A Guide to the Custom PCB Assembly Process

If you are interested in custom PCB assembly, there are several different technologies that you can choose from. These technologies include through-hole technology and SMT technology. Depending on your requirements, the process may combine both of these technologies. In addition, a custom PCB assembly requirements can include Embedded components.

Solder paste printing

Solder paste printing is the process of applying solder on the PCB. It is an essential aspect of the prototype PCB assembly process. There are several different types of soldering techniques. Some are simpler and more affordable than others. For example, mesh screen printing is the least expensive way to apply solder paste. However, it doesn’t work well for small SMDs. In addition, it leaves flux on the PCB, and human handling often transfers oil or dirt onto the board. A dirty board is a practical and aesthetic problem.

Solder paste is a mixture of metals and other substances. Typically, the paste contains tin and lead. Nowadays, lead-free soldiers are available globally. However, there are other types of solder paste printing, including a mix of tin, BGA assembly and copper.

The solder paste printing process is critical to the success of the PCB assembly process. A bad solder paste printing process can lead to costly rework. As a result, an electronics manufacturer must thoroughly understand the solder paste printing process. Moreover, the printing process must be repeatable and stable.

In custom PCB assembly services, solder paste printing is one of the most crucial steps. It requires accurate placement of solder paste and the correct amount of paste to cover the pads. We can do this by screen-printing, foil printing, or jet-printing the paste. However, if the paste is not correctly applied, it will result in poor soldering and other defects.

Squeegee pressure

Squeegee pressure is the force used to print the solder paste onto the printed surface of a custom PCB. The squeegee should apply enough force to push the solder paste across the printable area without creating excessive pressure. High squeegee pressure can cause the solder paste to shear and spread across the PCB’s flat surface. To prevent this, squeegee pressure should be low and only work as much as necessary to achieve a clean stencil. Generally, the recommended pressure is around 300 grams for every 25mm squeegee blade.

Aside from the amount of pressure used to apply solder paste to the PCB, it is essential to ensure that the stencil has adequate wall thickness. The stencil’s aperture should be about 10% smaller than the land’s diameter, while the stencil’s thickness should be less than 512N/25mm. Aim for an optimal squeegee pressure by scraping the solder paste off the steel plate and then using this value as a guideline.

The speed of the squeegee during Production pcb assembly is crucial to a successful snap-off. High-speed printing can cause insufficient coverage of the printed area, causing a ‘pad-to-pad’ shorting. In addition, poor board support, stencil condition, and even squeegee speed can affect the final result.

Another essential factor to consider is the type of squeegee. Some squeegees are made of polymer, while others are metal or plastic. The type used can affect the quality of the printed surface.

Reflow soldering

Reflow soldering is a common component in PCB assembly requirements, and the process is less complex than other methods. It involves raising the board’s temperature to the right level and re-melting solder to develop the proper solder joints. To ensure this process is effective, it is essential to use high-quality solder paste.

We must carefully control the temperature of the solder paste to prevent thermal shock. The solder paste must reach the optimum melting point within the shortest time possible. If the soldering temperature is too high, it may result in ineffective joints, and the excessive heat can cause damage to the circuit board components. A typical reflow time ranges between 30 and 60 seconds. If the reflow time is too short, some areas may not reach the correct temperature, and the board will have brittle joints.

When you melt the solder paste, it flows to the pads. Therefore, when soldering surface mount components, the paste will straighten the electronic components without a need for manual placement. This is ideal for normal handling, but it can lead to problems if we glue the components to the board. The electronic components will need to move to the reflow soldering oven in such cases.

Reflow soldering is a complex process that involves a variety of different parameters. The process begins with a preheat stage, which uses a small amount of heat to build up the board’s temperature. The final reflow stage uses a soldering temperature close to or above the rated temperature of the component. The final reflow process may include a conformal coating for the PCB. This is dependent on customer requirements. Reflow soldering is an essential part of PCB assembly services.

Printed circuit boards Embedded components

There are many considerations to take into account when you are designing a custom PCB. Your PCB design should be manufacturable, reliable, and functional. In addition, it should pass the stringent testing requirements of embedded systems. For example, some circuit boards require the PCB assembly of through-hole components (PTH components). These components require plated holes to enable them to transfer signals. Unlike traditional printed circuit boards
, PTH components do not accept solder paste. In addition, their tracks may not be the same width as the rest of the PCB.

