PCB Manufacturing Process Flow: Complete Fabrication Routes

Figure 1. Multi-Layer PCB Manufacturing Process

There is no single PCB manufacturing process flow that applies to every board. A double-sided plated-through-hole board, a multilayer PCB, a negative-plated board, a PTFE high-frequency board, a blind/buried-via build, and a board with mixed surface finishes can follow materially different production routes.

This page is organized as a PCB process-route library. It shows the manufacturing sequence for each major board or process type, including the conditional operations that are inserted only when the design requires them. For the engineering logic behind CAM, DFM, compensation and production-data release, see the main PCB manufacturing process guide.

Standard multilayer flow:
Panel Cutting → Post-Cutting Bake → LDI Registration → Inner-Layer Dry Film → Inner-Layer Etching → Inner-Layer AOI → Brown Oxide → Lamination → Drilling → Deburring → Electroless Copper → Panel Plating → Outer-Layer Dry Film → Dry-Film Inspection → Pattern Plating → Outer-Layer Etching → Outer-Layer AOI → Solder Mask → Legend → Surface Finish → Electrical Test → Routing → Final Inspection → Packaging.

Optional branches such as metallized-slot routing, solder-mask via plugging, impedance testing, second drilling and V-scoring are inserted only when required.

PCB Manufacturing Process Flow Selector

PCB / requirement	Recommended route on this page	Main process difference
Double-sided PTH PCB	Double-sided pattern-plating flow	No inner-layer imaging or multilayer lamination.
Multilayer PCB	Multilayer pattern-plating flow	Adds inner layers, AOI, brown oxide and lamination.
Negative-plated PCB	Negative-plating flows	Copper build occurs before negative-film imaging and negative etching.
Hole copper without matching surface-copper build	Selective hole-copper plating flow	Adds dedicated hole-plating film and separate copper/tin plating stages.
PTH + NPTH requiring separate drilling timing	PTH / NPTH split-drill flow	NPTH drilling is inserted after pattern plating and before etching.
Controlled-depth metallized slot	Semi-metallized controlled-depth slot flow	Through-slot and step-slot machining occur at different production stages.
PTFE / Rogers-type high-frequency material	PTFE plasma-treatment flows	Adds material conditioning and plasma before copper deposition; a separate pre-solder-mask conditioning step is also used.
Mechanical blind/buried-via build	Blind/buried-via negative-plating branch	Adds sub-board processing, copper reduction and additional plating/imaging loops.
Special electrical or registration verification	Special test routes	Test operations are inserted at defined checkpoints rather than at the normal final-test position.
Mixed surface finish / gold fingers	Surface-finish branch routes	Gold plating, masking, tape protection, HASL or other finish operations change the downstream order.

1. Core PCB Fabrication Process Flows

These are the base production routes. Special holes, materials, finishes and tests are added as branch operations to one of these core flows.

1.1 Bare Board / Blank Panel — Direct Process Core route

1. Panel Cutting
2. Drilling
3. Negative Etching
4. Routing
5. Final Inspection
6. Packaging
7. Finished-Goods Warehouse

Used for simple blank-board processing that does not require the laminated single-sided route.

1.2 Bare Board / Blank Panel — Laminated Process Core route

1. Panel Cutting
2. Post-Cutting Bake
3. Negative Dry Film — single-side lamination and exposure
4. Negative Etching
5. Lamination
6. Drilling
7. Secondary Negative Etching
8. Routing
9. Final Inspection
10. Packaging
11. Finished-Goods Warehouse

This branch is used when the blank-board construction requires lamination. Copper must remain available before drilling in this route.

1.3 Single-Sided and Pseudo-Double-Sided PCB Core route

1. Use the approved single-sided manufacturing route
2. Drill all non-plated holes according to the released drill definition
3. Complete single-sided circuit formation
4. Apply required finish and profile operations
5. Final Inspection
6. Packaging

A double-sided layout with no metallized holes is treated as a pseudo-double-sided board and follows the single-sided route rather than the normal PTH double-sided process.

