Before you finalize your PCB manufacturer you will be required to do a lot of screening and review. Without adequate screening you should not rush to pick your PCB manufacturer. When screening you will have to ask the right questions to your PCB manufacturer so that you stay away from dubious manufacturers and go ahead with the most dependable PCB manufacturers. 

All the questions you would be asking your China PCB manufacturer would be directed towards two major areas namely the quality of the PCBs delivered and secondly, the turnaround time for the delivery of the PCBs. You may want to first find out the experience level of the manufacturer. When your PCB manufacture comes with a vast experience the chances are that they have already seen similar requirements which enable them to handle your requirements too easily. Inexperienced manufacturers will experiment on your requirements and could they could obstruct your production cycle by delivering flawed PCBs. Give priority to companies with a vast experience. 

Secondly, does the supplier have their own manufacturing facility? Do not blindly presume that your supplier has their own manufacturing facility. They may not have their own manufacturing unit and they could just be acting as the mediator. You will have to therefore identify the most reliable manufacturers in the industry who not only claim to have a large manufacturing facility but actually have their own manufacturing unit. 

Will your supplier be able to ship to your location? Your manufacturer should be licensed to export their products to other countries and in particular to your location without any issues. There is no point engaging in a long discussion and price negotiation without establishing the ability of the manufacturer to deliver to your location. 

How soon can the manufacturer be able to commence the work on your PCB needs? If they are already running other orders and if they have maxed out on their manufacturing capacity then your order has to wait until they complete the other orders. You should make sure that their turnaround time works for you and it matches your production cycle. 

In case you should cancel the order, what is the cancellation policy of your PCB manufacturer? Make sure you get a clear picture on the order cancellation policy before you place the order so that you are not running into any unpleasant surprises in case you should go for order cancellation. 

Does the PCB manufacturer have any minimum order requirement? If yes, what is the minimum order requirement? You should also find out what is the maximum order quantity. In case you should scale up your PCB manufacturing needs will it be within the maximum capacity of the manufacturer? You will have to establish all these factors because PCB is an ongoing requirement of your company and you will need a dependable manufacturer that could meet your requirements. They should be able to meet not only your current requirements but also your ongoing requirements.