IPC-2292 Guide: SPEDs, Design Rules & Requirements for Flexible Printed Electronics

If you’re designing printed electronics on flexible substrates, IPC-2292 is the document you need on your desk. Unlike general guidelines, this 72-page standard establishes specific design requirements that separate compliant products from rejected ones. After years of working with flexible circuits and printed electronics, I can tell you that understanding IPC-2292 thoroughly will save you countless revision cycles and qualification headaches.

This guide breaks down everything you need to know about IPC-2292, from Standard Printed Electronic Designs (SPEDs) to substrate selection, printing processes, and how this standard fits into the broader printed electronics ecosystem.

What is IPC-2292?

IPC-2292, titled “Design Standard for Printed Electronics on Flexible Substrates,” establishes specific requirements for designing printed electronic applications on flexible materials. Released in May 2018 with Revision A published in 2022, this 72-page document covers component mounting, interconnecting structures, and design classifications for flexible printed electronics.

The key word here is “standard” rather than “guideline.” While IPC-2291 provides advisory guidance for printed electronics design processes, IPC-2292 sets mandatory requirements. When a procurement document specifies IPC-2292 compliance, you must meet these requirements, not just consider them.

Document Attribute	IPC-2292 Details
Full Title	Design Standard for Printed Electronics on Flexible Substrates
Document Type	Design Standard (mandatory requirements)
Page Count	72 pages
Original Release	May 2018
Current Revision	IPC-2292A (2022)
Developed By	Flexible Printed Electronics Design Standard Task Group

IPC-2292 specifically addresses flexible substrates with bendability but excludes stretchable materials like fabrics, textiles, and stretchable polymers. Those applications fall under IPC-8952 for e-textiles.

IPC-2292 Scope: What Flexible Substrates Are Covered

Understanding the scope of IPC-2292 is critical before starting any design work. The standard covers materials with flexibility or bendability that are not rigid, but explicitly excludes stretchable substrates.

Flexible Substrates Within IPC-2292 Scope

Substrate Type	Typical Thickness	Max Processing Temp	Common Applications
Polyimide (PI)	12.5 – 125 µm	400°C	Aerospace, medical, automotive
PET (Polyethylene Terephthalate)	25 – 125 µm	150°C	Consumer electronics, RFID
PEN (Polyethylene Naphthalate)	25 – 125 µm	200°C	Displays, sensors
Paper	50 – 200 µm	150°C	Smart packaging, disposable electronics
Thin glass	25 – 100 µm	600°C	High-frequency, optical applications

Materials Outside IPC-2292 Scope

The following materials require different standards:

Material Type	Applicable Standard	Notes
Textiles and fabrics	IPC-8952	For coated/treated e-textiles
Stretchable polymers	IPC-8952	TPU, PDMS, silicone elastomers
Rigid substrates	IPC-2221/2222	Traditional PCB design standards
Knitted e-textiles	IPC-8921	Conductive yarn integration

This distinction matters because applying IPC-2292 to stretchable substrates will result in designs that cannot meet the standard’s requirements. The mechanical behavior of stretchable materials fundamentally differs from flexible-only substrates.

Standard Printed Electronic Designs (SPEDs) Explained

One of IPC-2292’s most valuable contributions is defining three Standard Printed Electronic Designs (SPEDs). These classifications help designers, manufacturers, and customers communicate using common terminology.

SPED 1: Single-Layer Printed Electronics

SPED 1 represents the simplest printed electronics construction. It consists of a single conductive layer printed on a flexible substrate, typically with a protective overcoat.

Typical SPED 1 Applications:

• RFID antennas and tags
• Simple touch sensors
• Membrane switches
• Basic heating elements
• Single-layer capacitive sensors

SPED 1 Design Considerations:

• No crossover capability without jumpers
• Limited circuit complexity
• Lowest manufacturing cost
• Fastest production times

SPED 2: Multi-Layer Printed Electronics

SPED 2 allows for multiple conductive layers with dielectric separation, enabling more complex circuit designs including crossovers and improved signal routing.

