SAS PHY meeting reminder October 13, 10 am CDT

Thu Oct 13 05:38:27 PDT 2011

* From the T10 Reflector (t10 at t10.org), posted by:
* fred.fons at foxconn.com
*
Hi Alvin,
Now that you bring up the subject of normative language regarding the PCB
footprint in SFF-8482,	I just sent an email to Dal and Jay on this very
subject.
I would like to bring up the following points for discussion during today's
SAS Phy teleconference.
Following some recent discussion, I was prompted to do a thorough
line-by-line review of SFF-8482.
Based on that  review, I can't see how the statements regarding PCB
footprint in SFF-8482 could be considered "normative"?
Please consider the following:
      Page 6 , Rev 2.2, Section 4. Dimensioning Requirement, Sub-Section
      4.1 Connector Interface states the following:
      "The dimension requirements for the connector are limited to the
      mating interface only. In order to provide a uniform fit and to
      support the features outlined for each use model, all listed
      dimensions shall be met. See table 1.0"
Question #1:  How can dimension requirements for the connector be limited
to the mating interface only and yet the very next sentence "... all listed
dimensions shall be met" when Printed Circuit Board Layout is not part of
the mating interface?
      Also, Sub-Section 4.2 Printed Circuit Board Layouts contains the
      following:
      "PCB layouts are included to provide a base line design for multi
      sourcing of connectors and are not intended to address the electrical
      performance characteristics of PCB construction. Electrical
      performance characteristics, including impedance and crosstalk,
      should also be considered when determining the hole diameter. Printed
      circuit board (PCB) layer stack up, hole drill diameter, trace layer
      location, PCB material, copper plane anti-pads, hole pad diameter,
      and PCB thickness all have major contribution to the final electrical
      characteristics of the connector land pattern. PCB thickness of
      greater than 2.54 mm (0.100") with FR-4 material may result in a
      differential impedance of less than 85 ohms when the thruhole
      patterns are used. See Table 1."
Question #2:  "Base line design" suggests an informative reference design.
Further, how can "hole diameter"" be considered" if all listed dimensions
"shall be met"?
      The text below Figure 7 and Figure 8 includes the following:
      "Pad widths listed as reference dimensions are left open to the
      manufacturer to determine based on their internal design standards.
      In order to determine the pad widths for Surface Mount leads the
      following dimensions and tolerances shall apply:
      Solder Leads on 1.27mm spacing = 0.40+/-0.08mm
      Solder Leads on 0.80mm spacing = 0.30+/-0.05mm"
Question #3: How can Pad widths listed as reference dimensions are left
open to the manufacturer" and yet the next sentence states that "the
following dimensions and tolerances shall applyâ€?  Are they "open" or are
they defined?  They cannot be both.
      The text below Figure 8 also states the following:
      "Hole sizes listed as reference dimensions are left open to the
      manufacturer to determine based on their internal design standards.
      In order to determine the hole diameter for Solder Pins the following
      pin width dimensions and tolerances shall apply:
      Solder Pins on 1.27mm spacing = 0.40+/-0.08mm
      Solder Pins on 0.80mm spacing = 0.40+/-0.08mm"
Question #4:  How can "Hole sizes listed as reference dimensions are left
open to the manufacturerâ€ and yet the next sentence states that â€œthe
following dimensions and tolerances shall applyâ€  Once again, are they
"open" or are they defined?  They cannot be both.
Thank you in advance for taking the time to review these issues and
concerns.  I look forward to discussing them during today's teleconference.
Important Note, I must repeat: I do not see how statements regarding PCB
footprint in SFF-8482 can possibly be considered "normative" with all the
ambiguity contained in the sections reviewed above.
Best regards,
Fred A. Fons
Standards Development Manager
NWInG Sales, North America
Foxconn Electronics, Inc.
100 South 38th Street
Harrisburg, PA 17111-2220
Ph: +717-558-7518 Ext. 141
Fax: +717-558-9306
Cell: +717-460-1127
email: fred.fons at foxconn.com
www.foxconn.com
	     Alvin Cox							   
	     <alvin.cox at seagat						   
	     e.com>							To 
	     Sent by:		       T10 Reflector <t10 at t10.org>	   
	     owner-t10 at t10.org						cc 
								   Subject 
	     10/12/2011 06:27	       SAS PHY meeting reminder October    
	     PM 		       13, 10 am CDT			   
I have received a request for one item to be discussed:
Normative requirement for SAS drive backplane connector footprint.
Currently SFF-8482 is normative on the backplane connector footprint.
Formulti-sourcing should this apply to 12G as well? It was mentioned that
the footprint was more importanct than the receptacle on the last
conference call.
Additional items
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Topic: SAS PHY WG
Date: Thursday, October 13, 2011
Time: 10:00 am, Central Daylight Time (Chicago, GMT-05:00)
Meeting Number: 826 515 680
Meeting Password: newsas
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--
Alvin Cox
Seagate Technology, LLC
Cell 405-206-4809
Office 405-392-3738
E-MailÂ  alvin.cox at seagate.com
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