Low Volume PCB Assembly Process Ultimate Guide

There are times when you need printed circuit boards for your application, but you don’t need a large number of them. The solution lies in the low volume PCB assembly, which can help to reduce costs and optimize the quality of your boards.


If you want to know more about low volume PCBs, you’ve come to the right place! Take a look at our guide and learn more about the process.

1、What You Should Know About Low Volume PCB Assembly

When we say low-volume board assembly, we are talking about the number of boards that will be manufactured. The actual PCB assembly process remains the same, and the main idea of sticking to a small volume is to confirm whether the boards meet the client’s requirements.


In today’s market, manufacturing low volume PCBs means that you need anywhere between 25 and 5,000 boards. The number varies because it depends on your applications and desires.


Small volume assembly has the goal of optimizing the board’s quality and ironing out any issues that may appear. That is why techniques like DFM (design for manufacturing) and DFT (design for testing) are used in the process. They can make it easier to identify any problems, which can then be optimized before you go into mass production.


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2、PCB and Assembly Types Applied in Small Volume Production

For manufacturers, there is no difference in low volume PCBs or mass production of the boards. They can still design the products in a way that will fit the client’s requests.


The three main types of the printed circuit boards include:


♦ Rigid


♦ Flexible


♦ Flex-rigid


Rigid boards are quite essential, but they are still incredibly popular. However, modern applications often require a certain amount of flexibility, which is why the clients often ask for flex-rigid and flexible PCBs. Many manufacturers use specific strategies when designing rigid-flex boards.


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3、What Technologies Are Used for PCB Assembly?

The manufacturers use three different approaches throughout the PCB assembly process.


These are:


♦ Through-hole mounting – when using this method, the designers place components in the holes drilled for them on the board. It is an old-school approach that was popular decades ago, but it is not used that often today.


♦ Surface mount technology – here, you place components directly on the board’s surface. It has been the primary method for decades now as it can improve the board’s performance and quality.


♦ Mixed technology – in some cases, the wisest move is to combine both techniques. That is why the companies start with SMT but do not hesitate to use through-hole mounting whenever that is necessary.


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4、Benefits of Small Volume Assembly

Why would you need the low-volume PCBs production method? We already mentioned potential savings thanks to this process, but here are some other benefits of the small volume assembly:


♦ Possible design changes before going to mass production – if there is an issue, you can identify it on a lower number of boards. That way, you risk receiving thousands of flawed PCBs, and you can ensure that the design is optimised before heading into mass production. 


♦ Rigorous testing – testing is the best way to prove that a board can meet the application’s requirements.


♦ Quality assurance – the ultimate desire of every client is to have a PCB that will perform well. Low-volume production will help to improve the overall quality and ensure that the board meets your expectations.


♦ Cost control – it is wise to design a small number of boards first. After you ensure everything works the way it was intended, you can proceed to mass production, knowing you will be spending money on reliable PCBs.


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5、Design for Manufacturing in Low Volume PCBs

If you want to ensure the optimal quality of your product, it is essential to optimise layout design for manufacturing.


Believe it or not, the decision you make during this stage can affect both the quality and cost of your PCB production. You don't want to end up with thousands of boards that have a fabrication error. That is why it is essential to detect any imperfection on time.


5.1 What Is Design for Manufacturing (DFM)?

It is a process of optimising PCB design so that it stays free of errors during manufacturing and assembly. We can divide DFM into two different categories:


♦ Design for fabrication (DFF) – it takes care of all issues that have something to do with manufacturing.


♦ Design for assembly (DFA) – it mostly focuses on dealing with issues that engineers may experience in design.


The implementation of these strategies is vital for optimising the entire process, as well as ensuring that your product will hit the market on time. Furthermore, it guarantees that your PCB will perform superbly.


Some of the standard practices you may want to apply include:


Keeping an optimal distance between the components


Including only the necessary parts to avoid overloading the board


Choosing the right finish for your application


The good news is that the manufacturer can help you to get all these things right. They will analyse your Gerber files, diagrams, drawings, and other documents to suggests possible modifications.


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6、Design for Testing in PCB Assembly

The idea of this is to perfect your design so that it is ready for all the testing processes that may expect your board. During this stage, designers can suggest positions for test points on your PCB board.


The testing can include visual inspection, electrical testing, or X-ray inspection. The strategies applied in design for testing may vary from one project to another. The manufacturer may provide some insights on choosing the right testing methods, and making DFT efficient.


6.1 Two Common Approaches in DFT

There are two approaches you can use in DFT:


♦ Design for Functionality Testing – in this case, the tests’ complexity depends on the procedures you choose, and not from the board’s minutia. The easiest way to test the functionality is to turn on the board and wait for the display to show a particular message.


♦ Design for In-Circuit Testing – here you need to keep track of current levels and proper voltage on the completed PCB. It is a more exact way of testing and identifying issues and where they originate.


Whether you choose for a prototype or a low volume PCB assembly process, it is a better option to conduct testing on a small number of models. That is a smart way of reducing costs and ensuring everything will turn out fine once you move to mass production.


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7、Other Ways to Reduce Costs of PCB Assembly

DFM and DFT are beneficial methods to reduce costs, but there are different ways to save in the process of manufacturing PCBs.


These include:

♦ A sample program


♦ Reduced costs on repeated orders


7.1 A Sample Program

Reworking, modifying, or manufacturing the boards again means a lot of extra expenses, and it is something you want to avoid. That is why many companies resort to a pre-production sample program.


The idea is to design boards that would serve only to ensure the quality and performance are optimal. Once the PSB assembly process finishes, the manufacturer sends the boards your way to ensure that everything works properly.


If there are any concerns, the client should inform the company, and the engineers and other experts will resort to moving the issues. Once everything has been modified, it is time to move on to completing the order.


7.2 Reduced Costs on Repeated Orders

Once you become a trusted client and develop a bond with the manufacturer, you may be in for some commodities. Many companies don’t charge extra for NRE and stencils if you choose them for the mass production of your boards once everything goes well with the small volume PCB assembly process.


It is vital to discuss detailed terms with your manufacturer as they might come up with a customized deal for loyal clients.


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8、How to Choose the Manufacturer

It is not an easy job to choose the manufacturer to handle PCB manufacturing and assembly for your needs. You want a company with skilled engineers dedicated to their work, and experts who know everything about printed circuit boards.


Here are some pointers that can help you in making the right choice:


♦ A professional company – a reliable PCB manufacturer, won't care whether you order 5, 50, or 500 boards. They will do everything to ensure customer satisfaction, and they are willing to go the extra mile to make you a recurring client.


♦ Customize your order – the order process should be simple, and you should be able to customize it easily. That includes choosing the desired number, dimensions, layers, and other specifics of a board.


♦ Customer support – a reliable manufacturer has to be there for you every step of the way until your order is finalized.


♦ Quick delivery time – the best companies out there will ensure that you get your boards as soon as possible.


A company that can meet all the above criteria is WellPCB. They have been in the business for years and have a long list of satisfied clients. You can find a natural order form on their homepage, and the customer support is ready to help you at any point.


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If you choose to place an order for low volume PCBs, that can bring you many advantages. DFM and DFT techniques can assist in identifying any performance problems, and make sure that the board meets your application’s needs.


As long as you choose the right manufacturer, they will be there during the entire PCB assembly process. They will guide you to optimizing your boards to ensure their maximum performance while controlling and minimizing overall production costs.

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