| | Orientation (Degrees) | Notes | | :--- | :--- | :--- | | Chip Components (R, C, L) | 0°, 90° | Orientation with end terminations along X or Y axis | | MELF Components | 0°, 90° | Similar to chips but with cylindrical body | | SOD, SOT, Small Outline Diodes/Transistors | 0°, 90° | Orientation defined by pin 1 position | | Small Outline Packages (SOP) | 0° | Body parallel to X-axis, pin 1 at top-left | | Quad Flat Packs (QFP) | 0° | Body parallel to X/Y axes, pin 1 at top-left | | Ball Grid Arrays (BGA) | 0° | Body parallel to X/Y axes, ball A1 at top-left | | Leadless Packages (QFN, DFN) | 0° | Orientation defined by pad 1 indicator |
Implementing IPC-7352 requires a comprehensive approach that involves:
IPC-7352 is so complex in its variables (accounting for manufacturing tolerances, placement accuracy, and solder paste types) that manual calculation is effectively obsolete. The standard pushed the industry toward fully automated CAD library generators. It forced software vendors to build "IPC Compliant" buttons into their tools that run the full IPC-7352 algorithm instantly.
Includes guidelines for newer package types like bottom-termination components (BTCs), high-pin-count arrays, and ultra-miniature passives. Ipc-7352 Pdf
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If you open the to Chapter 5 (Land Pattern Calculations), you will find formulas like:
While some online forums or file-sharing sites may host unofficial copies, these are unauthorized and may be outdated or contain errors. Always procure the standard from an official source to ensure you have the correct, unaltered content. For immediate reference, many distributors provide a free, downloadable table of contents (TOC) in PDF format , which is a valuable tool for reviewing the document's structure before purchase. | | Orientation (Degrees) | Notes | |
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In practice, when creating a footprint in these tools, the user defines the part's origin (often the center of the component body) and the zero-degree orientation. When the board is placed, the assembly data (e.g., a .pos file) will output the coordinates and the final rotation angle relative to that zero orientation.
Footprint dimensions are not arbitrary. They are calculated dynamically using the maximum and minimum material conditions of both the component terminal and the board fabrication process. The primary factors include: IPC - 7352 - Generic Guideline for Land Pattern Design Always procure the standard from an official source
Taking into account the tolerances of the component body and leads.
In the open-source community, the IPC-7352 specification influences library conventions. For example, it provides specific rules for polarity marking in its appendices, which can be referenced when creating or reviewing component libraries.