How does AOI play a crucial role for the Surface Mount Technology Assembly?

By Mer-Mar Electronics | Date posted: | Last updated: January 11, 2022

There are several reasons why automated optical inspection (AOI) is increasingly playing a crucial role when it comes to surface mount technology assembly. Notable among them are:

  • Lines on PCB are getting finer.
  • PCBs are getting increasingly miniaturized and there is high component density.

This is besides the fact that, production volumes are typically high, and so are quality expectations. The conventional method of inspection clearly cannot serve the purpose of high-density PCB assembly products. It is for all these reasons that quality control is turning to automated machines for addressing quality issues.

How does AOI Technology work?

Automatic Optical Inspection (AOI), sometimes also referred to as Automated Visual Inspection, is essentially a control process. Simply put, it uses optical methods for inspection. It evaluates the quality of the surface mount technology assembly by way of visual information. With stringent quality benchmarks for electronic devices already laid down, it comes in handy in pointing out any defects.

The key advantage of these systems is that they can detect failures early. What this means is that you do not have to deal with costly errors once the final product is ready to go to the market. Instead, the quality can be checked at each stage of the SMT manufacturing process. This has definite financial advantages, not to mention the fact that you do not have to put your reputation at stake, should any errors crop up once your product reaches the market.

The two commonly used inspection, analysis and judgment methods include:

  • Design Rule Check
  • Computer-Aided Design, Data Comparison

Let us look at both of them in some detail:

Design Rule Check (DRC) Method

This method involves inspecting the design pattern basis some rules. For instance, in inspecting the SMT PCB assembly pattern, the rule that is followed is that all lines should rely on solder joints as terminals and that all lines share the same width and the spacing should be equal or more than the regulated value. The advantages of the DRC method include:

  • Ease of setting up
  • Speed of processing
  • Small volume of programming

The disadvantages of the DRC system, however, lie in:

  • Weakness in determining boundary capacity and boundary position

Computer-Aided Design (CAD) Data Comparison Method

This method involves comparing the image patterns stored in the AOI system with the practical image patterns. The challenge of this method, however, occurs on account of high requirement of data real time processing.

Inspection Functions of AOI Technology

AOI technology can be used for inspection of the following:

  • Bare Boards
  • Solder Paste Printing
  • Component Inspection
  • Solder Joints

When it comes to Bare Boards as well as solder joints, it is important to remember that inspections are not made in real time. For Bare Boards, the AOI items include:

  • Wiretapping
  • Scratches
  • Pinhole
  • Line spacing
  • Edge Roughness, and more

AOI items for solder joints include:

  • Missing components
  • Component placement direction
  • Component Number
  • Solder joint quality, and more

In case of Solder Paste and Component Inspection, the inspections are made in real time.

Structure of an AOI System

For Bare PCBs

It relies on the comparison function. The image signals are sent to the control subsystem that makes its judgment on the defects. Marks are made on the PCB in real time and defects can be magnified and checked. This method allows for high inspection speed.

For Solder Joints

Optical cameras are used to capture 3D images of solder joints that are, in turn, compared with standard solder joint images. This enables the defects to be clearly seen and ascertained.

For Solder Paste Printing

It consists of a camera and optical fiber x-y system for solder paste printing at surface mount technology assembly. It enables the solder paste thickness to be measured. The inspection primarily works on the principle of transforming shapes into optical changes.

To sum up

It is easy to see why AOI is one of the best inspection tools in the surface mount technology environment. Not only is it reliable it is extremely cost-effective too. You can count on it to detect both catastrophic failures as well as quality defects.

We provide SMT PCB assembly for high mechanical strength, flexibility, durability, reliability and high performance. Whether you need a low volume or high volume, semi-automatic or fully automatic SMT PCB assembly, we have a system in line with meeting your throughput & budget requirements.

Get a Quick Quote for SMT PCB assembly by submitting your requirements or you can email us at or call us at (760) 244-6149 with all specification.

