Multilayer PCB Manufacturing Processes

A step to step guide

Multilayer PCB manufacturing involves complex processes to create high-density interconnections. Advanced techniques like lamination, etching, and plating are utilized to produce durable, reliable circuit boards that power modern electronics.

Step 1: Incoming Check

Check all the data provided to make sure the designing of the PCB is manufacturable, functional, reliable and cost effective. Raise questions if EQ, then issue MI for production.

Step 2: Material Cutting

Cut the materials into panel according to MI. Including core, Prepreg, copper foils. Tooling holes need to be drilled at this step.

Step 3: Pre-treatment

Prepare for the inner layer DFR(Dry Film Resist) lamination. To increase DFR adhesion, etch the surface of copper foils by jet-scrubber, buffbrushing.

Step 4: Inner Layer D/F Lamination

Laminate Dry Film on cores. D/F is used as a photosensitive material forphotolithography.

Step 5: D/F Exposure

Expose light onto the D/F.LDI (Laser Direct Imaging),which doesn't require mask application,is analternative solution.

Step 6: DES

Same as the following. Developing the photoresist; Etching away unwanted copper; Stripping the remaining resist to reveal the circuit pattern.

Step 7: Black Oxide

Etch the surface of copper surface to ensure adhesion of coppe and Prepreg.

Step 8: Lay-up

Laminate Dry Film on cores. D/F is used as a photosensitive material forphotolithography.

Step 9: Hot Press

Heat the laminated layers under pressure in a vacuum melt Prepreg by heat to multilayer PCB formation. Other processes by the following will be the same as a double-sided PCB.

Step 10: Drilling

Drill on board to form through holes.

Step 11: Desmear

Remove the smear and resin residues left in the drilled holes, to ensure good electrical connectivity and improve the copper plating quality.

Step 12: PTH

Electroless Copper Plating, a thin layer of copper is deposited on the hole walls through a chemical process, making them conductive.

Step 13: Panel Plating

Electroplating, the thin copper layer is further reinforced with additional copper through electroplating, ensuring robust andreliable electrical connections.

Step 14: Pre-treatment

Prepare for the next step, D/F lamination. To increase dry film adhesion, etch the surface of copper foils by jet-scrubber,buff brushing.

Step 15: Outer Layer D/F Lamination

Laminate Dry Film on copper foils. D/F is used as a photosensitive material for photolithography.

Step 16: D/F Exposure

Apply masks(films) on D/F and expose light onto the surface of copper foils. Currently, we use both ways, D/Fand LDI(Laser Direct Imaging), which doesn't require mask application.

Step 17: DES

Developing the photoresist; Etching away unwanted copper; Stripping the remaining resist to reveal the circuit pattern.

Step 18: O/L Inspection

Use AOI for outer layer inspection, to check for defects such as scratches, misalignments, and incomplete etching, ensuring the final board meets the required specification.

Step 19: Pre-treatment

Clean and roughen the copper surface to increase the adhesion between the copper surface and solder resist.

Step 20: Solder Masktting

Apply photosolder resist on one side then pre-baking, then printing solder resist on the other side, pre-baking, then exposure-develop-curing.

Step 21: Silkscreen

Screen printing or injet printer printing the legend.

Step 22: Surface Finish

Apply surface treatment according to the specification, like Lead-free HASL, OSP, Immersion Gold/Tin/Ag etc.

Step 23: Profile

CNC routing, V-scoring, or punching, to de-panel the board from working panel.

Step 24: E-testing

Use Probe flying testing for prototype and small series, and E-test fixture for production orders.

Step 25: FQA & FQC

Final Quality Control and Final Quality Assurance for the finished PCB.

Step 26: Packing & Shipping

Packing according to the specification and ship to worldwide customers.

