What Is FR4 Printed Circuit Board, FR4 PCB?

- May 26, 2016-

FR-4, is a widely acceptable international grade desination for fiberglass reinforced epoxy laminated that are flame retardant (self extinguishing). After add copper layer on one or each side FR4, it become to Copper Clad Laminate (CCL), and this is the non-conductive core materail for normal printed cricuit board (PCB). Printed circuit board using FR4 as core material will be named as "FR4 PCB".

PCB is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper clad laminate substrate. Sometimes, PCB also named Printed Wiring Board (PWB) or etching wiring board if no extra electronic components was added on.

Classification of FR4 Printed Circuit Board
According to number of copper trace layers, FR4 printed circuit board is normally divided into following types:

    Single Sided (S/S), or Single layer;
    Double Sided (D/S), or double layer, 2Layers, 2L;
    Four Layers (4L), Six Layers (6L), Eight Layers (8L), Ten Layers (10L)
    Board with more than 10L

In fact, for board more than four layers, people will named it "Multi-layer PCB". According to that standard, there're only three types of PCB: Single, Double and Multi-layers.

If divide the board according to manufacturing technology, major based on hole diamter size, it'll divid into two types:

    Normal through hole (diameter >=0.20mm (8mil)
    HDI (diameter <=0.15mm (6mil)

According to copper thickness, it can be divided into

    Normall copper: copper thickness: 0.5 OZ, 1.0 OZ, 2.0 OZ,
    Heavy copper: copper thickness: >= 3 OZ

According to core material, it can be divided into

    Rigid FR4 PCB: Only FR4, it is rigid for whole board;
    Rigid-flex circuits: Rigid FR4 plus flexible circuits;

According to Tg value of FR4, it can be divided into

    Normal Tg: Value 130, 135, 140;
    High Tg: Value 170, 180;

According to radio frequency (RF) level of PCB, it can be divided into

    Normal: < 300 Mhz
    High Radio Frequency: 300MHz ~ 3GHz,or even bigger

According to board thickness, it can be divided into

    Normal: >=0.30mm
    Extra Thin: 0.10~0.30mm;

In a word, according to different standard, FR4 PCB can be divided into different classfication. Please contact us for more information about the FR4 Printed Circuits

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