Subject: | |
From: | |
Reply To: | |
Date: | Fri, 9 Nov 2007 16:58:41 +0000 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
Lon,
What your PCB producer told you does not make sense.
Although the tin-lead alloy might have different wetting performance on flash gold pads, it should not have non-wetting in any event. If the flash gold is still there after soldering process, you have solderability problem with the boards. X-ray inspection is not a solderability test.
Liang Yin
Process Research Engineer
Unovis Solutions
> Date: Fri, 9 Nov 2007 16:23:00 +0100
> From: [log in to unmask]
> Subject: [TN] non wetting
> To: [log in to unmask]
>
> Dear Technetters,
>
> We had two boards out of 25 with a nonwetting problem. After reflow there was no solder on the flashgolden pads. Instead all the solder had gone to the leads of the 0805 capacitor.
>
> Our pcb producer comes with the following conclusion:
>
> "Our Q-dept. just informed me that they did x-ray inspection of the 2 boards you sent us back recently. Apparently there have been components used which contain up to 20% lead. During reflow-soldering the tin-lead on those components will melt first and absorb all the solder paste even before the tin which is included in the solder paste will melt. A golden flashgold pad without any tin will be the result. The tin will accumulate on the components and create those solder-balls instead.
>
> In a second test we did lead-free soldering on the side which contains no components. The two PCBs showed excellent tin-wetting on this side. All pads – big and small ones – are nicely covered with tin. So basically we will reject any complaint - the boards are ok."
>
>
> Does this make sense?
>
> Regards,
>
> Lon Weffers
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 15.0
> 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
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------
_________________________________________________________________
Boo! Scare away worms, viruses and so much more! Try Windows Live OneCare!
http://onecare.live.com/standard/en-us/purchase/trial.aspx?s_cid=wl_hotmailnews
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
|
|