Single-sided PCB

Basic PCB with copper layer on one side

Double-sided PCB

Circuits on both sides, interconnected

Multilayer PCB

Stacked-layer PCB for complex electronics

HDI PCB

High density PCB with laser drilling microvias

Heavy Copper PCB

PCB with thick copper layers for high current

High Frequency PCB

PCB optimized for high-frequency signal integrity

Backplane PCB

Robust PCB for modular system connectivity

Metal Core PCB

PCB with metal core for improved heat dissipation

Flexible Circuits

Thin, bendable PCB for flexible electronics

Rigid-flex PCB

PCB combining both rigid and flexible layers

Semi-Flex PCB

FR-4 PCB with depth controlled milling technology

MiniLED PCB

PCB for high-efficiency MiniLED displays

Halogen-free PCB

Eco-friendly PCB with halogen-free materials

Rigid Polyimide PCB

Durable PCB made by Polyimide material

IC Substrate

High-performance, miniaturized base for IC

Embedded Components

Embedded parts in PCB for space-saving integration

Resistors

Passive component that limits electrical current flow

Capacitors

Stores and releases electrical energy in circuits

Inductors

storing energy through magnetic fields

Transistors

Amplify or switch electronic signals

Transformers

Convert voltages and isolate circuits electrically

LED Lighting

Energy-efficient, long-lasting light source

Integrated Circuits

Compact components for complex electronic functions

Switch

Controls the flow of electricity

Connectors

Join electrical circuits for signal transmission

Circuit Protection

Protects circuits from overloads and damage

Semiconductors

Materials that control electrical current flow

Batteries

Stores and provides electrical energy

RF & Wireless

Transmission and reception of radio frequency signals

Electromechanical

Devices with electrical and mechanical components

Power, Circuit Protection

Protect and control electrical power circuits

Cables, Wires

Conduct and connect electrical power and signals

Laser Stencil

Laser-cut stencil for accurate components placement

SMT + Reflow

Surface Mount assembly with Reflow soldering

DIP + Wave

Through-hole parts using DIP and wave soldering

SMT + DIP Mixed

Both SMT and DIP components on one board

Lead-free Assembly

PCB assembly without the use of lead solder

IC Programming

Programming integrated circuits for specific functions

BGA Rework

Repair of Ball Grid Array (BGA) chips

Conformal Coating

Protective coating to against moisture and contaminants

Injection Molding

Process of shaping materials by injecting into molds

Functional testing

Testing to verify product's function and performance

Cabel & Wire Harness

Soldering pre-made cables and wires on board

Ageing Test

Test to simulate long-term wear and performance

Box Build

Electronic component integration into enclosures

EMS

Electronic Manufacturing Services

Kitted Assembly

Customer sources some parts and we handle the rest

Turnkey Assembly

Complete assembly service from design to final product

Glossary

An exploration of terms and definitions

Datasheet

Comprehensive specifications and technical details

FAQ

Common questions and answers for quick information reference

Blog

Our insights, stories, and perspectives

Union Profile

Discovering identities and building connections

Core Strength

Building stability, balance, and power

Quality Policy

Commitment to excellence and continuous improvement

Contact Us

Reach out, connect, and explore solutions

PCB Assembly Processes

A step to step guide

The PCB assembly process is a systematic sequence that transforms a bare PCB into a functional electronic device. It involves multiple stages utilizing specialized equipment and quality controls, ensuring reliable and efficient integration of components according to design specifications.

Step 1: Incoming Check

Initial inspection and verification of received materials, including bare PCBs and components, before they enter the assembly process, to ensure that materials comply with customer requirements and specifications.

Step 2: Material Baking

Baking the bare PCBs and the moisture-sensitive components(such as certain ICs, BGAs, and plastic-packaged components) prior to assembly.

Step 3: PCB Conveying

Prepare for the inner layer DFR(Dry Film Resist) lamination. To increase DFR adhesion, etch the surface of copper foils by jet-scrubber, buffbrushing.

Step 4: Solder Paste Printing

Laminate Dry Film on cores. D/F is used as a photosensitive material forphotolithography.

Step 5: D/F Exposure

Expose light onto the D/F.LDI (Laser Direct Imaging),which doesn't require mask application,is analternative solution.

Step 6: Hi-Speed Mounting

Same as the following. Developing the photoresist; Etching away unwanted copper; Stripping the remaining resist to reveal the circuit pattern.

