High Tg PCBs

High Tg PCBs

The glass transition temperature of PCB, referred to as Tg is an important factor to consider when fabricating PCBs for high temperature applications.  

High Tg FR4 PCB Manufacturer – Sierra Assembly Technology

At Sierra Assembly Technology Inc., we are a trusted high Tg FR4 PCB manufacturer in the United States, delivering precision-engineered, heat-resistant PCB fabrication for industries requiring boards that perform under extreme thermal conditions. Our solutions include high Tg PCB, high temperature fabrications, and custom High Tg FR4 PCB projects that ensure reliability, durability, and superior electrical performance.

Whether you need high temperature fiberglass cloth boards or are searching for a reliable high Tg FR4 PCB supplier, Sierra provides boards designed for applications ranging from automotive and aerospace to medical, defense, and industrial electronics.

What Is a High Tg FR4 PCB?

The Tg of PCB, or glass transition temperature, indicates the temperature at which the board’s resin matrix shifts from a rigid solid to a soft, elastic state. Exceeding the Tg can cause warping, delamination, and failure.

A High Tg PCB uses FR-4 substrate materials with Tg ≥ 170°C, maintaining mechanical stability, electrical reliability, and dimensional precision even in high-temperature environments. These boards are ideal for heat resistant PCB fabrication in demanding electronics applications.

Key Benefits of High Tg FR4 PCBs

Feature

Benefit

High-Temperature Performance

Operates efficiently in environments above 170°C without structural deformation.

Dimensional Stability

Maintains shape and layer alignment under thermal cycling.

Electrical Reliability

Minimizes signal loss and maintains performance under heat.  

Mechanical Strength

Reinforced with high temperature fiberglass cloth for durability.

Cost Efficiency

Fewer layers may be needed due to material reliability, reducing production costs.

Steps We Follow in High Tg PCB Manufacturing

Our high Tg PCB manufacturing process ensures precision, durability, and heat-resistant PCB fabrication performance.

  1. Material Preparation: Selecting premium high temperature fiberglass cloth and FR-4 laminates to achieve the required Tg of PCB.
  2. Layer Lamination: Sequential lamination bonds multiple layers, maintaining exact thickness and alignment.
  3. Drilling and Via Formation: Microvias, blind, and buried vias are laser-drilled to ensure precise interconnections.
  4. Surface Finishing: Boards receive ENIG, HASL, Immersion Silver, or OSP treatments for durability and solderability.
  5. Testing and Quality Control: Each board undergoes X-ray inspection, in-circuit testing, and optical checks to meet strict quality standards.

Materials and Technical Specifications

We use premium FR-4 laminates and high temperature fiberglass cloth for high temperature fabrications. All boards are tested to meet ISO 9001:2015, AS9100D, IPC-A-610, and J-STD-001 compliance.

Material

Tg (°C)

Td (°C)

CTE-Z (ppm/°C)

Typical Applications

Shengyi FR-4

170

300

55

Standard high-Tg PCB projects

ITEQ FR-4

175

345

45

Automotive, industrial electronics

Panasonic FR-4

180

350

50

 Aerospace, defense, medical devices  

Rogers 4350B

280

390

50

High-frequency, high-performance electronics

Our PCB Customization Capabilities

 Sierra offers a wide range of customization options to meet diverse PCB design and performance requirements. From layer count and board thickness to surface finishes and solder mask colors, our capabilities are designed to support both standard and complex PCB applications while ensuring reliability, precision, and compliance with industry standards.

Specification

Options

Layers

1–40 layers

Thickness

0.3mm – 6.5mm

Copper

0.5oz – 2oz

Surface Finish

ENIG, HASL, Lead-Free HASL, Immersion Silver, Immersion Tin, OSP

Trace/Space

Min 2mil / 2mil

Colors

Green, White, Black, Red, Blue

Board Size

Min 6mm x 6mm

Testing and Quality Assurance for High Tg FR4 PCBs

At Sierra Assembly Technology, quality is our top priority. Every high Tg FR4 PCB undergoes rigorous testing to ensure reliability, especially under high-temperature conditions:

  • Thermal Stress Testing: Ensures the PCB maintains integrity at elevated temperatures matching the specified Tg of the PCB.
  • Electrical Testing: We verify continuity, insulation resistance, and signal integrity to guarantee optimal performance in your application.
  • X-Ray Inspection: Detects hidden defects, such as voids or delamination in high-temperature fiberglass cloth layers.
  • Mechanical Testing: Checks for durability and dimensional stability, ensuring the board withstands thermal expansion and operational stresses.
  • Standards Compliance: All high Tg FR4 PCBs are tested according to ISO 9001:2015, AS9100D, IPC-A-610, and IPC J-STD-001 standards.

With these checks, our high Tg PCB fabrication process guarantees boards that perform reliably in automotive, aerospace, industrial, medical, and military applications. This thorough testing also helps us deliver heat resistant PCB fabrication that meets the exact requirements of our clients.

Applications of High Tg FR4 PCBs

  • Automotive: Engine controllers, EV modules
  • Aerospace: Avionics, navigation systems
  • Medical Devices: Diagnostic and imaging equipment
  • Defense & Military: Communication and radar systems
  • Industrial Electronics: Power distribution, high-temperature sensors

Why Choose Sierra Assembly Technology?

We are a top high Tg FR4 PCB supplier because we combine precision engineering, advanced materials, and U.S.-based customer support:

  • Experience: Decades of expertise in high Tg PCB and heat resistant PCB fabrication.
  • Customization: Tailored solutions for high temperature fabrications of any complexity.
  • Speed: Quick-turn prototypes and scalable production runs.
  • Support: Technical teams guide you from design to delivery.
  • Quality Assurance: Certified ISO 9001:2015, AS9100D, IPC-A-610, and J-STD-001 processes.

Get Started with High Tg FR4 PCBs

Looking for a reliable high Tg FR4 PCB manufacturer in the U.S.? Sierra Assembly Technology provides high temperature fabrications, high Tg PCB, and custom FR-4 solutions for industries demanding high-performance boards.
Contact us today to discuss your project and request a quote for your heat-resistant PCB fabrication needs. Let us help you build boards that deliver unmatched thermal stability and electrical reliability.


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