Production PCB assembly requirements can be a complex process. First, the components must be precisely placed. Two main methods for assembling a PCB are surface mount and through-hole. Surface-mount technology requires the pins of the components to line up with the board’s pads. In addition, some components use a bottom-side adhesive to fix them to the PCB.

The embedded component PCB assembly process involves several different techniques that are crucial to the successful completion of a production PCB assembly. First, it requires a careful selection of materials for the embedded components. This will lower the risk of PCB manufacturing failures. It also decreases the size and weight of the final product.

SMT Stencils and Prototype PCB Assembly Fixtures

To assemble Double Sided PCBs, you’ll need a full turnkey PCB assembly fixture and a pair of prototype stencils. The fixture is custom-machined and requires a two-day lead time. The prototype stencils are essential in aligning SMT pads.

The manufacturer offers frameless, prototype, and framed versions of their stencils. In addition, they offer several surface finish options, including ENIG and tin/lead. They serve industries including computer, communications, and aerospace. These PCB assembly services are available with a wide variety of features and capabilities.

The standard operating pressure of squeegees is 0.13 to 0.27kg per linear centimeter of the printable area. Therefore, the squeegee must induce sufficient inertia to ensure successful printing. Another critical parameter to monitor is the squeegee’s speed. It must be lower than the upper constraint value to prevent damage to the stencil. Higher speeds cause higher friction between the stencil and solder paste.

Flying Probe Testing

Another option for stencils is etching. This process creates an aperture in the board’s surface. This allows for stencils with varied thicknesses. During the process, we cover the desired part with a temporary mask. This is an inexpensive and simple process. A few different types of acids are helpful in the etching process.

Quick turn PCB assembly services are especially ideal for the assembly process. They are typically made of fiberglass or thermoset plastic to ensure extreme strength and electrical properties. The downside is that they do not come with finished boards.

Conformal coating

A PCB assembly process requires the use of the conformal coating. This coating is an ultra-thin layer that conforms to the shape and layout of the printed circuit board. It protects the PCB from external factors and increases its operating life.

There are several types of conformal coatings, each with its benefits and disadvantages. To choose the best one for your PCB assemblies, you need to consider the conditions where it will work and your specific repair needs. In addition, the temperature at which the PCB board will operate plays a vital role in the adhesion of the coating.

A conformal coating protects the printed circuit board from adverse conditions such as airborne pollutants, mechanical vibrations, and high temperatures. It also increases the overall reliability of a PCB. It also protects the components inside the board, ensuring it functions properly. The process can also protect the components from damage caused by moisture and corrosive substances.

One way to determine if a production PCB assembly process uses conformal coating is by using a technical data sheet (TDS). The technical data sheet (TDS) is a military specification that defines the characteristics of conformal coatings. The TDS depends on various tests that assess the durability of the coating. As a result, the coating has to hold up to different conditions for quick turn PCB assembly services.

There are several ways to apply conformal coating. One of the most common is using it on both sides of a circuit board. Dip coating is another option, but it requires masking off the PCB before applying it. The process involves dipping the PCB into a chemical solution. The speed of immersion, the time spent in the coating, and the board’s temperature are important parameters for PCB assemblies.

How to Choose a PCB Box Build Assembly Company

PCB box build assembly is a crucial process for a manufacturer who wants to ensure the quality of their products. They depend on the expertise of PCB assemblers to create the components required for their products. Most of today’s PCBs are CAD-based, so it is essential to find a PCB assembly company that understands the complexities of PCB design and PCB manufacturing services. Look for printed circuit board manufacturers with certifications like CE, RoHS, and IPC.

How to Order PCB Assembly Services

When you need PCB assembly services, the first step is to get a quote. This quote will contain the quantity of assembled PCBs, assembly type, and delivery options. You can also choose whether to supply your parts or order PCB assembly service. For example, you can provide some parts but leave the rest to the PCB assembly company. In addition to supplying the components, you can also supply your design specifications. This option is helpful if you have spare parts or components or if the components you’re ordering are fragile or sensitive.

If you’re ordering a PCB assembly service, you’ll want to know when you’d like the completed product. Different PCB assembly companies calculate lead times differently. Be sure to tell them when you want the mixed assembly to begin, when you’d like to make the final payment, and when you expect the components to arrive. The longer the lead time, the cheaper the PCB assembly service will be. However, you should never skip tests and inspections to save on costs in PCB assemblies.

Providing accurate data is key to an error-free PCB assembly process. Therefore, you should include your BOM, pick and place file, centroid file, and Gerber data for each PCB job. You can also have a DO NOT POPULATE column in your BOM.

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