Subject: | |
From: | |
Reply To: | TechNet E-Mail Forum. |
Date: | Fri, 9 Nov 2001 14:46:05 -0600 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
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
---------------------------------------------------------------------------------
|
|
|