IEC PAS 63720:2026

• Abstract:

  IEC PAS 63720:2026 defines standardized routing parameter tables applicable to the design of rigid circuit board with mechanically or laser drilled vias.; These parameter tables are based on the concept of "Routing Classes" initially introduced in the French standard NF-93713 (1971-1989, cancelled: 2019). They are linked to the pitch of electronic components (e.g., BGA, QFN, connector, etc.) and thus allow a better coupling with component and circuit board manufacturers.; They can be easily integrated into EDA tools to facilitate the work of designers, while ensuring a common standard of communication between customers and manufacturers.; Routing classes should not be confused with IPC performance classes, which are used in the context of circuit board acceptance (IPC-A-600) as well as qualification and performance (IPC-6012) standards. Additional information on circuit board design is provided by IPC-2221 (Generic Standard on Printed Board Design), IPC-2222 (Sectional Design Standard for Rigid Organic Printed Boards) and IPC-2226 (Sectional Design Standard for High Density Interconnect (HDI) Printed Boards).; This document is based on French AFNOR Spec 2212 and was submitted as a PAS document.

• Status: Published
• Publication Date: 05-Aug-2026
• ICS: 31.180 - Printed circuits and boards
• ICS: 31.190 - Electronic component assemblies
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 12 - TC 91/WG 12
• Current Stage: PPUB - Publication issued
• Start Date: 06-Aug-2026
• Completion Date: 04-Sep-2026

IEC PAS 63720 ®
Edition 1.0 2026-08
PUBLICLY AVAILABLE
SPECIFICATION
Rigid circuit board - Routing parameters

ICS 31.180; 31.190 ISBN 978-2-8327-1426-3

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CONTENTS
CONTENTS . 1
FOREWORD . 3
1. Scope . 5
2. Definitions and conventions. 5
Definition of Routing Classes . 5
Conventions on parameters and values . 5
2.2.1. Parameter definitions . 5
2.2.2. Parameter values . 6
2.2.3. Terms and definitions . 6
3. Component packages and printed board structure . 8
Selection of the Routing Class according to the component package . 8
Board structure and Routing Classes . 9
4. Mechanical parameters . 10
Definitions . 10
4.1.1. Values . 10
4.1.2. Tolerances . 11
Illustrations . 12
Applicable parameters . 13
5. Conductor parameters. 13
Foreword . 13
Definitions . 14
5.2.1. Values . 14
5.2.2. Tolerances . 15
Illustration . 15
Applicable parameters . 16
6. Drilling parameters for plated-through holes and mechanically drilled vias . 17
Definitions . 17
Illustration . 18
Applicable parameters . 18
6.3.1. Minimum drilling diameter depending on the thickness to be drilled . 18
6.3.2. Minimum via pad diameters depending on the drilled hole . 19
6.3.3. Minimum pad diameters for plated-through holes for component insertion (by
soldering) . 19
7. Drilling parameters for laser-drilled microvias . 20
Definitions . 20
7.1.1. Values . 20
7.1.2. Tolerances . 20
Illustration . 21
Applicable parameters . 21
8. Solder mask parameters . 21
Definitions . 21
8.1.1. Values . 21
8.1.2. Tolerances . 22
Illustration . 22
Applicable parameters . 22
9. Ink marking parameters. 23
Definition . 23
Illustration . 24
Applicable parameters . 24

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Rigid circuit board - Routing parameters

FOREWORD
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IEC PAS 63720 has been prepared by IEC technical committee 91: Electronics assembly
technology. It is a Publicly Available Specification.
It is based on French AFNOR Spec 2212 and was submitted as a PAS document.
The text of this Publicly Available Specification is based on the following documents:
Draft Report on voting
91/2112/DPAS 91/2123/RVDPAS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Publicly Available Specification is English.
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specific document. At this date, the document will be
– reconfirmed,
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NOTE In accordance with ISO/IEC Directives, Part 1, IEC PASs are automatically withdrawn after 4 years.

