# PP (prepreg) in PCB

_Published: 2016-04-02_

PP is prepreg that is to connect the inner layer and offer the insulation

PP (prepreg)  is a kind of base materials of Printed Circuits Board.

It is an un-curable resin with non-conductive, which using for connecting the inner layer and offer the insulation.

Following is a 4 layers PCB stackup which including two pieces of 0.07 mm 1080 pp, there the 1080 pp is to connect top layer with 2 layer,and connect bottom layer with 3 layer, meanwhile pp is non-conductive.

![4 layer PCB stackup](http://www.bestpcbs.com/faq/images/4-layer-pcb-stackup-1.01mm.gif)pp in 4 layers  PCB stackup

It consists of glass fiber and resin. The resin is un-curable status, called-** B-Stage. **

** Basic Types of PP**

** **Glass fiber types: 1080，2116，7628; list the normal thickness FYI:1080 pp:3 mil; 2116 pp: 4.2 mil; 7628 pp:7 mil;

Resin types: Phenolic Resin, Epoxy Resin, Polyimide Resin ,PI, Bismaleimide Triazine, BT

PP is for FE4 PCB, so if you wound like to know more about other PCB, for example [Ceramic PCB](http://www.bestpcbs.com/products/ceramic-pcb.htm), [MCPCB](http://www.bestpcbs.com/products/metal-core-pcb.htm), meanwhile don’t hesitation to contact us if any question.