What is substrate? Substrate is the basic material for manufacturing PCB, In the case ,we generally say what is the substrate, the substrate refers to the copper clad laminate.
Today, printed circuit board has become indispensable main components of the vast majority of electronic products.Single-sided and double-sided PCB are fabricated based on the basic materials-Copper Clad Laminate,CCL, to obtain the desired circuit graphics that selectively pole processing、electroless copper plating、copper plating、etching and other processes.Another type of multi-layer printed circuit board manufacturing, but also to the core of the thin copper clad plate as the base, the conductive graphics layer and prepreg alternately through the one-time laminated bonding together to form three or more conductive graphics layer Interconnection. It can be seen, as the substrate material in the manufacture of printed circuit boards, whether it is copper clad laminate or prepreg, they are all play very important role in the printed circuit board .It has conductive, insulated and support three function. The performance、quality、processability of manufacturing 、manufacturing costs、manufacturing level of printed board, depends on the substrate material to a large extent.
Development history of substrates
Substrate materials technology and production, has gone through half a century of development, the world’s annual output has reached 290 million square meters, this development moment is driven by the innovation development of electronic machine products, semiconductor manufacturing technology, electronic installation technology, printed circuit board technology.
Since 1943, with phenolic resin substrate made of copper clad sheet began to enter the practical, the substrate material developed rapidly.In 1959, the United States,Texas Instruments produced the first piece of integrated circuits, and came up with a higher and high-density demand assembly for printed circuit board, thus promote the production of multilayer board. In 1961, the United States, Hazeltine Corpot ation company successfully developed multilayer technology using metallized through-hole method. In 1977, BT resin achieve the industrial production, provides a new type of high and low Tg substrate material to the multilayer board development of the world.
In 1990, in Japan,IBM Corporation announced the laminated multilayer board new technology that used photosensitive resin as the insulation layer, in 1997, the multilayer technology included laminated multilayer board, high-density interconnection were moving towards maturity. At the same time, the plastic packaging substrate,BGA, CSP is a typical representative ,has rapid development. The late of 90s of 20th century, some non-bromine, antimony green flame retardant and other new substrates rise quickly and enter into the market.
Kinds of substrate
In general, substrate materials used in printed circuit board can be divided into two categories: rigid substrate material and flexible substrate material.Generally CCL is an important specie of rigid substrate material.It is using reinforced material, impregnated with resin adhesive, by drying, cutting, folding into blanks, and then covered with copper foil, using steel plate as a mold, and forming in the hot press and in the high temperature.The prepreg for multi-layer board, it is semi-finished products that CCL in the production process of (mostly glass cloth impregnated with resin, and finished after drying process).
There are many ways to classify copper clad laminates. It can be divided into five categories according to different reinforced material: paper base, glass fiber cloth base, composite base (CEM series), laminated multilayer board base and special material base (ceramics, metal core base).It can be divided into phenolic resins (XPc, XxxPC, FR-1, FR-2, etc.),epoxy resins (FE-3) and polyester resins, etc.according to the different resin adhesive, it is paper base,CCI that we often see.There are epoxy resin (FR-4, FR-5)for Common fiberglass cloth base CCL it is the most widely used type of fiberglass cloth base at present. In addition, there are other special resins (glass fiber cloth, polyamide fiber, non-woven fabrics and other materials as reinforced material): bismaleimide modified triazine resin (BT), polyimide resin (PI) , Diphenylene ether resin (PPO), maleic anhydride imide-styrene resin (MS), polycyanate resin, polyolefin resin, etc.
It can be divided into two types of boards: flame retardant (UL94-VO, UL94 -V1 grade) and non-flame retardant (UL94-HB grade) according to CCL flame retardant performance. In recent years, with more attention to environmental issues, CCL is separated from a new bromine-free CCL varieties in the flame-retardant, can be called “green flame retardant CCL”. With the rapid development of electronic product technology, it has higher performance requirements to CCL. Therefore, it is divided into general performance CCL, low dielectric constant CCL, high heat resistance CCL (general board’s L is at more than150℃), low coefficient of thermal expansion CCL (generally used for packaging substrate ) and other types accordint to CCL performance.
Standard for substrate
With the development and continuous improvement of electronic technology, new requirements are continuous put forward to PCB substrate materials, thus can promote continuous development of copper clad plate standards. At present, the main standards of the substrate materials are as follows: Japan:JIS standard, USA: ASTM、 NEMA、MIL、IPC、ANSI、UL standards, UL:BS standards, Germany: DIN、VDE standards, France：NFC、UTE standards, Canada：CSA standards, Australia： AS standard, the former Soviet Union：FOCT standards, the international: IEC standards.
Pls see below form: