1.2mm Thinkness Yellow Oil Double Sided PCB Gold Finish 2 Layer Structure

A double-sided PCB (Printed Circuit Board), also commonly referred to as a two-layer PCB, is a type of printed circuit board that features conductive copper layers on both sides of a non-conductive insulating substrate. Unlike single-sided PCBs (which only have a conductive layer on one side), its core design allows for circuit traces, components, and interconnections to be arranged on two opposing surfaces, enabling more complex circuit functionality while maintaining a relatively compact form factor.

Key Characteristics & Construction :

A double-sided PCB is typically constructed from a core material, most commonly FR-4, which is a fiberglass-reinforced epoxy laminate. This insulating substrate is clad with a layer of copper on both sides.

• Vias: The defining feature of a double-sided PCB is the use of vias, which are small, plated through-holes that create an electrical connection between the circuit traces on the top and bottom layers. This "bridge" allows for a much more flexible and intricate routing of signals, as traces can cross over each other without shorting.

• Layers: The board has a simple stack-up: a bottom copper layer, the insulating substrate, and a top copper layer. Additional layers like a solder mask (to protect traces from oxidation and prevent solder bridges) and silkscreen (for component labels and markings) are applied to both sides.

Manufacturing Process :

The manufacturing process for a double-sided PCB involves several key steps:

1. Design & Layout: The circuit is designed using specialized software, with careful consideration for the placement of components and the routing of traces on both sides.

2. Drilling: Holes for components and vias are drilled through the board.

3. Plating: A crucial step for double-sided boards is electroplating, which deposits a thin layer of copper into the drilled holes to form the vias, ensuring electrical connectivity between the two sides.

4. Imaging & Etching: A photoresistive film is applied to both sides, and a UV light exposes the circuit pattern. The exposed areas harden, and the unexposed copper is chemically etched away, leaving only the desired circuit traces.

5. Soldermask & Silkscreen: The protective solder mask and silkscreen layers are then applied to both sides of the board.

Advantages: 

• Increased Component Density: By utilizing both sides, you can fit more components into a smaller board size, leading to miniaturization and a more compact design.

• Greater Circuit Complexity: The ability to route traces on two layers with vias allows for more intricate and complex circuit designs that would be impossible on a single-sided board.

• Cost-Effective: While more expensive than single-sided boards, double-sided PCBs are still a very affordable option compared to multi-layer PCBs, making them a great balance of complexity and cost.

Key Elements That Define a Double-Sided PCB:

1. Dual Conductive Layers: Two thin sheets of copper foil (the conductive medium) are bonded to the top and bottom surfaces of the substrate. These layers are etched into precise "circuit traces" (paths for electrical signals) to connect electronic components.
2. Insulating Substrate: A central non-conductive layer (typically made of materials like epoxy resin reinforced with glass fiber, known as FR-4) separates the two copper layers. It provides structural support and prevents electrical short circuits between the top and bottom conductive traces.
3. Vias for Interconnection: Since the two copper layers are isolated by the substrate, small holes called vias are drilled through the entire board. These vias are plated with metal (e.g., copper) to create electrical pathways, allowing signals or power to flow between the top and bottom circuits—this is a defining feature that enables the "double-sided" functionality.