BIRD 37 Enhancement To The Package Model Spec.

To All:

Below is BIRD37 from Stephen Peters which is a proposed update to BIRD28.3.

Bob Ross
Interconnectix, Inc.

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                 Buffer Issue Resolution Document (BIRD)
BIRD ID#: 37
ISSUE TITLE: Enhancement To The Package Model (.pkg file) Specification
REQUESTER: Stephen Peters
DATE SUBMITTED: June 23, 1996
DATE ACCEPTED BY IBIS OPEN FORUM: Pending

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STATEMENT OF THE ISSUE: The current package model electrical description,
(as proposed in Bird 28.3 and accepted by the forum) has the restriction
that all the sections of a package stub connect in a series fashion, with
no branches or stubs allowed. This limits the usefulness of the
description when trying to describe BGA or other packages where branches
or forks off the main package stub may be present. This BIRD corrects
this deficiency by adding two new subparameters to the [Pin Numbers] keyword
called 'Fork' and 'Endfork'
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STATEMENT OF THE RESOLVED SPECIFICATIONS: Following are the specific changes
to the specification (spec as amended by Bird 28.3).

1. The Sub-params list of the [Pin Numbers] keyword is changed to that
shown below

|Sub-Params: Len, L, R, C, Matrix, Fork, EndFork

2. The text following the first paragraph of the Usage Rules section of the
[Pin Numbers] keyword is replaced by the following:
|
| Subparameters:
| The Len, L, R, and C subparameters specify the length,
| inductance, capacitance and resistance of each section of
| each stub on a package. If a particular section
| exhibits coupling to an adjacent (same numbered) section of
| a different package stub then the Matrix subparameter is used.
| The Fork and Endfork subparameters are used to denote branches
| from the main package stub.
| Len The of a package stub section. Lengths are given
| in terms of arbitrary 'units'.
| L The inductance of a package stub section, in terms of
| 'inductance/unit length'. For example, if the total
| inductance of a section is 3.0nH and the
| length of the section is 2 'units', the inductance
| would be listed as L = 1.5nH (i.e. 3.0 / 2).
| C The capacitance of a package stub section, in terms of
| capacitance per unit length.
| R The DC (ohmic) resistance of a package stub section, in
| terms of ohms per unit length.
| Matrix Use of this subparameter means that this package stub
| section's electrical parameters are presented as part of
| a coupling matrix. The data for the matrix is included
| between the [Model Data]/[End Model Data] keyword pairs
| as described below.
| Fork This subparameter indicates that the sections
| following (up to the Endfork subparameter) are part
| of a branch off of the main package stub. This
| subparameter has no arguments.
| Endfork This subparameter indicates the end point of a
| branch. For every Fork subparameter there must be
| a corresponding Endfork subparameter. As with the
| Fork subparameter, the Endfork subparameter has no
| arguments.
|
| Specifying a Len or L/R/C value of zero is allowed. If
| Len = 0 is specified, then the L/R/C values are the total
| for that section. If a non-zero length is specified, then
| the total L/R/C for a section is calculated by multiplying
| the value of the Len subparameter by the value of the L,
| R or C subparameter.
|
| Using The Subparameters to Describe Package Stub Sections:
| A section description begins with the Len subparameter and
| end with the backslash (/) character. The value of the Len, L,
| R and C subparameters and the subparameter itself are
| separated by an equals sign (=); whitespace around the equals
| sign is optional. The Fork and Endfork subparameters
| are placed between section descriptions (i.e. between the
| concluding backslash of one section and the 'Len' parameters
| that starts another) and are delimited from the section
| descriptions by a backslash. All package stub descriptions must
| contain the same number of sections however, a particular
| section description can contain no data (i.e. the description
| is given as 'Len = 0 /').
|
| Legal Subparameter Combinations for Section Descriptions:
| A) A single Len = 0 subparameter, followed by a slash.
| The is used to describe a section with no data.
|
| B) Len and a single Matrix subparameter, followed by a
| backslash. The Len subparameter specifies the length of that
| section while the Matrix subparameter indicates that this
| section of this package stub is electrically coupled to the
| corresponding (same numbered) section of an adjacent package
| stub (or stubs) and the coupling terms are listed in a matrix
| format. The matrix description must include both the 'self'
| inductance/capacitance/resistance (as required) of a section
| as well as the mutual coupling terms. If one section is
| described using the the Matrix subparameter then the
| corresponding (same numbered) sections on ALL other package
| stubs must use the Matrix subparameter.
|
| C) Len, and one or more of the L, R and C subparameters. If
| the Len subparameter is given as zero, then the L/R/C sub-
| parameters represent lumped elements. If the the Len sub-
| parameter is non-zero, then the L/R/C subparameters represent
| distributed elements.
|
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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION:
     This bird grew out of the need to describe a particular structure found
in BGA type packages. In these packages, the trace that connects the die
pad to the via for the 'ball' does not stop there. For manufacturing
reasons the trace continues out to the edge of the board and thus forms
a 'stub' or branch off the main pad to ball (or pin) connection. Because
of the need to stick with the existing section based description, the
fork and endfork subparameters were chosen.
Received on Mon Jun 24 11:10:18 1996