Top 7 Proven Ways to get the Low Cost PCB Assembly

By Mer-Mar Electronics | Date posted: | Last updated: August 16, 2021
Low-Cost PCB Assembly

There are a number of factors that impact the price of PCB assemblies. Being aware of them can go a long way in keeping your costs under check. Below are 7 actionable ways that can help you lower your PCB assembly cost:

#1. Sourcing Location

First up, the location from where you source your PCB has an impact on the cost. While at first glance, opting for an offshore producer may seem to be cost-efficient, you need to look at several additional factors. One of them is, of course, the shipping cost involved. Additionally, you also need to budget for any delays in shipping that can derail your entire project and have cost implications. Moreover, with a PCB manufacturer in your region, communication is far easier and errors on account of any gaps in communication can be stymied.

#2. Design Strategies

You need to begin with optimizing the schematic design of the bare PCB. Some of the factors influencing costs of bare PCBs include:

  • Optimizing the layer count – As more layers are added, typically the cost goes up.
  • Number of vias – While vias play a significant role in building interconnections on a circuit board, an increase in the number of vias adds to the cost.
  • Shape – Essentially standard shapes come at a lower cost while special shapes are typically more expensive.
  • Surface finish – The right surface finish prevents pads from oxidizing as it also improves performance. It is therefore imperative to choose the surface finish that best fits your product and the environment it has to work in.

Your design strategies can also have a significant impact on costs. Some of the design tips to keep in mind include:

  • Placing surface mount components on one side.
  • Labelling designators correctly, which makes the set-up process hassle free. In addition, proper labeling ensures any errors in manual placements can be avoided.

#3. An Effective BOM

A Bill of Material is a comprehensive list of raw materials, assemblies, sub assemblies, components and more for manufacturing. A detailed BOM should include the following details for assemblers:

  • Part Number
  • Manufacturer name
  • Reference Designator
  • Quantity
  • Description
  • SMT (Surface Mount) Method, and more.

It is also recommended that component replacements be added to the BOM. That way as components gets upgraded no time is wasted in locating replacements, thus delaying production.

With a comprehensive BOM you tend to save essential time as also cost, besides the fact that you do not need to deal with costly errors.

#4. Choose the right components

While it may seem prudent to go in for highly sophisticated parts, you need to remember that those may also cost a fortune. It is therefore important to undertake a cost benefit analysis in choosing optimal parts that do not compromise the quality, without putting undue pressure on costs. Component sourcing also plays an especially important part in determining costs. Typically, PCB Assemblers enjoy economies of scale and can offer better prices on account of their ongoing relationship with component providers.

#5. Order volume and lead time

Typically order volume is inversely proportional to the cost. It is therefore prudent to estimate your order volumes in one go to be able to place a consolidated order and reap the cost advantage. Similarly, it works well to plan your order as orders with low lead times typically command a higher cost.

#6. Turnkey PCB Assembly Services

It works best to go with a service provider that can offer you turnkey PCB assembly services as opposed to contracting different service providers. Not only do you get a substantial cost advantage, you also tend to benefit from the fact that there are no communication gaps as there is only one point of contact.

#7. Testing and inspection of Low-Cost PCB Assembly

While testing is generally considered to be a cost head, the fact remains that low cost cannot be chased at the expense of quality. In fact, from visual inspection to automated optical inspection (AOI) to automated X-ray inspection (AXI) there are a wide array of inspection techniques that a professional service provider offers which save you from costly errors at a later stage. In the absence of appropriate testing, it can lead to a situation where you may even need to deal with product recalls and a face a dent to the company reputation.

To sum up

Low-cost PCB Assembly can definitely be achieved without compromising on the quality of the PCB, by following these seemingly simple tips.

So, Are you looking for low cost PCB assembly? Mer-Mar Electronics specializes in PCB assembly services with customized features. We provide complete turnkey, low volume PCB assembly wherein we take care of the entire PCB assembly, fabrication, component mounting, assembly, testing, and delivery. With our skilled engineers and dedicated workforce, we are well-equipped for small batch PCB assembly that can be delivered in the shortest lead time and with the cost-effective manner.

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How to Identify the Ideal PCB Repair Service Provider?

