Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
ITEQ Standard & High-Tg FR-4 Laminates: The Complete Engineering Guide
In the competitive landscape of PCB fabrication, selecting the right substrate is the difference between a high-yield production run and a catastrophic field failure. For the hardware engineer, the choice often leads to ITEQ, a global leader in high-performance copper-clad laminates (CCL).
While many projects start with “standard FR-4” as a placeholder, the shift toward lead-free assembly and high-density interconnects (HDI) has made ITEQ high Tg FR-4 the industry’s new baseline for reliability. This guide provides a deep-dive, engineer-to-engineer look at the ITEQ FR-4 portfolio, helping you navigate the thermal and mechanical nuances of IPC-4101 slash sheets and high-Tg resin systems.
Before diving into part numbers, we must define the physics of the substrate. FR-4 (Flame Retardant 4) is a composite material composed of woven fiberglass cloth with an epoxy resin binder. The “Tg” or Glass Transition Temperature is the most critical thermal metric for an engineer.
What is Tg and Why Does it Matter?
Tg is the temperature range at which the resin transitions from a rigid, “glassy” state to a more pliable, “rubbery” state. It is not the melting point, but rather the point where the material’s physical properties—specifically its Coefficient of Thermal Expansion (CTE)—undergo a significant change.
Standard Tg (130°C – 140°C): Suitable for low-layer count boards and low-heat consumer electronics.
Medium Tg (150°C): A bridge material for improved reliability in handheld devices.
High Tg (170°C+): The standard for multilayer boards, automotive electronics, and anything undergoing lead-free reflow.
When a PCB exceeds its Tg, the resin expands much faster in the Z-axis (vertical) than in the X or Y axes. In high-layer count boards, this expansion puts immense stress on the plated through-holes (PTH), often leading to via barrel cracking. Choosing an ITEQ high Tg FR-4 material restricts this expansion, ensuring through-hole reliability through multiple reflow cycles.
Core ITEQ FR-4 Product Line: Standard to High-Tg
ITEQ offers a spectrum of materials categorized by their thermal robustness and chemical composition. Below are the primary workhorses of the ITEQ portfolio.
1. ITEQ IT-180A: The Industry Standard for High-Tg
The IT-180A is arguably ITEQ’s most famous material. It is a multifunctional, phenolic-cured, filled epoxy system designed for high-layer count PCBs and lead-free assembly.
Tg (DSC): 175°C
Td (Decomposition Temp): 350°C
Key Strength: Exceptional Z-axis CTE (typically 2.7% from 50°C to 260°C).
Application: Servers, networking, automotive control units, and heavy copper boards.
2. ITEQ IT-158: The Medium-Tg Reliability Specialist
For applications that require better-than-standard performance without the premium cost of 175°C materials, IT-158 provides a robust middle ground.
As “Green” initiatives take over, halogen-free materials have moved from niche to mandatory.
IT-170G (Tg 175°C): A halogen-free, phosphorous-containing epoxy system that offers superior thermal resistance.
IT-180GN (Tg 175°C): Designed specifically for rigid-flex applications where minimal and uniform flow performance is required.
Technical Comparison: ITEQ Material Properties
When architecting a stackup, the datasheet values are your primary constraints. Below is a comparative look at the thermal and electrical performance of ITEQ’s FR-4 range.
Table 1: ITEQ FR-4 Material Comparison Matrix
Property
Units
IT-158 (Mid-Tg)
IT-180A (High-Tg)
IT-170G (Halogen-Free)
Tg (DSC)
°C
150
175
175
Td (Decomposition)
°C
345
350
380
Dk @ 1 GHz
–
4.4
4.2
4.1
Df @ 1 GHz
–
0.016
0.017
0.010
Z-Axis CTE (α1)
ppm/°C
50
45
40
Z-Axis CTE (α2)
ppm/°C
250
250
240
Moisture Absorption
%
0.12
0.12
0.10
T288 (Time to Delam)
min
> 15
> 30
> 30
Analysis of Thermal Stability (Td and T288)
While Tg is the “headline” spec, Td (Decomposition Temperature) is the silent hero. Td is the temperature at which the material loses 5% of its weight due to chemical breakdown. For lead-free assembly (where reflow peaks at 260°C), a Td of >340°C is essential.
Furthermore, T288 measures how many minutes the material can withstand a 288°C solder float before delaminating. High-Tg materials like IT-180A offer significantly more “headroom” for rework and multiple reflow cycles compared to standard FR-4.
Lead-Free Assembly and PTH Reliability
The transition to lead-free (RoHS) soldering has increased reflow temperatures from ~215°C (SnPb) to ~255°C (SAC305). This 40°C difference is brutal on PCB substrates.
