IPC/JPCA-4104 Explained: Complete Guide to HDI and Microvia Materials for PCB Fabrication

When you start working on HDI (High Density Interconnect) designs, material selection becomes significantly more complex than traditional PCB projects. You’re no longer just choosing between FR-4 grades—you’re dealing with photoimageable dielectrics, resin-coated copper foils, and specialized build-up materials that each behave differently during laser drilling, lamination, and plating. IPC/JPCA-4104 is the standard that brings order to this complexity.

This joint IPC-JPCA specification provides the classification system, qualification requirements, and performance standards for HDI and microvia materials. Whether you’re specifying materials for a smartphone mainboard, an advanced IC substrate, or your first HDI prototype, understanding IPC/JPCA-4104 helps you communicate clearly with fabricators and select materials that will actually perform in your application.

What is IPC/JPCA-4104?

IPC/JPCA-4104 (full title: “Specification for High Density Interconnect (HDI) and Microvia Materials”) is a jointly developed standard by IPC (Association Connecting Electronics Industries) and JPCA (Japan Printed Circuit Association). It covers the various conductive and dielectric materials used in the fabrication of HDI structures and microvias.

The standard includes 23 specification sheets (slash sheets) that define qualification and conformance requirements for materials including photoimageable dielectric dry films and liquids, epoxy blends, resin-coated copper foils, and other build-up materials. IPC/JPCA-4104 also introduced six test methods developed specifically for HDI and microvia material evaluation.

Why a Joint IPC-JPCA Standard?

HDI technology originated largely in Japan during the 1990s, where companies like Ibiden, Shinko, and CMK pioneered sequential build-up (SBU) processes. When IPC developed standards for HDI materials, collaborating with JPCA made sense—it brought together Western and Asian expertise and ensured the standard would be globally applicable. This joint development is why you’ll see both organization names in the designation.

Where IPC/JPCA-4104 Fits in the HDI Standards Family

IPC/JPCA-4104 should be used in conjunction with two companion standards:

IPC/JPCA-2315: Design Guide for High Density Interconnects and Microvias—provides design rules and guidelines for HDI structures.

IPC-6016: Qualification and Performance Specification for HDI Layers or Boards—covers finished board requirements and acceptance criteria.

Together, these three documents provide a complete framework for HDI material specification, design, and qualification.

Understanding the IPC/JPCA-4104 Material Classification System

One of the most valuable aspects of IPC/JPCA-4104 is its systematic approach to classifying HDI materials. The standard recognizes three fundamental material types, each designated by a two-letter code.

Level 1: Material Type Designations

This first-level designation tells you the fundamental nature of the material. Most HDI build-up materials fall into either the IN (pure dielectric) or CI (combination) categories.

Level 2 and Beyond: Detailed Classification

Beyond the basic material type, IPC/JPCA-4104 uses additional classification levels to specify:

For Insulators (IN):

• Reinforcement type (glass, non-woven, none)
• Resin chemistry (epoxy, polyimide, BT, etc.)
• Form factor (dry film, liquid, sheet)
• Processing method (photoimageable, thermally cured)

For Conductors (CD):

• Metal type (copper, aluminum)
• Foil type and treatment
• Thickness range

For Combination Materials (CI):

• Dielectric and conductor specifications combined
• Bonding method and characteristics

Application Levels: H vs. I

IPC/JPCA-4104 defines two application levels that determine which tests are required:

Most PCB designers will work with Level H materials, while Level I materials are targeted at advanced packaging and substrate applications. Some materials are qualified for both levels.

IPC/JPCA-4104 Specification Sheets Overview

The 23 slash sheets in IPC/JPCA-4104 cover a wide range of HDI material types. Here’s an overview of the key categories:

Photoimageable Dielectric Materials

Photoimageable dielectrics (PIDs) can be patterned using UV exposure and development, similar to photoresist. This allows via formation without laser drilling in some applications.

Thermally Cured Dielectric Materials

Thermally cured dielectrics require laser drilling for via formation but often provide better electrical and thermal properties than photoimageable alternatives.

Resin-Coated Copper (RCC) Foils

RCC foils are among the most widely used HDI materials. They combine the dielectric and outer copper layer into a single material that simplifies the build-up process.

Specialty Materials

Additional slash sheets cover materials including:

• PPE/PPO (Polyphenyl Ether/Polyphenylene Oxide) blends for high-frequency applications
• Polyimide-based dielectrics for high-temperature applications
• BT (Bismaleimide Triazine) resin systems
• Low-Dk materials for high-speed signal applications

Key Material Types Covered by IPC/JPCA-4104

Understanding the practical differences between HDI material types helps you make better selection decisions.

