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Category: PCB Designing

Automated Optical Inspection (Aoi)

08Mar
by Admin  
0

Automated Optical Inspection or the AOI process is the method of inspection gaining popularity with the increasing usage of microelectronics. Over time, it has become an integral solution for the SMT industry. But what exactly is the AOI process?

As the name suggests, it is an automated visual inspection of the PCB in manufacturing. Post the assembly of components on the PCB, it is important to inspect it for any defects. For this, the AOI machine is used. The Air machine is equipped with a camera system to scan for any defects on the board which could further lead to board failure. It can be used at any stage of manufacturing i.e. pre or post-reflow or during both to ensure a flawless placement of PCB.

AOI inspects the PCB for any area defects. It helps ensure accurate component placement by identifying any component offset, absence or presence of components, component skew, flipped or severely damaged components. It also checks the solder joints for excessive or missing solder joints and ensures that there isn’t any wrong part or foreign element present on the PCB.

Types of AOI Inspection

AOI processors are available in two categories, the 3D AOI which is the latest version and its predecessor i.e. the 2D AOI, which was introduced somewhere in the early 1980s.  Despite being an age-old technology, with regular modifications, the 2D AOI is still very much dominating the market. However, the increasing complexity of PCB and reduced size of the PCBs have put 3D AOI ahead of 2D AOI.

  • 2D AOI: It is the most commonly used technology with multiple high-resolution cameras, 10 to 15 MP resolution, and precise lenses equipped to inspect tall devices of more than 5mm. The technology makes use of sophisticated inspection algorithms to detect any possible defects on the PCB. It is highly in demand because of its flexible inspection capabilities and is cost-effective. But it stands incapable of providing volumetric measurement data and true-co-planarity inspection.
  • 3D AOI: It is the latest technology that uses laser measurement especially to provide a 3D measurement of height-sensitive devices. Over years, it has been used mostly to inspect solder paste deposition on PCBs right after the screen-printing process. It comes in handy in detecting co-planarity defects that may have been ignored when inspecting through the 2D AOI process. It has a lesser false call rate than the 2D AOI and is capable of providing volumetric measurement data and true-co-planarity inspection. But it is an emerging technology with shadowing issues and high cost.

Whether it is the 2D AOI or the 3D AOI Technology, both aid in ensuring the quality of the PCB by providing incomparable reliability, especially in the case of complex boards with thousands of solder joints and intricate components.

How To Place Components On a Circuit Board?

12Dec
by Admin  
0

Component placement is one of the initial and most important stages of PCB designing. It must be done with utmost care in order to save time and avoid rework. Here are some tips to help the designer with effective component placement.

  1. Grouping and positioning of components: One of the most important tips is to group components with similar functions together as they generate the same amount of heat and other currents, and helps in maintaining temperature levels and avoiding any damage. For instance, PMICs, convertors, LDOs etc. can be grouped as a power management section. Then based on the group dynamics, the other sections can be placed. For example, the power supply section must be placed away from digital or analogue parts, and components that generate electromagnetic noise or radiation must be kept away from more sensitive signals, this helps increase the efficiency by allowing for better control of the return path. To increase the assembly process’s efficiency and reduce positioning errors, one must ensure that the ICs are all aligned in the same direction. A simple rule is to place all the components with similar functions in my direction. Another rule to keep in mind is the distance between sections and components. This prevents dangerous interference between the mixed signals. Also, make sure a space of at least 50mil is maintained between components. Another element that should be considered while placing the components is that components that handle high-speed signals must be grouped and placed at a short distance from each other to simplify the routing of the traces.
  1. Keeping components away from heat sources: It is always suggested to avoid placing other components close to power components that generate heat. For instance, MOSFETs, IGBTs, PMICs and voltage regulators generate a fair amount of heat, sometimes the rise in temperature can affect the functioning of other components. Therefore, try placing such components away from other components.
  1. Creating solid ground planes: The uniformity of the ground plane should always be maintained as they facilitate the onset of signal and power integrity issues. In any case, where maintaining uniformity isn’t possible, be extremely cautious when placing components across the interruption as that could cause an interruption of the return path for those signals and affect the functionality of the PCB. Also, avoid an excessive number of routes as that too could cause an interruption of the return path.
  2. Placement near the PCB edges: It is always advisable to place components that require screw fixing near the edges so as to avoid unwanted contact of cables with other components. In addition to that, make sure no component is placed too close to the edge, at least a gap of 100mil between each component and the edge of the board should be maintained.
  3. Enough space for the traces: With an increasing demand for compact-size portable technology, PCBs, too are required to be of the minimum dimensions. But, it is important to not be misled and to be aware that there is a limitation to the miniaturization of circuits. While designing your PCB, ensure it is of an optimal size where enough space is left to route all the traces.
  4. Thermal management: Lastly, the thermal management of the PCB is very important. Certain components generate a considerable amount of heat during their operation. If not placed properly, this could increase the overall temperature of the board and lead to burning or other damage. To avoid this situation, such components must be placed in the centre of the PCB. This helps in the thermal management of the PCB by evenly distributing the generated heat across the board.