Typical SPED 2 Applications:

• Multi-zone touch interfaces
• Complex sensor arrays
• Display backplanes
• Printed transistor circuits
• Smart labels with logic functions

SPED 2 Design Considerations:

• Requires via or through-connections between layers
• Dielectric layer quality critical for reliability
• Registration accuracy between layers essential
• Higher manufacturing complexity than SPED 1

SPED 3: Three-Dimensional Printed Electronics

SPED 3 covers printed electronics processes that fully build and functionalize devices in three-dimensional space. This includes conformal printing on non-planar surfaces and stacked structures.

Typical SPED 3 Applications:

• In-mold electronics (IME)
• Conformal antennas on curved housings
• 3D printed electronic devices
• Structural electronics
• Integrated sensor housings

SPED 3 Design Considerations:

• Requires specialized printing equipment (aerosol jet, 3D printing)
• Substrate geometry affects print quality
• Complex process control requirements
• Highest manufacturing cost and complexity

SPED Classification	Layers	Complexity	Typical Cost	Production Volume
SPED 1	Single	Low	Lowest	High volume
SPED 2	Multiple	Medium	Moderate	Medium volume
SPED 3	3D/Conformal	High	Highest	Low-medium volume

IPC-2292 Product Classifications: Class 1, 2, and 3

Like traditional PCB standards, IPC-2292 recognizes three end-product classes based on reliability requirements and intended use. The class you specify determines acceptance criteria, testing requirements, and inspection frequency.

Class 1: General Electronic Products

Class 1 applies to printed electronics where the primary requirement is function of the completed assembly. Cosmetic imperfections are acceptable if they don’t affect electrical performance.

Class 1 Application Examples:

• Disposable medical sensors
• Promotional items with printed electronics
• Short-life consumer products
• Basic smart packaging
• Educational demonstration devices

Class 2: Dedicated Service Electronic Products

Class 2 covers products requiring extended performance and longer life where uninterrupted service is desired but not critical. Some cosmetic imperfections are permitted within defined limits.

Class 2 Application Examples:

• Commercial wearable devices
• Industrial sensors
• Consumer electronics with printed components
• Automotive interior lighting
• Smart home devices

Class 3: High-Reliability Electronic Products

Class 3 is reserved for applications where continued performance or performance-on-demand is critical. Equipment downtime cannot be tolerated, and the printed electronics must function when required.

Class 3 Application Examples:

• Medical implantable devices
• Aerospace systems
• Military applications
• Life-support equipment
• Critical infrastructure monitoring

Requirement	Class 1	Class 2	Class 3
Cosmetic defects	Allowed if functional	Limited	Minimal
Testing frequency	Basic	Moderate	Extensive
Documentation	Standard	Enhanced	Full traceability
Inspection criteria	Relaxed	Standard	Stringent
Process control	Basic	Documented	Statistical process control

Printed Electronics Types in IPC-2292

IPC-2292 defines printed electronics types based on the printing process and how the technology integrates with conventional electronics. The printed electronics type must be specified in procurement documents.

Type 1: Printed Circuitry Only

Type 1 uses printing processes to create conductive interconnects and passive components, with conventional pick-and-place for active components.

Type 2: Hybrid Printed and Conventional Electronics

Type 2 combines printed electronics with conventional PCB technologies. This might include a printed electronics layer laminated to a traditional rigid or flex circuit.

Type 3: Fully Printed Electronics

Type 3 uses printing processes to fully build and functionalize devices, including active components created through printing rather than pick-and-place assembly.

IPC-2292 Design Requirements for Flexible Printed Electronics

The appendix of IPC-2292 provides extensive fabrication and design feature guidance. Here are the critical design considerations every engineer should understand.

