The Basics of PCB Manufacturing
As with any complex machine, pcb manufacturing involves several different stages. A quality PCB manufacturer has a deep understanding of each step and is focused on providing on-time delivery.
Initially, the inner layers of a PCB are printed on a special film. This includes a copper layer that will be the basis of circuitry.
The first step of making a circuit board involves creating a design. Designers lay out a blueprint that fulfills the requirements as outlined by the project. Once this is encoded into software, designers send pcb manufacturing the blueprints to PCB fabrication houses for production. Almost all fabrication houses run a Design for Manufacture (DFM) check to ensure that the blueprints fulfill the tolerances required during the manufacturing process.
Using a printer that uses extremely precise printing technology, manufacturers make photo films of the blueprints. These photo films are then printed on a piece of laminate, which is the body of the structure. Copper is pre-bonded to this material, and a layer of photo-reactive chemicals that will harden after being exposed to ultraviolet light covers the copper. This helps to align the blueprints and actual prints of the inner layers.
Then, another powerful chemical eats away at the copper that is not protected by the photo resist. The unwanted copper is washed off using another solvent, and the hardened resist is also removed from the preferred copper. Once all the layers are clean and ready to be pushed together, technicians put them in a bonding press. A computer will automate the process of heating the stack, applying pressure, and cooling it at a controlled rate.
PCBs are made from multiple layers of dielectric and conductive materials that are laminated together. These boards are used in a wide range of electronic devices and machines, from consumer electronics to fire alarms.
The first layer is the substrate, which is a thick material such as fiberglass. This is what provides the structural integrity of the circuit board. It is then covered in a copper layer, which can either be foil or a full-on copper coating. The copper layer serves as a pathway for electrical signals to travel, much like your nervous system carries information between your brain and muscles.
The PCB plan is printed on a special type of printer known as a plotter printer, which uses a special kind of film to make the blueprint. The individual layers are then lined up and a hole, called a registration hole is punched through them. This allows the layers to be aligned correctly before drilling begins. The holes are drilled using an automated process that is based on the Extended Gerber design. This process helps reduce manufacturing errors and ensures quality production.
Drilling is similar to using a power drill on wood, but on a much larger scale. The drilling process is typically supervised by a trained operator. This person monitors for force, vibrations and temperature. They also control the fluids, solids and chemicals used to lubricate the drill bit, isolate high pressure areas of rock that may break out, and flush out any broken rock.
For PCBs with two or more layers, a hole is needed for mounting components. The holes must be made conductive, so they are electroplated with copper to form plated through holes. They are then ready for components to be soldered on.
This PCB fabrication step involves applying a thin layer of oxide to the copper foil on the inner layer. This ensures that the copper foil bonds properly with the insulating epoxy resin layers between the inner and outer layers. The layers are then bonded together in a machine called a laminator. The machines are steered by computers, and the layers must be precisely aligned to avoid any mistakes. The machine also applies heat and pressure to the layers to bind them tightly and create an effective insulation between the inner and outer layers.
Printed Circuit Boards are the backbone of all electronic information products. Their quality determines their functionality, reliability and performance. During production, visual inspections are essential to detect defects and errors that could affect product quality. These inspections are usually done manually with a naked eye or with the help of microscopes. This is a slow and inaccurate process that can lead to costly mistakes.
Fortunately, automation techniques have been developed that can replace human inspectors and improve productivity. One of these tools is AOI, which uses high-resolution images to inspect PCBs for a variety of attributes. These include missing components, mislabeled parts, and improper PCB Manufacturing Supplier alignment of layers. Moreover, it can also detect soldering issues on Ball Grid Arrays and other hidden pads.
Unlike manual inspection, automated optical inspection (AOI) is fast and accurate. It compares the image of a test board with images from a database of good and bad boards to determine whether it meets all the required specifications. It is especially useful for detecting surface defects, which are difficult to spot with the naked eye.
Printed pieces that go through a lot of wear and tear benefit from lamination techniques that reduce the damage. You’ve probably seen laminated credit cards and formal documents; lamination makes them less prone to tearing, water damage, and stains. Lamination also keeps the print from fading or looking dull or dirty.
A clean copper-sided panel receives a photo film and a type of resist that’s made from photo-reactive chemicals that harden after exposure to UV light. Technicians then place each layer on pins that hold them in a decontaminated environment. This helps to ensure that there is an exact match between the blueprint and what’s on the film and resist.
These films are then exposed to a laser and the areas that will become the traces, pads and metal ground of a PCB are identified. An automated optical inspection then inspects the layers for defects, which can be corrected at this point. The layers are then laminated together with a clear epoxy resin to protect them from moisture, oil and dust. The resulting product is a multilayer PCB that’s ready for assembly.