We hope the above-suggested tips come in handy and help you fight out the common obstacles in building an efficient PCB. Gelco always seeks to present you with the best possible solutions and expert advice.

Key Aspects of the Component Placement Process

03Nov
by Admin  
0

Once the Solder Pasting is done and properly inspected, comes the turn of Component Placement. Each component is removed from its packing using a vacuum or gripper nozzle, checked by the vision system and placed in the desired location. This is an automated system done at a very high speed. The technology used for this phase depends highly on the types and design of the PCB being manufactured.

But to achieve a reliable and repeatable process, one must be considerate of certain aspects, these are:

  • Type of data available: One must be mindful while selecting the software for designing the PCB. They must possess the ability to output various types of data. The most commonly used are the Gerber data and the ‘CAD’ data. They are standard electronics industry file formats and are best for generating placement programs. They are used to communicate design information to PCB manufacturers
  • PCB design: How a PCB is designed and panelized is important for the component placement process. Here are some considerations:
    • Panel size: The machines have a specified maximum and minimum size for the panels they can process. Ensure your panel fits within the estimated size.
    • Handling strips: It is important to penalize the PCB as mostly the components are placed too close to the edge and for the convenience of the PCB handling mechanism within the various machines.
    • Fiducial marks: Simple shapes are placed within the track layer of the PCB, called the Fiducial marks. They help in avoiding any confusion of aspects and enable accurate positioning of all the components on the design board.
    • Component size and position: The components might vary in size, therefore using program optimizing software, one must ensure that the smaller components are placed before the larger ones to avoid any disturbance.
  • Nozzles: Nozzles are used to hold the component securely between the picking and placement steps. Based on the component surface, the type of nozzle is chosen. It is very important to pick the correct type of nozzle and ensure no problems with the nozzle for accurate and consistent placement.
  • Vision system: The machine’s vision system checks every component to ensure that all the programmed part dimensions match, checks for any damages and programs each component with the correct tolerance parameters.
  • PCB support: The material used to make PCBs must be of adequate thickness to ensure proper support. Any inconsistency can challenge the component placement process. If it is not well supported, the placement pressure will lead it to deflect.
  • How components are supplied: Common ways of supplying components are by using tape/reel, tubes and trays. Larger quantities don’t possess much concern as they can be directly loaded onto the machine but when in smaller quantities, they cannot be directly loaded onto the machine but rather need to be hand placed or put into a different packaging that might raise a quality concern.

As you can see, the component placement process might sound easy but is quite tedious and the above-stated aspects need to be taken care of to maintain consistency and ensure repeatable results.

Understanding The Stages of The Surface Mount Process

01Jul
by Admin  
0

Surface Mount Technology has revolutionised the PCB designing process. Its on-surface mounting technique has given way to developing complex circuits with compact assemblies at a lesser cost. It makes use of SMD i.e. the Surface Mount Device which are electronic components used within the surface mount assembly process, they come in various shapes and sizes.

