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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