Greg--Yes, you could have a reliability issue and EVERY lead trimmed after reflow
requires reflow or mandatory inspection at 10x power for class 3 products and for
class 2 products under certain situations (NO document SPC pogram).

This situation is covered very well in ANSI/J-STD-001B Requirements for Soldered
Electrical and Electronic Assemblies, clause 7.1.5 Lead Trimming.  "Leads may be
trimmed after soldering provided the cutters do not damage the component or solder
conneciton due to physical shock.  When lead cutting is performed after soldering,
the sodler terminations SHALL either be reflowed or visually inspected at 10X to
ensure that the original solder conneciton has not been dmaged (e.g., fratcured) or
deformed. If the solder conneciton is reflowed this SHALL be considered part of the
soldering process and SHALL not be considered rework.  This requirement is not
intended to apply to components which are dsigned such that a portion of the lead is
intended to be removed after soldering (e.g., break-away tie bars."

This same information is repeated in IPC-A-610 Acceptability of Electronic Assemblies
in clause 4.2.2


Jack Crawford, IPC Project Manger - Assembly
2215 Sanders Road, Northbrook IL  60062-6135
[log in to unmask]        http://www.ipc.org
847-509-9700 x 393
fax 847-509-9798

>>> Greg Kaskey <[log in to unmask]> 04/13/98 12:32PM >>>
All,

I am looking for empirical data to support the following:

A through hole component (5 leaded) is to be installed on the solder side
(all other components are on the component side of the board except this
5 leaded component) of the board being hand soldered from the component
side of the board.  The 5 leads (0.020 square lead in a 0.035 diameter
hole )coming through on the component side has about a 0.200 inch
clearance around them for clipping accessibility.

Is there a way to get a reliable solder joint of the through hole leads
when the leads are clipped, after being soldered by hand,  very close to
the surface of the board, say 0.020 inches to 0.010 inches or less?  Does
the clipping through the solder fillet cause a reliability issue with the
solder joint?

The reason for having the leads clipped flush is because there is a part
of the plastic enclosure coming very close to the leads and this would
cause interference between them.  I would appreciate any useful
information to resolve this issue.  Could the leads first be cut to
length then be soldered by hand in some way?

Thanks Much,
Greg Kaskey
Senior PCB Designer
Checkmate Electronics, Inc.
770.594.6000 x228
[log in to unmask]

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