1. Scope
This document defines standardized routing parameter tables applicable to the design of rigid circuit
board with mechanically or laser drilled vias.
These parameter tables are based on the concept of "Routing Classes" initially introduced in the French
standard NF-93713 (1971-1989, cancelled: 2019). They are linked to the pitch of electronic components
(e.g., BGA, QFN, connector, etc.) and thus allow a better coupling with component and circuit board
manufacturers.
They can be easily integrated into EDA tools to facilitate the work of designers, while ensuring a common
standard of communication between customers and manufacturers.
Routing classes should not be confused with IPC performance classes, which are used in the context
of circuit board acceptance (IPC-A-600) as well as qualification and performance (IPC-6012) standards.
Additional information on circuit board design is provided by IPC-2221 (Generic Standard on Printed
Board Design), IPC-2222 (Sectional Design Standard for Rigid Organic Printed Boards) and IPC-2226
(Sectional Design Standard for High Density Interconnect (HDI) Printed Boards).
2. Definitions and conventions
Definition of Routing Classes
Routing Classes (RC) are design rules for routing printed boards. This concept is based on the previous
NF C93-713 standard.
Each Routing Class, from RC1 to RC10 corresponds to a set of parameters that are compatible with a
given type of component package and consistent in terms of PCB manufacturing difficulty. A higher RC
allows for a greater level of component density, but implies a higher degree of manufacturing difficulty,
which increases costs, it can even makes production impossible. Classes RC1 and RC2 should only be
used for designs which contain conductors with high copper thicknesses
Class RC10 is given prospectively. Organic substrates for semiconductors or SiP (system in package)
requiring conductor widths/spacings above Class 10 are not covered in this document.
Routing Classes are not inspection criteria or quality requirements for the delivered product and
should therefore not be confused with control classes. Each user and manufacturer is
responsible for identifying the applicable Routing Classes according to the expected quality and
performance requirements for the end product.
Conventions on parameters and values
2.2.1. Parameter definitions
Routing Class parameters are divided into six main sections and identified by two letters. Uppercase
characters indicate a value, while lowercase characters specify a tolerance.
Table 1 - Parameters and conventions
Value Tolerance Section parameters
ME me MEchanical
CO co COnductors
VM (TM) vm (tm) Vias (Holes) - Mechanically drilled
UV uv UVia (microvia)
SM sm Solder Mask
MA ma MArking
Note: for each section, the parameters are identified by two letters and a number. For example, CO4 means
conductor parameter no. 4, while me13 means mechanical parameter no. 13 and represents a tolerance.
2.2.2. Parameter values
Values are associated in the tables for each parameter/Routing Class using the following conventions:
 The first value, shown, is the preferred value.
 An additional value in brackets, indicates a limit value that should not be exceeded and whose use
should be restricted as far as possible.
 Values in square brackets, indicate the possibility of choosing from the specified range of values.
 N/A (not applicable) or no value, means a non-recommended configuration.
2.2.3. Terms and definitions
2.2.3.1. Components
QFP (Quad Flat Package)* Pressfit Contact*
A generic rectangular component package, An electrical contact that can be pressed into a
containing an electronic device, with surface hole in an insulator or printed board with or
mount terminals on all four sides. without plated-through holes.
QFN (Quad Flat No-lead)* NSMD (Non-Solder Mask Defined)
A generic rectangular component package, The solder mask opening is larger than the
whose contours are terminated by metal lands
copper pads of the component's footprint.
on all four sides of the package base.
BGA (Ball Grid Array)* SMD (Solder Mask Defined)
A surface mount package, wherein the balls for The solder mask opening is smaller than the
terminations are formed in a grid, on the copper pads of the component's footprint.
underside of the package.
SMD (Surface-Mount Device)* Pitch*
A leaded or leadless device (part) that is The nominal center-to-center distance of
adjacent features (when the elements are of
capable of being attached to a printed board by
surface mounting. equal size and their spacing is uniform).
* Source: IPC-T-50M EN
2.2.3.2. Drilling and vias
Microvia*
Blind via*
A blind structure (as plated) with a maximum
A via that connects an outer layer to one or more
aspect ratio of 1:1 and terminating on, or
inner layers, but does not go through the entire
penetrating a target land, with a total depth (X)
printed board.
of no more than 0.25 mm [0.00984 in]. It is
measured from the structure's capture land foil
Buried via*
to the target land.
A via that does not extend to the surface of a
printed board.
Microvia/Via-in-pad
Mechanical via
Microvia or via with capture pad, within a
components copper pad.
A via drilled with a drill bit on mechanical drilling
equipment.
Aspect Ratio (Hole)*
Stacked via (microvia)*
The ratio of the length, or depth, of a hole to its
preplated diameter.
A structure formed by vertically aligning
vias/microvias, directly on top of each other (or
on top of a buried via).
Plated-Through Hole (PTH)*
Filled via*
A hole with plating on its walls, that makes an
electrical connection between conductive
A via filled with material applied into the via
patterns on internal layers, external layers, or
targeting full penetration and encapsulation of
both, of a printed board.
the hole.
Filled and capped via*
Via*
A plated structure formed by mechanical, laser A filled via with a secondary metallized coating
covering the via. The metallization is on both
or photo-defined means that is used as an
interlayer connection but is not intended for sides.
inserting a component lead or metallic part.

