日本語
What Is PCB TG Value and Why It Matters for High Heat Boards
When designing any electronic device, especially those facing high temperatures (think car engines or industrial machinery), there's one critical spec you cannot ignore: the PCB's TG value.
The PCB's "Melting Point": Understanding the TG Value
The "TG" stands for Glass Transition Temperature.
To understand it simply, imagine ice. Ice transitions from a hard solid to a soft liquid at its melting point, 0℃ (32°F).
The TG value is the analogous point for a PCB's substrate material (usually fiberglass and resin, like FR-4). When the PCB material's temperature reaches its TG value, the rigid resin starts to soften and transition from a hard, glassy state into a softer, rubbery state.
Crucially, the board doesn't melt at this temperature; it just loses significant rigidity and dimensional stability. If a board operates consistently above its TG, it can lead to:
Lamination issues: Layers separating, especially around plated through-holes.
Dimensional changes: The board warping or expanding, causing component stress.
Reliability failure: Intermittent connections or shorts due to material instability.
Why Higher TG is a Must for Modern Electronics
In the past, a standard TG of 130℃ was enough for most consumer electronics (like standard home appliances or computers). However, three major trends have made higher TG materials essential:
Miniaturization and Power Density: As components get smaller, more heat is concentrated in a tiny area. The PCB itself must tolerate this localized thermal stress.
Lead-Free Soldering (RoHS Compliance): Standard lead-free solders (like SAC305) require soldering temperatures around 240℃ to 260℃. This exposes the board to much higher process temperatures than traditional tin-lead soldering, making a higher TG imperative to prevent damage during assembly.
High-Reliability Applications: Devices operating in harsh environments—such as automotive engine control units (ECUs), outdoor LED lighting, and military/aerospace electronics—require materials that maintain integrity even when ambient temperatures are extreme.
Matching TG to the Application
We generally categorize TG values into three main tiers:
| TG Tier | Typical Value | Application | Key Takeaway |
| Standard TG | 130℃ to 140℃ | Home electronics, simple computing, general use. | Cost-effective for low-stress environments. |
| Mid-TG | 150℃ to 160℃ | Servers, high-end PCs, industrial controls. | Good balance of cost and higher thermal resilience. |
| High-TG | ≥170℃ | Automotive, medical devices, high-power LEDs. | Required for extreme thermal environments and repeated high-heat cycles. |
Choosing the right material ensures the PCB remains stable during both the assembly process (reflow) and its entire service life. A board's TG should always be significantly higher than its maximum continuous operating temperature.
Our Commitment at PCBgogo
As a manufacturer, we understand that selecting the right material is the first and most critical step in producing a reliable board.
At PCBgogo, we don't just ask about your layer count; we focus on your application environment. We stock and utilize a wide range of materials, from standard TG to specialty 170℃ high-TG laminates. Our process controls are specifically optimized to handle the unique lamination and drilling challenges presented by high-TG materials, ensuring that the finished board meets its promised thermal performance.
