IPC-222x - Basic Standards for Electronics Design

Introduction

Designing electronics is not an easy task. Developing the product concept, selecting components, choosing assembly technologies, creating the PCB layout, and performing many other analyses and tests are only part of the process. A product should not only meet functional, legal, aesthetic, and cost requirements - it shall be easy to build and reliable. This is where methods like: DFM, DFA, and DFR come into play. It is very important to remember that these are just part of the broader concept known as Design for Excellence (DFX).

In this context (when designing electronic devices) it is worth to know the group of basic IPC standards related to PCB design, namely the IPC-2220 series, referred to as IPC-222x, where "x" represents a number: 1, 2, 3, and so on. These standards help to address many manufacturing, quality, and reliability issues in advance. As a result, you may reduce the number of design changes (interations) and shorten the time-to-market for new products.

It is also worth remembering that the current revision status of IPC standards can be verified on the IPC Document Revision Table.[1]

So, now let's dive into the topic...

IPC-2221

IPC-2221 Generic Standard on Printed Board Design is the main document in the IPC-2220 series, describing the general principles of printed board design regardless of technology. The standard includes, among other things, requirements for minimum spacing between traces, guidelines for selecting trace widths based on current and temperature rise, rules for designing pads and vias, as well as various types of coupons for PCB quality control.[2]

This document serves as the foundation, while the other standards in this series should be treated as supplements specific to a given PCB technology.

IPC-2222

IPC-2222 Sectional Design Standard for Rigid Organic Printed Boards addresses specific requirements for rigid boards. This document provides recommendations on material selection (e.g., glass transition temperature Tg, prepreg choice, dielectric thickness), as well as trace routing, vias, laminate thickness tolerances, and other aspects related to manufacturability (DFX).

In its scope (section 1 of the document), IPC-2222 states that the standard supports the PCB designers in achieving a goal of "first design iteration work as intended".[3]

IPC-2223

IPC-2223 Sectional Design Standard for Flexible/Rigid-Flexible Printed Boards. This standard defines specific requirements for flexible and rigid-flex boards.

The document discusses material selection and their mechanical and physical properties (e.g., the use of stiffeners, design limitations related to bending and assembly cycles, the impact of moisture), electrical parameters (e.g., impedance control), recommendations for thermal aspects, manufacturability, hole and interlayer connection geometry, conductor routing, as well as topics related to documentation and quality assurance.[4]

IPC-2224

IPC-2224 Sectional Standard for Design of PWBs for PC Cards. This document contains general requirements for PCB design in the form of PC cards. It covers design aspects and requirements related to material selection (e.g., laminates, copper foil, coatings, solder mask), electrical parameters, thermal considerations, component assembly, and PC card layout recommendations.[5]

This standard is outdated and will not be further developed. It has the status of Obsolete.[1]

IPC-2225

IPC-2225 Sectional Design Standard for Organic Multichip Modules (MCM-L) and MCM-L Assemblies defines design requirements specific to MCM-L modules, meaning silicon structures and small passive electronic components mounted on laminate (Laminated MCM) using technologies such as Wire Bonding, Die Bonding, or Flip-Chip.

Similar to the standards discussed earlier, this document covers detailed issues related to material selection, coatings, layout, quality control, and more.

Fun fact: MCM-L modules are technically very similar to the "Chip On Board" (COB) approach. The main difference lies in their application. COB is typically a complete, purpose specific modules, known as Application Specific Electronic Assemblies (ASEA). The MCM-L represents subsystems that are assembled into a specific device. In IPC-2225, MCM-L modules are referred to as Application Specific Electronic Modules (ASEM).[6]

IPC-2225 is no longer being developed and has the status: "No Longer Maintained."[1]

IPC-2226

IPC-2226 Sectional Design Standard for High Density Interconnect (HDI) Printed Boards. Boards classified as High Density Interconnect (HDI) have technologies such as microvias, trace widths ≤0.1 mm, spacing between traces ≤0.1 mm, and similar design rules. IPC-2226 categorizes HDI constructions into six types (Type I–VI) depending on their structure.[7]

In summary, IPC-2226 defines the requirements for HDI PCB design, including material selection, sizing and placement of microvias, layout recommendations, thermal considerations, and a wide range of other guidelines.

IPC-2226 (latest rev A, 09/2017) is listed in the IPC revision table with the status "No Longer Maintained."[1]

IPC-2228

IPC-2228 Sectional Design Standard for High Frequency (RF/Microwave) Printed Boards. This standard defines specific requirements for the design of PCBs operating in the radio frequency and microwave range, where traces shall be considered as transmission lines rather than ordinary electrical connections.[8]

The IPC-2228 standard is applied to the design of RF/microwave products, where PCB materials shall meet the requirements of IPC-4103, and the PCB itself shall be manufactured in accordance with IPC-6018.

Other IPC standards

In addition to the IPC-222x series, it is also worth considering other IPC standards related to electronics design. Here are a few interesting examples:

• IPC-7351 Generic Requirements for Surface Mount Design and Land Patterns
• IPC-7352 Guideline for Surface Mount Design and Land Patterns
• IPC-2141 Controlled Impedance Circuit Boards and High Speed Logic Design
• IPC-7095 Design and Assembly Process Implementation for BGAs
• IPC-7093 Design and Assembly Process Implementation for Bottom Termination Components (BTCs)

Summary

Smart design means (among other things) designing based on IPC standards. The IPC-222x series structures the requirements from general principles to detailed topics (rigid, flex, HDI, SiP, ceramics). Combining these guidelines with DFX practices, PCB manufacturer recommendations, and quality engineering related methods such as APQP, D-FMEA, SPC, and MSA delivers measurable results: fewer design changes, shorter project implementation time, and higher product reliability.

When designing any devices (including NPI / starting production), I recommend applying Elon Musk's approach, which I described in the article: Five-step Design Method by Elon Musk. I also strongly recommend performing a D-FMEA risk analysis, it is truly an excellent tool when applied correctly.