* Source: IPC-T-50M EN
2.2.3.3. End product and other processes
Sequentially-Laminated Multilayer Printed Hot Air (Solder) Leveling (HASL)
Board*
A physical deposition process using a solder
A multilayer printed board that is formed by bath, into which the printed board is immersed
laminating together, through-hole, plated in a bath of molten solder and withdrawn across
double-sided or multilayer boards. (Thus, some a set of hot air knives (forced hot air flow) to
of its conductive layers are interconnected with remove excess solder.
blind or buried vias).
Routing (milling)* V-Scoring*
A mechanical method that removes a portion of The machining of a shallow, precise V-shaped
the material outlining a printed board, using a groove into the top and bottom surfaces of the
cutting bit, in order to facilitate ease of breakout, laminate, in a straight line, in order to facilitate
(removal) from the manufacturing or assembly ease of breakout, (removal) from the
manufacturing or assembly panel.
panel.
Finished copper thickness End Product*
The finished copper thickness takes account of An individual part or assembly, in its final
the initial copper thickness (base copper), the completed state.
thickness after one or more copper platings and
thickness reductions due to the various
manufacturing processes.
* Source: IPC-T-50M EN
3. Component packages and printed board structure
Selection of the Routing Class according to the component
package
The conductor dimensions and spacings and therefore the Routing Classes (RC) to be used, are closely
linked to the layout and pitch of the package's lead pins.
The following tables show which RC should be used, depending on the type of package chosen and the
associated routing requirements. Other functional criteria may lead to a different routing class to the
recommended RC.
Wherever possible, use the lowest RC and limit the use of higher classes for local component routing.
When several RC are used for the same board, the highest RC (even used locally) defines the board's
RC and therefore its price.
The boxes marked with a tick () represent the recommended RC for the components mentioned. A
higher RC may be required in certain situations, such as the need to route two conductors between vias.
In addition, a lower RC may also be used if routing requirements are lower.

Table 2 - Preferred Routing Classes (RC) by component type
Routing Classes
Pitch
Component types
RC1-
(mm)
RC4 RC5 RC6 RC7 RC8 RC9 RC10
2,54  
1,27   
1,0    
0,8   
Matrix components (BGA or
similar)
0,65    
0,5     
0,4     
0,3     
> 0,5   
SMC: QFP, QFN,
connectors, discrete 0,5    
...