Double layer pcb manufacturing is a complex process that requires high precision. There are many steps involved, including capturing schematics with CAD tools, etching and drilling.
Prepare the etching solution by mixing 120ml hydrochloric acid with 480ml distilled water in a well-ventilated area. Be sure to wear gloves and eye protection.
Printed Circuit Board Design
Double layer PCBs offer an optimal balance of affordability and performance, making them ideal for a wide range of consumer, commercial, and industrial uses. They double the routing space on each side of the board, allowing designers to add more complex circuit pathways without increasing the size of the device. The increased flexibility and design capabilities of this type of PCB also make them a great choice for teaching students about PCB layout and routing.
The double-sided PCB manufacturing process starts with a CAD/CAM design and DFM check. These processes find and fix errors in traces, holes, and double layer pcb manufacturing component placements before the production process begins. Then, the raw PCB substrate material is selected from a variety of options, such as FR-4 fiberglass. A copper layer gets laminated to both sides of the substrate, and a photosensitive coating called photoresist is applied over it. This masks the areas where the trace pattern will be printed later on, and is exposed to UV light to harden. The conductive pattern then gets printed on the copper surfaces, and the photoresist is stripped away.
Next, the circuit paths are transferred to the bare copper using chemical and electroplating methods. Then, the copper gets etched to remove any areas that weren’t hardened by the photoresist. The resulting copper layer is then soldered to the insulating layers, and the surface-mount components are placed using specialized equipment.
Copper Plating
Copper plating is an important step in the process of creating a double-sided PCB. It adds a layer of conductive metal, allowing circuits on both sides of the board to be connected with one another. This step is critical for ensuring that all the parts are properly connected and that the finished product will work as intended.
To begin this process, technicians apply photoresist to the outer layers of the PCB in a yellow room. Then, they expose the photoresist to UV light to harden it. After this, they add copper foil to the substrate material and pre-bond it to the laminate material. This will become the base for the PCB.
Next, the technicians wash the board with alkaline to remove any resist that didn’t harden. This step also exposes non-conductive areas on the inner layer of the PCB. Workers then etch the copper away to reveal the inner layer of the circuit board. This process also creates a grid of copper film, which serves as a connection point for components on the circuit board.
Finally, the copper is plated with pyrophosphate, which adds a layer of copper to the metal. This coating protects the copper from oxidation, and it provides a uniform color that looks shiny and bright. The copper can be plated in two ways: rack or barrel. The barrel method is more effective for large surfaces, such as molded contact points and connectors.
Etching
A double-layer PCB has copper coatings on both sides and an insulating layer in between. Circuit connections are made through traces etched into these conductive layers. To avoid shorting between the two layers, proper design and layout are crucial. This includes balancing signal frequency requirements and routing techniques. The PCB must also double layer pcb be cleaned properly after etching. This is crucial for preventing signal transmission problems, and it can be very costly to repair.
The etching process starts with a raw PCB substrate, such as FR-4 fiberglass, and a copper foil layer is laminated to it on both sides. A photosensitive material called photoresist is then applied to the exposed copper surface. UV light then strikes the photoresist and hardens it. This is used to transfer the trace pattern from the Extended Gerber file to the PCB.
After the photoresist has hardened, it is then removed by a chemical solution that exposes the copper. The excess copper is then etched away, leaving behind the circuit pathways on both sides of the board. The pathways are then verified by an automated optical inspection machine.
To prepare the etching solution, you need to mix 120ml of hydrochloric acid with 480ml of water and 60ml of hydrogen peroxide. This solution should be kept in a well-ventilated area and must be handled carefully. It can emit harmful vapors, so it is recommended to wear gloves, eye protection, and a gas mask or respirator.
Soldering
Double-sided PCBs are a common choice for many types of electronic devices. They allow for a higher density of components and make it easier to layout circuits. However, these boards require extra attention during soldering. The components are positioned on both sides of the board, so any misalignment can affect the quality of the assembly. Additionally, the board needs to be cleaned to remove any flux residue. This can be done with water, acetone, or any other solvent that is compatible with the PCB and its components.
A double-sided circuit board starts with a substrate, usually made of FR-4 fiberglass. Copper foil is then laminated to the surface of the substrate, and a photosensitive coating called photoresist is applied. This is used to transfer the desired circuit trace pattern. The resulting pattern is transferred to the copper through UV light, which also hardens the photoresist. The resulting pattern can then be exposed to the components, which are soldered to the conductive paths on both sides of the board.
Unlike multilayer PCBs, double-sided circuit boards are more versatile and easier to modify or repair post-production. However, they are less durable and may not be as robust as single-sided circuit boards. They are also more susceptible to noise and crosstalk than their multilayer counterparts. This can be minimized by careful trace routing, which is the key to preserving signal integrity.
