Keyword: pcb board, PCB, circuit board, printed circuit board
1 semi-cured resin material pcb board (B stage resin material ) Epoxy resin is widely used in the B-stage or in the manufacture of semi- cured material pcb board. When epichlorohydrin and bisphenol -A stick together the two monomers is a polymer obtained after the . This polymer is called B-stage resin may be softened and dissolved by certain solvents . This resin and paper or glass fiber cloth is obtained by mixing a filler such as B-stage epoxy resin materials, and are used in the production of multi- substrate pcb board. They have good chemical and solvent resistance and high temperature strength is lower in the direction of the z-axis expansion and other properties. 2 PTFE ( polytetrafluoroethylene ) substrate PTFE is a thermoplastic material . When a glass fiber reinforced , pcb board it is made of a substrate has several advantages , especially in the high frequency (RF) and microwave applications.
The resin constituting the composite material and glass fiber cloth thickness distribution dielectric constant and dielectric loss factor affecting uniformity. With microwave printed circuit board as a major change in dielectric properties of moving parts inevitably leads to performance degradation substrate PTFE glass fiber cloth material having pcb board the dimensions of 1220mm x914mm (48in x36in) for producing a substrate for the entire thickness distribution in a precise tolerance of 0.02 persons 0. 0015in, plate edge without any tapered protrusions . In addition , PTFE substrates in a wide temperature , humidity and the frequency range pcb board with a low dielectric constant and dissipation factor . Such that the molecular structure of PTFE has a very low moisture absorption of the substrate ( 0.02% ) . When the thermoplastic material is heated, both the suction has a phase change in a chemical change .
They constitute a three-dimensional molecular crosslinked network grid, Once heated and formed , they can not be reheated and restructured . Applications in the field of microwave substrate a thermosetting resin , exhibit a very high use value. Effects of moisture can cause the electrical properties of the substrate lower , especially for impedance, which is easily understood . Therefore, PTFE offers a very high electric strength , even in harsh environmental conditions all have electrical insulation properties. Therefore , in addition to the RF fields and micro Phi , PTFE substrate is also frequently pcb board used in the wet conditions that still need to maintain high insulation resistance areas A typical example is the high or low input impedance current measuring device and an amplifier . Greater advantage of PTFE layer having a high bonding strength between the copper foil and the peel strength based on this . In the re-assembly process, some of the conductor to be exposed to extremely high temperatures , which requires a high peel strength. Even if only 0.5oz/ft2 ( thickness 17.5m) PTFEI foil fiberglass cloth also showed a minimal 1. 8N/mm (101b/in) peel strength . PTFE substrate without any flame retardants pcb board can meet UL-94, vo other necessary flammability rating . Microwave applications based on thermosetting resin, the substrate requirements of good flame resistance properties even at the expense of other parameters, such as the peel strength or the substrate is not required to meet the thinnest vo level , which is a significant advantage PTFE substrate . In addition to glass fiber cloth as the PTFE filler , ceramic filler -containing PTFE substrate has been developed, it is not only inexpensive , but it is now clear for RF, microwave printed circuit board substrate.
This substrate is used for two-sided printed circuit board strip -line structure of the production and application of multiple substrates pcb board. Different types of epoxy substrate as follows : NEMAFR-3 retardant epoxy paper ; Common glass epoxy G-10, heat-resistant glass epoxy G-11; flame retardant epoxy glass FR -4; and heat retardant glass epoxy FR-5. Flammability performance is achieved by a halogen pcb board such as chlorine or bromine substitution resins obtained several functional groups . 3 polyester substrate ( Mylar substrate ) Polyester substrate is a polyester resin and an unsaturated copolymerizable monomer such as styrene made . Glass fiber reinforced polyester with a filler , thereby obtaining a laminated polyester foil substrates. Commercially available substrate is the standard NEMA grade FR-6. They are usually shiny , such as white or red , and relatively cheap . Their electrical properties similar XXXPC substrate , the mechanical properties are also comparable . Their spatial stability and water resistance are good, but in the welding , pcb board the plate and the plate bending Alice relatively large. 4 silicone substrate Silicone acrylate resin substrate is a glass- reinforced material to strengthen the silicone ester resin. Chemical agents and they have good heat tolerance, the temperature range of 175 - 400'C, according to their type. Manipulation ester resin systems pcb board of the silicon substrate between the copper foil and a good binding is difficult, although the electrical properties of these substrates is excellent , but its high cost limits their use. 5 Honey amino board Melamine resins and glass fiber reinforced materials, the type manufactured by combining honey amine board , they have very high surface hardness and a high arc resistance .
However, their main drawback is poor dimensional stability , especially with pcb board humidity changes the cycle . 6 polyamide substrate Polyamide is made of glass fiber cloth or aramid fiber or quartz fiber reinforced substrate constituted , has good electrical and mechanical properties, high copper bonding strength, good heat resistance and low z-axis expansion . They are used in demanding military and aerospace sectors as well as a dedicated multi-layer circuits.pcb board However, their poor copper foil peeling strength , high temperature soldering copper sink will tilt. 7 Teflon substrate Teflon ( PTFE ) substrate is a glass fiber reinforced through the obtained substrate having a low dielectric constant pcb board, it is used in the small leadless components consisting of the RF applications. Due to its high thermal Expansion coefficient , Teflon substrate limited application . 8 mixed media substrate In today's microwave and high speed digital printed circuit board pcb board, the use of mixed media substrates has become more common.
A material which is high-speed board C prepreg , which may be used as a blank or pre- Man HOI an outer dielectric provide an important signal routing , resulting in multi-layer printed circuit board in a non-critical layer FR-4 with cheap offers a good solution . Speed board blanks used as a pre- diffuse low-loss HOI media, pcb board you can make a high-speed digital devices controlled impedance , RF, and microwave printed circuit boards thinner pcb board, lighter , faster , thus improving their performance. This product by a modified BT resin impregnated expanded polytetrafluoroethylene (ePTFE) composition. By the resin in the air gap ePTFE replaced, and ePTFE membrane became carrier or resin delivery system . Integration of the medium becomes tough ePTFE , improved reliability , pcb board and high -density thin and macro circuit provides excellent surface smoothness.
