Rigid PCB Design For Manufacturability Guide Updated: February 19th, 2021 ©Bittele Electronics Inc. BITTELE ELECTRONICS DFM GUIDE FOR PCB DESIGNERS PAGE 1 OF 68 Table of Contents 1.0 – Introduction............................................................................................................................................ 5 1.1 Scope..................................................................................................................................................... 5 2.0 Required Documents ................................................................................................................................. 6 2.1 Gerber Files – RS-274X Format ............................................................................................................... 6 2.2 ODB++ ................................................................................................................................................... 7 2.3 Drill / Route File ..................................................................................................................................... 7 2.4 Netlist File ............................................................................................................................................. 8 2.5 Centroid File / Pick and Place File ........................................................................................................... 8 2.6 Assembly Bill of Materials (BOM) ........................................................................................................... 8 2.7 Drawings ............................................................................................................................................... 9 2.8 Standard Manufacturing Specifications ................................................................................................ 10 3.0 Laminate Materials Selection ................................................................................................................... 11 3.1 Material Selection & Properties ........................................................................................................... 11 3.2 Laminate Material and Thickness ......................................................................................................... 12 3.3 Prepreg Designation and Thickness ...................................................................................................... 12 3.4 Copper Weight & Heavy Copper for Materials ..................................................................................... 13 3.5 RF Substrates ....................................................................................................................................... 14 3.6 Metal-Core PCBs .................................................................................................................................. 15 3.7 Multi-Layer Stack-Up ........................................................................................................................... 16 3.8 Multi-Layer Stack-Up Recommendation ............................................................................................... 16 3.9 Buried Capacitance .............................................................................................................................. 19 3.10 Material Substitutes (North America vs China) ................................................................................... 20 4.0 Standard PCB Manufacturing Capabilities ................................................................................................ 21 4.1 PCB Technology Matrix ........................................................................................................................ 21 4.2 Etch Factor .......................................................................................................................................... 23 4.3 Drill Selection ...................................................................................................................................... 24 4.4 Aspect Ratio ........................................................................................................................................ 25 4.5 Annular Ring ........................................................................................................................................ 25 4.6 Tear Drop Pads .................................................................................................................................... 26 4.7 Hole Clearance .................................................................................................................................... 26 4.8 Conductor Clearance ........................................................................................................................... 27 Document Contents ©Bittele Electronics 2021 BITTELE ELECTRONICS DFM GUIDE FOR PCB DESIGNERS PAGE 2 OF 68 4.9 Via Holes Treatment ............................................................................................................................ 27 4.10 Finished Board Thickness ................................................................................................................... 28 4.11 Overall Finished Profile Tolerance ...................................................................................................... 28 4.12 Board Outline .................................................................................................................................... 29 4.13 Edge Bevel ......................................................................................................................................... 29 5.0 HDI Technology Capabilities..................................................................................................................... 30 5.1 Tight Trace Width / Spacing (Trace/Space) ........................................................................................... 30 5.2 BGA ..................................................................................................................................................... 30 5.3 Micro-via ............................................................................................................................................. 31 5.4 Multiple Laminations/ Sequential Lamination ...................................................................................... 33 6.0 Surface Finish: Options and Requirements ............................................................................................... 35 6.1 HASL/LF-HASL ...................................................................................................................................... 35 6.2 ENTEK/OSP .......................................................................................................................................... 36 6.3 ENIG .................................................................................................................................................... 37 6.4 Full Body Hard Gold ............................................................................................................................. 38 6.5 Selective Gold ...................................................................................................................................... 38 6.6 Double Gold (Full-Body + Selective Gold) ............................................................................................. 39 6.7 Edge Connector Plating ........................................................................................................................ 39 6.8 Wire Bonding (Soft Gold) ..................................................................................................................... 39 6.9 ENEPIG ................................................................................................................................................ 40 6.10 Immersion Tin .................................................................................................................................... 40 6.11 Immersion Silver ................................................................................................................................ 41 6.12 Comparison Chart .............................................................................................................................. 42 7.0 Solder Mask: Options and Requirements ................................................................................................. 43 7.1 – What is a Solder Mask? ..................................................................................................................... 43 7.2 – Types of Solder Mask ........................................................................................................................ 43 7.3 – Solder Mask Design Rules.................................................................................................................. 44 7.4 – Solder Mask Colours ......................................................................................................................... 45 7.5 – Substitutes (North America vs China) ................................................................................................ 46 7.6 – Solder Mask Tenting ......................................................................................................................... 46 7.7 – Solder Mask Plugging .......................................................................................................................