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Introduction of PCB laminated semi curing sheet

Published:

2022-11-23 15:29

Introduction to PCB laminated semi curing sheet:

I What is a semi curing sheet (Prepreg is the abbreviation of Pre pregnant), which is a sheet bonding material synthesized by resin and carrier.

A. Resin is a thermosetting material, which is a high molecular polymer. At present, epoxy resin is commonly used. It has three life cycles to meet the requirements of pressing plate:

A-Stage: It is a brominated propylene glycol+epichlorohydrin liquid epoxy resin. The resin of A-Stage is also called Varnish.

B-Stage: Glass fiber is soaked in A-grade resin, dried by hot air or infrared ray, and partially polymerized to form a solid film, which is called B-Stage.

C-Stage: In the process of pressing plate, B-stage resin melts into liquid at high temperature, and then undergoes polymer polymerization to become a solid polymer. The resin that bonds copper foil with the substrate to become a solid is called C-Stage. The flame resistant epoxy resin made of brominated malondinol is called FR-4 epoxy resin.

B. Glass fabric: It is a kind of reinforcing material formed by interweaving warp and weft after inorganic materials are fused at high temperature and cooled into a hard amorphous state.

Summary:

1. The prepreg is a kind of B-stage film formed by partially polymerizing reaction after the glass cloth is soaked in the configured varnish by the machine (Treater) and dried.

2. The glass cloth model shall be selected according to the thickness requirements of different dielectric layers.

3. At present, the base material and resin in the prepreg used by most companies are FR-4 flame resistant epoxy resin.

II Characteristics of the prepreg: The characteristics of the prepreg include the characteristics before and after the pressing plate. Characteristics before lamination:

A. RC% (Resin content): refers to the weight percentage of resin components in the film except glass cloth. The amount of RC% directly affects the ability of resin to fill the hollow between wires, and determines the thickness of the dielectric layer behind the pressing plate.

B. RF% (Resin flow): refers to the percentage of resin flowing out of the plate in the total weight of the original prepreg after pressing the plate. RF% is an index reflecting the fluidity of the resin, and it also determines the thickness of the dielectric layer behind the pressing plate

C. VC% (volatile content): refers to the proportion of the weight of volatile components lost in the original weight of the prepreg after drying. The amount of VC% directly affects the quality of the pressing plate.

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