By Mer-Mar Electronics | Date posted: | Last updated: June 7, 2022
PCB Repair Service

The PCBs (Printed Circuit Boards) are crucial for the success of every electronic equipment, is a given. The fact, however, remains that PCBs are subject to physical damage such as cracks and corrosion. In addition, PCBs can deteriorate on account of extremes of temperature, voltage fluctuations, contaminants like dust, and more.

It is imperative that planning for malfunctioning of PCBs, therefore, be an important part of your overall approach. You cannot be looking around for a PCB repair service provider at a time when your production schedule is tight and you are already facing downtime on account of board failure. The right repair and reworking of the PCBs can result in saving of millions of dollars.

How exactly do you choose the service provider for circuit-board repair or rework? Here are three important aspects to look out for:

  • Expertise level of PCB Rework and Repair service provider
  • The kind of equipment they have
  • Cost advantage

Let us look at each of them in some detail:

Expertise Level of PCB Rework and Repair Service Provider

To repair and rework a PCB requires tremendous technical expertise. It is important therefore to look for a company that has skilled engineers and technicians. The number of years the company has been in business can be a good indicator of this. If a company has been operating for a long time, its technicians are likely to have in their arsenal, industry best practices that will come in handy in the PCB repair and will ensure that you do not have to re-invent the wheel.

Another aspect to look for is the kind of industry standards the company adheres to. If the company adheres to IPC standards in PCB Manufacturing, for example, you can rest assured that you are safe. In the absence of this certification, it will not be prudent to allow them to handle advanced microprocessors and digital signal processor circuits. The kind of training that technicians are given is also a good indicator of the company’s reliability.

It will also be good to check out the value-added services the company has on offer. These could include:

  • Improving the PCB Design
  • Remanufacturing obsolete components
  • Replacing parts
  • Implementing end-of-life strategies, and more.

State-of-the-art equipment

A service provider who is equipped with the latest, state-of-the-art equipment can go a long way in not only offering quality repairs but also significantly reducing turnaround time.

A mix of equipment that can address digital, analog as well as power section of circuit cards is ideal. Some of the equipment to look out for, include:

  • In-circuit testers- These can go a long way in testing digital as well as analog ICs. The tests check for Boolean output of the chips.
  • Data I/O programmers- These can read and store data in programmable logic devices.
  • Hot-air IC installation and removal systems- These are helpful for reflow solder as they ensure temperature controlled warm air.
  • Signature analysis- This is a diagnostic tool that forms a unique impedance signature that determines the health of the junction. The deflection signature can help in the analysis of whether the component is good, bad or does it lie in between these extremes.
  • Oscilloscopes- These are useful to analyze voltage waveforms.
  • Digital voltmeters- They help in measuring voltage with precision in the selected range.
  • Cap and inductance meters- They help analyze capacitors, ESR, dielectric leakage and frequency response.
  • Calibrators- These help in the adjustment of temperature and pressure.
  • Mings- These are hand-held devices that help check ICs
  • Simulation testers- They test the functionality of the PCB assembly.

A service provider equipped with such equipment is definitely in an outstanding position to offer you quality PCB repair and rework.

Cost Advantage

A large service provider can offer repair and rework services at cost-effective price points if they enjoy economies of scale. Besides larger setups have the necessary bandwidth to offer a host of value-added services related to PCB redesign. With smaller setups the cost is likely to be extremely high. In turn, the cost will not justify the rework and make it inefficient.

To sum up

The choice of the right service provider will ensure that your PCBs are as good as new and adhere to industry specifications. It is therefore extremely important for you to be able to make the right choice of a reliable partner that will lead to major cost advantages and ensure that your project remains efficient.

As a leading electronics manufacturing company, we have 4 decades of solid experience in assembling printed circuit boards and PCB assembly rework and repair service through innovative tools and technologies. We ensure effective resoldering or desoldering of certain surface-mounted components on the printed circuit boards. With the increase in lead-free requirements, the PCB repair process has become even more complex, but we have trained personnel to work on lead-free assembly, rework, and inspection.

