About product and suppliers:
            1,268 4 layer impedance pcb products are offered for sale by suppliers on Alibaba.com, of which other pcb & pcba accounts for 22%, pcba accounts for 6%. 

A wide variety of 4 layer impedance pcb options are available to you, 

There are 469 suppliers who sells 4 layer impedance pcb on Alibaba.com, mainly located in Asia. The top countries of supplier is China, from which the percentage of 4 layer impedance pcb supply is 100% respectively.