Michael,
My understanding of the word immersion is that it means "completely covered
by", though our copy of J-STD 003 is not with me to check the context.
Having said that, it seems to me that it would not be an 'Edge Dip" test if
the whole board were to be immersed, and this is backed up by me reading :
"...the specimen shall be immersed into the molten solder edgewise to a
depth of 1"+/- .08".
It's quite clear to me that an area of the board, bordered by a line 1" in
from the card edge, must be wholely immersed in (completely covered by)
molten solder. i.e. the rest of the board remains above the solder surface.
So you fix your board to a gadget that raises and lowers it at 1+/- 0.08"
per second. You lower the board, edge first and at the prescribed rate,
into molten solder until the leading edge is 1"+/- .08" below the surface
of the solder. Leave the board there at that depth for between 2.7 and 3.3
seconds before starting to pull it out again at the prescribed rate.
It does mean that the zone at the surface will be immersed for at most 3.3
seconds, while the leading edge (one inch down in the solder) will be
immersed for 5.46 seconds at most. To me, this is how the term "3 +/- 0.3
secs minimum" should actually be interpreted - the surface zone immersion
can be timed at 3 +/- 0.3 seconds, but the writer knows that the rest of
the strip will be immersed for longer, though he's at a loss how to express
it all meaningfully in words. How would you express it?
Peter
I'll ask a question in return
"Mcmaster, Michael" <[log in to unmask]> 24/01/2003 09:47 AM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to "Mcmaster,
Michael"
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: [TN] Solderability Test Interpretation/Guidelines
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.
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?
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).
I look forward to your input.
Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263
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