Conductor Design Requirements

Design Parameter	Consideration	Typical Range
Minimum trace width	Process dependent	50 µm – 500 µm
Trace spacing	Based on voltage and class	100 µm – 1000 µm
Conductor thickness	Affects resistance and flexibility	1 µm – 25 µm
Aspect ratio	Height-to-width ratio	Process specific
Corner radius	Avoid 90° corners	Minimum 2x trace width

Substrate Material Selection Criteria

When selecting flexible substrates for IPC-2292 compliant designs, consider these factors:

Thermal Considerations:

• Processing temperature compatibility
• Coefficient of thermal expansion (CTE)
• Glass transition temperature (Tg)
• Dimensional stability during curing

Mechanical Considerations:

• Bend radius requirements
• Flex cycle life requirements
• Tensile strength
• Surface roughness for ink adhesion

Electrical Considerations:

• Dielectric constant (Dk)
• Dissipation factor (Df)
• Surface resistivity
• Volume resistivity

Ink-to-Substrate Compatibility

IPC-2292 emphasizes the importance of ink-to-substrate compatibility. The standard addresses:

• Surface energy matching for proper wetting
• Adhesion testing requirements
• Curing temperature compatibility
• Chemical compatibility during processing
• Long-term adhesion stability

Ink-to-Ink Compatibility

For multi-layer designs (SPED 2 and SPED 3), ink-to-ink compatibility becomes critical:

• Dielectric-to-conductor adhesion
• Interlayer chemical compatibility
• Thermal expansion matching
• Via and interconnect reliability

Printing Processes Covered by IPC-2292

IPC-2292 covers all known printing processes for electronics, with provisions to add new processes as they emerge.

Printing Process	Resolution	Throughput	Best For
Screen printing	50-100 µm	High	High-volume, thick deposits
Inkjet printing	20-50 µm	Medium	Prototyping, digital patterns
Aerosol jet	10-20 µm	Low	Fine features, 3D surfaces
Gravure	20-50 µm	Very high	Roll-to-roll production
Flexographic	50-80 µm	Very high	Packaging electronics
Slot-die coating	N/A (coating)	Very high	Uniform layers

Screen Printing for Printed Electronics

Screen printing remains the workhorse of printed electronics manufacturing. It excels at depositing thick conductive layers with good conductivity but has resolution limitations.

Screen Printing Advantages:

• High throughput capability
• Thick deposit possible (5-25 µm)
• Low equipment cost
• Wide material compatibility

Screen Printing Limitations:

• Resolution limited to ~50 µm
• Screen wear affects repeatability
• Pattern changes require new screens

Inkjet Printing for Printed Electronics

Inkjet offers digital flexibility with no tooling changes required for pattern modifications.

Inkjet Advantages:

• No tooling or screens required
• Easy pattern modifications
• Good resolution (20-50 µm)
• Low material waste

Inkjet Limitations:

• Lower throughput than screen printing
• Thin deposits require multiple passes
• Nozzle clogging concerns
• Limited ink viscosity range

Aerosol Jet Printing

Aerosol jet printing enables the finest features and conformal printing on 3D surfaces, making it essential for SPED 3 applications.

Aerosol Jet Advantages:

• Finest resolution (10 µm lines)
• Conformal printing on 3D surfaces
• Wide ink viscosity range
• Large standoff distance

Aerosol Jet Limitations:

• Lowest throughput
• Highest equipment cost
• Overspray management required
• Complex process control

IPC-2292 vs IPC-2291: Understanding the Difference

Engineers often confuse IPC-2291 and IPC-2292. Here’s the definitive comparison:

Attribute	IPC-2291	IPC-2292
Document type	Design Guideline	Design Standard
Nature	Advisory	Mandatory requirements
Page count	24 pages	72 pages
Scope	General printed electronics	Flexible substrates specifically
Release date	2013	2018 (Rev A: 2022)
SPED definitions	No	Yes (SPED 1, 2, 3)
Joint standard	IPC/JPCA-2291	IPC only
Use case	Design process flow	Design requirements compliance

When to use IPC-2291:

• Early-stage design planning
• Understanding design process flow
• General printed electronics guidance
• Identifying applicable standards

When to use IPC-2292:

• Flexible substrate design work
• Procurement specification
• Manufacturing compliance
• Customer requirements documentation

IPC-2292 vs IPC-8952: Flexible vs E-Textiles

Another common point of confusion is the boundary between IPC-2292 and IPC-8952.

