TECHNET Archives

December 2016

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Thu, 15 Dec 2016 15:05:13 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (90 lines)
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
> 
> 
> ISO 9001 & 13485 Certified
> Follow us on LinkedIn|Friend us on Facebook
> 
> 
> -----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
> 22 Empire Drive
> St. Paul, MN 55103
> 651-846-7728
> [log in to unmask]<mailto:[log in to unmask]>
> 
> [cid:[log in to unmask]][cid:[log in to unmask]
> 0]<http://www.molex.com/>
> 
> 
> ________________________________
> 
> 
> 
> CONFIDENTIALITY NOTICE: This message (including any attachments) may contain Molex confidential information, protected by law. If this message is confidential, forwarding it to individuals, other than those with a need to know, without the permission of the sender, is prohibited.
> 
> This message is also intended for a specific individual. If you are not the intended recipient, you should delete this message and are hereby notified that any disclosure, copying, or distribution of this message or taking of any action based upon it, is strictly prohibited.
> 
> English | Chinese | Japanese
> www.molex.com/confidentiality.html
> WARNING: Export Control This message, including any attachments, may contain technical data within the definition of the International Traffic in Arms Regulations (ITAR), and subject to the Export Control Laws of the U.S. Government. Transfer of such information by any means to a foreign person, whether in the United States or abroad, without proper export authorization or other approval from the U.S. Department of State is prohibited.

ATOM RSS1 RSS2