PCB Fabrication Processes Brief Introduction - Abbysan.com

1 PCB FabricationProcessesBrief IntroductionOrig2004/08/21 Edit2011/01/04 ContentsPCB Processes Flow Chart ..(001) Layer Processing ..(002) Lamination ..(032)7 ..(058)10 Plating ..(071)11 Layer (102)136. 1. Solder Mask ..(123)15 6. 2. Silk Screen ..(147)17 7. 1. Gold Finger Plating ..(158)18 7. 2. HASL ..(173)20 7. 3. Routing ..(190)21 Test & FQC ..(205)22 PCB FabricationProcesses Brief Introduction3D/S BoardLaminationENIG G/F PlatingHASL PackingShippingM/L s I/L manufactureHASLF inal Finish according to customer requirementDrillingCopper PlatingOuter LayerSolder MaskSilk ScreenE-Test & FQCOQCE ntek OSPI mmersion AgOQCE-Test& FQCR outingI/L CuttingPCB Processes Flow Chart4 RoutingG/F PlatingEntek OSP or Immersion Silver should be applied afterFQCI nner Layer ProcessingBase materials before cuttingBase materials after cuttingStack panels and send to next processBefore bevelingAfter beveling1-3

2 Pre-treatmentBrush foreign materials away from board surfaceAfter pre-treatment brushing1-4 Roller CoatingBefore roller coatingRoller coatingAfter roller coatingDouble sided send to drilling Multi-Layer send to inner layer pre-treatment 1-1 Cutting1-2 BevelingI/L Flow1-1 Cutting1-2 Beveling1-4 Roller Coating1-5 Exposure1-6 DES Line1-7I/L holes1-3 Pre-treatment51-5 ExposureExposureBoard surface after exposure1-6 DES LineBefore developingAfter developingAfter etchingAfter stripping away the film1-7I/L holesBefore hole formationAfter hole formation6 Inner Layer Processing (continued)Mass Lamination Process2-1 Brown OxideInner layer surface before brown oxidationInner layer surface after brown oxidation2-2 Pre Lay-upCut prepreg before pre-layup Above 8L boards should punch holes before pre-lay up CuttingP/P roll is cut into pieces to prepare for pre-lay upPrePreg Hole Punchingpunch the holes used for laminationStep 1 Step 2 Step3 Step 2 Step3 Step4 Step5 Step 1 Multilayer board procedure.

3 7ML Flow 2-1 Brown Oxide2-2 Pre-lay up2-4 Lay up2-5 Lamination2-6 Unload boards2-3 Pinning 2-8 Routing2-9 Beveling2-7 Drill tooling holesMass Lamination (continued)2-4 Lay upCopper foil cuttingbottom copper foil placed on the press plateLay upupper copper foil placedCover the press plate2-5 LaminationHot pressCool press2-3 Stack-up Pinning4L boardsabove 8L boardsHot copper rods melt spots to preserve layer shown after pinning8 Mass Lamination (continued)2-7 Drill target holesX-ray target hole drillingBoard surface after X-ray drilling2-8 RoutingBefore routingAfter routingBefore beveling After beveling2-9 BevelingStep 1 Step 2 Step 42-6 Unload boardsStep 39 Drilling Process3-1 Backing &Entry boardcuttingBefore cutAfter cuttingStack for next boardsEntry boards3-2 Add pinsStack panelsAdd pins3-3 DrillingAdd entry boardTape EdgesDrill3-4 Pin removalPins shownAfter pin removalDrilling Flow3-1 Entry and Backing3-2 Alignment Pins3-4 Pin removal3-3 Drilling 10 Copper Plating4-1 DeburrDeburr pre-treatment.

4 Non-woven rollersHigh pressure water rinseWater column spray pressure15kg/cm24-2 Desmear1. SwellingDip boards into high temperature alkali bath liquids (which containes organic solvent) to swell the resin the brushing & high pressure water rinse to clean away the fibers on the board surface and in the DesmearCleaning away the resin smears attached on the hole wall to expose a clean copper wall after desmearresin smear on hole wallCP Flow4-1 Deburr4-2 Desmear4-4 Copper Plating4-3 PTH 11 Copper Plating (continued)4-3 PTHPTH:Plated Through Holesprovide conductive connections between layers, and mechanical support for componentsPTH process Desmear Hole conditioning Micro-etch Activation Acceleration Electroless copper indicates Electroless copper plating on base copper and hole wall4-4 PlatingPTH plating must establish minimum hole wall thickness, and increase surface copper thickness to meet specification or customer requirement.