Attribute	IPC-2292	IPC-8952
Substrate type	Flexible (non-stretchable)	Textiles and e-textiles
Materials covered	PET, PEN, PI, paper, thin glass	Woven, knitted, coated fabrics
Stretchability	Not covered	Covered
Component mounting	Standard approaches	Textile-specific methods
Release date	2018	2022

If your substrate can stretch significantly (more than a few percent), you likely need IPC-8952 rather than IPC-2292.

Related IPC Standards for Printed Electronics

IPC-2292 doesn’t exist in isolation. Here’s how it connects with other printed electronics standards:

Standard	Title	Relationship to IPC-2292
IPC-2291	Design Guideline for Printed Electronics	General design process guidance
IPC-6902	Qualification and Performance Specification	Qualification requirements
IPC-9257	Electrical Testing of Flexible PE	Testing requirements reference IPC-6902
IPC-4591	Functional Conductive Materials	Ink specifications
IPC-4921	Base Materials (Substrates)	Substrate specifications
IPC-6903	Terms and Definitions	Industry terminology
IPC-9204	Flexibility and Stretchability Testing	Test methods

IPC-6902: Qualification Requirements

IPC-6902 establishes qualification and performance requirements for printed electronics on flexible substrates. When IPC-2292 specifies design requirements, IPC-6902 defines how to verify that those requirements are met.

IPC-9257: Electrical Testing

IPC-9257 specifies test equipment, parameters, data collection, and fixturing methods for electrical testing of flexible printed electronics. It ensures products meet the electrical design criteria detailed in IPC-6902.

Useful Resources for IPC-2292 Implementation

Official IPC Resources

Resource	URL	Description
IPC-2292 Standard Purchase	https://shop.ipc.org/ipc-2292	Official standard document
IPC-2292A (2022 Revision)	https://shop.ipc.org/ipc-2292	Current revision
IPC Table of Contents Preview	https://www.ipc.org/TOC/IPC-2292.pdf	Free TOC preview

Related Standards Purchase Links

Standard	Source	Price Range
IPC-2291	IPC Store	$50-100
IPC-6902	IPC Store	$80-150
IPC-9257	IPC Store / ANSI	$60-120
IPC-8952	IPC Store	$80-150

Industry Resources

Resource	URL	Description
ANSI Webstore	https://webstore.ansi.org	Standards purchase
GlobalSpec Standards	https://standards.globalspec.com	Standards information
IPC Design Standards Overview	https://www.electronics.org/ipc-design-standards	Standards listing
FlexTech Alliance	https://www.semi.org/en/communities/flextech	Industry consortium

Training and Certification

Resource	Provider	Description
IPC Designer Certification	IPC	CID/CID+ programs
Printed Electronics Training	PIEK Training	European training provider
FlexTech Education	SEMI	Industry education programs

IPC-2292 Implementation Best Practices

Based on practical experience implementing IPC-2292 in production environments, here are recommendations for success:

Design Phase Best Practices

1. Specify the SPED classification early in the design process
2. Define the product class (1, 2, or 3) based on end-use requirements
3. Document substrate selection rationale with thermal, mechanical, and electrical justification
4. Perform ink-to-substrate compatibility testing before finalizing designs
5. Include design margins beyond minimum requirements for manufacturability

Manufacturing Phase Best Practices

1. Establish statistical process control for Class 2 and 3 products
2. Document all process parameters for traceability
3. Implement in-process testing at critical points
4. Maintain environmental controls for humidity and temperature
5. Train operators on IPC standards and requirements

Testing and Qualification Best Practices

1. Reference IPC-6902 for qualification requirements
2. Use IPC-9257 for electrical test protocol development
3. Document all test results with full traceability
4. Establish acceptance criteria before testing begins
5. Implement corrective action procedures for failures

Frequently Asked Questions About IPC-2292

What is the difference between IPC-2292 and IPC-2291?