1.4 Double-Sided Pattern-Plating PCB Core route

1. Panel Cutting
2. Post-Cutting Bake
3. Aluminum Entry-Sheet Drillingif required
4. Mechanical Drilling
5. Metallized Slot Routingif required
6. Deburring
7. Electroless Copper
8. Panel Plating
9. Outer-Layer Dry Film
10. Dry-Film Inspection
11. Pattern Plating
12. Outer-Layer Etching — thiourea cleaning where specified
13. Outer-Layer AOI
14. Surface Brushing / Grindingif required
15. Solder-Mask Via Pluggingif required
16. Solder Mask
17. Solder-Mask Inspection
18. Legend / Silkscreen
19. HASL, ENIG or specified Surface Finish
20. Impedance Testif required
21. Electrical Test
22. Second Drilling / V-CUTif required
23. Routing
24. Feature Inspection
25. Final Inspection
26. Packaging
27. Finished-Goods Warehouse

This is the standard positive pattern-plating route for a two-layer board with metallized holes.

1.5 Multilayer Pattern-Plating PCB Core route

1. Panel Cutting
2. Post-Cutting Bake
3. LDI Registration
4. Inner-Layer Dry Film
5. Inner-Layer Etching
6. Inner-Layer AOI
7. Brown Oxide
8. Lamination
9. Aluminum Entry-Sheet Drillingif required
10. Mechanical Drilling
11. Metallized Slot Routingif required
12. Deburring
13. Electroless Copper
14. Panel Plating
15. Outer-Layer Dry Film
16. Dry-Film Inspection
17. Pattern Plating
18. Outer-Layer Etching — thiourea cleaning where specified
19. Outer-Layer AOI
20. Surface Brushing / Grindingif required
21. Solder-Mask Via Pluggingif required
22. Solder Mask
23. Solder-Mask Inspection
24. Legend / Silkscreen
25. HASL, ENIG or specified Surface Finish
26. Impedance Testif required
27. Electrical Test
28. Second Drilling / V-CUTif required
29. Routing
30. Feature Inspection
31. Final Inspection
32. Packaging
33. Finished-Goods Warehouse

Compared with a double-sided board, the multilayer route adds inner-layer imaging, inner-layer AOI, brown oxide and lamination before the through-hole process.

1.6 Double-Sided Negative-Plating PCB Negative plating

1. Panel Cutting
2. Post-Cutting Bake
3. Drilling
4. Deburring
5. Electroless Copper
6. Negative Plating
7. Post-Plating Surface Grinding
8. Negative Dry Film
9. Dry-Film Inspection
10. Negative Etching
11. Outer-Layer AOI
12. Surface Brushing / Grindingif required
13. Solder-Mask Via Pluggingif required
14. Solder Mask
15. Solder-Mask Inspection
16. Legend
17. HASL, ENIG or specified Surface Finish
18. Impedance Testif required
19. Electrical Test
20. Second Drilling / V-CUTif required
21. Routing
22. Feature Inspection
23. Final Inspection
24. Packaging
25. Finished-Goods Warehouse

This flow uses copper build before negative-film imaging and negative etching.

1.7 Multilayer Negative-Plating PCB Negative plating

1. Panel Cutting
2. Post-Cutting Bake
3. LDI Registration
4. Inner-Layer Dry Film
5. Inner-Layer Etching
6. Inner-Layer AOI
7. Brown Oxide
8. Lamination
9. Aluminum Entry-Sheet Drillingif required
10. Drilling
11. Metallized Slot Routingif required
12. Deburring
13. Electroless Copper
14. Negative Plating
15. Negative-Plating Surface Grinding
16. Negative Dry Film
17. Dry-Film Inspection
18. Negative Etching
19. Outer-Layer AOI
20. Surface Brushing / Grindingif required
21. Solder-Mask Via Pluggingif required
22. Solder Mask
23. Solder-Mask Inspection
24. Legend
25. HASL, ENIG or specified Surface Finish
26. Impedance Testif required
27. Electrical Test
28. Second Drilling / V-CUTif required
29. Routing
30. Feature Inspection
31. Final Inspection
32. Packaging
33. Finished-Goods Warehouse

The multilayer negative-plating route adds the complete inner-layer and lamination sequence before the negative-plating outer-layer process.

