like the effect on thermal reliability
> for
>    environmental extremes)
>    leave the mask opening only slightly larger than via (tent)
>    do a post hasl mask to cover over via ( causes 2x the thickness of mask
> at
>    overlap, could be a problem with uBGA ball only 14mils dia to start
> with may
>    not touch pads)
>
>
> We use #3 but have problems with rework leaving solder plugged vias that
> look
> like shorts in xray.
>
> If there are some other ideas or thoughts on how to design the via masking
> under
> the BGAs I would like input. Thanks!
>
> --------------------------------------------------------------------------
> -------
> 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
---------------------------------------------------------------------------------

ATOM RSS1 RSS2