I was just going through some old mail and now I'm feeling guilty about
something.
Although Jeffrey McGlaughlin nailed the answer for me (below), Gary Ferrari
asked me to forward an answer because he is not registered here, and I
FORGOT!
(sorry, Gary!)
I checked with the J-STD-001 guru, and sent him a copy of the reference you
sent me. He said it did not come from the 001. He will look into it and get
back to me.
However, he fully agrees with me on what I told you. You can request, on
the assembly purchase order, to assemble and inspect the board to Class 3,
regardless of the bare board being manufactured to Class 2.
thanks,
Jack
[for anyone that doesn't remember and doesn't want to scroll, I was
questioning this statement: "Please NOTE that the final performance class
for printed board assemblies (assembled,soldered, cleaned and tested)
cannot be any greater than the performance class called out for the bare
printed board. That is, in order to obtain a Class 3 with the assembly
printed board assembly, an IPC Class 3 recognition of the bare printed
board (anything with a Class 2 or 1 with the bare printed board prevents
obtaining a Class 3 with the printed board assembly) must be first
obtained."]
SNOPES RATING: FALSE!
On Thu, Apr 25, 2019 at 10:59 AM Dave Schaefer <[log in to unmask]> wrote:
> Jack,
>
> What you have outlined is exactly what we do both for bare PCBs and
> Assemblies.
>
> What we cannot do is sell our products as fully Class 3 compliant.
> At the same time our customers are getting a rock solid product built to
> C3 assembly standards.
>
> Class 3 bare PCBs are largely identified as such because of the additional
> testing and process requirements involved
> but there are certainly some unique Class 3 characteristics that need to
> be addressed during design.
> The only time I will call out full Class 3 bare PCB requirements is when a
> full Class 3 product is contractually required (C3 = at least 10x C2 bare
> PCB cost);
> examples would be Military, Satellite, Avionics, and some Medical
> assemblies.
>
> Hth,
> Dave
>
>
>
> On Thu, Apr 25, 2019 at 9:54 AM Jack Olson <[log in to unmask]> wrote:
>
>> Well, maybe I wasn't clear, (or maybe my thinking is way off-base!),
>> but our bare boards are currently manufactured as Class 2 except for two
>> notes where
>> 1) we don't allow drill break-out from the pads and
>> 2) we want thicker plating in the holes.
>> (1mil desired with no value less than 0.8, instead of 0.8mil desired with
>> no value less than 0.7)
>> Those two requirements are easily understood by our suppliers.
>>
>> If we are confident that we are getting good class 2 boards, then we want
>> all the benefits of a robust assembly process, so we specify class 3 for
>> our assemblies and we are willing to pay whatever that costs.(at this
>> point
>> the bare board is just another component in the assembly BOM).
>>
>> A previous comment noted something about what my customers require, but in
>> this case I AM the customer and have to specify whatever we need, so I'm
>> willing to switch to Class 3 Bare Boards if I need to.
>> (but I have a doubt that a supplier is going to do anything much
>> differently for class 3 than he would for class 2, we just have to pay
>> more
>> for testing and documentation)
>>
>> Anyway, if it's a rule then it's a rule, but your comment that "The use of
>> one class for a specific characteristic does not mean that all other
>> characteristics must meet the same class" seems to support our scheme over
>> the statement in the "IPC Checklist" page 8.
>>
>> thanks,
>> Jack
>>
>> .
>>
>> On Thu, Apr 25, 2019 at 6:09 AM McGlaughlin, Jeffrey A <
>> [log in to unmask]> wrote:
>>
>> > Jack -
>> >
>> > From 600F section 1.4 "Acceptability criteria in this document have
>> > separated so that printed board product may be evaluated to any one of
>> the
>> > three classes. The use of one class for a specific characteristic does
>> not
>> > mean that all other characteristics must meet the same class. Selection
>> > should be based on minimum need..."
>> >
>> > So how do you classify the bare board as Class 3?
>> >
>> > Onward through the fog,
>> > Jeffrey
>> >
>> > Jeffrey McGlaughlin, C.I.D.
>> > Engineering Designer
>> > ST RE Str Eng & Analysis
>> > Office: 614.424.7582| Fax: 614.458.7582
>> > [log in to unmask]
>> >
>> > This message is intended only for the use of the individual or entity to
>> > which it is addressed, and may contain information that is privileged,
>> > confidential and/or otherwise exempt from disclosure under applicable
>> law.
>> > If the reader of this message is not the intended recipient or the
>> employee
>> > or agent responsible for delivering the message to the intended
>> recipient,
>> > any disclosure, dissemination, distribution, copying or other use of
>> this
>> > communication or its substance is prohibited. If you have received this
>> > communication in error, please return to the sender and delete from your
>> > computer system.
>> >
>> >
>> >
>> >
>> > -----Original Message-----
>> > From: DesignerCouncil <[log in to unmask]> On Behalf Of Jack Olson
>> > Sent: Wednesday, April 24, 2019 10:55 AM
>> > To: [log in to unmask]
>> > Subject: [DC] Bare Board Class must be >= Assembly Class?
>> >
>> > Message received from outside the Battelle network. Carefully examine it
>> > before you open any links or attachments.
>> >
>> > Greetings,
>> >
>> > I stumbled into a checklist on the IPC
>> > website,
>> > http://www.ipc.org/4.0_Knowledge/4.1_Standards/PCBA-Checklist18.pdf
>> >
>> > and on page 8 is a statement I have never heard before.
>> >
>> > "Please NOTE that the final performance class for printed board
>> > assemblies (assembled,soldered, cleaned and tested) cannot be any
>> > greater than the performance class called out for the bare printed
>> > board. That is, in order to obtain a Class 3 with the assembly printed
>> > board assembly, an IPC Class 3 recognition of the bare printed board
>> > (anything with a Class 2 or 1 with the bare printed board prevents
>> > obtaining a Class 3 with the printed board assembly) must be first
>> > obtained."
>> >
>> > Does anyone know which IPC document this came from?
>> >
>> >
>>
>>
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