The Complete PCB Manufacturing Process: From Copper Clad Laminate to Finished Product

A PCB (Printed Circuit Board) is a critical component in electronic products that carries electronic components and enables electrical connections. Chips, memory, connectors, and passive components in smartphones, servers, automotive electronics, and AI devices all rely on PCBs for signal transmission.

A typical PCB undergoes multiple stages including copper clad laminate (CCL), inner-layer circuitry, multilayer lamination, drilling, hole metallization, outer-layer circuitry, solder mask, surface finishing, shaping, inspection, and shipment. This article uses a multilayer rigid PCB as an example to introduce the complete manufacturing process.

I. PCB Manufacturing Begins with Copper Clad Laminate (CCL)

PCB manufacturing starts with CCL (Copper Clad Laminate). CCL is typically composed of copper foil, electronic glass fabric, and resin systems: copper foil is used to form conductive traces; glass fabric provides mechanical strength and dimensional stability; resin systems are used for insulation and interlayer bonding.

From the upstream materials perspective, copper ore undergoes smelting, refining, and processing to form electronic copper foil; glass raw materials are melted, drawn, and woven into electronic glass fabric; chemical raw materials are used to produce epoxy resin, BT resin, and other material systems. These materials are impregnated, stacked, and pressed to ultimately form copper clad laminate, which serves as the base material for PCB manufacturing.

II. Inner-Layer Pattern Transfer: Forming Internal PCB Circuits

After the CCL enters the PCB factory, the inner-layer circuitry is produced first. The typical process flow is: board surface treatment → dry film lamination → exposure → development → etching → film stripping. The circuit patterns from engineering files are transferred onto the photosensitive dry film through exposure. After development, circuit-protecting patterns are formed, excess copper is removed via etching, and finally the film is stripped. The remaining copper layer becomes the inner-layer conductive traces.

In high-density products such as smartphones and high-speed servers, trace width/spacing, interlayer alignment accuracy, and etching stability are all important control parameters.

III. Multilayer Lamination: Forming Complex Circuit Structures

Multilayer PCBs are formed by stacking inner-layer circuit boards, prepreg (PP), and copper foil in a designed sequence. Under high temperature and high pressure, the resin in the prepreg flows and cures, bonding the different circuit layers into a single integrated structure.

After lamination, the PCB contains multiple conductive and insulating layers internally. The higher the layer count, the greater the requirements for material matching, interlayer alignment, resin flow, and lamination uniformity.

After lamination is completed, the PCB moves into the drilling and hole metallization stages, where through-hole structures are used to establish interlayer connections.

IV. Drilling and Hole Metallization: Establishing Interlayer Connections

After multilayer PCB lamination, the different circuit layers must be connected through hole structures.

Depending on the product structure, PCBs can be drilled using mechanical drilling or laser drilling to form through-holes, blind vias, and buried vias.

Since the initial hole walls are mainly composed of resin and glass fiber and are non-conductive, they must undergo: desmear and deburring → hole wall activation → electroless copper deposition → copper electroplating thickening. After hole metallization, a continuous copper layer forms on the hole walls, enabling electrical connections between different circuit layers.

Blind vias, buried vias, and microvias are important technologies in HDI (High-Density Interconnect) PCBs.

V. Outer-Layer Pattern Formation: Completing the Final Circuits

After hole metallization is completed, the PCB enters the outer-layer circuit production stage.

Outer-layer circuits typically go through: photosensitive material lamination or coating → exposure → development windowing → pattern electroplating → film stripping and etching. The outer-layer process is similar to inner-layer circuit production, but requires pattern electroplating to increase the thickness of circuits, pads, and hole copper areas to meet electrical connection, soldering, and reliability requirements.

After the outer-layer circuit production is completed, the internal circuits, external circuits, and interlayer connection structures form a complete electrical circuit.

VI. Solder Mask, Surface Finishing, and Shaping

After outer-layer circuits are completed, the PCB must undergo solder mask application, surface finishing, and shaping.

Taking photosensitive solder mask as an example, the typical solder mask process includes: cleaning → coating photosensitive solder mask ink → pre-baking → exposure → development windowing → post-baking curing. The solder mask protects copper traces, prevents oxidation, and reduces the risk of soldering shorts. After development, windows are formed at pad locations to facilitate subsequent component soldering.

Subsequently, the PCB undergoes surface finishing to improve pad solderability and durability. Common processes include: HASL (Hot Air Solder Leveling); ENIG (Electroless Nickel/Immersion Gold); OSP (Organic Solderability Preservative); Immersion Silver; Immersion Tin. Different processes vary in cost, flatness, oxidation resistance, and soldering performance.

After surface finishing, the PCB is shaped by routing, V-cut, or punching to achieve the customer-required dimensions and panel configuration.

VII. Inspection and Shipment: Entering the Electronics Manufacturing Stage

After all manufacturing processes are completed, PCBs must undergo rigorous inspection. Common inspection items include: AOI (Automated Optical Inspection); electrical testing; impedance testing; reliability testing; visual and dimensional inspection. These inspections confirm whether PCBs have opens, shorts, circuit defects, impedance anomalies, dimensional deviations, or reliability issues.

Qualified PCBs are cleaned and dried, then protected with anti-static bags, vacuum packaging, desiccants, and cushioning materials before being delivered to downstream customers. After entering the downstream stage, PCBs go through SMT assembly, reflow soldering, and system assembly, ultimately being used in products such as smartphones, servers, automotive electronics, communication equipment, and industrial devices.

PCB Manufacturing Connects the Industry Chain Across Materials, Manufacturing, and End Applications

PCB manufacturing connects upstream materials including copper foil, electronic glass fabric, and resins, as well as manufacturing equipment for lamination, drilling, electroplating, and inspection, along with electronics manufacturing and end-product companies. According to Prismark data, global PCB production value in 2025 was approximately $84.891 billion, with mainland China accounting for about $48.459 billion, roughly 57% of the global total.

With growing demand for AI servers, high-performance computing, data centers, and high-speed communications, PCBs are upgrading toward high-layer-count, high-frequency high-speed, and high-density interconnect configurations. According to China Galaxy Securities citing Prismark data, from 2024 to 2029, the AI server-related PCB market is projected to grow at a compound annual growth rate of 18.7%; among these, AI server-related HDI is expected to grow at approximately 29.6%, and 18-layer-and-above multilayer boards at approximately 33.8%.

From CCL to the final PCB product, the entire process involves multiple stages including materials, equipment, processes, and inspection. The upgrading of PCB manufacturing capabilities also reflects the continuous improvement in connection density, signal transmission speed, and reliability required by electronic devices.