Create a set of PCB design flow processes
that you can use as a guide to step you through the development of a PCB
layout. An efficient design flow helps
you avoid duplicating steps. Once you
have completed a step, you should never need to repeat it.
A
comprehensive design review should take place between all applicable
disciplines: i.e. Hardware Engineer, Project Management, Layout, Mechanical,
and Manufacturing.
For
the PCB designer the following information needs to be determined: Layer
stack-up and plane layers, PCB thickness and board material, default trace
width, component complexity and quantity of new components, proto board or
production/auto route or manual route, high speed rules, impedance control,
testability and Schedule.
2. COMPONENT
DATA SHEETS
Engineering
Department will submit all component data sheets, (web link), prior to the
start date of a PCB layout, of all of the components that cannot be located in
your Library Handbook.
3. MECHANICAL DATA SHEET
Engineering
Department will also provide a Board Outline constraint drawing if one is
available, or as soon as possible. The mechanical constraint drawing should be
drawn from the top side, include all mounting holes, fixed connector locations,
indicate the Layer Stack-up and board thickness of the PCB. The origin for the
constraint drawing should be the lower left mounting or tooling hole.
4. PART NUMBER & BOARD NAME ASSIGNMENT
After
the Engineering Department submits the data sheets, a part number and a board
name are assigned to the PC Board.
5. LIBRARY MANAGEMENT
As
you create your library parts, using the naming convention that you developed,
populate the applicable PCB Library with
the new decals, representing the pin assignments and all applicable notes and
documentation for each part. Keep the PLB file “Up to Date” every time new
parts are built.
6. CUSTOM BOARD OUTLINE
Select
the correct PADS “Start File” that matches the layering scheme that the
Engineer has provided and copy the master “Start File” to a new name.
Fill
out the Title Block.
Enter
the Board Outline.
Add
all Mounting/Tooling Holes and Fiducials that are necessary then glue them
down.
Move
the Targets to the outer extremities of the board outline.
Fully
dimension the board edges and at least one mounting hole.
Create
the “Auto router Keep-in/out” inside the Board Outline
7. STANDARD BOARD OUTLINE
If
a Standard Board Outline is selected from the Library, the PCB Designer will
fill out the Title Block and edit the text on Layer 26 that will eventually go
on the Silkscreen.
Setup
the correct Layer and Color Scheme.
8. NETLIST
At
the start of the PCB design, the Engineering Department will provide a net
list, from the schematic capture tool, in PADS format starting with the
PADS-PowerPCB header:
!
PADS-POWERPCB-V4.0-METRIC!
The
net list will contain all of the correct PADS Decal Shape Names.
The
net list will not contain Pin Names over four characters long.
The
following is a list of acceptable pin names: Collector = C, Emitter = E, Base =
B,
Anode
= A, Cathode = C, Source = S, Drain = D, Gate = G, Positive = 1, Negative = 2.
Import
the netlist into PowerPCB. If errors are found, in the netlist, the Designer
will report them to the Project Engineer. The Project Engineer will fix the
problems and provide the PCB Designer with an updated netlist.
After
the net list is successfully imported into PADS, the PCB Designer will
Tools/Disperse the parts.
9. REPORTS
Create
and e-mail to Project Engineer Unused Pins, Part List 2 & Statistic
Reports.
PCB
Designer must review Unused Pins list for 2 pin components.
Project
Engineer must review Unused Pins list for possible schematic errors.
10. PART PLACEMENT
The
Designer and Engineer will perform the part placement, or Engineers suggested
layout.
The
placement must meet the Engineers guidelines and design rules. Engineer will
provide the design rules.
The
placement must meet all manufacturing requirements.
The
placement must meet all routability requirements.
Tools/Verify
Design - check clearance to ensure no over lapping parts.
Use
CAM Plane option and use a 2D-Line to separate the different Plane Nets, or use
the Split/Mixed Plane option.
Use
the View/Nets feature to discriminate different nets by color.
12. First (1ST) SET OF QUALITY CONTROL PRINTS (PDF Format)
1:1
scale Drill and Assembly drawing laser print or bond paper.
All
new Library Decals must be checked for Solder Pattern accuracy.
Print
Split Planes if applicable for Project Engineer to check.
13. FINAL PART PLACEMENT
After
Split Planes and New library Decals are checked, PCB Designer will make final
part placement adjustments.
PCB
Designer will make final silkscreen adjustments.
14. GENERATE OUTPUT FOR MECHANICAL PART PLACEMENT 3D MODEL CHECKS
USING SolidWorks or PRO‑E TRANSLATORS
Now that you have completed half of the job to complete a project, a more challenging task awaits you on Part 2 of this tutorial...
Have fun!
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