High TG Gold Finger Multilayer Fr4 PCB Printed Circuit Board Prototype

High TG Gold Finger Multilayer Fr4 PCB printed circuit board Prototype

Quick detail:

What is High Tg PCB (printed circuit board)

•        In recent years, there are more and more customers request to manufacture PCB with high Tg, in the following we would like to describe what is high Tg PCB.

•     TG means Glass Transition Temperature Temperatures that are associated with long term operations must be considered in the manufactured of printed circuit boards that will be exposed to high thermal loads.. The function of a circuit board will be affected if its temperature exceeds the designated Tg value. You can count on Super PCB for a high TG PCB that won’t fail you.

•     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 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 and high Tg FR4 is, in the hot state, especially in the heat absorption with moisture, the high Tg PCB substrate will perform better than general FR4 in the aspects of mechanical strength, dimensional stability, adhesiveness, water absorption and thermal decomposition.

•     High Tg refers to the high heat resistance.With the rapid development of electronic industry, especially the electronic products represented by computer, toward high function, high multiple stratification, need PCB substrate material of higher heat resistance is an important guarantee.Represented by SMT, CMT's emergence and development of high density installation technology, make the PCB in the small aperture, fine lines, thin, more and more inseparable from the support substrate, high heat resistance.

•     Commonly so FR - 4 and the difference between high Tg FR - 4: is under the hot, especially in the heat after moisture absorption, its material mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion situations vary, such as high Tg products is significantly better than the ordinary PCB substrate materials.

FR4 Material Types

FR-4 has many different variations depending on the thickness of the material and chemical properties, such as the standard FR-4 and G10. The following list shows some common designations for FR4 PCB materials.

Standard FR4: This is the most common type of FR4. It provides good mechanical and moisture resistance, with heat resistance of about 140℃ to 150℃.

FR4 With High Tg: FR4 with high Tg is suitable for applications requiring high thermal cycling and temperatures greater than 150℃. Standard FR4 is limited to around 150℃, while FR4 with high Tg can withstand much higher temperatures.

FR4 With High CTI: FR4 with high CTI (Chemical Thermal Interaction) has better thermal conductivity than regular FR4 material. It has a comparative tracking index higher than 600 Volts.

FR4 without copper laminate: FR4 without copper laminate is a non-conductive material with excellent mechanical strength. It is mainly suitable for insulating boards and board supports.

FR4 G10: FR-4 G10 is a solid core material with excellent mechanical properties, high thermal shock resistance, excellent dielectric properties, and good electrical insulation properties.

The requirements of high frequency pcb material:

(1) the dielectric constant (Dk) must be very stable

(2) Dielectric loss (Df) must be small, which mainly affects the quality of signal transmission, the smaller the dielectric loss so that the signal loss is also smaller.

(3) and copper foil thermal expansion coefficient as far as possible, because inconsistencies in the change in the cold and heat caused by copper foil separation.

(4) low water absorption, high water absorption will be affected in the damp when the dielectric constant and dielectric loss.

(5) Other heat resistance, chemical resistance, impact strength, peel strength, etc. must also be good.

What Is FR4 PCB Material?

FR-4 is a high-strength, high-resistant, glass-reinforced epoxy laminate material used to fabricate printed circuit boards (PCBs). The National Electrical Manufacturers Association (NEMA) defines it as a standard for glass-reinforced epoxy laminates.

The FR stands for flame retardant, and the number 4 differentiates this type of laminate from other similar materials. This particular laminate has woven glass-reinforced epoxy resin.

FR-4 PCB refers to the board manufactured with adjacent laminate material. This material is incorporated in double-sided, single-sided, and multi-layered boards.

ONESEINE'S STANDARD FR-4 MATERIAL PROPERTIES

High Glass Transition Temperature (Tg) (150Tg or 170Tg)

High Decomposition Temperature (Td) (> 345º C)

Low Coefficient of Thermal Expansion (CTE) ((2.5%-3.8%)

Dielectric Constant (@1 GHz): 4.25-4.55

Dissipation Factor (@ 1 GHz): 0.016

UL rated (94V-0, CTI = 3 minimum)

Compatible with standard and lead-free assembly.

Laminate thickness available from 0.005” to 0.125”

Pre-preg thicknesses available (approximate after lamination):

(1080 glass style) 0.0022”

(2116 glass style) 0.0042”

(7628 glass style) 0.0075”

FR4 PCB Applications:

FR-4 is a common material for printed circuit boards (PCBs). A thin layer of copper foil is typically laminated to one or both sides of an FR-4 glass epoxy panel. These are commonly referred to as copper clad laminates. The copper thickness or copper weight can vary and so is specified separately.

FR-4 is also used in the construction of relays, switches, standoffs, busbars, washers, arc shields, transformers and screw terminal strips.

Here are some key aspects related to the thermal stability of FR4 PCBs:

The thermal stability of FR4 PCBs refers to their ability to withstand and operate under different temperature conditions without experiencing significant degradation or performance issues.

FR4 PCBs are designed to have good thermal stability, meaning they can handle a wide temperature range without warping, delaminating, or suffering from electrical or mechanical failures.

Glass Transition Temperature (Tg): Tg is an important parameter that characterizes the thermal stability of FR4. It represents the temperature at which the epoxy resin in the FR4 substrate undergoes a transition from a rigid state to a more flexible or rubbery state. FR4 PCBs typically have a Tg value around 130-180°C, which means they can withstand elevated temperatures without significant changes in their mechanical properties.

Coefficient of Thermal Expansion (CTE): CTE is a measure of how much a material expands or contracts with changes in temperature. FR4 PCBs have a relatively low CTE, which ensures that they can withstand thermal cycling without excessive stress or strain on the components and solder joints. The typical CTE range for FR4 is around 12-18 ppm/°C.

Thermal Conductivity: FR4 itself is not highly thermally conductive, which means it is not an excellent heat conductor. However, it still provides adequate heat dissipation for most electronic applications. To enhance the thermal performance of FR4 PCBs, additional measures can be taken, such as incorporating thermal vias or using additional heat sinks or thermal pads in critical areas to improve heat transfer.

Soldering and Reflow Processes: FR4 PCBs are compatible with standard soldering and reflow processes commonly used in electronic assembly. They can withstand the elevated temperatures involved in soldering without significant damage or dimensional changes.

It's important to note that while FR4 PCBs have good thermal stability, they still have limits. Extreme temperature conditions, such as very high temperatures or rapid temperature changes, can potentially cause stress, delamination, or other issues. Therefore, it's important to consider the specific operating environment and choose appropriate materials and design considerations accordingly.

FR4 PCBs are known for their excellent thermal stability, high mechanical strength, and resistance to moisture and chemicals. These properties make them suitable for a wide range of applications, including consumer electronics, telecommunications, automotive, industrial equipment, and more.

The FR4 material consists of a thin layer of copper foil laminated onto a substrate made of woven fiberglass cloth impregnated with epoxy resin. The copper layer is etched to create the desired circuit pattern, and the remaining copper traces provide the electrical connections between components.

The FR4 substrate offers good dimensional stability, which is important for maintaining the integrity of the circuitry over a wide range of temperatures. It also has low electrical conductivity, which helps prevent short circuits between adjacent traces.

In addition to its electrical properties, FR4 has good flame retardant properties due to the presence of halogenated compounds in the epoxy resin. This makes FR4 PCBs suitable for applications where fire safety is a concern.

Overall, FR4 PCBs are widely used in the electronics industry due to their excellent combination of electrical performance, mechanical strength, thermal stability, and flame retardancy.