Have a knowledge of the difference between copper substrate and FR-4

Copper is one of the most expensive metal substrates and conducts heat many times better than aluminum and iron substrates. Aluminum substrate is generally a single layer, is a type of PCB board. Aluminum substrate is considered to be a generic term for PCB boards used specifically in the LED industry because of their good thermal conductivity. It is suitable for high frequency circuit heat dissipation, building decoration industry, high and low temperature change area, precision communication equipment, etc. LED aluminum substrate is divided into front and back. The white side is welded with LED pins and the other side is welded with aluminum. After coated with heat-conducting paste, it is used to contact heat-conducting parts.

The high-end practical design is also a double panel which is divided into circuit layer, insulation layer, aluminum, insulation layer and circuit layer structure. Rarely used in multilayer board, ordinary multilayer board can be bonded with insulation layer and aluminum alloy. Aluminum substrate good heat dissipation, good processability, dimensional stability and electrical performance make it widely used in integrated circuits, automobiles, office suite software comparison, high-power electrical equipment, power equipment and other fields.

Copper substrate is also divided into single panel, double panel and multi-layer plate according to the different number of layers. Compared with aluminum plate, copper plate due to special material, heat dissipation is relatively good, the price is relatively high. Widely used in high frequency circuit, high and low temperature change, precision communication equipment heat dissipation, building decoration and other industries. There are generally gold-impregnated copper substrate, silver-plated copper substrate, tin-sprayed copper substrate, copper oxide substrate and so on.

The circuit layer of copper substrate requires a large current-carrying capacity, so thicker copper foil should be selected, the thickness is generally 35μm~280μm; The thermal conductive insulating layer is the core technology of copper substrate. The core thermal conductive composition is composed of aluminum oxide and silicon powder and epoxy resin filled polymer. It has low thermal resistance (0.15), excellent viscoelasticity, thermal aging resistance, and the ability to withstand mechanical and thermal stress.

The metal base of copper substrate is the supporting member of copper substrate, which needs high thermal conductivity. Generally copper plate, suitable for drilling, punching and cutting and other conventional mechanical processing. The metal layer (block) mainly plays the role of heat dissipation, shielding, covering or grounding. Due to the difference of the performance of copper and aluminum and the corresponding PCB processing technology, copper substrate has more performance advantages than aluminum substrate.

Hf board is generally pressed by FR4 fiberboard, and it is the whole piece of epoxy glass cloth, the whole board color is more uniform and bright. Density is greater than the low frequency plate, is the focus of weight.

Many low frequency plate is laminated with low-end material, such as: paper base board, composite substrate, epoxy board (also called 3240 epoxy board, phenolic board), FR-4 glass fiber board (composite board), paper substrate and composite substrate, the overall density is lower, on the back of the color should be consistent, but it's easy to see internal basic no glass fiber fabric substrate.

The difference between epoxy board and FR4 glass fiber splicing board is that the color depth of the back substrate is different. When the epoxy board is scraped at the fracture point by hand or other tools, it is easy to see that there is white powder and the color is off-white. The FR4 splice board is easier to see because it is pressed from FR4 fiberglass cloth scraps，FR4 CTI and you can see the large stripes on the back of the whole board.

Basic production process of copper substrate:

1, cutting: the copper substrate raw materials will be cut into the size required for production.

2. Drilling: Conduct positioning drilling on copper base plate to provide help for subsequent processing.

3. Line imaging: the required part of the line is presented on the copper substrate.

4, etching: retain the required part after line imaging. The rest need not be partially etched away.

5, screen blocking welding: to prevent non-solder spots from being stained with solder, to prevent tin into the cause of short circuit. Solder resistance layer is very important in wave soldering, it can effectively protect the circuit from moisture.