Jack,

 

            Thought I would forward my thoughts and post them for debate. I
am not sure that I interpreted your list correctly but here are my
questions/suggestions.

 

Thank you,

 

Ted T.

             

The drawing revision description block shall identify the specific changes
made. 

It is not acceptable to just reference to the Engineering Change Proposal
(ECP) 

or other engineering document that initiated the change

 

(Ted T) Drawing revision block should consist of ECN/CN number, revision
letter, description of the changes/list of the changes, who performed them,
who checked/verified the changes were made and the date for production
release  

 

Whenever the drawing, or computer transferrable media, requires a revision,
the 

description shall identify whether the revision impacts form, fit, function

 

(Ted T) This should be covered in the ECN. Why would you want to note on a
drawing that form fit or function has been altered? Wouldn't that have been
covered in the design review? If you are in a use up condition your ECN
should control material use i.e. use part number XXX until part number ZZZ
is exhausted then disposition XXX accordingly.   

 

Three fiducials (or registration targets) shall be located on grid and on
each layer 

of data pattern. Each additional layer or data pattern shall have fiducials
located 

at the same points which, shall register with each other, layer to layer.

 

(Ted T) Why would you need layer to layer registration? Are other IPC doc's
going to be updated to specify the tolerance expected to be held by the
board suppliers? If not what function due they serve other then being able
to cut and paste layers more accurately?

 

The method of excising individual boards shall be included in the assembly
pallet 

description

 

(Ted T) I think most designers do not know what the CM will use for
singulation off the top of my head I can count 5 types of singulation; pizza
style cutter, break apart fixture, guillotine, punch and die and router
Would the designer be expected to contact the CM to verify which method will
be used.  If they change or use multiple CM's how will those affect the
drawing if they use two different methods or the new CM has a more effective
way of performing singulation? Will you be required to revise your print
according to the type of singulation being used?

  

 


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