Thank you everyone for your responses. I had suspected that copper dissolution was the culprit, except for the fact that there is not the annular ring deterioration that I would have expected to see. Checking the initial thickness of the barrel with a cross section looks like the first step I need to take in this investigation. If copper dissolution is the smoking gun, then is reducing the soldering iron temp and making sure that the tech's do not place the iron directly on the pin the answer? I will try to let you know what I find when the issue is resolved so that all can benefit from any gained knowledge and experience. Thank you again for your input. Tom Burek, CID+ From: "David D. Hillman" <[log in to unmask]> To: <[log in to unmask]> Date: 07/28/2011 06:03 AM Subject: Re: [TN] AW: [TN] Missing PTH Barrels in Connector Sent by: TechNet <[log in to unmask]> Hi Rex - I would agree with you if the cross-section shows that there was sufficient copper remaining in the PTH at the manual soldering process but I don't know if we can make that assumption. As others have suggested, if the PTH copper was "thin" at the pwb fabrication stage and the soldering processes prior to manual soldering remove all or nearly all of the copper, then it would not be surprising to see the solder wick straight up the lead as there is nothing in the PTH for solder to wet. The group's recommendation of having a cross-section done would eliminate a number of possible root causes right away. Dave Hillman Rockwell Collins [log in to unmask] Rex Waygood <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 07/28/2011 02:32 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Rex Waygood <[log in to unmask]> To <[log in to unmask]> cc Subject Re: [TN] AW: [TN] Missing PTH Barrels in Connector I would agree. From the description this is a fast process, the solder wicks straight up the pin (one interpretation of this is that 'straight' means 'immediately'), copper dissolution takes time and wetting to a normal barrel would be apparent and then degenerate as the barrel disappears. If the barrel were very thin then it could disappear quickly. Have you done as recommended and checked your barrels? We have done experiments to measure dissolution in our wave. It is significant and cannot be ignored. Rework cycles make this much worse. Regards Rex -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Neifer, Gebhard Sent: 28 July 2011 07:43 To: [log in to unmask] Subject: [TN] AW: [TN] Missing PTH Barrels in Connector As the amount of tin in a reflow and in a hand solder process is limited, to me it looks like copper dissolution is probably not the main cause of your issue... Gebhard -----Ursprüngliche Nachricht----- Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Joyce Koo Gesendet: Donnerstag, 28. Juli 2011 04:23 An: [log in to unmask] Betreff: Re: [TN] Missing PTH Barrels in Connector What is the barrel thickness? Did you etch it and see how is the seed layer and subsequent 1st layer adhesion the the PWB? Any etchback can be observed? You do not need to answer my question. As long as you find out the answer. -------------------------- Sent using BlackBerry ----- Original Message ----- From: Thomas Bauer [mailto:[log in to unmask]] Sent: Wednesday, July 27, 2011 10:07 PM To: [log in to unmask] <[log in to unmask]> Subject: Re: [TN] Missing PTH Barrels in Connector 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. 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