{"id":5739,"date":"2026-11-03T08:29:48","date_gmt":"2026-11-03T08:29:48","guid":{"rendered":"https:\/\/flj-pcb.com\/?page_id=5739"},"modified":"2026-11-03T08:29:48","modified_gmt":"2026-11-03T08:29:48","slug":"fr4-pcb","status":"publish","type":"page","link":"https:\/\/flj-pcb.com\/en\/pcb-manufacturer\/fr4-pcb\/","title":{"rendered":"FR-4 PCB"},"content":{"rendered":"
\n
Home<\/a> \/ PCB Manufacturing<\/a> \/ FR-4 PCB<\/div>
Custom boards \u00b7 a proven material platform<\/span>

FR-4 PCBManufacturing<\/h1>

The material behind everyday electronics.The board built for your product.<\/p>

FLJ manufactures FR-4 printed circuit boards for prototypes and production, from simple control boards to dense multilayer circuits. Choose the material grade, copper and finished construction for your application, with PCB assembly available alongside bare-board fabrication.<\/p>

Get an FR-4 PCB quote \u2192<\/a>Explore the material \u2193<\/a><\/div><\/div><\/div>

A stable circuit platform<\/strong>Glass reinforcement supports the board and its components.<\/span><\/p>

Electrical insulation<\/strong>The resin-and-glass dielectric separates the copper circuitry.<\/span><\/p>

Practical production economics<\/strong>Established materials and fabrication routes serve a wide range of electronics.<\/span><\/p><\/div><\/div><\/section>\n

Material construction<\/a>FR-4 material choices<\/a>Board options<\/a>Manufacturing & supply<\/a><\/div><\/div>\n
Glass + resin + copper<\/span>

The Material Behind an FR-4 Board<\/h2>

FR-4 is a family of flame-retardant, glass-reinforced epoxy laminates. The finished PCB brings that insulating structure together with the copper circuit.<\/p>

Woven glass fabric gives the laminate mechanical reinforcement. Cured epoxy binds the fabric and forms the insulating matrix around it. Copper foil bonded to the laminate becomes traces, pads and planes during fabrication.<\/p>

The familiar green surface is usually solder mask, a separate protective coating over selected areas of the outer circuit. Its color does not identify the laminate grade beneath it.<\/p>

Core and prepreg: the same material system, different jobs<\/h3>

A copper-clad core is already cured. Prepreg contains partially cured resin and reinforcement for bonding the layers of a multilayer board. During pressing, its resin flows around the copper features and cures. Glass style, resin content and pressing determine the resulting dielectric construction. That finished spacing, together with the material properties, matters when setting an impedance geometry.<\/p>See how a multilayer PCB is built \u2192<\/a><\/div><\/div>

\"Illustrative
Material roles illustrated separately. Not to scale; a complete production stackup includes its specified layers and features.<\/figcaption><\/figure><\/div><\/section>\n
Start with what the circuit needs<\/span>

Choose the FR-4 Grade for the Application<\/h2>

Two FR-4 boards can have different thermal and electrical behavior. The resin system, glass construction and material grade matter alongside the board’s layer count and thickness.<\/p><\/div>

Material choices and their purpose<\/caption>
Material direction<\/th>Where it earns its place<\/th>What makes the difference<\/th><\/tr><\/thead>
General-purpose FR-4<\/th>Control, interface, instrumentation and everyday electronic circuits.<\/td>A practical balance of insulation, mechanical support, availability and cost.<\/td><\/tr>
Higher thermal performance<\/th>Constructions facing greater assembly heat exposure or more demanding thermal cycling.<\/td>Glass transition, decomposition resistance and expansion behavior work together.<\/td><\/tr>
Lower-loss material systems<\/th>Longer or faster signal paths where dielectric loss becomes significant.<\/td>Grade-specific Dk and Df, glass construction and the electrical geometry.<\/td><\/tr>
Application-specific properties<\/th>Products with halogen, tracking-resistance or moisture-bias reliability needs.<\/td>Halogen-free, high-CTI and CAF-resistant properties are separate material choices.<\/td><\/tr><\/tbody><\/table><\/div>
01 \/ Thermal behavior<\/span>

More than a Tg number<\/h3>

Tg marks a change in the resin’s mechanical state. Above that transition, stiffness and expansion behavior change. Td describes decomposition under a specified thermal test. Reflow and rework expose the complete copper-and-laminate structure to heat, so the resin transition, decomposition resistance and expansion response are considered together. Tg is not the board’s continuous operating-temperature rating.<\/p>

Expansion also has a direction. Through-thickness movement of the laminate loads the plated copper in a hole as the board heats and cools. The grade’s expansion behavior, board thickness, hole construction and thermal exposure all influence that stress.<\/p>Compare PCB materials and stackups \u2192<\/a><\/article>

02 \/ Electrical behavior<\/span>

Match the dielectric to the signal path<\/h3>

Dk affects propagation and, together with the trace and reference-plane geometry, characteristic impedance. Df describes dielectric loss. Both depend on the material construction and the conditions under which they are measured.<\/p>

A high-Tg material is not automatically a low-loss material. FR-4 can support controlled-impedance circuits; longer and faster channels may benefit from a lower-loss construction. The signal path, rather than a universal frequency cutoff, determines when a specialty laminate is useful.<\/p><\/article><\/div>