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January 2003

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Subject:
From:
Dave Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Sat, 25 Jan 2003 17:29:19 -0600
Content-Type:
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Hi Mike! You are on the right page and your focus is just fine! The only
portion of the test sample that you are required to evaluate is the 1 inch
portion that is immersed (or "submerged" if that creates a better visual
image). The portion of the test coupon above the solder bath should not be
evaluated. Most folks will use a test specimen slightly larger than 1 inch
square so that their test fixtures can be used without infringing on the
area of interest and to avoid potential test coupon edge effects -
especially if the test coupon is removed from a circuit board. The 003
specification only has a depth requirement - if your test specimen is wider
than an 1 inch then you can also evaluate those regions per the 003
solderability criteria provided you don't exceed the 2"x2" maximum coupon
size and ignore any test coupon edge effects. Many folks testing use a test
coupon approximately 1.25"x1.25". Hope this helps. And I am curious - were
you on the plunge or dip side of the discussion?

Dave


                                                                                                                                       
                      "Mcmaster,                                                                                                       
                      Michael"                 To:       [log in to unmask]                                                               
                      <[log in to unmask]        cc:                                                                                     
                      OM>                      Subject:  Re: [TN] Solderability Test Interpretation/Guidelines                         
                      Sent by: TechNet                                                                                                 
                      <[log in to unmask]>                                                                                                
                                                                                                                                       
                                                                                                                                       
                      01/24/2003 07:18                                                                                                 
                      PM                                                                                                               
                      Please respond to                                                                                                
                      "TechNet E-Mail                                                                                                  
                      Forum."; Please                                                                                                  
                      respond to                                                                                                       
                      "Mcmaster,                                                                                                       
                      Michael"                                                                                                         
                                                                                                                                       
                                                                                                                                       






It's starting to come into focus better but I'm still not 100% certain
about the "immersion".

Is the whole sample (or at least the portion to be evaluated) submerged to
a depth 1" below the level of the solder?  If my sample is 2" square, do I
lower it so that the bottom is 1" below the surface (what I call "dip") or
3" below the surface ("submerge")?

If the latter, is it equally valid to lower the sample so that the top is
level with the top of the solder bath, but only evaluate the bottom 1" of
the coupon since the top 1" did not meet the requisite 1" below the bath
level?

Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263


   ----------
   From:   Dave Hillman[SMTP:[log in to unmask]]
   Reply To:       TechNet E-Mail Forum.;[log in to unmask]
   Sent:   Friday, January 24, 2003 4:34 PM
   To:     [log in to unmask]
   Subject:        Re: [TN] Solderability Test Interpretation/Guidelines

   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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