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March 1998

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Subject:
From:
Jack Crawford <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 17 Mar 1998 19:08:06 -0600
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Sean, I ask that you refer to page v in the forward, top of the right column in bold.
"J-STD-001 establishes the minimum acceptability requiremnts for printed board
assemblies soldering. This document, IPC-A-610, when addressing soldring is a
companion and complimentary document, providing pictgorial interpretation of the
requirements of J-STD-001. . . "

In J-STD-001B Table 11-1 Hardware Defects, defect number 20 is "Fractured, distrubed,
cold, or excess solder connections (see 9.2.4.1.)

J-STD-001 Clause 9.2.4.1 Solder Connection Defects states in part "The following
solder joint conditions MUST be considered defects:  a. Franctured solder connections
 b. Distrubed solder connections"

A fractured solder joint as depicted in IPC-A-610 Figure 4-21, whether caused by
mechical shock from trimming as indicated in 610 Clause 4.2.2 or from the stress of
bending the lead and tearing away from the solder fillet is still a "fractured or
disturbed solder joint."

Another applicable area of 610 is 4.1 under Figure 4-1 which states in part that an
acceptable solder fillet ". . . exhibits good wetting of the solder to the parts
being joined."  This is repeated under 610 Figure 4-3 (and J-STD-001B clause 9.2.4)
"The acceptable solder connection MUST indicate evidence of wetting and adherence
when the solder blends to the soldered surface. . ."  You indicate that the solder is
tearing away from the leads when you bend them; they may not have good wetting and
don't seem to have adherence.

I'm sure the question most readers have is that, knowing that mechanical stress in a
solder connection WILL have deleterious effects, why haven't you taken action to
stabilize the lead before soldering?  The stress that you are leaving in those
connections, even though you may not see the damage now at 3X is quite likely to rear
its uggle head in the not too distant future.

I've info'd the leaders of the IPC-A-610 and J-STD-001 task groups; they may have
additional comments to add.  Jack

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

>>> Sean Hager <[log in to unmask]> 03/17/98 06:18PM >>>
Greetings,

Please assist in questions with 610 interpretaion:

4.2.2 - Nonconforming Defect - Class 1,2,3 - Evidence of fracture between
lead and solder fillet.

     How does this requirement apply to leads that are NOT trimmed?  The
way I read it, this requirement is under the            "Trimmed Lead"
Section of the Soldering requirements.  We have seen untrimmed leads that
have evididence of a     small seperation between the top of the fillet and
the lead face when slightly bent.  We have attempted to minimize
this bending, but have not successfullly eliminated it.  I would tend to
think that the stresses on the fillet from a slight          bend are far
less than those caused by the shock of a cut.

     Nonconforming Defect: Yes or No?

     If nonconforming, is 4.2.2 the location of the definition by which it
is nonconforming?

     If nonconforming, will rework result in superior solder fillet
reliability (compared to Use As Is)?

     For that matter can a Nonconforming Defect (according to strict
interpretation) be dispositioned UAI based on a         judgement of defect
severity? (i.e. 5.2 Nonconforming Defect - 1,2,3, - Assemblies shall be
free of dirt, lint,dross,etc. -    Does this mean that even a single piece
of particulate matter is rejectable?  Again I am assuming that this takes
the  definition to far, and the intent is simply clean boards. ) The
foreward of 610 only mentions rework, repair, or scrap as    options under
Nonconforming.

     (BTW: since not trimmed, these leads do not get inspected at 10X.
Some inspectors claim the fractures are not        obvious under normal
inspection magnification - 3 Diopter)

This turned out kind of long so I will save other questions for my next
Email.

Thanks in advance and good day!

Sean Hager

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