What is called high Tg FR4 PCB?

2019-12-06 | Author : FanyPCB

With the rapid development of the electronics industry, high Tg materials are widely used in computers, communication equipment, precision instruments and so on. in the following, we wil descirbe what is high Tg FR4 PCB.
Normally high Tg refers to high heat resistance in PCB raw material, the standard Tg for copper clad laminate is between 130 – 140℃, High Tg is generally greater than 170℃, and middle Tg is generally greater than 150℃. Basically the printed circuit board with Tg≥170℃, we call high Tg FR4 PCB. As the rapid development of electric industry, especially for the computer as the representative of electronic products, developing toward the high performance, high multilayer requires PCB substrate material with higher heat resistance to ensure high reliability. On the other hand, as a result of development of SMT, CMT with high density pcb assembly technology, the PCB manufacturing with small hole size, fine lines and thin thickness are more and more inseparable from the support of high heat resistance.
If the Tg of PCB substrate is increased, the heat resistance, moisture resistance, chemical resistance and stability of printed circuit boards will be improved as well. The high Tg applicates more in the lead free pcb manufacturing process.
Therefore, the difference between general FR4 PCB and high Tg FR4 PCB is, in the hot state, especially in the heat absorption with moisture, the high Tg FR4 PCB substrate will perform better than general FR4 in the aspects of mechanical strength, dimensional stability, adhesiveness, water absorption and thermal decomposition.
FR4 is a code name for grade of Epoxy Glass material.
Tg means Glass Transition Temperature.
When the working temperature reaches to the melting point, that means the temperature exceeds the Tg value, the status of pcb material will be changed from glassy to liquid, which will affect the function of pcb. And this value is related to the stability of the pcb dimension.
As usual, made with Tg ≥ 170℃ pcb material, which is called high Tg  FR4 printed circuit board. With the rapid development of the electronics industry, high Tg material is widely used in computer, communication equipment, precise apparatus and instrument and etc.
The characteristics of High Tg materials are listed below:
Higher heat resistance;
Lower Z-axis CTE;
Excellent thermal stress resistance;
High thermal shock resistance;
Excellent PTH reliability.
Pcbway offers some popular High Tg materials:
S1000-2 & S1170: Shengyi materials;
IT-180A: ITEQ material;
TU768: TUC material.
The specifications we can make, please check below:
Layer: 2-28 layers
Pcb size: Min. 10*15mm, Max.500*600mm
Finished board thickness: 0.2-3.5mm
Copper weight: 1/3oz-4oz
Surface Finish: HASL with lead /HASL lead free/Immersion gold/ Immersion silver/Immersion Tin/OSP-Organic Solderability Preservatives – RoHS
Soldermask: Green/Red/Yellow/Blue/White/Black/Purple/Matt Black/Matt Green
Silkscreen: White/Black
Min copper tracks/spacing: 3/3mil
Min holes: 0.1mm
Quality Grade: Standard IPC II