Everything an engineer needs to choose, design and manufacture a high Tg PCB — an interactive laminate Tg database, a visual comparison chart, a thermal-stress explainer and a material selector. Built for PCB designers who want to get the glass transition temperature right the first time.
The glass transition temperature (Tg) is the point where a laminate's resin shifts from a hard, glassy solid to a soft, rubbery state. Above Tg the board loses stiffness and its z-axis expansion accelerates sharply. The higher the Tg, the higher the temperature your board can tolerate before that happens.
Classic FR-4. Fine for low-cost, low-temperature consumer boards and prototypes.
BaselineA modest step up in thermal headroom for general industrial use and simple lead-free builds.
ImprovedThe workhorse for lead-free multilayer, automotive, telecom and high-reliability boards.
★ The sweet spotPolyimide, BT, cyanate ester & low-loss systems for aerospace, RF and extreme environments.
ExtremeBelow Tg the laminate expands slowly in the z-direction. Above Tg, that expansion can jump 4–6×, pulling on copper-plated through-holes and microvias until barrels crack. A higher Tg keeps you in the safe, glassy zone through assembly and operation — explore this live in the Why Tg Matters tool below.
Search, filter and sort ~20 common PCB laminates by Tg, Td, z-axis CTE, dielectric constant, halogen-free status, lead-free suitability and relative cost. Click any column header to sort. Export your filtered view to CSV.
| Material ▲▼ | Class ▲▼ | Tg (°C) ▼ | Td (°C) ▲▼ | z-CTE ▲▼ | Dk ▲▼ | HF ▲▼ | Lead-free ▲▼ | Cost ▲▼ | Typical use |
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A side-by-side view of glass transition temperatures across the material classes, with the mid-Tg (150 °C) and high-Tg (170 °C) thresholds marked. Bars animate the moment they scroll into view.
Drag the temperature slider and pick a material's Tg. Below Tg the laminate stays glassy and stable. Cross it and the z-axis expansion accelerates, stressing the plated through-holes. This is exactly why a high Tg buys you reliability through lead-free reflow.
Status: The board is well below its Tg of 170 °C — fully glassy and stable. Plenty of thermal headroom.
Model: CTE-z ≈ 50 ppm/°C below Tg, rising toward ~250 ppm/°C above it — a simplified illustration of real laminate behavior, not a datasheet value.
Answer five quick questions about your project and get a recommended Tg class, target Td, and candidate laminates — a starting point to discuss with your fabricator.
Getting Tg right is part material selection, part stackup discipline. These guidelines help your high Tg design survive assembly and the field.
Pick Tg above your worst-case operating temperature, then make sure Td and time-to-delamination comfortably exceed your peak reflow profile and number of thermal cycles. For lead-free multilayer, Td and T260/T288 often matter more than Tg alone.
Call out the exact resin system (e.g. Isola 370HR, Shengyi S1000-2M) and Tg/Td on the fab drawing. "High Tg" alone invites substitution that can change CTE, Dk and reliability.
High layer counts, fine PTH and stacked microvias punish high z-CTE. Favor low-CTE laminates, keep symmetric stackups, and balance copper to limit warpage that gets worse near Tg.
For high-speed and RF, Tg is thermal, but Dk and Df govern signal integrity. Choose a laminate that satisfies both — many high-speed systems (Megtron, I-Tera, Rogers) are also high Tg, but a generic high-Tg FR-4 is not automatically low-loss.
High Tg resins can be stiffer and more brittle, and laminates absorb moisture. Bake before assembly, mind drilling parameters, and account for mechanical handling on thin, rigid panels.
Mixing materials (e.g. FR-4 cores with a low-loss surface layer) creates CTE and bonding mismatches. Validate the combination with your fab and keep prepreg/core systems compatible.
Higher Tg/Td laminates behave differently on the shop floor. Knowing where they diverge from standard FR-4 helps you set realistic expectations on yield, cost and lead time.
High Tg / high Td materials are harder and more abrasive, increasing tool wear. Fabs adjust feeds, speeds and retract rates, and high Td resists epoxy smear in the hole — which is good for plating adhesion.
These resins typically need higher lamination temperature and pressure and longer cure cycles. Press profiles must follow the laminate datasheet to fully cure and reach the rated Tg.
Higher Td chemistry reacts differently to permanganate desmear and plasma. Process windows are tuned per material to get clean holes without over- or under-etch.
Lower-CTE high Tg laminates hold layer-to-layer registration better on high counts, and must survive 3–6 lead-free reflows peaking at 245–260 °C without delamination — the core reason high Tg exists.
Relative material cost by class (standard FR-4 = baseline 1.0). Real pricing also depends on layer count, copper weight, glass style, volume and fab yield.
From under-hood electronics to satellites, here's where each Tg tier earns its keep.
Under-hood ECUs, powertrain, BMS and inverters face heat, vibration and lead-free assembly — classic high-Tg, low-CTE territory.
High-layer backplanes, switches and 5G gear need thermal robustness plus low Dk/Df — Megtron, I-Speed and FR408HR class.
Avionics, satellites and downhole tools demand polyimide or cyanate ester for extreme temperature and dimensional stability.
Motor drives, PLCs and power supplies cycle hot for years; high Tg resists delamination and creep over long service life.
High-power LEDs run hot; high Tg FR-4 or aluminum-core (IMS) boards manage junction temperature and heat dissipation.
Radar, antennas and mmWave use Rogers RO4000 / PTFE where stable Dk over temperature matters more than a conventional Tg.
Imaging, implantable and sterilizable devices need high reliability and, for autoclave cycles, elevated thermal tolerance.
BGA and chip-scale substrates use BT (bismaleimide-triazine) resin for high Tg, low CTE and tight feature stability.
Phones, wearables and appliances increasingly move to mid/high Tg to survive lead-free assembly and thinner stackups.
Quick, engineer-oriented answers to the questions we hear most.
Take your material choice from this tool straight to a fabricator. PCBSync manufactures high Tg PCBs across the full Tg range — from 170 °C FR-4 to polyimide and low-loss systems.
High Tg PCB ↗