PCB Board Material And Parameter Introduction

PCB circuit board sheet introduction: According to the brand quality level from bottom to top is divided as follows: 94HB-94VO-22F-CEM-1-CEM-3-FR-4

Detailed parameters and uses are as follows:

94HB: Plain cardboard, not fireproof (lowest material, die punching, cannot be used as power strip)

94V0: flame-retardant cardboard (die punching)

22F: Single Half Fiberglass Plate (Die Punching)

CEM-1: single-sided glass fiber board (must be drilled by computer, can not be punched)

CEM-3: double-sided half glass fiber board (in addition to double-sided cardboard is the lowest end of the double-sided material, a simple double-sided board can use this material, will be cheaper than the FR-4 5 ~ 10 yuan / square meter)

FR-4: Double-sided Fiberglass Board

Classification of flame retardant characteristics can be divided into 94VO-V-1 -V-2 -94HB four kinds

Prepreg: 1080 = 0.0712mm, 2116 = 0.1143mm, 7628 = 0.1778mm

FR4 CEM-3 is for sheet metal, fr4 is fiberglass, cem3 is composite substrate

Halogen-free refers to a substrate that does not contain halogens (such as bromobromoiodide), because bromine generates toxic gases when burned, and environmental protection is required.

Tg is the glass transition temperature, ie, the melting point.

The circuit board must be flammable, cannot burn at a certain temperature, and can only be softened. The temperature point at this time is called the glass transition temperature (Tg point), and this value is related to the dimensional durability of the PCB board.

What are the advantages of high Tg PCB boards and the use of high Tg PCBs?

High Tg Printed Circuit Boards When the temperature rises to a certain threshold, the substrate changes from a "glassy state" to a "rubbery state," and the temperature at that time is called the glass transition temperature (Tg) of the board. That is, Tg is the maximum temperature (° C.) at which the substrate maintains rigidity. That is to say, ordinary PCB substrate materials continue to produce softening, deformation, melting, etc. at high temperatures, and also show a sharp decline in mechanical and electrical properties. This affects the service life of the products. Generally, the Tg plate is 130. Above °C, high Tg is generally greater than 170°C, medium Tg is greater than 150°C; Tg≥170°C usually PCB printed board, called high Tg printed board; Tg of substrate is improved, and heat resistance of printed board is increased. Moisture resistance, chemical resistance, stability and other characteristics will be improved and improved. The higher the TG value, the better the temperature resistance of the sheet, especially in the lead-free process, high Tg applications are more; high Tg refers to high heat resistance. With the rapid development of the electronics industry, electronic products represented by computers, in particular, are moving towards higher functionality and higher levels of multilayer development, and require higher heat resistance of PCB substrate materials as a prerequisite. The emergence and development of high-density mounting technologies represented by SMT and CMT have made PCBs increasingly inseparable from the substrate's high heat resistance in terms of small apertures, fine lines, and thinness.

Therefore, the difference between the general FR-4 and high Tg: At the same time under high temperature, especially after heat absorption, the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion, etc. There are differences in the situation, high Tg products are obviously better than ordinary PCB substrate materials.