even the components from the same brand, different location may have  
different reliability... that may spell out in the contract as part  
of "function" -  dictate a specific bin or dash number of components  
should be used... Die shrink even it is form/fit, some times got  
different temp range for application... if you use a small part piggy  
back using adopter PCB, although it fit the foot print of the same  
space on the assembly, the mechanical impact might be different...  
(stack and shock resonance of the whole system, for example).  be  
careful... off the topic... (saw a lot using form fit function as  
equivalent, but sometime, cause trouble... because the  
interpretation... IMHO.
On Dec 15, 2016, at 10:05 AM, Stadem, Richard D. wrote:

> I agree with Joey's description of a lot, below, but from a very  
> general perspective only.
>
> I do know that there are strict definitions of a lot of parts  
> coming from the same process, built at approximately the same time,  
> and inspected, tested, and otherwise certified as a group under the  
> same revisions of a set of governing documents (data package).
>
> Sometimes, especially in the medical field, if there is a change in  
> the process where the change requires a revision of the assembly,  
> test, or inspection documentation or procedure, the parts must have  
> separate or distinct lot numbers assigned so as to be able to track  
> them to the change. It does not matter if they were all started as  
> one lot; if there was a significant change (one that could possibly  
> have affected the final characteristics of the product), they must  
> be identified as a separate lot or a sub-lot of the original lot  
> code/date code. They do this to make it easier to trace the  
> history, should they have to.
>
> From a counterfeit component standpoint, parts from different  
> factories, even though manufactured from the same original lot of  
> materials using the same process, are considered to be different  
> lots and cannot share the same lot code.
>
> Some companies even insist that the level of "same lot code" goes  
> down to the raw materials they were manufactured from, ie, one lot  
> of BGAs manufactured at the same time must be of different lot  
> codes if their dies are of different lots.
>
> Some companies even require reworked CCAs to be tagged as a suffix  
> of the lot they originated from, and treated as a separate lot with  
> respect to traceability.
>
> And speaking of counterfeit CCAs, many companies now consider a  
> reworked CCA where the same components are re-used in a rework  
> process but sold as never-reworked or reworked without proper  
> documentation as counterfeit if not documented as such with a  
> different lot code from those never reworked. For these companies,  
> they usually consider solder touchup to be finishing of the  
> original soldering process, not rework. The general rule is that if  
> the part must be removed and replaced to fix the issue, then it is  
> rework. If the issue can be fixed with a single heat application  
> and the part does not need to be removed, then it is touchup.  
> Solder bridges, insufficient solder, excess solder, even tombstoned  
> or billboarded chip caps and resistors, all of those would be  
> examples of touchup. Wrong polarity components, wrong parts, parts  
> assembled in the wrong location, etc., must be removed, and  
> therefore a new part must be installed, and the removed parts  
> scrapped (not re-used elsewhere which would require a second heat  
> cycle). Failure to do so without the proper waiver, deviation, etc,  
> are considered non-conforming (even counterfeit) and not only  
> require the proper documentation, but a different lot code  
> identifier so if they should fail (possibly as a result of the  
> rework) they can be identified separately from the originating lot  
> that they once belonged to.
>
> This simple question is very complex; there is no simple answer.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jose A Rios
> Sent: Wednesday, December 14, 2016 4:10 PM
> To: [log in to unmask]
> Subject: Re: [TN] Definition of the word lot in IPC-6013 - Bayesian  
> Filter detected spam
>
> As a former pwb fab guy, we used to treat a lot as each individual  
> 'work order' on the floor. We would not group all individual fab  
> work orders of the same p/n and treat them as a single lot because  
> there is typically mix of processing dates (lamination dates, drill  
> dates, plating dates, and so on).
>
> I think the generally accepted definition is something along the  
> lines of: "lot is a group of parts processed together and presented  
> for inspection at the same time".
>
> 6012 for example, defines sampling plans in Table 4-3, the table  
> specifies also whether the sampling is lot based (once per lot),  
> panel based or individual pwb based.
>
> José (Joey) Ríos, Sr QA Engineer
> Mission Assurance
> Kavli Institute for Astrophysics & Space Research Massachusetts  
> Institute of Technology [log in to unmask] <mailto:[log in to unmask]>
> (617)324-6272
>
>
>
>> On Dec 14, 2016, at 3:39 AM, Bush, Brien <[log in to unmask]>  
>> wrote:
>>
>> You can refer to sampling standards at  ANSI/ASG Z1.4
>>
>>
>> Experience the benefits of Precision Engagement
>>
>> Brien Bush
>> Manufacturing Applications Specialist
>> Phone: 603.249.9190  |   Fax: 603.249.9192
>> [log in to unmask]  www.cirtronics.com
>>
>>
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>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Lehmicke, Michael
>> Sent: Tuesday, December 13, 2016 11:03 PM
>> To: [log in to unmask]
>> Subject: [TN] Definition of the word lot in IPC-6013 - Bayesian  
>> Filter
>> detected spam
>>
>> When IPC-6013 talks about acceptance testing, it references a  
>> sampling plan per # of parts in a "lot".
>>
>> I am curious what the definition of a "lot" is. Can anyone help?
>>
>> Mike
>>
>> Mike Lehmicke
>> Project Engineer
>> DSS Division
>> Molex, LLC-Printed Circuit Solutions
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>> St. Paul, MN 55103
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