IPC-2222 Explained: Design Standard for Rigid Organic PCBs

You’ve got your IPC-2221 down cold—conductor spacing, clearance requirements, material basics. But when it comes to actually designing a rigid multilayer board, you’re finding that the generic standard only gets you so far. Where are the specific rules for PTH aspect ratios? What about scoring depths for panelization? How do you specify laminate requirements for lead-free assembly?

That’s where IPC-2222 comes in. This sectional design standard picks up where IPC-2221 leaves off, providing the rigid board-specific requirements that turn generic design principles into manufacturable products. If you’re designing anything from a simple two-layer board to a complex multilayer stackup on FR-4 or similar rigid materials, IPC-2222 is your companion document.

What Is IPC-2222?

IPC-2222 is the sectional design standard for rigid organic printed boards, officially titled “Sectional Design Standard for Rigid Organic Printed Boards.” It establishes specific requirements for designing single-sided, double-sided, and multilayer rigid PCBs using organic laminate materials.

The key word here is “sectional”—IPC-2222 doesn’t replace IPC-2221, it supplements it. You need both documents working together: IPC-2221 for generic requirements (conductor spacing, clearance, creepage) and IPC-2222 for rigid board-specific rules (laminate properties, hole requirements, mechanical tolerances).

IPC-2222 Version History

The current version, IPC-2222B, reflects modern manufacturing capabilities including advanced via structures, tighter tolerances, and materials compatible with lead-free assembly processes.

IPC-2222 Standard Overview

How IPC-2222 Works with IPC-2221

Understanding the relationship between these two standards is critical. They’re designed as a layered system where IPC-2221 provides the foundation and IPC-2222 adds rigid board-specific details.

IPC-2221 vs IPC-2222: What Each Standard Covers

When a requirement exists in IPC-2221, IPC-2222 typically references it rather than repeating it. When IPC-2222 provides a requirement, it takes precedence for rigid board designs.

When to Use IPC-2222 vs Other Sectional Standards

If your board is rigid and doesn’t fall into a specialized category (HDI, RF, embedded components), IPC-2222 is your sectional standard.

IPC-2222 Board Type Classifications

IPC-2222 defines six distinct board types based on layer count and via complexity. This classification system helps designers select appropriate design rules and helps manufacturers understand fabrication requirements.

Type 1 Through Type 6 Definitions

Selecting the Right Board Type

The type classification affects not only design rules but also cost and lead time. Type 5 and 6 boards require sequential lamination processes and more complex fabrication, increasing both price and manufacturing time.

Material Selection per IPC-2222

IPC-2222 provides specific guidance on selecting rigid laminate materials based on electrical, thermal, and mechanical requirements. Material selection directly impacts reliability, especially for lead-free assembly processes.

Laminate Material Properties

Common Rigid Laminate Materials

IPC-2222 emphasizes that material selection must consider the entire product lifecycle—not just the operating environment, but assembly processes including reflow temperatures. For lead-free assembly (peak temps around 260°C), high-Tg materials are essentially mandatory.

Lead-Free Material Requirements

Mechanical Requirements in IPC-2222

IPC-2222 establishes dimensional and mechanical requirements specific to rigid boards, including thickness tolerances, board dimensions, and fabrication allowances.

Board Thickness Tolerance

Thickness tolerance affects impedance control—thicker or thinner dielectric changes the characteristic impedance of your traces. For controlled impedance designs, tighter tolerances or impedance testing may be necessary.

Bow and Twist Requirements

Surface mount assemblies require flatter boards because excessive bow or twist can cause solder joint defects during reflow. IPC-2222 specifies tighter requirements for SMT applications.

Read more IPC Standards:

MIL-PRF-38534: Hybrid Microcircuits Military Specification Guide for Engineers

MIL-PRF-31032: The Definitive Guide to Military-Grade PCB Requirements

MIL-PRF-19500: Military Semiconductor Device Specification Explained

MIL-PRF-123: High-Reliability Ceramic Capacitor Military Standard

MIL-I-46058CMIL-I-46058C: Military Conformal Coating Specification Complete Guide

MIL-HDBK-263: ESD Control Handbook & Implementation Guide

J-STD-075 Guide: PSL Classification for Passive Components & Assembly Process Limits

J-STD-035 Guide: Acoustic Microscopy for IC Package Inspection & Defect Detection

J-STD-033 Guide: MSD Handling, Floor Life, Baking & Dry Storage Requirements

J-STD-032 Explained: Ball Grid Array Ball Construction & Performance Specs

J-STD-027 Guide: Mechanical Outline Standard for Flip Chip & CSP Packages

J-STD-020 Guide: MSL Classification, Reflow Profiles & Moisture Sensitivity Testing

IPC/WHMA-A-620 Explained: Complete Guide to Cable & Wire Harness Standards

IPC-SG-141: Complete Guide to S-Glass Fabric Specifications for PCB Laminates

IPC-QF-143: Complete Guide to Quartz Fabric Specifications for RF/Microwave PCB Laminates

Hole and Via Requirements

One of the most valuable sections of IPC-2222 covers hole and via design—requirements that go well beyond what IPC-2221 provides.

