Saturday, August 30, 2008

Things Need to Know Before Starting PCB Layout

Prior to beginning a new PCB layout, what does the PCB Designer need?

Following is an outline of the items required prior to beginning on a layout by the designer for him to complete his work in a timely manner. This is a partial list for a specific type of layout and does not apply to all types of printed circuit layouts. Any specific type may require additional items and some will require less. i.e. A PCB used in a computer has different layout requirements than those used in “down hole” equipment. The items listed are general items needed by a designer in any field.

1. Mechanical Outline:

Board Outline, Connector Placement, Pre-placed components ,I/O , Mechanical Constraints, Keep-Outs (Routing and Component), Mounting Holes, Connector Key Slots, Tooling Holes, Ventilation Holes, etc.

2. Design Rules

Technology , Trace and Space, Delay Rules, Matched Pairs, Busses, Differential Pairs, Layer Copper Weights, Component Placement, etc.

3. Logic Data
Net-list, Reference Schematic.

4. Library Parts
Footprints, Pad Stacks, Coupons, etc

5. Board Stack-Up
Number of Signal Layers, Number of Plane Layers, Layer Balance.

6. Test Requirements
Functional and In-Circuit Test (ICT)

7. Power Requirements
Voltage Planes, Vcc, Vdd, +3 V, +12V, etc. and Ground Planes.

8. Assembly Process
Wave Solder, Reflow Solder, Manual Solder.

9. Panelization
Fabrication, Assembly.

10. Schedule
Layout, Fabrication, Assembly.

If the above list does not include items required by your type of design, feel free to add your specific considerations. Hopefully this list will give you a more “heads up” of what to ask for from your Engineer. Use it to your advantage.

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