Joyce, the is no issue with exposed basis metal after cutting, and from what I've
been hearing lately, not even very high concern if the cut extends into the solder
fillet.  However, there is a very serious concern about induced fracture to the
connection from the cutting process.  Whether the process be pinch cutters or rotary
shears, there is a pressure and vibration applied to the connection during the
cutting operation.  There is a high probability of fracture of the wetted connection
from the fillet to the lead.  A-610B (and same requirement in proposed 610C) requires
that leads trimmed after soldering be 100% inspected at 10x power.  Alternatively
(and probably simpler) is to just reflow the connections.  Of course, that opens
discussion on potential failure mechanisms from the additonal rework.

I'm out of the office and can't point you at the specific paragraph number in 610B.
In 610C is 6.3.4.3.  If you'd like to review the 610C, you are welcome to download
Adobe Acrobat files from our web site.  You will need FREEWARE Acrobat Reader 3.0 or
later to view the files. Point your browser to http://www.ipc.org and click on the
link to "Assembly" .  Scroll down a little and click on the link to "Technical
Committee Section".  You will be prompted to enter a user name which is (all lower
case):  technical   and then you will enter the password (all lower case):
technical2

You'll then see the all twelve chapters you can download.  BE ADVISED THAT YOU MAY
NOT WANT TO DO THIS IF YOU ARE USING A MODEM CONNECTION.  Chapter 4 (mechanical
assy), 5 (component install), and 6 (soldering) plus several others are each over 1
MB in size.  Chapter 12 (SMT) is nearly 3.7 MB.

Hope this helps you and anyone else that would like to take a look at the current
state of the new draft.  Jack

==========================================
APEX - the industry's premier trade show in Electronics
Manufacturing, March 12-16, 2000, Long Beach, California.
More information on website www.ipc.org/html/apex.htm
-----------
Jack Crawford, IPC Director of Assembly Standards and Technology
2215 Sanders Road, Northbrook IL  60062-6135
[log in to unmask]
847-790-5393
fax 847-509-9798

>>> joyce <[log in to unmask]> 03/06/99 07:35AM >>>
Based on Mil-STD-2000A, you are required to reflow the PTH location after
cutting the components leads.  Is there any similar requirement in IPC class
3 assembly?
Thank you very much for all your help.
joyce koo
e-mail: [log in to unmask]

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