All kinds of substrate materials have their own characteristics. Here's a side-by-side comparison of them.
(a) Phenolic paper substrate
The phenolic paper substrate is an insulating laminate material using phenolic resin as a binder and wood pulp fiber paper as a reinforcing material. Phenolic paper-based copper clad laminates can generally be punched and processed with advantages of low cost, low price, and relatively low density. However, its lower operating temperature, moisture resistance and heat resistance are slightly lower than those of epoxy glass cloth substrates.
The paper substrate is mainly single-sided CCL. However, in recent years, double-sided copper-clad laminates have also appeared for through-holes in silver paste. It is more resistant to silver ion migration than normal phenolic paper based copper clad laminates.
The most commonly used product models of phenolic paper-based CCL are FR-l (flame retardant) and XPC (non-flame retardant).
(b) Epoxy paper substrate
Epoxy paper substrate is a paper-based CCL made of epoxy resin. It is slightly better than FR-l in terms of electrical and mechanical properties. Its main product model is FR-3, and the market is mostly in Europe.
(3) Epoxy glass cloth substrate
Epoxy glass cloth substrate is a type of substrate with epoxy resin as the binder and electronic grade glass fiber cloth as the reinforcing material. Its adhesive sheet and core thin copper clad laminate are important substrates for making multilayer printed circuit boards.
Epoxy glass cloth substrates have higher mechanical properties, dimensional stability, impact resistance, and moisture resistance than paper substrates. Its excellent electrical performance, high operating temperature, its performance is affected by the environment. In the processing technology, it has a great advantage over other resin glass cloth substrates. This type of product is mainly used for double-sided PCBs, with a large amount. Epoxy glass fiber cloth substrate, the most widely used product model for the FR-4, in recent years due to electronic product installation technology and PCB technology development needs, there have been high Tg FR-4 products.
(four) composite substrate
Composite substrate, which mainly refers to CEM-l and CEM-3 composite based copper clad laminates. Using wood pulp fiber paper or cotton pulp fiber paper as core material reinforcement and glass fiber cloth as surface reinforcement, both are impregnated with fire-retardant epoxy copper clad laminates called CEM-l. Glass fiber paper is used as the core material and glass fiber cloth is used as the surface layer reinforcement material. Both are impregnated with flame-retardant epoxy resin and the resulting copper clad laminate is called CEM-3. These two kinds of copper clad laminates are the most common compound-based copper clad laminates. The composite-based copper clad laminates have a mechanical property and a manufacturing cost that fall between the epoxy glass fiber cloth base and the paper base copper clad laminate. It can be punched and machined. The CEM-3 board manufactured by some foreign manufacturers is higher than the general FR-4 performance level in terms of traceability of leakage resistance, dimensional accuracy of plate thickness, and dimensional stability. The use of CEM-1 and CEM-3 in place of FR-4 substrates and the production of double-sided PCBs are now widely used in the world.
(five) special resin glass fiber cloth substrate
Special resin glass fiber cloth substrate, in the pursuit of high electrical performance, high heat resistance, the main purpose, resulting in a number of special resin glass fiber cloth substrate. Commonly used are polyimide resin (PI), polytetrafluoroethylene resin (PTFE), epoxy resin (CE), bismaleimide triazine resin (BT), thermosetting polyphenylene ether resin (PPE Or PPO) etc. They exhibit high heat resistance (high Tg), low water absorption, low dielectric constant, and dielectric loss tangent in terms of performance. However, generally, there are problems such as high manufacturing cost, slightly increased rigidity, and poor PCB processibility compared with the FR-4 substrate.
The characteristic of the cup head square neck Bolt is that the head is made into a semicircular ball, and a section of square neck is made under the head. A section of square hole shall also be made on the connected part connected with this bolt. When the bolt is inserted into the connected part and the nut is screwed on, the bolt will not rotate because of the square neck. Its head is relatively smooth, and it is not easy to hook other objects.
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