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2. Hole Plating and Mechanical Branch Flows

These routes are inserted when hole copper, non-plated holes, plated slots or controlled-depth features cannot be handled by the standard drilling/plating sequence.

2.1 Selective Hole-Copper Plating — Hole Copper Without Matching Surface-Copper Build Hole plating

1. Drilling
2. Electroless Copper
3. Panel Plating
4. Hole-Plating Dry Film
5. Dry-Film Inspection
6. Selective Hole Copper Plating — copper only, no tin
7. Dry-Film Stripping
8. Post-Plating Surface Grinding
9. Outer-Layer Dry Film — normal outer-layer artwork
10. Dry-Film Inspection 1
11. Tin Plating — tin only, no additional copper
12. Outer-Layer Etching
13. Normal Downstream Process

This positive-process branch separates hole-copper build from the later outer-layer tin-plating/etch-resist operation.

2.2 Normal Board / Blind-Buried Sub-Board Hole-Plating Flow Hole plating

1. Previous Processas applicable
2. Laminationwhen applicable
3. Drilling
4. Desmear / Hole Cleaning
5. Electroless Copper
6. Panel Plating
7. Hole-Plating Dry Film
8. Selective Hole Copper Plating — copper only, no tin
9. Dry-Film Stripping
10. Post-Plating Surface Grinding
11. Inner-Layer Dry Film
12. Inner-Layer Etching
13. Normal Downstream Process

The manufacturing specification uses this negative-route branch for normal boards and blind/buried-via sub-boards that require a dedicated hole-plating cycle.

2.3 PTH + NPTH Split-Drill Flow Split drilling

1. Previous Process
2. Pattern Plating
3. Second Drilling — NPTH features
4. Dry-Film Stripping
5. Etching
6. Normal Downstream Process

This sequence keeps selected NPTH features out of the earlier metallization route by drilling them after pattern plating.

2.4 Semi-Metallized Controlled-Depth Slot Flow Controlled depth

1. Drilling
2. Through-Slot Routing
3. Normal PCB Processing
4. Pattern Plating
5. Dry-Film Stripping
6. Controlled-Depth / Step-Slot Routing
7. Outer-Layer Etching
8. Normal Downstream Process

The through slot participates in plating first; the controlled-depth machining is performed after resist stripping and before final outer-layer etching.

2.5 Metallized Slot / Edge-Plating Base Flow Metallized mechanical feature

1. Previous Process
2. Drilling
3. Slot / Edge Routing
4. Deburring
5. Electroless Copper
6. Normal Plating and Downstream Process

Metallized slots and edge-plating features must be machined before copper deposition so the exposed walls can be metallized.

2.6 Controlled-Depth Metallized Feature — Standard Branch Controlled depth

1. Previous Process
2. Lamination
3. Drilling
4. Controlled-Depth Slot Routing
5. Deburring
6. Electroless Copper
7. Normal Downstream Process

Used when the controlled-depth feature must be metallized after machining.

2.7 Controlled-Depth Metallized Feature — With Laser-Drilled Feature Controlled depth

1. Previous Process
2. Lamination
3. Drilling
4. Controlled-Depth Slot Routing
5. Deburring
6. Laser Drilling
7. Plasma Treatment
8. Chemical Cleaning
9. Electroless Copper
10. Normal Downstream Process

This branch inserts laser drilling and additional hole-wall preparation before electroless copper.

3. Blind/Buried-Via and Repeated-Drilling Process Flows

Complex interconnect structures can require sub-board fabrication, copper reduction, resin-plugging support operations and more than one metallized drilling cycle. For a broader overview of buildup structures, see HDI PCB manufacturing.

1. Panel Cutting
2. Post-Cutting Bake
3. Inner-Layer Dry Film
4. Inner-Layer Etching
5. Inner-Layer AOI
6. Brown Oxide
7. Lamination
8. Bake 1
9. Edge Milling
10. Resin / Smear Removal
11. Copper Reduction
12. Drilling
13. Deburring
14. Electroless Copper
15. Negative Plating
16. Negative-Plating Surface Grinding
17. Negative Dry Film
18. Dry-Film Inspection
19. Negative Etching
20. Normal Downstream Process

This route is used as a sub-board manufacturing branch for applicable mechanical blind/buried-via constructions.

