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
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Fish
Sent: Wednesday, July 04, 2001 12:24 AM
To: [log in to unmask]
Subject: Re: [TN] J-STD-002 and -003 solderability testing...
Guy,
What makes 100% solderability testing of the components, wires, and boards
referenced in J-STD-001, 5.2 a valid version of process control? If a
mandated process step is process control, we sure have different perceptions
of process control. We think of process control as an organic element that
the process operator changes to maintain and improve quality. Yano,
something out of Shewhart's work that started in the 1920s. Tell me, does
IPC- 9191 "General Guidelines for Implementation of Statistical Process
Control (SPC)" also suggest 100% sampling?
You speak of managing risk and making business decisions. We appreciate
that your comments speak to everyday processes within many companies. What
in J-STD-001 says that you can still be compliant after making business
decisions that are not in compliance with the standard? We read it as "all
or nothing." We thought precluding making business decisions about the
standard was the intent all the SHALLs when we went from rev B to rev C.
Guy, you're correct, Mike's requirement for "objective evidence" is not from
J-001, 5.4 [or 5.2]. On the other hand, most quality systems require
objective evidence to demonstrate that you do what you say you do [and
obtain certification from outside auditors]. So if you say you comply with
J-STD-001, you need to be able to prove it!!! [The realization of a need to
demonstrate compliance is probably the inspiration for this thread. You
know . "Lordy, how are we going to do THAT?"]
On you opinion that 100% solderability testing is vital to obtaining 75%
barrel fill, we only float [sacrifice] a single board in each lot and we get
GREAT barrel fill, well except in the cases of a couple of nasty ground
planes, but we know we get cut some slack on those.
Where are STC BIG dogs?
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