Plated-Through Hole (PTH) Requirements

Aspect Ratio Guidelines

Higher aspect ratios make plating more difficult. The plating solution struggles to reach the center of deep, narrow holes, potentially creating thin spots or voids that cause reliability issues.

Land (Pad) Requirements

The annular ring is the copper remaining around a hole after drilling. Insufficient annular ring can cause lifted pads or unreliable connections—IPC-2222 specifies minimums based on product class.

Dielectric Spacing Requirements

IPC-2222 provides requirements for dielectric spacing between conductive layers, which affects both electrical performance and manufacturability.

Minimum Dielectric Thickness

Thinner dielectrics enable tighter coupling for impedance control but increase manufacturing difficulty and cost. IPC-2222 balances electrical requirements against practical fabrication constraints.

Clearance Areas in Planes

Plane clearances prevent shorts during drilling and provide manufacturing margin for registration tolerances.

Scoring and Routing Guidelines

For panelized boards, IPC-2222 provides specific requirements for scoring (V-groove) and routing (tab-route) separation methods.

V-Score Requirements

V-scoring is cost-effective for straight edges but creates stress during depanelization that can damage nearby components or traces.

Tab Routing Requirements

Tab routing with mouse bites provides cleaner edges and less mechanical stress but costs more than V-scoring.

Assembly Design Considerations

IPC-2222 includes DFM (Design for Manufacturability) guidance specific to rigid board assembly.

Component Placement Guidelines

Fiducial Requirements

Fiducials enable accurate machine vision alignment during automated assembly. IPC-2222 specifies requirements that ensure reliable pick-and-place operation.

Tools and Resources for IPC-2222

Official Documentation

Related IPC Standards

Design Software Integration

Most PCB design software doesn’t directly import IPC-2222 requirements—you need to translate the standard’s requirements into your tool’s design rule format.

Frequently Asked Questions About IPC-2222

Do I need both IPC-2221 and IPC-2222 for rigid board design?

Yes. IPC-2222 is a sectional standard that supplements—not replaces—IPC-2221. You need IPC-2221 for generic requirements like conductor spacing, clearance, and creepage, plus IPC-2222 for rigid board-specific requirements like hole aspect ratios, laminate properties, and mechanical tolerances. Using IPC-2222 alone will leave gaps in your design specification.

What’s the difference between IPC-2222 board Types 4, 5, and 6?

All three are multilayer boards, but they differ in via complexity and design requirements. Type 4 uses only through-hole vias—the simplest multilayer construction. Type 5 adds blind and buried vias for higher routing density. Type 6 includes controlled impedance requirements for high-speed designs. Each successive type adds complexity, cost, and manufacturing lead time.

Which laminate Tg should I specify for lead-free assembly?

For lead-free assembly with peak reflow temperatures around 260°C, specify high-Tg laminate with Tg ≥170°C. Standard FR-4 (Tg 130-140°C) may survive lead-free reflow but offers minimal margin and increased risk of delamination or barrel cracking. Mid-Tg materials (150-160°C) are borderline. High-Tg provides the reliability margin most applications need.

How does IPC-2222 relate to IPC-6012 for board qualification?

IPC-2222 covers design requirements—what you specify in your documentation. IPC-6012 covers qualification and performance—how the fabricated board is tested and accepted. They work together: design per IPC-2222, qualify and accept per IPC-6012. Your fabrication drawing should reference both standards along with the applicable product class.

Can I use IPC-2222 for HDI boards with microvias?

IPC-2222 covers standard rigid boards including those with blind and buried vias (Type 5). However, for true HDI designs with microvias, sequential lamination complexity, and via-in-pad structures, IPC-2226 is the appropriate sectional standard. If your design uses laser-drilled microvias or stacked/staggered microvia structures, reference IPC-2226 instead of or in addition to IPC-2222.

Designing Rigid Boards with Confidence

IPC-2222 fills the gap between generic design principles and manufacturable rigid boards. It answers the specific questions that come up during rigid PCB design—questions that IPC-2221 alone can’t address.

Start your designs by selecting the appropriate board type (1-6) based on your complexity requirements. Choose materials that meet your thermal and electrical needs, paying particular attention to Tg for lead-free compatibility. Apply the hole and via requirements to ensure reliable interconnections. Use the mechanical tolerances to set appropriate expectations with your fabricator.

The standard has evolved through multiple revisions to keep pace with manufacturing technology and assembly processes. IPC-2222B reflects current capabilities for high-density designs, lead-free assembly, and complex via structures. Combined with IPC-2221 for generic requirements, it provides a complete specification framework for rigid organic printed boards.

Remember that IPC-2222 represents minimum requirements and industry consensus—your specific application may demand tighter tolerances or additional requirements. Use the standard as your foundation, then add application-specific requirements as needed to ensure your design meets its performance goals.