Computer Aided Manufacturing or ‘CAM’ Engineering is the most critical part of printed circuit board manufacturing as this is where design criteria’s are measured and checked to ensure the designed is able to be manufactured.
Some of the basic checks include:
· Track width and clearance is appropriate for the copper thickness requirement
· Solder mask bridges between IC’s have sufficient space
· Sufficient annular ring for all plated holes
· Minimum hole-to-hole clearance
· Minimum hole-to-pad clearance
· Minimum hole- to-track clearance
· Sufficient inner layer clearances
· Minimum silkscreen height
· Minimum silkscreen lines
· Ensure no exposed copper after solder mask (except the pads and SMT components)
· Where vias are to be tented (covered) with solder mask, adjust the solder mask file accordingly
· Multi-layer stack-up sequence
CAM engineering will then set up the required file packages which can be downloaded at each stage of production as required:
· Photo-plotting all films for copper layer primary image, photo-printing primary image, solder mask, component legend silk-screen
· CNC drill files – initial plated through hole drilling files
· CNC route files – profiling, internal and external notches and cut outs
· CNC non-plated drill file - there may be further non plated holes to be drilled
· CNC v-grooving files – v-cut or v-grooving these days is predominantly processed with CNC v-grooving machines
· Net list probe test/ jig test files for bare board electrical testing
· A job card/traveller will be generated listing all the required finishes on the printed circuit board order for each stage of fabrication which include the following:
o Customer Name
o Part Number / Revision
o Layer count
o Stack up sequence
Material type
o Finished Thickness
o Copper thickness
o Unit size
o Finished panel size if panellised
o Production panel size
o Surface finish
o Solder mask colour
o Silkscreen component legend colour
o Special instructions
Fabrication packages are created which are used in various workflow production stages including films for drilling templates/checks and fabrications drawings for final QA which list all the finished requirements with tolerances depending on the fabrication requirement; Class 2, Class 3, Mil Spec, etc.
CAM Engineering will receive the customers Gerber files which may or may not be panellised. For this example, we can assume that the PCB Gerber files were supplied as a single unit. We would then proceed to panellise these to ensure productivity through SMT assembly by adding top & bottom tooling strips with tooling holes and fiducial marks. The example below is panellised 4 up (2x2) with 10mm top & bottom tooling strips with 4 x 3.0mm tooling holes and 3 x fiducial marks with solder mask clearance.
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PCB Global’s CAM engineering is always processed and updated with the customer’s permission and authorisation to ensure the highest quality PCB Gerber files are provided to allow for minimum EQ’s, ensuring the fastest possible lead time for all of our customers. For further tips and information when designing and laying out your printed circuit board design file please do not hesitate to contact our PCB Global team at sales@pcbglobal.com