Step 7: Multi Function Mounting

Etch the surface of copper surface to ensure adhesion of coppe and Prepreg.

Step 8: Visual Inspection

Laminate Dry Film on cores. D/F is used as a photosensitive material forphotolithography.

Step 9: Reflow Soldering

Heat the laminated layers under pressure in a vacuum melt Prepreg by heat to multilayer PCB formation. Other processes by the following will be the same as a double-sided PCB.

Step 10: AOI

Drill on board to form through holes.

Step 11: DIP

Remove the smear and resin residues left in the drilled holes, to ensure good electrical connectivity and improve the copper plating quality.

Step 12: Wave Soldering

Electroless Copper Plating, a thin layer of copper is deposited on the hole walls through a chemical process, making them conductive.

Step 13: Inspection & Testing

Electroplating, the thin copper layer is further reinforced with additional copper through electroplating, ensuring robust andreliable electrical connections.

Step 14: De-panel

Prepare for the next step, D/F lamination. To increase dry film adhesion, etch the surface of copper foils by jet-scrubber,buff brushing.

Step 15: Conformal Coating

Laminate Dry Film on copper foils. D/F is used as a photosensitive material for photolithography.

Step 16: Final Assembly

Apply masks(films) on D/F and expose light onto the surface of copper foils. Currently, we use both ways, D/Fand LDI(Laser Direct Imaging), which doesn't require mask application.

Step 17: Ageing Test

Developing the photoresist; Etching away unwanted copper; Stripping the remaining resist to reveal the circuit pattern.

Step 18: Packing & Shipping

Use AOI for outer layer inspection, to check for defects such as scratches, misalignments, and incomplete etching, ensuring the final board meets the required specification.

China PCB Manufacturer

Focus on quick turnaround prototype, small to medium PCB manufacturing since 2010.

Single-sided PCB

Single-sided PCBs, also known as print-and-etch boards, are boards with traces…

Heavy Copper PCB

Heavy(thick) Copper PCB is compared with standard copper weight PCB, standard…

Double-sided PCB

Double-sided PCBs feature conductive copper on both sides, allowing for more…

High Frequency PCB

High Frequency/high speed PCBs are mostly used in the applications which…

Multilayer PCB

Multilayer PCB consists of multiple conductive copper layers separated by…

Backplane PCB

Backplane PCBs are specialized multilayer boards featuring numerous connectors for…

HDI PCB

High Density Interconnect (HDI) PCBs are advanced circuit boards characterized…

Metal Core PCB

Metal core PCBs (MCPCBs or IMS PCBs) incorporate a metal core instead of…

Flexible Circuits

Flexible circuits, or flex circuits (FPCBs), are electronic circuits designed to be bent…

Halogen-free PCB

Environmentally friendly PCB with no halogen content.

Rigid-flex PCB

Rigid-flex PCBs combine rigid and flexible substrates in a single board, enabling…

Rigid Polyimide PCB

High-performance PCBs with durable polyimide material.

Semi-Flex PCB

Semi-flex PCBs combine the stability of rigid boards with the versatility of flexible…

Halogen-free PCB

Environmentally friendly PCB with no halogen content.

MiniLED PCB

High-density circuit board for MiniLED backlighting and display.

Halogen-free PCB

Environmentally friendly PCB with no halogen content.
DFM Check
PCB Fabrication
Components Sourcing
SMT + Reflow
DIP + Wave
Cable & Wire Harness
Inspection & Testing
Global Shipping
DFM Check
PCB Fabrication
Components Sourcing
SMT + Reflow
DIP + Wave
Cable & Wire Harness
Inspection & Testing
Global Shipping

Services

About Us

Get In Touch

  • RM 801B, Building 3A, TongTai Times Center, FuHai Street, FuYong, Bao'an, ShenZhen, GuangDong, China 518103
  • [email protected]
  • +86 755 2976 9763
  • 24H hotline: + 86 189 2464 7160
Youtube Linkedin-in Facebook-f Whatsapp Weixin
© 2025 Union Circuits. All rights reserved.