The Z-Axis Expansion Problem
Because the fiberglass weave constrains expansion in the X and Y directions, the resin is forced to expand vertically.
Total Z-Expansion (50-260°C): Standard FR-4 can expand up to 4.5% or more.
IT-180A Performance: Typically stays below 3.0%.
In a 20-layer server board with high-aspect-ratio vias, that 1.5% difference is the difference between a via that survives 1,000 thermal cycles and one that fails during the very first reflow. For any design with more than 8 layers or via pitches below 0.5mm, ITEQ high Tg FR-4 is not an option—it is a requirement.
Conductive Anodic Filament (CAF) growth is an electrochemical migration that occurs along the glass-to-resin interface. It causes internal shorts between adjacent vias or traces, especially in humid environments under high voltage bias.
ITEQ’s high-Tg series is specifically engineered for CAF Resistance.
Tight Resin Bond: Advanced phenolic curing agents create a more homogenous bond to the glass fibers, closing the microscopic “capillaries” that CAF usually travels through.
Low Moisture Absorption: By maintaining absorption rates below 0.15%, ITEQ materials like IT-180A and IT-170G prevent the electrolyte medium required for CAF growth.
Fabricator’s Angle: Processing ITEQ Materials
A high-performance material is only as good as the factory’s ability to process it. One of the reasons ITEQ dominates the market is “Friendly Processing.”
Drilling and Desmear
High-Tg materials are generally harder and more abrasive than standard FR-4.
Drilling: ITEQ materials like IT-180A require specific drill bit management. Most Tier 1 fabricators use specialized carbide bits and manage “hit counts” to prevent resin smear in the holes.
Desmear: ITEQ materials are compatible with standard permanganate desmear lines. However, for high-density designs, plasma desmear is often utilized to ensure a perfectly clean copper-to-resin interface.
Lamination Guidelines
For engineers designing their own stackups, understanding ITEQ’s lamination cycle is vital.
Heating Rate: Typically 1.5 – 3.0°C/min. Too fast causes voids; too slow causes resin starvation.
Pressure: 300 – 400 psi is the standard vacuum hydraulic press range.
Bake Time: When the core reaches 185°C, it must be held for at least 60 minutes to ensure full cross-linking (curing) of the resin.
Sourcing and Engineering Resources
To move from a datasheet to a physical board, you need the right tools and partners.
ITEQ Official Online Database: The primary source for broadband Dk/Df tables and resin content data.
IPC-4101 Slash Sheets: Refer to slash sheets /126, /129, and /131 for high-performance ITEQ equivalents.
Stackup Consulting: For real-time material availability and factory-specific stackup verification, exploring specialized ITEQ PCB resource hubs is highly recommended.
UL File E178114: Verification of flammability and thermal ratings for regulatory compliance.
Frequently Asked Questions (FAQs)
1. Is ITEQ IT-180A a direct replacement for Isola 370HR?
In many applications, yes. They are both high-Tg (175°C-180°C), phenolic-cured, filled epoxy systems. They share similar thermal expansion profiles, making them technically interchangeable in most high-reliability stackups. However, always verify Dk/Df values if you are designing for controlled impedance above 10 GHz.
2. Why should I use ITEQ IT-170G instead of IT-180A?
If your project requires Halogen-Free compliance (Green electronics) or if your design has extremely tight CAF resistance requirements, IT-170G is the better choice. It also offers slightly lower Dk/Df than IT-180A, which can provide a marginal signal integrity benefit.
3. Does “High-Tg” affect the signal speed?
Tg itself does not dictate signal speed; that is the job of the Dielectric Constant (Dk). However, high-Tg resins often use more advanced fillers that can lower the Dk compared to standard FR-4, resulting in slightly faster propagation delays.
4. What is the shelf life of ITEQ Prepreg?
Prepreg (B-stage resin) is chemically active. It typically has a shelf life of 3 months when stored in a climate-controlled room (below 20°C and <50% humidity). Once it exceeds this date, the resin flow characteristics change, risking delamination.
5. Can I use standard FR-4 for 5G applications?
Standard FR-4 is generally limited to signals under 3-5 GHz. At 5G frequencies (especially mmWave), the signal loss (Df) of standard FR-4 is too high. You would need to move to ITEQ’s high-speed series like IT-968 or IT-988G.
Final Verdict: The Choice for High Reliability
In the world of PCB engineering, you rarely get fired for choosing a high-performance material. While standard FR-4 has its place in cost-sensitive consumer gadgets, the thermal robustness of ITEQ high Tg FR-4 makes it the mandatory foundation for 2026 infrastructure.
Whether you are building an automotive battery management system (BMS) with IT-170G or a 32-layer server backplane with IT-180A, ITEQ provides the thermal headroom and mechanical stability needed to survive the assembly line and thrive in the field.
Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
