John
You don't mention what class your product is.
If I was faced with this sort of rework, I would go with the cut and remove, but would not worry about the exposed copper. The lead can have exposed copper on the other end (per 610, figure 4-18) so why on earth would one worry about the cut off part? I'd just cut off the part on topside and leave the bottom side alone.
As for testing, we build class 3, so if someone looks at a board while holding a tool we tend to retest it. After any sort of rework - retest is mandatory. If you are building less mission critical sorts of things maybe you can avoid it, my preference would be to test it though. And you say it's part of a mod - does the rest of the mod need to be tested?
But it comes down to what your customer's needs are (since they will likely end up paying for it) and what they are willing to pay for.
Good luck!
regards
Graham Collins
Process Engineer, Litton Systems Canada, Atlantic Facility
(902) 873-2000 ext 6215
>>> [log in to unmask] 08/20/01 02:47PM >>>
Thanks Phil and George. Good Points so far.
Our customer does not specify bout the bare copper. However, I am greatly
concerned about IPC requirements/standards in terms of removing these caps.
In addition, these are finished assemblies so is it recommended to put these
units back through a functional test after removal of these capacitors?
Thanks,
John
John Fahey
Manufacturing Engineer
Echelon Corp
415 Oakmead Parkway
Sunnyvale
CA 94085
[log in to unmask]
Phone: 408 938 5330
Fax: 408 328 3804
-----Original Message-----
From: Phil Nutting [mailto:[log in to unmask]]
Sent: Monday, August 20, 2001 10:36 AM
To: [log in to unmask]
Subject: Re: [TN] T/H Capacitor Removal- IPC standards?
John and Charles,
But aren't there some people who expect to have all trimmed leads
soldered after trimming so no bare copper shows through? We have a
customer who requests this attribute.
Phil
-----Original Message-----
From: Charles Caswell [mailto:[log in to unmask]]
Sent: Monday, August 20, 2001 1:28 PM
To: [log in to unmask]
Subject: Re: [TN] T/H Capacitor Removal- IPC standards?
That would be my prefered methos. Least risk of damage to the board,
lowest cost. I wouldnt even clip the solder side.
Charles Caswell
Process Lead, PCB
Frontier Electronic Systems
-----Original Message-----
From: John Fahey [mailto:[log in to unmask]]
Sent: Monday, August 20, 2001 12:17 PM
To: [log in to unmask]
Subject: [TN] T/H Capacitor Removal- IPC standards?
Good Morning.
As part of a design mod, I have been requested to remove 2 Through Hole
resistors from one of our assemblies. There are @2000 boards.
What is the recommended process for removing Through Hole capacitors. Is
there any IPC guidelines?
I would like to just clip the leads on the top and bottom of the board
for
an easy rework. This will leave part of the leads soldered in the
holes,
but I am not aware of any issue with this apart from the fact it may not
look pretty!
Any advice would be much appreciated.
Thanks again,
John
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