Before design activity can begin, the 'ground work' must be laid to establish the form, fit and function of any printed circuit board. Successful PCB design happens when Marketing, Program Management, Engineering, Manufacturing or Production Control, Test and Integration, Material Control and Quality Assurance work in concert toward a design that functions as the customer requires, with a reasonable performance margin, for a reliable product
life cycle that the customer needs..., and for the price that the customer will pay and a profit margin that makes the company healthy and successful.
An overall approach is needed to support the entire program, not just the needs of any one department or small group of individuals. Having a board work in the Engineering Lab is not proof of a manufacturable product, it is only proof of concept... not designed to the rules required to make a reliable, manufacturable, testable, and deliverable product.
Before layout, the team members from Planning, Engineering, Manufacturing, Material Control, QA, and Test need to be consulted and given a opportunity to review the 'potential product' to give their valuable input as early in the design process as is practical to make sure that all disciplines are informed and their design considerations
are evaluated and planned for, in the initial stages of the design. This does not mean that an engineer can't prototype his or her circuit before these meetings, but the meetings are essential if you are to produce the product in a cost effective manner.
The PCB Designer must be prepared by knowing the needs of the different departments involved and being sensitive to those needs in developing the printed circuit design.
The following are examples of questions that could be asked by the PCB designer at the Pre-Layout design review meeting.
To be discussed :
When do we need the design done (how about a schedule)?
What is our cost target for the PCB?
How many units do we expect to ship per year? per month? per quarter?
How are we going to test the PCB? In-house? Outside?
What are the customer requirements? (this will be Marketing's info)
What is the expected life of the product?
What Logic families are we dealing with?
What frequencies will we be dealing with?
What limitations do we have electrically?
What limitations do we have mechanically?
What limitations do we have environmentally?
Are there any high current devices to be concerned about?
If so, what currents and voltages?
What sort of thermal challenges will the design encounter?
How will the board be mounted?
What sort of connectors will be needed?
What sort of user interfaces (panels, switches) will there be?
What sort of indicators or displays will be required?
What agency approvals will be required?
What are the physical constraints for the PCB assembly
What bus structures will be employed?
Do we need impedance matching?
Will we need stripline, micro-strip or special RF or Microwave technologies?
What material(s) do we wish to use?
Will the board(s) be solder coated?
How will the boards be assembled?
Will the boards be through hole? Surface mount?
Do we have library parts for all the component footprints?
Do we need data sheets for specific components to build those parts in the library?
Etc., etc, etc...
A proper review of the design parameters prior to beginning work on the PCB is paramount. If you don't have the review, you will most likely be doing the board over again...