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June 2005

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Subject:
From:
"Ingemar Hernefjord (KC/EMW)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Ingemar Hernefjord (KC/EMW)
Date:
Thu, 2 Jun 2005 08:20:51 +0200
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text/plain (96 lines)
You seem to bother a lot. Our requirement is repair capability at least 5 times. Are you talking ordinary copper lands or PTH connectors? Seems as you mean SMT lands. If you got normal PWBs you should have no problems,considered you follow normal solder temperature and heat exposure procedures. FR4 boards are very, very tough. I've never seen lamination, but I've surely seen lifted traces after repair trials on cheap boards from the far East (toys, watches, kitchen equipments etc) On the other hand, such boards are not done for repair. So, all is dependent on your boards quality level...and your operator's skill.
Why not hang a pic on Steve's wall?
Ingemar Hernefjord
Ericsson Microwave Systems

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Harman
Sent: den 2 juni 2005 02:36
To: [log in to unmask]
Subject: [TN] Rework considerations.


Hello, this group has helped me in the past and I am looking forward to
hearing others comments on this question on rework.

 

    I have an 8 layer board that is approx.   3.5 x 1.25 inches.  On the
board I have several components; however the one that I am specifically
concerned with is a battery connector.  The question I have is to ensure
that I am not over looking anything or causing long term reliability
issues by reworking this section of the board three times.

 

Here is the history. 

    First time was normal SMT operation.  Due to bad components we had
to manually remove the connector and replace with new connectors.
(Second time)  The connectors that we manually reworked were still not
the correct ones we wanted but allowed us to continue production. We had
it in our mind that when the real ones come that we would rework the
boards by removing the connector manually again and replacing it with
the final version. (Third time) 

 

I am concerned about delaminating causing the connector to fall off
easily with little or no force. (The test that I am performing is a
destructive test and comparing the shear force to boards with just the
original SMT process.) As a baseline

 

Temperature cycling 100 degrees to -10 and then repeating the test above
after visual inspection.

 

What other testing would the group recommend to ensure that the
reliability of the solder joint or pad leaching is not an issue? Are
there any other reliability issues that I am not considering, and if so
what are they, and is there any other testing or analysis that can be
recommended to give me a better confidence rate. 

 

Thanks

 
 
 
 
 
 
 
 
 
 
 
 David Harman

 

 

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