16 Points
First, get a clear understanding of the properties of PCB assembly (PCBA) costs.
Some of the Biggest Cost Drivers Include
(1) Assembly Type Surface Mount (SMT) (SMD Components) Through Hole (DIP)
(2) Component placement only requests top-level components to request double-sided assembly
(3) Total number of components (SMD + DIP)
(4) Component package size 1206 0804 0603 0402 020101005
(5) Component packaging (reel first) Reels Tubes Trays Cut strips with or without ties Loose bags
(6) Automatic optical inspection (AOI) of automatic SMT chip through-hole insertion through-hole sliding line wave soldering required process< br> X-ray selective solder manual solder assembly
(7) Quantity and batch size
(8) Special parts preparation requirements (lead length, height min/max, spacing)
(9) Total cost of complete bill of materials (BOM)
(10) Number of printed circuit board (PCB) layers and materials used
(11) Coating requirements (full or selective coatings are usually required for medical or military) Number of spray or brush coats – coating area specified by coating tolerance
(12) Potting requirements
(13) Assembly compliance requirements RoHS (lead-free) non-RoHS (lead-containing) IPC-A-610D Class I, Class II or Class III ITAR
(14) Electrical function circuit test
(15) Transportation Requirements Standard ESD (Electrostatic Discharge) Bag Non-Standard/Special Container
(16) Delivery
These 16 points affect the assembly price, so you can choose the best one to save costs, and when you source parts, you can have multiple component sources for each component, and it’s easy to control some costs.
Some agents also have a strong price backing a component, reducing cost sources more quickly
Set up processes to obtain low-cost resources between your design engineering and procurement departments. This is easier said than done. Conflicting priorities between design engineering and procurement can hinder this process.
One solution is to create material cost reduction committees. Management works with procurement and engineering to identify high-value cost-cutting opportunities. They are also working to identify strategic components that require multiple sources to ensure continuous production.
How to Ensure Optimal Electronic PCB Assembly
Having a PCB capable of withstanding any electrical, mechanical or structural adverse effects throughout its expected life is certainly the goal of this product.
For manufacturing, the threat comes from cracks and breaks, while for assembly the threat is an open or short circuit that can damage components and boards.
These threats can be mitigated or even eliminated by optimal electronic PCB assembly processes. What is the best electronic PCB assembly? Let’s answer that question first, then define a way to ensure its implementation.
What Is the Best Electronic PCB Assembly?
Printed circuit board assemblies or PCBAs account for about half of the steps in the manufacturing phase of PCB development.
In fact, all of this is focused on preparing the board for component mounting, actually mounting the components, or making sure they are securely mounted. Follow these steps to meet your general requirements for attaching surface mount technology (SMT) or through-hole components.
In most instances. However, performing the following steps does not guarantee that the circuit board will be manufactured to meet quality, reliability or speed goals.
All but the simplest circuits generally have constraints, limitations or special conditions that must be adhered to by PCB development. These may include or be one of the following:
Delivery Schedule Restrictions
For many designers, one of the most important aspects is manufacturing turnaround time. The ability of a CM to quickly build a board can greatly impact development cycle time.
Operational Life Cycle
Reliability is especially important if your design is used in a critical system, such as a Class 3 medical device, as system failure can lead to incorrect diagnosis and even loss of life.
Component Limit
Many industries and original equipment manufacturers (OEMs) have stringent requirements for the components that can be used in their systems. For example, suppliers to the military and the aerospace industry require supply chain documentation to avoid counterfeit components.
Acceptance Quality Level (AQL) Limits
Quality should always come first as it affects your production levels and return on investment (ROI). However, some customers have higher standards, possibly because of environmental or scaling deployment concerns.
Levels of Manufacturability
Depending on the system your board belongs to, there are various manufacturing levels of acceptable performance. Meeting the highest requirements of which IPC-6011 defines the level for PCBs, the requirements for assembly are to minimize defects and ensure that the end user can rely on its high level of performance.
Yield Targets
Another important metric that directly affects product development costs is yield, which is the ratio of available boards to actually built boards. Maximizing this rate is and should be a production goal of every design, as it plays an important role in determining your profit margin.
Test Requirements
The only way to assess a board’s ability to achieve its intended goals is to pass a test. This testing may be to evaluate the design by design testing or evaluating the physical properties of the board through manufacturing testing.
Regulations and Standards
All circuit boards are subject to regulatory control. At a minimum, there are standards for plate construction and materials. There is also Quality Management and Risk Mitigation which is standard if your PCB will be used in sensitive or critical systems such as medical devices and aerospace systems.
Since electronic PCB assembly is the final stage of circuit board manufacturing, it assumes the role of verifying that your circuit board meets all applicable standards such as those listed above. Therefore, optimal electronic PCB assembly depends not only on the process of securely connecting components, but also on the ability to identify design and manufacturing defects that can make good, safe connections difficult or impossible.
Recommendations for the Best Electronic PCB Assembly
Functionally, electronic PCB assembly is performed by a contract manufacturer (CM). However, your CM is limited by the data and information you provide. Therefore, your design decisions play a crucial role in the assembly process. Following the recommendations below will go a long way in helping your CM achieve the best possible electronic PCB assembly for your design.
Choose the right components – source components from reliable sources and plan for possible shortages.
l Make sure your design package is accurate and complete – the best rule of thumb is to be clear when designing your data. This includes not only materials, layout and stacking, but also images, instructions and any special considerations.
