PCB News - FR-4 material—pcb multilayer circuit board manufacturers have something to say

FR-4 material-pcb multilayer circuit board manufacturers have something to say

PCB multilayer circuit boardmanufacturers have a professional technical R&D team, master the industry's advanced technology, and have reliable production facilities, testing facilities and functional physical and chemical laboratories. The FR-4 we are talking about here is the most commonly used sheet material model in the production of PCB multilayer circuit boards.
Very superficial, the most widely used copper clad laminates and prepregs in the world are the products named FR4 from NEMA, accounting for more than 54% of the total output of laminates, and the products that account for about 14% of the total output are single Face or double-sided FR-4 board, the remaining about 40% is used for multi-layer board is thin FR-4 laminate. The historical reason why FR-4 dominates the market is mainly because it has greatly exceeded the paper-based laminate in terms of thermal performance, improved moisture resistance and chemical resistance, higher bending strength and good shedding strength. .

Because of its moisture resistance and chemical resistance, FR4 is the first laminate material that can be used for spring-through double-sided boards. In addition, the price-performance ratio of FR-4 is supreme. Over the years, the industry has speculated that FR-4 will give way to newly developed laminate materials suitable for higher assembly density. However, due to cost reasons, circuit board designers are still looking for ways to use FR-4 in high density assembly.

The reinforcing material used for FR4 laminates is electronic glass cloth (E-glass). Because it has particularly good mechanical properties, satisfactory electrical insulation, special properties, heat resistance, moisture resistance and acid resistance, E-type glass fiber cloth has become a very good electrical reinforcement material. All fabrics used in FR4 are woven with a smooth appearance according to the method of weaving baskets. The exterior is covered with a layer of lacquer, which is used to strengthen the joint signature between glass fiber and natural resin. During the shrinking process, the thickness and number of glass fibers are voted The basic weight and thickness of the finished fabric, the thickness of the glass fiber cloth used for the printed board is mostly 6~172m, and the prepreg composed of glass fiber cloth voted for the thickness of the laminate. Generally, the thickness of FR4 laminate is bam~1L57mm (according to the interval of 25pm), and the specific thickness depends on the glass fiber cloth style and the natural resin content of the semi-finished sheet used. The performance of the laminate is mainly determined by the structure, because the buyer must put forward careful requirements. For a given thickness, there are many structures that can meet the given tolerance requirements. Changes in the natural resin content (sometimes referred to as the ratio of material to glass fiber cloth) will affect the performance of the laminate.

The overall system of epoxy natural resin is composed of a variety of active epoxy compounds, through the synthesis of a single epoxy group and tetrabromofluorescein A (TBPA) to obtain a standard bifunctional epoxy natural resin (its each There are two active epoxy compounds on each polymer chain). The chain length between the groups determines the rigidity of the compound and the thermal properties of the laminate. During the curing process, the epoxy group and the curing agent react to produce a three-dimensional polymer matrix. As a part of the polymer chain, if bromine is added to TBBPA, TBPA has special flame retardant properties. According to the UL94 test of the Underwriters Laboratory, in order to make the finished laminate have V0 flame retardancy, it is necessary to add bromine between 16% and 21% by weight.

The PCB circuit board products in the PCB multilayer circuit boardmanufacturers cover 2-28 layer boards, HDI boards, high TG thick copper boards, soft and hard bonding boards, high frequency boards, mixed media laminates, blind buried vias, metal substrates and non- Halogen board.