Prashant,

The main reason you may/would want your own DFM guidelines is:

1) The DFM guidelines define "your" process and capabilities.  If you're not an OEM or EMS and don't have a process they you need something like the IPC Guidelines as a starting point.
2) The DFM guidelines define "your" technology.  For instance RF products have their own unique design criteria.  Other technologies do too and therefore you may need to define specific rules.
3) Not to say anything bad about the IPC Guidelines as they are a great starting point, but they are created around a group consensus.  By that I am saying they are not the tightest of standards.
4) You may have some unique equipment, fixturing, technology unique to you process that you need to define.
5) As you identify a unique situation where you need to define a specific criteria for your DFM you can do it quickly where updating an IPC guideline can take years.
6) I have done several comparisons between EMS's, OEM's, and our standards and they all vary.  Some are more design friendly (vendor A) and some are ultra conservative (vendor B).  If you identify what works well for you (meets your technology and space constraints) then you know no matter where you move your product it should perform well.  If you design to Vendor B and move it to vendor A you could have issues.
7) With the introduction of SMT, DFM Guidelines are more about inspection, repair, and reliability.  By that I mean I can place component closer than I can inspect and repair.  I can also create situations where I can affect the reliability.
8) you may be designing product that will go to multiple manufacturing sites/EMS.  And each site or EMS may have therefore own DFM guidelines.  Whose DFM guidelines do you design to?


Good Luck



RUSSELL NOWLAND
ALCATEL-LUCENT
REPAIR ENGINEERING SUPPORT
14000 Quail Spring Parkway, Suite 100
Oklahoma City, OK 73134
T: +1 405 302 1660
F: +1 405 302 1622
M: +1 405 203 0034
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of prashant chopra
Sent: Thursday, September 29, 2011 7:34 AM
To: [log in to unmask]
Subject: [TN] DFM Guidelines v/s IPC Guidelines

Hi,

Hello everyone. I have a very basic question here.

Why do we require our own specific DFM guidlines (every OEM / CM will have their own specific DFM Guideline) when we have the IPC guidelines defined and available?

I am looking for the pointers and specific examples which can highlight the need to have and develop specific DFM guidelines for a company.

Thanks in advance.

Regards
Prashant

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------