PCB Fabrication

China PCB Manufacturer

Union Circuits 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 on only...

Double-sided PCB

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

Multilayer PCB

Multilayer PCB consists of multiple conductive copper layers separated by insulating...

HDI PCB

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

Heavy Copper PCB

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

High Frequency PCB

High Frequency/high speed PCBs are mostly used in the applications which involve special...

Backplane PCB

Backplane PCBs are specialized multilayer boards featuring numerous connectors for daughter...

Metal Core PCB

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

Flexible Circuits

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

Rigid-flex PCB

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

Semi-Flex PCB

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

MiniLED PCB

Semi-flex PCBs combine the stability of rigid boards with the versatility of flexible ones, making them...

Halogen-free PCB

Environmentally friendly PCB with no halogen content.

Rigid Polyimide PCB

High-performance PCBs with durable polyimide material.

Halogen-free PCB

Environmentally friendly PCB with no halogen content.

Halogen-free PCB

Environmentally friendly PCB with no halogen content.

Value-Added Services

Our value-added services are designed to enhance your experience and provide additional benefits beyond our core offerings. From quality guarantees to personalized support, we are committed to going the extra mile to ensure your complete satisfaction.

Free DFM Check

Ensure the PCB design meets specific manufacturability criteria before going into production, aim to identify potential issues that could affect manufacturing efficiency, quality, and costs.

Quick turn PCB Manufacturing

For prototypes, small batches, and applications where speed is crucial, our quickturn services can significantly reduce your lead time from design to finished product.

HMLV Orders

High Mix Low Volume PCB production, offering a wide variety of PCBs in small quantities, tailored to meet your specific needs.

Reverse Engineering

Analyzing and recreating the layout and function of a PCB from real PCB sample to understand its design, components, and functionality.

Multilayer PCB Manufacturing Processes

1

Engineering

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.

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.

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.

4

Inner Layer D/F Lamination

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

5

D/F Exposure

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

6

DES

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

7

Black Oxide

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

8

Lay-up

Laminate copper foils, Prepreg and black oxided cores to a single panel.

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.

10

Drilling

Drill on board to form through holes.

11

Desmear

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

12

Desmear

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

13

PTH

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

14

Panel Plating

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

15

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.

16

Outer Layer D/F Lamination

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

17

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.

18

DES

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

19

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.

20

Pre-treatment

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

21

Solder Mask

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

22

Silkscreen

Screen printing or injet printer printing the legend.

23

Surface Finish

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

24

Profile

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

25

E-testing

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

26

FQA & FQC

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

27

Packing & Shipping

Packing according to the specification and ship to worldwide customers.

Key Manufacturing Equipment

Drilling
LDI
VCP
Laminator
AOI

General PCB Specification

No.ItemFeatureStandardAdvanced
1Layer CountMin~Max1~16L48 L(Max.)
2MaterialTypesFR-4, Aluminum/ Copper-base, RogersFR-4(Halogen-free), Arlon
3Panel SizeMax508 x 610 mm(20” x 24”)508 x 1500 mm(20” x 34”)
4Finished ThicknessMin~max0.2~5.0mm(0.005~0.126”)0.2~6.5mm(0.005~0.165”)
5Trace Width/SpaceInner/ Outer layer3/3mils(0.075/0.075mm)2/2mils(0.05/0.05mm)
6Mechanical DrillingMin0.008”(0.20mm)0.006”(0.15mm)
7Mechanical DrillingMax0.197”(5.0mm)0.256”(6.5mm)
8Laser DrillingLaser drilling(min)0.006”(0.15mm)0.004”(0.10mm)
9Aspect RatioMax12:0120:01
10Copper ThicknessMin~max0.5~6 OZ20 OZ(max)
11Solder MaskColorGlossy/Matt Green, white, black, red, blueYellow, pink, purple
12SilkscreenColorWhite, black/
13Surface FinishTypesHASL, Immersion Gold/ Tin/ Silver, Plating hard Gold, OSP ENEPIG
14RoutingBit diameter0.093”, 0.062”, 0.031”0.021”
15ProfileTolerance±0.006”(0.15mm)±0.004”(0.10mm)
16V-scoringAngle30°20°/ 45°/ 60°
17Plating hard GoldThickness0.032”(0.8um) typical0.050”(max)
18Special Processes/Carbon Ink, Peelable Mask, depth controll milling/

Our Certifications

PCB Market Share by Layer Count

Multi-layer PCB leads in both market share and revenue, reflecting industry trends toward more complex, high-performance electronics. The increasing demand for consumer electronics, IoT devices, and automotive applications continues to boost the multi-layer PCB market significantly.

Single-sided PCB
15%
Double-sided PCB
20%
Multilayer PCB
65%

Related IPC Standards

Guidelines and specifications used in the electronics manufacturing industry to ensure the quality, reliability, and consistency of electronic products.

PCB Acceptance