Photoimageable Dielectrics (PID)

Photoimageable dielectrics were among the earliest HDI materials and remain popular for certain applications. They use a photosensitive resin that can be selectively exposed and developed to create via openings.

How They Work:

1. PID is applied to the substrate (as dry film laminate or liquid coating)
2. A photomask defines via locations
3. UV exposure cross-links the dielectric in non-via areas
4. Development removes unexposed material, creating via openings
5. Metallization deposits copper into the vias

Advantages:

• No laser drilling required
• Can achieve very small via diameters
• Good for high-volume production
• Lower equipment cost than laser systems

Limitations:

• Resolution depends on exposure system quality
• Some chemistries have higher Dk than alternatives
• May have lower thermal stability than non-photoimageable options
• Limited by development process capabilities

Resin-Coated Copper (RCC) Foils

RCC foils revolutionized HDI manufacturing by addressing the limitations of fiberglass-reinforced prepregs for build-up layers. They consist of copper foil coated with a B-stage (partially cured) resin on the treated side.

Construction:

• Ultra-thin copper foil (typically 12-18µm)
• B-stage resin coating (typically 30-60µm)
• Optional: Ultra-thin glass reinforcement (MHCG type)

Manufacturing Process:

1. RCC is laminated to the core under heat and pressure
2. Resin flows to fill surface topography and cures
3. Laser drilling creates blind microvias
4. Metallization and patterning complete the layer

Advantages:

• Excellent laser drilling characteristics
• Very thin dielectric layers achievable (down to 25µm)
• Good resin flow fills circuit topography
• Available in various resin systems (epoxy, PPE, polyimide blends)

Limitations:

• Higher cost than standard prepreg
• Non-reinforced versions have lower dimensional stability
• Requires controlled storage conditions

Liquid Dielectrics

Liquid dielectrics offer the lowest cost option for HDI build-up layers and can be applied in very thin, uniform coatings.

Application Methods:

• Screen printing
• Roller coating (vertical or horizontal)
• Curtain coating
• Spray coating

Advantages:

• Lowest material cost per square meter
• Excellent thickness uniformity achievable
• Can fill fine features and topography well
• Compatible with various curing schedules

Limitations:

• Requires specialized application equipment
• More process-sensitive than dry film materials
• May have consistency variations batch-to-batch

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

Performance Requirements in IPC/JPCA-4104

The standard specifies minimum performance requirements that materials must meet through standardized testing. Six new test methods were developed specifically for IPC/JPCA-4104.

Critical Performance Properties

Laser Drilling Compatibility

For materials intended for laser-drilled microvias, IPC/JPCA-4104 addresses:

Via Quality Metrics:

• Clean ablation without charring
• Minimal resin smear at via bottom
• Consistent via diameter and taper
• No delamination or glass fiber protrusion

Compatible Laser Types:

• CO₂ lasers (10.6µm wavelength) – most common for RCC and unreinforced dielectrics
• UV-YAG lasers (355nm) – for copper direct ablation and fine features
• Excimer lasers – for ultra-fine via formation

Thermal Reliability

HDI materials must survive multiple thermal excursions during sequential lamination and assembly:

How to Specify IPC/JPCA-4104 Materials

When working with your fabricator on HDI designs, proper material specification ensures you get the performance you need.

On Design Documentation

Include material callouts in your fabrication notes:

Example Callout: “Build-up dielectric layers shall conform to IPC/JPCA-4104/10 or equivalent. Minimum copper adhesion 0.7 N/mm after thermal stress.”

For most designs, specifying the slash sheet provides sufficient guidance. Add specific requirements only when your application demands it.

Working with Fabricators

Before finalizing HDI material selection:

1. Discuss target layer count and stackup – Materials affect achievable thicknesses and via structures
2. Confirm laser drilling capabilities – Not all materials work with all laser systems
3. Review impedance requirements – Dk values affect trace geometry
4. Consider reliability testing needs – Some applications require IST or HATS testing
5. Evaluate lead time and cost – Specialty materials may have longer procurement cycles

Avoiding Common Specification Mistakes

Don’t: Specify brand-name materials exclusively (e.g., “Use Ajinomoto ABF GX-92 only”)

Do: Specify the IPC/JPCA-4104 slash sheet with critical performance parameters

Don’t: Ignore material compatibility with your process flow

Do: Verify that specified materials work with the fab’s laser, plating, and lamination equipment

Don’t: Over-specify when standard materials will work

Do: Use application-appropriate materials—not every HDI needs low-Dk dielectrics

IPC/JPCA-4104 Material Selection Guide

Matching materials to applications requires balancing performance, cost, and manufacturing considerations.

