PCB Printed Circuit Boards Raw Materials Classification

PCB printed circuit boards Raw Materials Classification

Rogers 4350 raw material

Common performance indicators of substrate

(1) DK: The dielectric constant of the material. Only by reducing DK can a high signal propagation speed be obtained.

(2) Df: The dielectric loss angle of the material; the lower this angle, the lower the signal propagation loss is.

Note that DK is mainly related to the impedance of the signal network and also related to the capacitance between the plates, and Df is mainly related to the loss of the signal network. Factors affecting DK are:

Resin (DK of epoxy resin is between 3～4);

Glass fiber cloth (DK between 6～7);

Resin content (RC value).

(3) Tg: glass transition temperature, which has the greatest impact on vias. The glass transition temperature is the characteristic of the polymer, which refers to the resin from hard (glassy) to soft (rubbery). This is the temperature at which the shape changes.

At present, the Tg value of FR-4 board is generally 130-140, and in the manufacture of printed boards, there are several process problems that exceed this range, which will have a certain impact on the processing effect and final state of the product. Therefore, increasing Tg is a primary method to improve the heat resistance of FR-4. The Tg classification is as follows.

Ordinary Tg sheet: 130～140℃.

Medium Tg sheet: 140～150℃.

High Tg board: greater than 170°C (PCB boards with more than 8 layers must use high Tg boards).

Flexible material:

DUPONT, PI

Aluminum material:

BERGQUIST, CUSTOM AL Base

About printed circuit boards Materials Classification

1. PCB Material

Currently, the commonly double-sided PCB material is FR-4 and CEM-3 substrate. Both materials are flame retardant (UV 94-V0). FR4 material is a copper-clad laminate made of electronic grade alkali-free glass fiber cloth impregnated with flame-retardant brominated epoxy resin, copper foil on one or both sides, and hot pressing.

The CEM-3 type material is an electronic grade alkali-free glass non-aromatic cloth with flame-retardant brominated epoxy resin filled in the middle insulation layer, and one sheet is filled with flame-retardant brominated epoxy resin on both sides of the non-woven fabric. Copper foil is on one or both sides of Resin electronic-grade alkali-free glass fiber cloth and is then formed by hot-pressing into copper-clad laminate.

2. PCB Material Types

KB FR4 raw material

FR-1: phenolic paper substrate, breakdown voltage 787V/mm surface resistance, volume resistance lower than FR2

FR-2: phenolic paper substrate, breakdown voltage 1300V/mm

FR-3: epoxy paper substrate

FR-4: epoxy glass fiber board

CEM-1: epoxy glass cloth-paper composite board

CEM-3: epoxy glass cloth/glass mat board

HDI board: High-density interconnect

Copper-clad laminate is also called substrate. The reinforcing material is soaked with resin, one or both sides are covered with copper foil, and a board material is formed by hot pressing, which is called copper-clad laminate. This is the basic material of PCB, often called substrate. When it is used in multilayer PCB board production, it is also called “core.”

Commonly used copper clad laminates are as follows:

FR-1: phenolic cotton paper; this kind of substrate is alternatively called bakelite (more economical than FR-2)

FR-2: Phenolic cotton paper

FR-3: Cotton paper, epoxy resin

FR-4: glass fiber cloth, epoxy resin

FR-5: glass fiber cloth, epoxy resin

FR-6: matte glass, polyester

G-10: glass fiber cloth, epoxy resin

CEM-1: cotton paper, epoxy resin (flame retardant)

CEM-3: cotton paper, epoxy resin (non-flame retardant)

CEM-4: glass cloth, epoxy resin

CEM-5: glass cloth, polyester

AIN: aluminum nitride

SIC: silicon carbide

At present, the copper-clad laminates supplied on the market can be divided into the following categories in terms of base material:

Paper substrate

Glass fiber cloth substrate

Synthetic fiber cloth substrate

Non-woven substrate

Composite substrate

Other

Copper-clad laminate refers to substrates such as paper and fiberglass cloth, which are filled with resin to make bonding sheets (adhesive paper and tape). After combining several bonding sheets, one or both sides are equipped with copper foil. It is cured by heat and pressure to make a plate-shaped product.

Shielding board material refers to a copper-clad laminate with a shielding layer or patterned circuit in the inner layer. As long as the circuit on both sides is processed, it can become a multilayer circuit board. This is also called a “copper clad laminate with shielding layer.”

Multilayer materials refer to copper-clad laminates and adhesive sheets (adhesive cloth) used to make multilayer circuit boards. Recently, this has come to include grease-coated copper foil (RCC) for multi-layer laminates. The so-called multi-layer board refers to a circuit board with two layers of patterned circuits on both surfaces and the inside.

Special substrates refer to laminates, metal core substrates, etc. used in the additive process, which are not included in the above-mentioned types of special plates.

Metal core substrates also include resin-coated substrates (FBC, etc.) Others are:

 Aluminum core base substrates

Copper core base substrate

Ceramic core base substrate

Glass base substrate

Basic Knowledge of PCB Materials:

Copper-clad laminate, also called PCB substrate.

(1) A plate-shaped material formed by filling a reinforcing material (glass fiber cloth, referred to as glass fiber cloth) with resin (pp sheet), covering one or both sides with copper foil, and hot pressing, called a copper-clad layer pressure plate (Copper Clad Laminates, [CCL]).

(2) The basic material for PCB, it is often called board.

(3) When it is used in the production of multilayer boards, it is also called core board (or core).

Copper foil

(1) The thickness of copper foil is measured in oz (ounces), and oz itself is the unit of mass. Usually, the thickness of copper foil is expressed as “thickness” by mass. The thickness of copper foil is usually defined as “oz”, 1oz copper thickness—spread one ounce of copper evenly on one square foot area. At this time, the thickness of the copper foil is called 1oz copper thickness, and its thickness is exactly 1.37mil (about 1.4mil).

The standard thickness of copper foil is 12μm (1/3oz), 18μm (Hoz), 35μm (1oz),and 70μm (2oz).