5 Indicates the plated copper layer 12 Outer Layer Processing5-1 Pre-treatPumice Line Clean foreign material from board surface and roughen board surface to increase adhesion to dry filmBoard surface before pre-treatBoard surface after pre-treat5-2 Etch Resist Dry film consists of PE film, photopolymer film resist and PET filmPETPEHeat and senteringpress to apply the dry film on the board :O/L Flow5-1 Pre-treatment5-2 Etch Resist5-4 DES Line5-3 Exposure 13 Outer Layers (continued)5-3 ImageExposureExposure:Blue material is light-sensitive, so UV energy will cause a chemical reaction to cure the areas that are exposed by the room5-4 DES LineBefore developingAfter developingAfter etchingAfter stripping away the film 14 Solder Mask Process6-1-1 Pre-treatPumice Line:Clean foreign material and roughen the board surface to increase solder mask adhesionBefore pre-treatAfter pre-treat6-1-2 PrintPrinting:Apply photoimagible mask on board surface to protect circuitry, prevent copper surface oxidation and act as solder resist6-1-3 Pre-curePre-curing.

6 Partially remove solvent so surface is not tackyS/M Flow6-1-1 Pre-treatment6-1-2 Printing6-1-4 Developing6-1-3 Pre-curing 6-1-5 Post-Curing15 Before maskAfter maskSolder Mask Process6-1-5 Post curingPost Cure :Final cure to increase surface hardness and resist soldering(board appears sameas in previous step)166-1-4 DevelopRemove the solder mask which wasn t exposed to UV curingDeveloping:Before developingAfter developingSilk Screen Process6-2-1 Screen printingLegend:Text and/or numbers printed on the final board surface using non-conductive ink. Commonly used to identify components (and orientation or polarity), and identifying board part number and revision level.

7 PCBIC 111R 168 PCBIC 111R 168R28U376-2-2 Post curingLegend baking oven:The ink used for silk screen printing contains hardening ingredients that are activated thermally, so it is cured at high temperature. This is called Polymerization or a crosslinkage reaction S/S Flow6-2-1 Screen printing6-2-2 Post curing 17 Gold Finger Plating7-1-1 Blue TapeCover entire board with semi-transparent film to mask from plating Before PCBIC111 Apply Blue tapeAfter Covering 111 PCBIC1117-1-2 OpeningExpose the gold finger PCBIC 111 Remove for PlatingIC111 PCBIC 111 Exposed Fingers PCBIC 1117-1-3 GoldPlateGold plating line.

8 Pre-treat Ni plating Au activation Gold Plate Rinse BakeBeforeAfter pre-treatAfter Ni-platingAfter gold plating PCBIC 111 PCBIC 111 PCBIC 111 PCBIC 1117-1-4tape removalRemove the blue tape covering from the board Board surface after gold finger plating PCBIC 111G/F Flow7-1-1 Blue Tape7-1-2 Expose7-1-4 Tape removal7-1-3 Gold plating 18 Hot Air Solder Level (HASL)7-2-1 Tape MaskMask areas that should not be coated with HASLB efore PCBIC 111 Apply tape manually PCBIC 1117-2-2 Tape pressureIncrease temperature and pressure to make the tape adhere to the gold surface PCBIC 111 Press tape to board surface7-2-3 Pre-treatHASL pre-treat.

9 Copper surface coating PCBIC 111micro-etch sprayFlux coating & dip7-2-4 HASLHot Air knives blow excess solder from board surface PCBIC 111 HASLFlow7-2-1 Tape Mask7-2-2 Tape Press7-2-4 HASL7-2-3 Pre-Treat 7-2-5 Post Treat7-2-7 Hole Count7-2-6 Tape Remove19 HASL process (continued)7-2-5 Post TreatPost treatment cleaning line brushes debris from the board surface PCBIC 1117-2-6 Tape RemovalSolder board surface after removing tape PCBIC 1117-2-7 HoleCountHole Counter :Uses light to perform automatic checking for correct hole count, will detect missed drilling and plugged holes PCBIC 11120 Routing Process7-3-1 RoutingRoute away the outer frame and board edge of the panels, and route slots if neededBefore PCBIC 111 Routing PCBIC 111 After PCBIC 1117-3-2V-CutV-Groove :cutter creates grooves for easier de-panelization after assembly.

10 PCBIC 111 PCBIC 111V-cuttingafter V-cut7-3-3 BevelingBevel:To aid gold finger insertion into socket, board edge is bevelledto 30~45 degree angle PCBIC 111 PCBIC 111 Bevelingedge after beveling7-3-4 Water RinseHigh pressure water rinse and brushes remove dust. Board are then stacked PCBIC 111 PCBIC 111 PCBIC 111 PCBIC 111 PCBIC 111 PCBIC 111 PCBIC 1117-3-1 Routing7-3-2V-cut7-3-4 Water Rinse7-3-3 Beveling F/M Flow21 Electrical Test & FQC8-1 ElectricalTestTest Fixture is developed using customer data, and will make sure finished board matches design. Test program will identify opens and shorts Board loaded into fixtureFixture engaged8-2 Repair PCBIC 111 Boards that didn t pass test are evaluated by the repair operator to determine whether the fault is real or false , to avoid was