personally, if you don't steam aging the part, solderability is not
necessary (at t=0)...if you do (t suppose = 6 or 12 month)...the result
will tell you it is necessary..(big difference between the good guy (/=
big guy) and the bad guy...batch to batch, MFG locations, all play the
role)...You MUST do it when MFG change locations (very often nowadays)
or change the plating house...you would not get the notification from
the distributor of the components but you will observe the solderability
difference..
jk
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: July 5, 2001 8:18 PM
To: [log in to unmask]
Subject: Re: [TN] J-STD-002 and -003 solderability testing...
Okay, I know I'm going to piss some people off...I'll test components
from
AVX, Murata Erie, Kemet, Vishay, Texas Instruments, Amkor, Signetics,
National Semiconductor, Fairchild, Motorola, etc...etc...and then I'll
find
that everything is okay... DO YOU THINK THIS IS NECESSARY? BE REAL!!!!
Don't you think that solderability is foremost in the vendors of these
components? Do you ACTUALLY think that we have to double-check what they
say
they are going to provide to us? That we have to check everything they
provide to us?
I'd like to hear from component manufacturers...do we need to check your
stuff? If we do, I would be ashamed....
-Steve Gregory-
J-STD-001C 5.2 Solderablity: Electronic/mechanical components and wires
to
be soldered shall meet the requirements of J-STD-002 or equivalent . . .
I
do not see a requirement for 100% solderability testing. I am not a
proponent of 100% solderability testing.
I submit that the standard requires you to "know" that the part you
intend
to use in production be solderable as defined in J-STD-002. I believe
you
can "know" this through statistical methods and sampling.
I set up a sampling plan for our board suppliers that specified sampling
by
date code. So, in the case where our supplier manufactured many
different
part numbers our testing requirements were reduced. We found the system
to
be effective (identified defective product and minimized inspection and
test), and our customers approved the system.
I think the part of the standard that might be getting you is 5.4
Soderability Maintenance: . . . ensure that all componets, parts,
leads,
wiring . . . are solderable.
But, I interpert this paragraph as addressing storage and handling. It
does
not mention testing or inspection. This paragrah requires the
manufacturer
to "know" that storage and handling has not degraded the components to
be
soldered.
The end item acceptability criteria in the J-STD-001 and IPC-A-610
assume
that the materials and methods used conform to the requirements of the
standard. This is not a version of process control it is a prerequisite
for
compliance.
A means by which we can provide assurance is SPC, rather than 100%
inspection. One of the four essential techniques in Statistical Quality
Control (from the Western Electric Handbook, 1956 based on Shewhart's
work)
is Statistical Sampling Inspection.
Guy Ramsey
Senior Lab Technician / Instructor
E-Mail: [log in to unmask] <mailto:[log in to unmask]>
Ph: (610) 362-1200 x107
Fax: (610) 362-1290
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