3.2 Double-Sided / Sub-Board Negative-Plating Branch Blind / buried via

1. Panel Cutting
2. Post-Cutting Bake
3. Copper Reduction
4. Drilling
5. Deburring
6. Electroless Copper
7. Negative Plating
8. Negative-Plating Surface Grinding
9. Negative Dry Film
10. Dry-Film Inspection
11. Etching
12. Normal Downstream Process

This shorter branch is used when the sub-board does not require the multilayer inner-layer/lamination sequence.

3.3 Multiple Metallized Drilling Cycles Repeated PTH drilling

1. Previous Process
2. First Metallized Drilling Operation
3. Bake 1
4. Plasma Treatment
5. Glass-Fiber / Hole-Wall Treatment
6. Second Metallized Drilling Operation
7. Bake 2
8. Plasma Treatment 1
9. Glass-Fiber / Hole-Wall Treatment 1
10. Electroless Copper 1
11. Normal Downstream Process

Used when a board has more than one drilling stage and each drilling stage creates metallized through-hole features.

Figure 2. multi-layer-pcb-negative-pattern-plating-process-infographic

4. Material-Specific PCB Manufacturing Flows

Material selection can insert extra conditioning steps even when the circuit geometry is unchanged. The routes below show the material-specific additions defined for the corresponding material families.

4.1 PTFE High-Frequency PCB — Pre-Electroless-Copper Plasma Flow PTFE / RF

1. Previous Process
2. Drilling
3. Deburring
4. Pre-Electroless-Copper Bake
5. Plasma Treatment
6. Electroless Copper
7. Normal Downstream Process

Applied to applicable PTFE drilled sub-boards, PTFE/non-PTFE hybrid drilled sub-boards, mother boards and pure PTFE multilayers. For deeper material-specific manufacturing detail, see the Rogers PCB fabrication process.

4.2 PTFE High-Frequency PCB — Pre-Solder-Mask Conditioning PTFE / RF

1. Previous Process
2. Pre-Solder-Mask Bake
3. Solder Mask / Solder-Mask Via Plugging
4. Normal Downstream Process

This is a separate PTFE conditioning insertion before solder-mask processing.

4.3 N4000-Series Material Route Special material

1. Previous Process
2. Inner-Layer AOI
3. Brown Oxide
4. Post-Brown-Oxide Bake
5. Lamination
6. Drilling
7. Deburring
8. Pre-Electroless-Copper Bake
9. Electroless Copper
10. Normal Downstream Process

The material route adds thermal conditioning after brown oxide and again before electroless copper.

4.4 MEGTRON4 / FR408HR Material Route High-speed material

1. Previous Process
2. Drilling
3. Deburring
4. Pre-Electroless-Copper Bake
5. Plasma Treatment
6. Electroless Copper
7. Normal Downstream Process

The defined route adds both pre-copper baking and plasma treatment after drilling.

4.5 IT-150DA Material Route Dedicated material route

IT-150DA requires a material-specific manufacturing route. Confirm the exact sequence for the current stackup, hole structure and fabrication requirements during engineering release; do not assume that a standard FR-4, PTFE or MEGTRON route applies.

5. Special Test and Inspection Process Flows

These are insertion routes: the specified test is placed at a defined checkpoint rather than simply added at the end of the board.

5.1 Hole-Resistance Test Flow Special test

1. Previous Process
2. Outer-Layer AOI
3. Hole-Resistance Test
4. Solder Mask
5. Normal Downstream Process

Used only when hole-resistance testing is required. For standard bare-board continuity and isolation methods, see PCB electrical testing.

5.2 Inductance Test — Routing Before Electrical Test Special test

1. Routing
2. Electrical Test
3. Inductance Test

Used for boards whose normal route profiles the PCB before electrical testing.

5.3 Inductance Test — Electrical Test Before Routing Special test

1. Electrical Test
2. Routing
3. Inductance Test

Used when the product route performs electrical testing before final profiling.