IPC-2291 is a design guideline providing advisory guidance for printed electronics design processes. IPC-2292 is a design standard with mandatory requirements specifically for flexible substrates. IPC-2291 covers the design flow broadly (24 pages), while IPC-2292 provides detailed requirements (72 pages) including SPED classifications and specific design rules.

Does IPC-2292 apply to stretchable electronics?

No. IPC-2292 explicitly excludes stretchable substrates such as fabrics, textiles, and stretchable polymers. For stretchable electronics and e-textiles, use IPC-8952 (Design Standard for Printed Electronics on Coated or Treated Textiles and E-Textiles). IPC-2292 covers flexible substrates that bend but do not stretch significantly.

What are SPEDs in IPC-2292?

SPEDs (Standard Printed Electronic Designs) are three design classifications defined in IPC-2292: SPED 1 is single-layer printed electronics, SPED 2 is multi-layer printed electronics with dielectric separation, and SPED 3 covers three-dimensional printed electronics including conformal printing and fully additive 3D construction.

How does IPC-2292 relate to IPC-6902?

IPC-2292 establishes design requirements, while IPC-6902 (Qualification and Performance Specification for Printed Electronics on Flexible Substrates) establishes qualification and performance requirements. When designing to IPC-2292, you verify compliance through the test methods and acceptance criteria defined in IPC-6902 and IPC-9257.

What printing processes does IPC-2292 cover?

IPC-2292 covers all known printing processes for electronics, including screen printing, inkjet printing, aerosol jet printing, gravure, flexographic, and 3D printing methods. The standard is written to accommodate new printing processes as they emerge and requires the printed electronics type to be specified in procurement documents.

Design for Manufacturing (DFM) Considerations in IPC-2292

IPC-2292 emphasizes that designs must consider manufacturing capabilities from the earliest stages. The standard includes a DFX (Design for Excellence) process framework that establishes a discipline of design review necessary to perform detailed analysis of manufacturability attributes.

Registration and Alignment Requirements

Multi-layer printed electronics (SPED 2) require precise registration between layers. Typical registration tolerances range from ±50 µm for high-end processes to ±200 µm for standard screen printing. Design rules must account for these tolerances when specifying via capture pads and layer-to-layer features.

Curing and Sintering Considerations

The curing process significantly impacts final conductivity and adhesion. IPC-2292 designs must specify curing requirements compatible with the substrate’s thermal limitations. For PET substrates limited to 150°C, this often requires photonic sintering or low-temperature conductive inks rather than conventional thermal curing.

Roll-to-Roll Manufacturing Compatibility

For high-volume applications, designs should consider roll-to-roll (R2R) manufacturing compatibility. This includes web handling requirements, registration systems, and inline curing capabilities. Designs optimized for R2R production can achieve significant cost reductions at scale.

Conclusion

IPC-2292 represents the definitive design standard for printed electronics on flexible substrates. Whether you’re designing RFID tags, flexible sensors, or complex multi-layer circuits, understanding SPEDs, product classifications, and design requirements is essential for successful product development.

The standard’s clear distinction between flexible (IPC-2292) and stretchable (IPC-8952) substrates, combined with the SPED classification system, provides a common language for designers, manufacturers, and customers. By following IPC-2292 requirements and leveraging related standards like IPC-6902 for qualification and IPC-9257 for testing, you can develop flexible printed electronics that meet industry expectations for quality and reliability.

As printed electronics technology continues evolving with new materials and processes, IPC-2292 will continue being updated. The 2022 Revision A already expanded coverage, and future revisions will address emerging technologies. Staying current with these standards is essential for anyone serious about flexible printed electronics design and manufacturing.