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IPC-7352 Mathematical Model

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: PCB Libraries Guideline
Forum Description: (online edition)
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=3675
Printed Date: 03 Oct 2026 at 9:31pm


Topic: IPC-7352 Mathematical Model
Posted By: Nick B
Subject: IPC-7352 Mathematical Model
Date Posted: 20 Aug 2026 at 11:00am
The IPC-7352 standard defines the mathematical model for creating reliable surface mount (SMD) PCB footprints by providing formulas to calculate pad width (X), pad spacing (G), and pad span (Z), based on component dimensions, solder fillet goals, and manufacturing tolerances.

The following images illustrate potential pad and terminal relationships under various Material Conditions - Minimum, Nominal, and Maximum.

  1. The Nominal Material condition of the component package & Nominal Terminal.
  2. The Minimum Material condition of the component package & Nominal Terminal.
  3. The Maximum Material condition of the component package & Nominal Terminal.
  4. The Minimum Material condition of the component package & Minimum Terminal.
  5. The Maximum Material condition of the component package & Maximum Terminal.


    The resulting pad stack must have terminal leads on the pad stack regardless of every possible Material Condition possible to pass assembly inspection and meet the requirements set forth in the IPC J-STD-001 Standard and the IPC-7352 Guideline.

    i.e.: regardless of the Component Package and Terminal Lead Material Condition, the Terminal Lead must never be exposed outside the calculated pad stack.

    Note: most component packages are created in the Nominal Material Conditions. The package tolerances play a key role in the resulting pad stack.

  6. Nominal Package Dimensions & no Package Tolerances.
The Footprint Expert uses the IPC-7352 Mathematical Model.
For details, see https://shop.ipc.org/ipc-7352/ipc-7352-standard-only/Revision-0/english - IPC-7352 .



FOOTPRINT EXPERT GUIDELINE Topics
https://www.pcblibraries.com/forum/terms-and-definitions_topic3672.html - Terms & Definitions         https://www.pcblibraries.com/forum/component-descriptions_topic3673.html - Component Descriptions         https://www.pcblibraries.com/forum/threetier-density-levels_topic3674.html - Three-Tier Density Levels
https://www.pcblibraries.com/forum/ipc7352-mathematical-model_topic3675.html - IPC-7352 Mathematical Model        Solder Joint Goal Tables: [ https://www.pcblibraries.com/forum/surface-mount-solder-joint-goal-tables-min-max_topic3676.html - Min/Max ] [ https://www.pcblibraries.com/forum/solder-joint-goal-tables-for-nominal-calculation_topic3677.html - Nominal ]
https://www.pcblibraries.com/forum/manufacturer-recommended-patterns_topic3678.html - Manufacturer Recommended         https://www.pcblibraries.com/forum/throughhole-terminals_topic3679.html - Through-hole Terminals         https://www.pcblibraries.com/forum/courtyard-excess_topic3680.html - Courtyard Excess
https://www.pcblibraries.com/forum/pcbl-footprint-naming-convention-surface-mount_topic3681.html - PCBL Footprint Convention: SM        IPC-7352 Naming Convention: [ https://www.pcblibraries.com/forum/ipc7352-footprint-naming-convention-throughhole_topic3682.html - Footprint TH ] [ https://www.pcblibraries.com/forum/ipc7352-pad-stack-naming-convention_topic3685.html - Pad Stack ]
https://www.pcblibraries.com/forum/oda-pad-stack-naming-convention_topic3686.html - ODA Pad Stack Convention         https://www.pcblibraries.com/forum/terminal-lead-forms_topic3687.html - Terminal Lead Forms         https://www.pcblibraries.com/forum/pad-shapes_topic3688.html - Pad Shapes         https://www.pcblibraries.com/forum/design-units_topic3689.html - Design Units
https://www.pcblibraries.com/forum/fpx-file-definition_topic3690.html - FPX File Definition         https://www.pcblibraries.com/forum/smd-pad-stack-rules_topic3691.html - SMD Pad Stack Rules         https://www.pcblibraries.com/forum/drafting-outlines-polarity-marking_topic3692.html - Drafting Outlines & Polarity Marking
https://www.pcblibraries.com/forum/package-and-terminal-tolerances_topic3693.html - Package & Terminal Tolerances         https://www.pcblibraries.com/forum/zero-component-orientation_topic3694.html - Zero Component Orientation
https://www.pcblibraries.com/forum/standard-reference-designators_topic3695.html - Standard Reference Designators        Component Families: [ https://www.pcblibraries.com/forum/surface-mount-component-families_topic3696.html - Surface Mount ] [ https://www.pcblibraries.com/forum/throughhole-component-families_topic3697.html - Through-hole ]



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