The Materials composition of rigid PCB

The rigid PCB has alternating layers of different materials laminated together by heat and adhesive to form a single object. So what materials is it mainly composed of?

1. Base material

Base material is fiberglass. The most common sign of this fiberglass is "FR4". This rugged core gives the PCB rigidity and thickness.

Cheaper PCB and perforated PCB will be made from other materials. For example, epoxy or phenolic resins that lack FR4 durability produce a very unpleasant odor when soldered, but at a much lower price. In addition, phenolic resins have a lower thermal decomposition temperature. If the soldering iron is held on the PCB for too long it will cause them to be layered, smoke, and scorched. This type of substrate is commonly found in low-end consumer electronics.

2. Copper

The next layer is a thin copper foil laminated to the PCB with heat and adhesive.

On a ordinary double sided PCB, copper is applied to both sides of the substrate. 

Only a PCB with copper on one side is a single-sided PCB. When we talk about double-sided or multi-layer PCBs, we refer to the number of copper layers in the PCB. HOYOGO's production layer is from 1 to 56 layers.

3. Solder mask

     The layer on top of the copper foil is called a solder mask layer. It covers the copper layer and insulates the copper trace from accidental contact with other metals, solder or conductive sites. This layer helps the user solder to the correct location and prevent solder jumpers. Solder masks are applied to most areas of the PCB, covering small traces, leaving the silver ring and exposing SMD pads so they can be soldered. Its most common color is green, but almost any color can be used. For example, HOYOGO has produced special solder masks such as pink, purple, and gray.

4. Silkscreen

A white silkscreen layer is applied on top of the solder mask layer. Silkscreen adds letters, numbers, and symbols to the PCB to facilitate assembly and to indicate people to better understand the PCB. We often use silkscreen labels to indicate the function of each pin or LED. The most common type of silkscreen color is white, but any other solder mask color can still be used. HOYOGO offers black, gray, red, or even yellow silkscreen colors. Generally, only one type of silkscreen color appears on the same PCB, and two or more colors rarely appear.

The composition of the rigid PCB is mainly the above materials. In addition, the price of the PCB will vary greatly depending on the choice of process and materials.