5.4 Registration / Alignment Test Flow Special inspection

1. Previous Process
2. Outer-Layer Etching
3. Registration / Alignment Test
4. Outer-Layer AOI
5. Normal Downstream Process

Added when the customer or engineering review requires dedicated registration verification.

5.5 Controlled-Impedance Verification Position Special test

1. Surface Finish / Relevant Final Process
2. Impedance Test
3. Electrical Test
4. Normal Final Processes

Impedance testing is conditional and follows the approved coupon/test plan. See impedance-control PCB manufacturing for the design and measurement context.

6. Surface-Finish and Auxiliary Process Routes

Surface finish can move or add operations in the downstream manufacturing sequence. The flows below show the finish combinations for which the manufacturing sequence is explicitly defined. For finish selection and finish characteristics, see PCB surface finish options.

6.1 Kapton / Protective Tape Application Flow Auxiliary

1. Previous Process
2. Final Inspection
3. Tape Application
4. Second Final Inspection
5. Next Process

This auxiliary route is inserted where the product requires tape application before the next operation or shipment-related processing.

6.2 Lead-Free HASL — Basic Downstream Flow Surface finish

1. Solder Mask
2. Solder-Mask Inspection
3. Legend
4. Lead-Free HASL
5. Routing
6. Normal Final Processes

If legend would be printed directly over a large solder-finished area, the order may be changed so the surface finish is completed before the affected legend operation.

6.3 HASL + Gold Fingers with Plating Leads Mixed finish

1. Previous Process
2. Gold-Finger Plating
3. Tape Protection
4. Leaded or Lead-Free HASL
5. Normal Downstream Process

Tape protects the plated-gold region during the solder-leveling operation.

6.4 HASL + Long/Short Gold Fingers Mixed finish

1. Previous Process
2. Solder-Mask Inspection
3. Gold-Finger Plating
4. Tape Protection
5. Leaded or Lead-Free HASL
6. Normal Downstream Process

The solder-mask inspection checkpoint is completed before the plated-finger and tape-protection sequence.

6.5 Secondary Dry-Film Hard-Gold / Soft-Gold Route Electroplated gold

1. Previous Process
2. Outer-Layer Dry Film
3. Dry-Film Inspection
4. Pattern Plating
5. Outer-Layer Etching
6. Second Outer-Layer Dry Film
7. Second Dry-Film Inspection
8. Copper / Nickel / Gold Pattern Plating
9. Hard-Gold or Soft-Gold Electroplating
10. Lead Removal / Peeling where required
11. Normal Downstream Process

This route separates the base outer-layer circuit formation from the later selective electroplated-gold operation.

6.6 Mixed Surface-Finish Process Family Route selected by finish combination

Mixed-finish boards do not have one universal sequence. The production route is selected according to the finish combination, such as HASL + gold fingers, ENIG + selective electroplated gold, OSP + gold fingers, immersion tin + gold fingers, immersion silver + selective gold, carbon ink combinations, or peelable-mask combinations. The masking, secondary dry-film, plating, tape-protection, legend, testing and routing order must follow the finish combination actually specified for the job.

7. How to Read These PCB Process Flows

Steps marked “if required” are conditional branches rather than mandatory operations. For example, a PCB without controlled impedance does not need the impedance-test insertion, a routed board does not automatically require V-CUT, and a board without plated slots does not use the metallized-slot branch.

Likewise, a board can move from one core route into a special branch and then return to the normal downstream process. A multilayer PTFE board, for example, still has a multilayer base route, but the drilling-to-copper sequence adds the PTFE plasma-treatment branch. A PTH/NPTH design can follow the normal pattern-plating route until the second-drilling insertion is required.

Process-route principle: the finished PCB specification determines which manufacturing route is released. Layer count, plated/non-plated hole structure, copper build, material family, via construction, controlled-depth features, surface finish and special test requirements can all change the sequence.

Need a Manufacturing Route Review?

Highleap Electronics provides PCB fabrication services for standard and advanced constructions. Send the fabrication package when the board requires special hole plating, PTFE/RF materials, blind or buried vias, mixed finishes, controlled-depth machining or non-standard testing so the correct production flow can be confirmed before release.