Application-Based Material Selection

Cost vs. Performance Trade-offs

Useful Resources for IPC/JPCA-4104

Official Standards and Documentation

• IPC/JPCA-4104 Standard – Purchase from IPC
• IPC/JPCA-2315 Design Guide – HDI design rules companion document
• IPC-6016 HDI Board Specification – Finished board requirements
• IPC-TM-650 Test Methods – Free access to test procedures

Material Supplier Technical Resources

• Ajinomoto Build-up Film (ABF) Product Information – Leading PID/film supplier
• Hitachi Chemical MCL Series – RCC and build-up materials
• Isola Laminate Product Selector – HDI-compatible laminates
• Panasonic Electronic Materials – Various HDI materials

Educational and Technical Guides

• Altium HDI Materials Guide – Good technical overview
• IPC APEX EXPO Technical Sessions – Annual conference with HDI presentations
• JPCA Show Resources – Japanese industry conference materials

Industry Organizations

• IPC – Association Connecting Electronics Industries
• JPCA – Japan Printed Circuit Association
• TPCA – Taiwan Printed Circuit Association

Frequently Asked Questions About IPC/JPCA-4104

What is the difference between IPC-4104 and IPC-4101?

IPC-4101 covers base materials for rigid and multilayer printed boards—essentially the core laminates and prepregs used in conventional PCB fabrication. IPC/JPCA-4104 specifically addresses the build-up and microvia materials used in HDI construction. While IPC-4101 materials form the core of your HDI stackup, IPC/JPCA-4104 materials are laminated on top during sequential build-up processes. Many HDI designs use IPC-4101 materials for the core and IPC/JPCA-4104 materials for the build-up layers.

Can I use standard FR-4 prepreg for HDI build-up layers?

Technically yes, but it’s generally not recommended. Standard FR-4 prepregs contain woven fiberglass reinforcement that causes problems during laser drilling—poor hole quality, glass fiber protrusion, and longer drill times. IPC/JPCA-4104 materials like RCC foils and unreinforced dielectrics are specifically designed for clean laser ablation. Some “laser-drillable” prepregs with spread-glass or non-woven reinforcement offer a middle ground, but pure IPC/JPCA-4104 materials typically give better results for microvia formation.

What slash sheet should I specify for a typical HDI smartphone board?

For most smartphone applications, IPC-4104/10 or IPC-4104/11 (epoxy-based RCC foils) are appropriate starting points. These provide good laser drilling characteristics, adequate thermal performance for lead-free assembly, and reasonable cost. If you need improved reliability for automotive-grade or similar requirements, look at IPC-4104/11 or /12 with higher Tg ratings. For high-speed applications like 5G antenna modules, you may need to move to lower-Dk specialty materials from higher-numbered slash sheets.

How does IPC/JPCA-4104 address lead-free assembly compatibility?

Lead-free assembly requires materials that can withstand higher reflow temperatures (typically 260°C peak vs. 225°C for leaded solder). IPC/JPCA-4104 slash sheets specify thermal requirements including solder float resistance and Tg values. For lead-free compatibility, look for materials with Tg ≥150°C and verified solder float performance at 288°C. Most modern IPC/JPCA-4104 materials are designed for lead-free processes, but always verify with your fabricator and review the specific slash sheet requirements.

Do I need to specify IPC/JPCA-4104 materials if my fabricator already knows what to use?

Even if your fabricator has standard HDI materials they typically use, referencing IPC/JPCA-4104 on your documentation provides several benefits: it creates a clear, industry-standard specification that any qualified fabricator can understand; it ensures material traceability and documentation for quality systems; it provides a baseline for discussing alternative materials if needed; and it protects you if there are performance issues—you have a documented specification to reference. At minimum, ask your fabricator which IPC/JPCA-4104 slash sheets their standard materials conform to.

Bringing It All Together

IPC/JPCA-4104 provides the common language for specifying HDI and microvia materials across the global supply chain. While the 23 slash sheets and classification system might seem complex at first, the structure becomes intuitive once you understand the basic material categories: insulators (IN), conductors (CD), and combinations (CI).

For most HDI applications, you’ll work primarily with resin-coated copper foils (CI type materials like those in slash sheets 10-12) or photoimageable dielectrics (IN type materials in slash sheets 1-3). The key is matching material properties—Tg, Dk, laser drilling characteristics, and reliability—to your specific application requirements.

Start by discussing material options with your fabricator early in the design process. They can advise on which IPC/JPCA-4104 materials work best with their processes and equipment. Include the appropriate slash sheet reference in your fabrication notes, and add specific performance requirements only when your application demands them.

As HDI technology continues advancing toward finer features and more complex structures, IPC/JPCA-4104 will continue evolving to address new material developments. Staying current with the standard helps ensure your designs leverage the best available materials while maintaining clear communication throughout the supply chain.