How PCB Manufacturing Process Works

During custom pcb manufacturing, some steps are involved in the PCB Manufacturing process. These include reflow soldering, optical inspection, layer alignment, laminating presses, and electroplating. All of these steps play an important role in the production of a PCB and must be conducted with the utmost precision.

Layer alignment and optical inspection

Printed circuit boards go through a series of inspections and tests to ensure they're in good working order. These inspections include optical inspection and automated optical inspection. Optical inspection checks for defects, while automated optical inspection looks at the inner layers of a pcb.

Optical inspection uses cameras to take still images and videos of the board. These images are then compared with the data from the board design to produce a complete picture of the unit.

The AOI has the capability to detect many PCB faults, but it isn't able to inspect connections underneath BGAs or another packaging. It can also measure the width of tracks, though that's usually not the most useful thing to know.

X-ray inspection works best for boards that are densely packed with components. This inspection method isn't always the best for large PCBs, however. It can also be costly.

Visual inspection, on the other hand, isn't as accurate as it sounds. It's hard to see defects on complicated boards with lots of small components.

X-rays allow for a more detailed inspection of solder joints. This is especially useful for boards with chip packages. A chip package can hide connections underneath, but the x-rays can also reveal bubbles in solder joints.

X-rays can also tell you how many components have been plated on the board. ALT systems are also great for determining how much solder paste has been deposited. However, x-rays can also suffer from interference and shielding.

A PCB's design must pass an inspection to be able to go on to the next step. These inspections include electrical tests, automated optical inspection and optical punching. If a PCB passes all tests, it moves on to the final steps of PCB fabrication.

Reflow soldering

Typically, the reflow soldering process is used for mass production PCB assembly. The process involves a series of steps, including the preheat and reflow phases. The preheat phase involves taking the PCB to a temperature of around five degrees Celsius lower than the lowest failure temperature of its components. The reflow phase involves taking the PCB to a higher temperature, usually 20 to 40 degrees Celsius higher than the soldering temperature. The process is conducted in controlled conditions. The goal of the preheat phase is to bring the PCB consistently to a pre-reflow temperature.

The reflow phase involves heating the PCB to a temperature of between 240 and 250 degrees Celsius. This is achieved by using an infrared lamp to heat the air. The goal of the reflow phase is to fuse solder joints. This process does not involve thermal shocks and produces solid joints.

The reflow soldering process also involves the use of a solder paste. The paste consists of a metal alloy suspended in a mixture of solvents. Its rheology and properties affect the quality of the paste deposition on the solder pads. The rheology of the paste depends on the amount and size of the metallic particles.

Another important step in the reflow soldering process is the thermal soak. This is a small area of the PCB board that is heated to a specific temperature. The temperature here is important because it ensures that all PCB card areas are receiving an adequate amount of heat. The temperature rises gradually so that no thermal shocks are experienced.

The reflow soldering method also involves the use of an infrared lamp. This is the best method for achieving an optimal soldering process. The heat travels through the PCB and the paste by conduction and radiation. It also helps to prevent excess intermetallic formation.

Laminating presses

Printed circuit board laminating presses use high temperature and high pressure to bond the inner layers together to form a multilayer PCB. They have precise control of temperature and pressure. They can be customized for a wide range of applications.

First, a technician puts prepreg, also known as epoxy resin, over the copper foil. The copper foil is then sandwiched between a stainless steel patch. Next, more sheets of prepreg are added. Once all the layers are in place, the stack is placed under a pressure of over 180 tons per square meter for up to two hours.

After two hours, the stack is unmolded, and the panels are deburred. Registration holes secure the stack before drilling. The PCBs are then moved to a cold press to cool. The final multilayer PCB is cooled by circulating cooling water.

A laminating press may be heated with steam, oil, or electrically. The press is designed to process printed circuit boards of all types. There are different types of materials that can be laminated, including polyurethane, polyester, and vinyl. Some lamination presses are internally cooled to speed up the processing.

The PCB lamination press process includes shape machining after the pressing stage. The pressures are applied from all sides of the press to bond the layers. These presses are highly efficient and can be customized to meet a variety of applications.

PCB Lamination Presses are designed to perform multilayer laminating for large production runs. They are also designed to provide excellent thickness uniformity. Typically, the press is heated electrically or by steam and has precise control of temperature and pressure. The laminating process can be used for a variety of materials, including copper-clad laminates.

Electroplating

During electroplating, a thin layer of metal is deposited over a substrate. This metal coating offers several benefits, including durability and resistance to chemicals. Several companies, such as jewellery manufacturers, rely on electroplating to enhance colour and durability.

The process is usually cheaper than other manufacturing processes. However, the process is complicated and can cause injury to workers if they are not properly ventilated. Some workers are exposed to hexavalent chromium, an oxidizer that is harmful to health.

Electroplating is also used by engineers to create 3D-printed parts. These parts offer design freedom and good mechanical properties. Moreover, they are light and can be printed on a variety of substrates.

An electroplating app allows PCB designers to upload a design and simulate the process. Users can study the effects of various parameters, such as plating rate, thickness uniformity, and even aperture dimensions. It can also provide an estimate of the manufacturing cost.

The application also provides an option for a PCB designer to modify the dimensions of the bath to meet certain specifications. This allows a designer to create a simulation that can be used to determine the maximum rate of copper wire plating and other thickness uniformity requirements.

This process also involves placing an insulating shield with an opening between the anode and PCB in the bath. This is to ensure the minimum thickness variation.

The electroplating process is also used by vehicle customization businesses to add custom parts to concept vehicles. It is also used by technicians to check electrical connections.

The app is powered by COMSOL Multiphysics version 5.0, which includes a simulation module and an Application Builder. This allows simulation experts to create apps that can be used by engineers and technicians in the manufacturing process.

Testing

Choosing the right testing process for your PCB manufacturing process can be tricky. A lot of factors can affect your product's quality. Failures can be costly and damaging. But there are several tests that can help you fine-tune your manufacturing process.

In-circuit testing is one of the most comprehensive testing methods. It can detect defects such as short circuits, open circuits, and misplaced components. It can also determine if the board is soldered correctly.

Functional testing can determine if the PCB is operating properly and in the right way. This type of testing is usually used for quality control purposes. But it may not detect early failures. In fact, functional testing may require complicated software and protocols.

Burn-in testing is another intense testing method. It runs power through the PCB continuously for 48 to 168 hours. It also puts the board under more stress than it is rated for. This test can detect hidden defects but should be used in conjunction with other tests.

Flying probe testing is a less expensive method than in-circuit testing. It uses multiple probes to make contact with the circuit board. It also reduces the amount of time each test requires.

Automated optical inspection (AOI) is another test that uses cameras to take high-resolution images of the board. These images are then compared with a database of good and bad boards. This method is more accurate than manual visual inspection.

The test can be used on small-batch boards, prototypes, and high-component density boards. The AOI can also be used at the end of the production line to make adjustments to the production process.

The AOI is a great way to check for quality in the production process. It can also help to identify issues before they cause problems. It can also be used as a replacement for more costly testing procedures