pcb_guideline
Table of Contents
bolay.co Library Convention
From Kicad Library Convention 0.8 - 19.01.2015
General Rules
- Writing uses C-style naming with the first letter of each word being capitalized. Ex: “Socket_Strip_Straight_2x06”
- Every acronym has all of its letters capitalized.
- Manufacturer name is capitalized as usual. Ex: NEC, Microchip
- When dimensions are used in part name, they are in millimeters, decimal places separated by a dot, and unit is not capitalized. Ex: “Cap_10x13mm_RM5”
- Filename is the same as the part name.
- The order of elements in names must be the same as the enumerations presented in this document.
Symbol Library Names
- Manufacturer.
- Category or family of parts. ex: “Capacitors”, “Spartan6”, etc.
General Rules for Symbols
- Using a 100mil grid, pin ends and origin must lie on grid nodes (IEC-60617).
- Pin has a length of 100mil or more in increments of 50mil if number needs more space.
- Origin is placed in the middle of symbol.
- Black-box components group pins logically, for example by function set, and ports in counter-clockwise position.
- Whenever possible, inputs are on the left and outputs are on the right.
- Field text uses a common size of 50mils.
- The reference field is prefilled with the reference designator of the symbol (IEEE 315-1975).
- The Value field is prefilled with the object name.
Symbol Names
- Name of symbol, may be shortened for common components or use reference designator of the symbol (IEEE 315-1975). ex: “Conn_4x2”, “C”, etc.
- Manufacturer.
- Part number, including extension for specific footprint. (JEDEC for common devices, ex: 1N4001)
- Any modification to the original symbol, indicated by appending the reason. Ex: different pin ordering: “Transistor_PNP_Pinswap1”
- Indication of quantity if symbol is an array. ex: resistor array: “Resistor_x8”
Footprint Library Names
- Part type (resistor, cap, etc), must be in plural form.
- Package type (SOIC, SMD, etc).
- Manufacturer.
- Part number.
General Rules for Footprints
Footprint tutorial : http://www.brorson.com/gEDA/land_patterns_20070818.pdf
- Follows datasheet recommendation unless intentional variation, for example longer pads for hand soldering.
- Pad 1 is on the left first, then at the top, except at the top for PLCC (IPC-7351).
- For through-hole components, footprint anchor is set on pad 1.
- For surface-mount devices, footprint anchor is placed in the middle with respect to device lead ends. (IPC-7351)
- Silkscreen is not superposed to pads, its outline is completely visible after board assembly, uses 0.15mm line width and provides a reference mark for pin 1. (IPC-7351)
- Courtyard line has a width 0.05mm. This line is placed so that its clearance is measured from its center to the edges of pads and body, and its position is rounded on a grid of 0.05mm.
- Courtyard clearance is 0.25mm except for components smaller than 0603 at 0.15mm, connectors, SMD canned capacitors and crystals at 0.5mm and BGA at 1.0mm. (IPC-7251, IPC-7351B)
- Cannot be duplicated to match a different pin ordering. This is to be handled in the symbol libraries.
- Footprint name must match its filename. (.kicad_mod files)
- The value and reference designator must be placed on silkscreen.
Names for footprints of Surface-Mount Devices (SMD)
- Specific package feature first, not separated by anything. Ex: “TSSOP”
- Package name, numbers separated from letters using hyphen. Ex: “SOT-89”
- Variation of package, separated by another hyphen. Ex: SOT-23 with 5 pins: “SOT-23-5”, Exposed pad under package: “QFP-48-1EP”
- If it's a manufacturer-specific package, name can be appended, separated by an underscore.
- Any modification to the original footprint, indicated by appending the reason. Ex: longer pads used to facilitate hand soldering of a QFN component: “QFN-52_HandSoldering”
Names for footprints of common devices, such as resistors, capacitors, etc
- Name of part, may be shortened for common components. ex: “Cap”, “Socket_Strip”, etc.
- Dimension, which may include at its end the positioning. Ex: “5x7mm_Horiz”, “1x02_Angled”
- Pad distance, in the form of an RM rating.
- Any modification to the original footprint, indicated by appending the reason.
Names for footprints of specific devices
- Name of part.
- Part number. Ex: “Oscillator_SI570”
- Any modification to the original footprint, indicated by appending the reason.
pcb_guideline.txt · Last modified: 2015/02/09 16:03 by sdolt