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.

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.

About Union

Established in 2010, Union Circuits is a leading PCB manufacturer and exporter specializing in quick-turn prototypes and small-to-medium volume production. Based in Shenzhen, our state-of-the-art facility ensures high-quality, fast-turnaround PCBs to meet your diverse project needs.

Since 2014, we’ve expanded into full PCB Assembly services, supported by 10 advanced SMT lines(4 dedicated to prototypes and 6 for production). This allows us to deliver end-to-end solutions, from fabrication to assembly, all under one roof. Committed to innovation and efficiency, we provide reliable, cost-effective PCB solutions for global clients.

Morden Facilities
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About Union

Established in 2010, Union Circuits is a leading PCB manufacturer and exporter specializing in quick-turn prototypes and small-to-medium volume production. Based in Shenzhen, our state-of-the-art facility ensures high-quality, fast-turnaround PCBs to meet your diverse project needs.

Since 2014, we’ve expanded into full PCB Assembly services, supported by 10 advanced SMT lines(4 dedicated to prototypes and 6 for production). This allows us to deliver end-to-end solutions, from fabrication to assembly, all under one roof. Committed to innovation and efficiency, we provide reliable, cost-effective PCB solutions for global clients.

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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

DFM Check

PCB Fabrication

Components Sourcing

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