The "orientation" of components when packaged in "Tape and Reel" is defined by
ANSI/EIA-481-C (specifically see Figure 1), and is fairly well followed by a
majority of manufacturers when packaging a majority, although not all, of their
components in "Tape and Reel".
The problem here is that there is no specific "standard" on how to "orient" or
"mount" a "Reel" into a "Pick and Place" machine, and there are in fact many
different machines that "orient" or "mount" the "Reels" in many different ways such
that they may "feed" the components in any of the four basic directions.
The problem of "Tape and Reel" mounting or loading orientation in any given location
in any given "Pick and Place" machine is a matter which has to be individually
resolved by each individual Manufacturing Engineer, for his individual "Pick and
Place" machine, which usually taken care of in the programming of that machine.
Additionally, components also come in "Tubes", "Coin Stacks", "Magazines", or
"Trays", (much of which is defined by JEDIC JEP95), which packaging presents similar
problems to the Manufacturing Engineer, respecting their orientation in his
particular individual "Pick and Place Machine".
IPC-7351 is not intended to specify either how components are mounted in "Tape and
Reel" or "Trays" or any other type of "packaging", or how such "packaging" is to be
"mounted" or "loaded" into any given automated assembly equipment. This is, and
always has been, and always will be, the individual responsibility of the
Manufacturing Engineer and or the operator of such equipment.
IPC-7351 is however specifically intended to be a standard for Library Components
and the orientation of those Library Components, as used in the "design" of a
Printed Circuit Board, such that respecting "component orientation", all components
in any given "design" will have a common standard "zero degrees of rotation" ("zero
rotation"), with respect to the "zero rotation" of the PCB, which is defined by the
Gerber File and Fabrication Drawing (which should correspond to each other unless
specifically noted on the Fab Dwg).
IPC-7351 can not dictate how manufacturers package their components, nor can it
dictate how those packaged components are mounted or loaded into automated assembly
equipment.
IPC-7351 does dictate that when individual components within "Component Libraries"
that are defined in accordance with IPC-7351 are utilized, that those components
will have a "standard orientation", and that any "rotation" of any individual
component will be based upon a standardized "zero rotation", with respect to the
"normal" orientation of the PCB itself, such that any Manufacturing Engineer will
have a "standard component orientation" to rely upon with respect to each component
on that PCB, such that the Manufacturing Engineer can make such "compensations" or
"adjustments" as may be necessary with regards to the "mounting" or "loading" of any
components into any automated manufacturing equipment, and the "programming" of such
equipment, irrespective of how each component is packaged or oriented within that
packaging.
The bottom line is this. IPC-7351 defines how components are to be made in a
"Standard Library", which will among other things insure that all of the components
within that "Standard Library" follow a standardized orientation based upon a
standard "zero rotation", which in turn will mean that your data in your "Pick and
Place File" will be correct and can be relied upon by the Manufacturing Engineer to
make your PCB quicker and without any errors, and cheaper without any additional
setup and NRE charges.
IPC-7351 resolves many of the problems that now exist with respect to component
"land patterns" and "component orientation", such that it will allow the utilization
of the automation that is already built into most of today's EDA / PCB Design
Software, as well as most of today's automated manufacturing equipment such as "Pick
and Place" machines.
While IPC-7351 may not satisfy everyone in every situation, it certainly is a
monumental step forward in standardizing the "Design" of PCB's such that the current
avenues of automation can be fully utilized, and new avenues of automation can be
developed, such as for example, the future standardization of "Pick and Place" file
"data" and "format".
While on the topic of IPC-7351, I should probably also mention that the "center" of
a component is chosen as the standard for locating all components, as opposed to Pin
1 or any other feature, such that the component can be "rotated about its center".
This will undoubtedly make some people happy, while upsetting others.
JaMi Smith
----- Original Message -----
From: "Jack C. Olson" <[log in to unmask]>
To: "(Designers Council Forum)" <[log in to unmask]>; "JaMi Smith"
<[log in to unmask]>
Cc: <[log in to unmask]>
Sent: Tuesday, October 26, 2004 11:42 AM
Subject: Re: [DC] Pin Numbering Question
>
>
>
>
>
> Since IPC-7351 is only following the same convention as EVERY reel of parts
> I have ever seen (always horizontal to the tape and polarity to the left),
> I don't
> know how anyone could be unhappy with it. Unless they would prefer changing
> all the component reels in existence? Yeah, right...
>
> Anyone who isn't happy about it wasn't paying attention to the
> manufacturing
> world in the first place.
>
> Jack C. Olson
> 10G Circuit Board Designer
> (630) 754-2431
>
>
>
>
<snip>
---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------
|