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Top PCB Assembly Techniques for the modern-day electronics industry!

By Mer-Mar Electronics | Date posted: | Last updated: June 7, 2022

When it comes to PCB Assembly Techniques, 3 basic technologies find their applications for the modern-day electronics industry. These include:

  • Through-Hole Technology (THT) Assembly Process
  • Surface Mount Technology (SMT) Assembly Process
  • Mixed Technology

Let us look at each of them in some detail:

Through-Hole Technology (THT) Assembly Process

This method of constructing electronic circuits involves inserting pin-through-hole components through holes that are drilled into the PCBs (Printed Circuit Boards). The ends are then affixed by way of molten solder.

The steps in Through Hole PCB Assembly include:

  • Placement of Components

    As the name suggest, this step involves placing the components precisely in accordance with the PCB design files. It is imperative that the placement of components conforms to the best practices of through-hole mounting to ensure reliability.

  • Inspection

    A rigorous inspection process to ascertain that the components are correctly placed follows. This process ensures that any changes can be immediately made and costly errors prevented.

  • Wave Soldering

    Now is the time to solder the components onto the circuit board. The wave soldering method involves bringing the solder to a temperature of around 500-degree F and having the board move over it slowly.

    Overall, through-hole PCB technology came as the much-needed replacement for techniques such as point-to-point construction, which were in use in modern electronics.

Surface Mount Technology (SMT) Assembly Process

This technology allows the components to be mounted directly on to the surface of the printed circuit boards with solder paste. This technology works for small components. The various steps involved in the SMT process include:

  • Solder Paste Printing

    This process involves using a solder paste printer and stencil to ensure that the solder paste is correctly applied on areas where the components need to be mounted.

  • Components Mounting

    The PCB is next sent to a pick-and-place machine where the components are mounted on the board, which in turn, stick to the board on account of the solder paste.

  • Reflow Soldering

    The board now passes through a reflow oven, which has a temperature of over 500-degree F. This enables the solder paste to melt. The melted solder is then cooled till strong joints between the components and the surface of the board are formed.

    The key advantage that surface mount technology brings is that it lends itself to small and lightweight PCBs, which in turn, work well with the trend of miniaturization that has taken the electronic world by storm.

    Also, as compared to the through-hole process, with its high degree of automation, surface mount technology lends itself to a high degree of accuracy besides keeping labor costs in check. Additionally, the drilling that through-hole mounting entails makes the boards more expensive to produce while also limiting the routing area for signal traces. While through-hole technology is used for bulkier components that are in need of added mounting strength, little surprise then that through-hole technology finds application in not just PCB for electronics but also telecommunications, aviation and more.

Mixed Technology

With the complexity in electronic products on the rise, mixed technology boards where both SMD and through-hole components are used, is also on an increase.

A mixed assembly involves using a combination of methods. Mixed technology assemblies could be by way of:

  • A single-sided mixed assembly, where both surface mount technology as well as through-hole technology is used on the same side of the board.
  • A split assembly, where one side of the printed circuit board is assembled with surface mount technology and the other side of the board is assembled with through-hole technology.
  • A double-sided mixed assembly, where both sides of the printed circuit board are assembled with a combination of through-hole technology and surface mount-technology.

A PCB with mixed technology needs thorough inspection by way of an Automatic Optical Inspection, which points out any imperfections.

Mixed technology finds extensive application in:

  • Communication hardware
  • Server Boards
  • LED lighting products
  • Video processing, and more

To sum up

In conclusion, as electronics become smaller and more complex, so do PCBs that power these devices. For Electronics PCB Assembly it means making use of advanced levels of engineering to offer reliable products.

Mer-Mar Electronics offers a multitude of PCB Assembly services that range from components’ procurement, fabrication, assembly, testing, and delivering the best quality end products to our customers. We have a team of professional engineers and technicians who will closely collaborate with you to ensure superior quality products are delivered in the quickest time possible. Through the fulfilment of several orders on a frequent basis, we’ve established ourselves as the leading supplier of PCB Assembly.

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