Make sure your BOM matches your layout – double check to avoid mismatches between component footprints and BOM component footprints. Otherwise, you may face board delays and extended turnaround times.
Leverage SMT and avoid through-hole parts as much as possible – Soldering surface mount devices (SMD) and through-hole parts is a different process; therefore, both processes take longer, and when many components are through-hole , it will take longer.
Use single-sided component placement – similar to using a different soldering technique, top and bottom mounts take longer than single-sided mounts.
Follow Design for Assembly (DFA) Guidelines – Applying DFA is essential for assembly optimization. Failure to do so may cost you valuable time making design corrections.
How to Do PCB Assembly?
There are many steps involved in the PCBA and manufacturing process. Follow the steps below to get the best quality final product.
Add Solder Paste
This is the most initial stage of the assembly process. At this stage, solder paste is added to the component pads wherever soldering is required. Put the solder paste on the pads and stick it in the right place with the help of the solder screen. This screen is made from a PCB file with holes.
Place the Components
With the solder paste added to the component pads, it’s time to place the component. The PCB goes through a machine that precisely places these components on the pads. The tension provided by the solder paste holds the component in place.
Reflow Oven
This step is used to permanently secure the components to the board. After the components are placed on the board, the PCB is passed through the reflow oven conveyor. The controlled heat of the oven melts the solder added in the first step, permanently connecting the components.
Wave Soldering
In this step, the PCB is passed through a wave of molten solder. This will create an electrical connection between the solder, the PCB pads and the component leads.
Cleaning
At this point, all welding processes have been completed. During the soldering process, a large amount of flux residue forms around the solder joint. As the name suggests, this step involves cleaning flux residues. Clean flux residue with deionized water and solvent. With this step, the PCB assembly is completed. Subsequent steps will ensure that the assembly is done correctly.
Test
At this stage, the PCB assembly is complete and inspections begin to test the placement of the components. This can
to execute in two ways:
manual
This inspection is usually done for smaller components, with a small number of components.
automatic
Perform this inspection to check for bad joints, wrong components, and misplaced components.
How to Choose the Right PCB Assembly Process
Selecting the correct PCB assembly process is important as this decision will directly affect the efficiency and cost of the manufacturing process as well as the quality and performance of the application.
PCB assembly is usually performed using one of two methods: surface mount technology or through-hole fabrication. Surface mount technology is the most widely used PCB assembly. Through-hole fabrication is used less often, but remains popular, especially in certain industries.
PCB Assembly: Surface Mount Technology
Surface mount technology is the most commonly used PCB assembly process. It is used in many electronic products, from USB flash drives and smartphones to medical equipment and portable navigation systems.
This PCB assembly process allows the manufacture of smaller and smaller products. If space is at a premium, then if your design has components like resistors and diodes, this is the way to go.
Surface mount technology enables a higher degree of automation, which means that boards can be assembled at a faster rate. This enables you to process PCBs in high volume and is more cost-effective than through-hole component placement.
If you have unique requirements, surface mount technology can be highly customizable and therefore the right choice. If you need a custom-designed PCB, this process is flexible and powerful to provide the desired results.
Using surface mount technology, components can be attached to both sides of the board. This double-sided board capability means you can apply more complex circuits without having to expand the scope of your application.
PCB Assembly: Through Hole Manufacturing
Although through-hole fabrication is being used less and less, it is still a common PCB assembly process.
PCB assemblies fabricated using through-holes are used for larger components such as transformers, semiconductors, and electrolytic capacitors, and provide a stronger bond between the board and the application.
As a result, through-hole fabrication provides higher levels of durability and reliability. This extra security makes the process the preferred option for applications used in sectors such as the aerospace and military industries.
l If your application must withstand high levels of stress (either mechanical or ambient) during operation, then the best option for PCB assembly is through-hole fabrication.
l If your application must operate at high speeds and at the highest level under these conditions, then through-hole fabrication may be the process for you.
l If your application must operate at high and low temperatures, the higher strength, durability and reliability of through-hole fabrication may be your best option.
Through-hole fabrication may be the best PCB assembly process for your application if it must operate under high pressure conditions and maintain its performance.
Also, due to constant innovation and growing demand for increasingly complex electronics that require increasingly complex, integrated and smaller PCBs, your application may require both types of PCB assembly techniques. This process is called “hybrid technique”.
About Wonderful
Shenzhen Wonderful Technology Co., Ltd. is China’s top model and small batch circuit board manufacturer.
The company targets precision circuit board samples and small batches as the main target market. Since its establishment, it has adhered to the development concept of good quality and important reputation.
Invest huge sums of money to introduce advanced equipment, strictly regulate the operating standards and QC standards for incoming and outgoing materials, to ensure that the shipped products reach Seiko quality.
The self-developed ERP management system can realize the whole process of paperless operations such as online ordering, online payment, online production progress query, online logistics tracking, and online statistical report production, which greatly improves work efficiency.
It ensures that each order can be shipped quickly. After more than ten years of development, the company’s products and services have been well received by the market.
As well as the opening of an electronic component mall, integrated circuits, semiconductors, resistors, capacitors and other products are sold.
The company’s scale is developing rapidly, and the sample and small batch shipment capacity reaches 500 models/day.
The products are widely used in communications, medical equipment, industrial control products, aviation, military products, testing instruments,Automotive, computers and other peripheral products.
We will continue to pay attention to customers, with efficient delivery speed and perfect after-sales service, to become the most trusted brand supplier in the PCB industry.
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