PCB Design is the process which convert the schematic to Gerber, and send to PCB factory for fabrication.

There including many PCB Design softwares(EDA) on market.(Candance, Mentor Graphis, Altium Designer, Eagle etc.)

MPN TECH provide PCB Design solutions, it based on the final schematic with PDF or ".sch" format, and below is the layout prepare list for quotation.

1) Finalized schematics (.sch format will be better);---Attached Templates for reference.

2) Components' datasheets (eg: ICs and specific connectors, resistor and capacitor must mention size. If can provide Labrary, that will be better);---Attached Templates for reference.

3) Figure and instructions for key component placement (DXF document if you have);---Attached Templates for reference.

4) PCB layer definition(If possible for multilayer PCB);

5) List of specific requirments (such as high frequency, impedance, trace length/width);

6) Finalized BOM, if can provide.---Attached Templates for reference.

Normally we didn't accept schematic changes once PCB Design started, especially routing started, this will have extra works. Also have extra cost.
Minor placement or silkscreen changes is fine before PCB Design closed.(Less than 5%).