TECHNET Archives

July 2010

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:
Reuven Rokah <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Reuven Rokah <[log in to unmask]>
Date:
Fri, 30 Jul 2010 18:33:33 +0300
Content-Type:
text/plain
Parts/Attachments:
text/plain (1 lines)
May be it's because of over baking at the PCBs shop.
Check bare boards at stock or at the PCB's shop samples.

Check if the legend / marking has discoloration also.

Reuven ROKAH 

e mail: [log in to unmask]
Think green before printing this mail... Thanks


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Friday, July 30, 2010 6:12 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Discoloration

Hi,

 No SMT reflow probably means it is simply a variation in FR4 sheets.

 Is there a spec as to color somewhere?

Bob Kondner

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Linda Langley
Sent: Friday, July 30, 2010 11:04 AM
To: [log in to unmask]
Subject: Re: [TN] PCB Discoloration

The assemblies come to us completely assembled and had the
discoloration.  

The boards are all hand solder, no SMT.  This board gets labeled, PEMs
pressed, then hand soldered at our supplier.  

All the darker boards are in the same date code.  

The PCB has two signal layers of 1oz copper plated to 2oz separated by
the laminate.  The finish is Immersion silver.  The board thickness is
3.18mm  

We do not know if the discoloration was a result of the assembly process
but are leaning away from this assumption.



Linda Langley CIT
Training Specialist
Jabil Circuit
248-292-6176

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, July 29, 2010 9:34 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Discoloration

Hi Linda!

While discoloration in itself is not a defect, I would be a little
worried about these seven boards. Especially since the rest of the lot
are not discolored like this: 


 http://stevezeva.homestead.com/PCB_Discoloration1.jpg

 

I don't see any delamination in the photos, but it sure looks like the
boards got pretty toasty. I wonder if it was because the boards were
sitting over a preheater or hot plate too long. From the looks of the
components on the board, most of it was probably hand soldered (those
PTH caps converted to SMT couldn't have taken reflow), and I imagine
that the solid plane on on the backside of the board was a real
heatsink. Preheating the board would have helped with soldering the PEM
nuts for sure, but maybe the preheater was set too high. I know a Hakko
IR preheater can smoke a board if you're not careful (not that I've ever
done that, but I know a friend of a friend who did. Hehehehe).

 

Anyways, those seven boards saw more heat than the rest of them did
based on the appearance in the photos. I don't think I'd buy off on
them...

 

Steve

 

 

 

From: Linda Langley [mailto:[log in to unmask]] 
Sent: Thursday, July 29, 2010 1:42 PM
To: Steve Gregory
Subject: FW: PCB Discoloration

 

Hi Steve,

 

Here I go again asking for help from my experts! Can you please post
these pictures? So I don't have to bother the whole forum, would you
know the name of the board guru that could answer my questions?

 

I am not sure if the discoloration is a defect, is this a form of
delaminating? Why would only seven boards turn this color? They are all
from the same lot.

 

Any information will be greatly appreciated.

 


Linda Langley CIT

Training Specialist

Jabil Circuit

248-292-6176

---------------------------------------------------
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
-----------------------------------------------------

______________________________________________________________________
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 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
-----------------------------------------------------


______________________________________________________________________
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 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
-----------------------------------------------------

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

ATOM RSS1 RSS2