TECHNET Archives

July 2011

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:
Thomas Bauer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Thomas Bauer <[log in to unmask]>
Date:
Wed, 27 Jul 2011 19:07:20 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (72 lines)
Hello

Do you know if there are inner layer pads helping secure the structural integrity of the pth? If not I could see how overheating during soldering could easily cause the barrel to pull out of the hole.

Thomas


On Jul 27, 2011, at 5:42 PM, "Tom Burek" <[log in to unmask]> wrote:

> Hello,
> I have a PCA that hand solders 6 connector pins to an 4 layer PCB 
> assembly.
> The finish on the PCB is Lead Free HASL (SN100CL) and the solder used to 
> hand solder the pins is SAC305.  The hand soldering is performed as a 
> secondary assembly operation after reflow.
> What happens to some of the assemblies, but not all of them, is that the 
> solder will wick straight up the pin, thereby not allowing a Solder joint. 
> The pin can be pulled right out of the hole, revealing a PTH with no 
> inner barrel.
> Completely wiped out as if it was never there in the first place.  This 
> phenomenon is not present on every PCB or every pin of the same connector. 
> The PCB's are part of a multi-board panel.
> 
> As far as I know the PCB started out with a barrel, but I cannot rely on 
> this being the case as I do not believe the technician checks 100% of the 
> PTH's prior to inserting the pin. 
> 
> Am I looking at excessive heat causing complete Copper Dissolution of the 
> PTH barrel? 
> or
> A PCB that may not have a barrel in every hole, part of the PCB 
> fabrication process?
> or
> Any other suggestion as to which direction to head would be appreciated.
> 
> Thanks in advance.
> 
> 
> Tom Burek, CID+
> 
> 
> 
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or [log in to unmask] 
> ______________________________________________________________________
> 
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 16.0
> 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2