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| Reply To: | TechNet E-Mail Forum. |
| Date: | Fri, 3 May 2002 09:09:48 -0500 |
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First of all I think to really understand the class 3 PCB criteria one must look at IPC-6012. As far as the 610 criteria look at 6.5.2 which will indicate this as a process indicator unless 5.4.1 or 10.7 is violated. 5.4.1 doesn't apply to this issue but 10.7 would if the traces have had a height reduction. These criteria come from the IPC-6012. Also look at 6.5.1 for the rerun. This is allowed for rerunning but you must have a high degree of assurance that the thermal cycle won't damage the parts. I have had to do this rerun before and with standard parts solder spec'ed to Mil-202 haven't seen a problem. But none of those were class 3 but class 2.
Kathy
02 06:10AM >>>
I agree with you, as far as trimming leads before soldering. I agree, a
solder - cut - solder process should be avoided if possible.
But, I can't find any place in the J-STD-001C or IPC-A-610C which bans
exposed copper. In fact, I can only find places where it is specifically
acceptable, even including nicked leads unless the damage is greater than
10% of the lead diameter or thickness. Unless the damage is the result of
careless or repeated bending.
Is this a topic worthy of discussion? Have I misinterpreted the standards?
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<DIV>First of all I think to really understand the class 3 PCB criteria one must
look at IPC-6012. As far as the 610 criteria look at 6.5.2 which will
indicate this as a process indicator unless 5.4.1 or 10.7 is violated.
5.4.1 doesn't apply to this issue but 10.7 would if the traces have had a height
reduction. These criteria come from the IPC-6012. Also look at 6.5.1
for the rerun. This is allowed for rerunning but you must have a high
degree of assurance that the thermal cycle won't damage the parts. I have
had to do this rerun before and with standard parts solder spec'ed
to Mil-202 haven't seen a problem. But none of those were class
3 but class 2. </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Kathy <BR><BR>02 06:10AM >>><BR>I agree with you, as far as
trimming leads before soldering. I agree, a<BR>solder - cut - solder process
should be avoided if possible.<BR><BR>But, I can't find any place in the
J-STD-001C or IPC-A-610C which bans<BR>exposed copper. In fact, I can only find
places where it is specifically<BR>acceptable, even including nicked leads
unless the damage is greater than<BR>10% of the lead diameter or thickness.
Unless the damage is the result of<BR>careless or repeated bending.<BR><BR>Is
this a topic worthy of discussion? Have I misinterpreted the
standards?<BR><BR></DIV></BODY></HTML>
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