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Subject:
From:
Dave Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 24 Jan 2003 18:34:24 -0600
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Hi Mike! I believe I can clear this one up for you - see my responses
within your original email. If you need additional help/clarification
please give me a call and I'll assist.

Dave Hillman
JSTD-003 Chairman
319-295-1615
[log in to unmask]


                                                                                                                                       
                      "Mcmaster,                                                                                                       
                      Michael"                 To:       [log in to unmask]                                                               
                      <[log in to unmask]        cc:                                                                                     
                      OM>                      Subject:  [TN] Solderability Test Interpretation/Guidelines                             
                      Sent by: TechNet                                                                                                 
                      <[log in to unmask]>                                                                                                
                                                                                                                                       
                                                                                                                                       
                      01/23/2003 07:47                                                                                                 
                      PM                                                                                                               
                      Please respond to                                                                                                
                      "TechNet E-Mail                                                                                                  
                      Forum."; Please                                                                                                  
                      respond to                                                                                                       
                      "Mcmaster,                                                                                                       
                      Michael"                                                                                                         
                                                                                                                                       
                                                                                                                                       






OK, I have one of those occasions where two parties disagree on the
procedure outlined in a specification.  In this case it's the Edge Dip Test
in J-STD-003 (section 4.2.1).  I'd appreciate the input of the experts on
Technet on the interpretations outlined below.  I'll try to do this so as
not to convey among which party I reside.

According to spec, the sample to be used is not to exceed 2"x2".  After
sample preparation, paragraph 4.2.1.4.2 says "...the specimen shall be
immersed into the molten solder edgewise to a depth of 1"+/- .08".  The
dwell time in the molten solder shall be 3.0+/-0.3 sec minimum.  Immersion
and emersion rates shall be 1+/- 0.08" per second."

The disagreement involves the definition of "immerse".  My Webster's
dictionary says that immerse can mean to dip or plunge.  One party
(dippers) interprets this procedure as lowering the specimen until 1" of it
is in the solder bath, then withdrawing it after 3 seconds and inspecting
for acceptability.   The other party (plungers) says that the whole sample
or at least that part which is to be inspected should be 1" below the
surface of the molten solder.

*** The JSTD-003 committee always wonders why we get hung-up on wording and
your questions highlight exactly why "wordsmithing" is important in
specifications.  In you case the definition of "immerse" is simplified by
the immersion requirements - per paragraph 4.2.1.4.2,  the test sample
shall be immersed into the solder bath at a rate of 1.0 +/- 0.08 inches per
second. You can describe that  motion as plunging or dipping  as long as
the motion meets the rate requirement.  Paragraph 4.2.1.4.2 also states
that the depth the test specimen needs to attain in the solder bath is 1.0
+/- 0.08 inches. You have both the immersion rate and immersion depth
specified - whether the motion is a "plunge" or a "dip" is immaterial to
the specification. The test has always been described as a "edge dip" test
to differentiate it from the solder flow test.

While I have you're attention I'd also appreciate comments on two issues
around the timing.  First, what does 3.0 +/- 0.3 sec minimum mean?  Minimum
is a minimum. To me, anything above the minimum is OK, below is not.  How
do I interpret the tolerance on this?

*** Congratulations - you have found an error in the JSTD-003! The "3.0 +/-
0.3 seconds, minimum" should read "3.0 +/- 0.3 seconds". The committee
tries to put tolerances on all values to assist in the clarity of the
specification. Since a tolerance is present the word "minimum" should not
be there. The new JSTD-003A specification revision does not include that
error.

And when do you start and stop counting the three seconds?  If you're a
dipper is it when the leading edge enters/exits the solder? Or the trailing
edge?  If a plunger, is it only once the leading (or trailing edge) reaches
the depth of 1"?  Depending on the answer, I can see that the trailing edge
could be in the solder for as little as 1 second (start and stop when
leading edge enter and exit solder) or as long as 5 seconds (start timing
when sample reaches 1" depth and stop timing once retraction starts).

*** The 3.0 +/- 0.3 seconds dwell time begins once the test sample has
reached the minimum specified test depth (1.0 +/- 0.08 inches). And yes,
that means the specimen is immersed longer than a total of 3 seconds as the
3 seconds does not include the time spent during the immersion and emersion
motion. Your interpretation of "immerse, dwell, emerse" agrees with the
specification. The committee also considered that thermal demanding test
specimens may require additional dwell time thus the reason for having
paragraph 6.4 in the specification.

I look forward to your input.
Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263




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