I don't believe that anybody has mentioned that depending on the component's
MSL, factory ambient humidity and how the assembly has been stored it has
most likely exceeded its floor limit and may very well need a bake cycle to
be removed without damage.
John
-----Original Message-----
From: Dorothy Lush [mailto:[log in to unmask]]
Sent: Friday, June 11, 2004 10:13 AM
To: [log in to unmask]
Subject: Re: [TN] Reusing desoldered components
Many more expensive IC's are made to be solderable more than one time. A
BGA, for instance, will have in it's spec's how many times it can be
reballed which is ususally more times than a PCB location can be reworked.
If in your removal of QFP's you use a good temperature controlled rework
station to reheat and remove the QFP in such a way that stays within the
parts heating specifications then you have alot of leeway for reworking
these IC's. In my experience parts with memory tend to be sensitive to
overheating. I have had good experince with the Metcal rework stations. They
are built to order and they are very good at giving you true temperature at
the component and the board surface. Best yet they do not require
calibration once in the field because of their design and you can depend on
the temperture reading you get.
Dorothy Lush
Manufacturing Manager
12Telecom International, Inc.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Randy Bock Sr.
Sent: Friday, June 11, 2004 10:11 AM
To: [log in to unmask]
Subject: Re: [TN] Reusing desoldered components
One has to ask is a $2.00 component worth loosing a $1,800.00 board ?? or
even a $500.00 one.
Randy Bock Sr.
Quality Manager
Pitney Bowes
AddressRight Printers
(p) 203 720-3861
(f) 203 729-5397
(email) [log in to unmask]
"Whittaker, Dewey (AZ75)" <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
06/11/2004 12:22 PM
Please respond to
"TechNet E-Mail Forum." <[log in to unmask]>; Please respond to
"Whittaker, Dewey (AZ75)" <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Reusing desoldered components
Bill,
This question is perfect for Doug's patented answer " it depends". Can you
or have we made a case where it is acceptable to re-use components? Yes.
Should you, if you have to ask, re-use components? No. Knowing your
end-use
requirements and environment is a must, but just the time and money to
read
and gather all the things you need to consider before making a decision
will
probably exceed the cost to scrap initially.
Dewey
-----Original Message-----
From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]]
Sent: Friday, June 11, 2004 8:17 AM
To: [log in to unmask]
Subject: Re: [TN] Reusing desoldered components
Daan,
Our policy is to not re-use any soldered parts. I've tried to rationalize
situations instances where this would be feasible, such as prior to
powered
up conditions, but can't win support due to a lack of proof that parts are
not over-stressed.
Pragmatically, I think there should be some guidelines for re-using parts,
limited to prior to powered up conditions. The same pundits who argue that
re-use of parts is verboten don't seem to have a problem re-using a board
from which parts were replaced.
Bill Kasprzak
Moog Inc., Systems Group, Process Engineer
-----Original Message-----
From: Dobbs, Marie [mailto:[log in to unmask]]
Sent: Friday, June 11, 2004 10:34 AM
To: [log in to unmask]
Subject: Re: [TN] Reusing desoldered components
Our rule of thumb. If it is removed it is replaced. We have never
conducted any studies on potential heat damage, but. Better safe than
sorry.
-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Friday, June 11, 2004 10:27 AM
To: [log in to unmask]
Subject: Re: [TN] Reusing desoldered components
Hi Daan:
I am not aware of any standards for recycle parts, but
wouldn't these parts be in the same situation as reworked parts? Some
times
there is a need to move parts due to misalignment or for trouble
shooting.
This requires them to go through the reflow process. Just my one cent.
Regards
Ramon
-----Original Message-----
From: Daan Terstegge [mailto:[log in to unmask]]
Sent: Friday, June 11, 2004 7:20 AM
To: [log in to unmask]
Subject: [TN] Reusing desoldered components
Hi Technet,
We've recently had delamination problems on boards which are populated
with some very expensive QFP's. To minimize the damage we want to
desolder these parts and use them again. Our customer wants some kind of
evidence that the functionality and long term reliability are not
affected, and they want this evidence (i.e. thermal profiles) to be
related to IPC specifications.
I'm not aware of any standard that specifies if reuse of desoldered
components is allowed, and which limitations apply to the temperature
profiles, but perhaps some of you knows such a standard ?
Best regards,
Daan Terstegge
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net
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