The Surface Mount Process starts with the designing of the PCB when based on the requirements, the components are selected and a layout is created. Once the design is finalised, the PCB is sent for manufacturing and the suited components are bought in to facilitate automation.

Stages of Surface Mount Process:
  • Machine Programming: After receiving the PCB panel and the components, the machines to be used are set up and programmed using CAD and Gerber data.
  • Solder paste Printing: The Solder Paste Printer uses stencil and squeegees to apply solder paste to the appropriate pads on the PCB. Nowadays, jet printers are making their way as post-printing modifications are more convenient. This is a critical phase, so be sure of any defects and unidentified defects will lead to defects further down the line.
  • Solder Paste Inspection: Based on the PCB design, there can be a separate machine used for the inspection or the solder printing machine can have the option of automated inspection. 2D and 3D technologies are used to enable a more thorough inspection of the print area including solder paste volume per pad.
  • Component Placement: The next step is placing the components where each component is removed from its packing using a vacuum or gripper nozzle, checked by the vision system and placed in the desired location. This is an automated system done at a very high speed. The technology used for this phase depends highly on the types and design of the PCB being manufactured.
  • Pre-Reflow Automated Optical Inspection: Once all the components are placed, the AOI i.e. Automated Optical Inspection machine is used to verify if all the components have been correctly placed.
  • First Article Inspection: The phase involves re-checking the first assembly design for any errors or defects. In the case of sub-contractors, they must get the first assembly verified by their customers. It might be time-consuming but is a very important step as any defect gone unnoticed can lead to high volumes of re-work.
  • Reflow Soldering: Once the component placement has been checked and verified, the PCB assembly moves into the soldering phase. The board is put into the reflow soldering machine where the PCB is heated to the desired temperature to form electrical solder connections between the components and PCB. The phase isn’t that complicated but the temperature needs to be managed to ensure acceptable solder joints without damaging the parts or assembly.
  • Post-Reflow Automated Optical Inspection: After the reflow Soldering, using the AOI machine the components are again checked for any errors or defects.
  • Process Verification using X-Ray Inspection: As many solder joints are hidden, there is a need to re-investigate the PCB using an X-Ray machine. X-Ray inspection provides a way to check underneath components such as BGA’s, the amount of voiding present within solder joints and also can be used to verify the solder hole fill after the soldering process.
  • Washing and Drying: Once the entire PCB is built and tested well, it is finally washed and dried before being packed and shipped for delivery.

PCB manufacturing using the SMT is an automated system requiring minimal human intervention. But setting up the required machinery and software, verification of errors and component quality assurance does require expertise. That is why it is always suggested to choose a reputed brand like Gelco EMS for your PCB requirements.

Surface Mount Technology For Your Pcb!

03Jun
by Admin  
0

There are several different techniques used to assemble PCBs and Surface Mount Technology is considered the most preferred of them all. But what is Surface Mount Technology and why is it an ideal option for your PCB?

Surface Mount Technology or SMT, as the name suggests is the mounting technique through which electrical components are directly mounted on the surface of the PCB. The conventional mounting technologies inserted the electrical components in a PCB through holes which would consume much space on a PCB. Whereas the SMT enables mounting on the surface itself giving way to optimal usage of the PCB space and reduction of wastage; allowing compact size PCBs. In addition to that, it also reduced the manufacturing cost and increased the scope of manufacturing automation.

Advantages

  • Components per unit area: Usage of limited space leaves room for additional components, therefore resulting in higher component density. Also, components can be placed on both sides of the PCB.
  • Component Connections: As the technique doesn’t involve holes which block the routing space in the inner and the backside layers, many more connections per component can be adjusted.
  • Scope for Correction: Minor errors in component placement are fixed automatically during the soldering process as the molten solder pulls components into alignment with solder pads. The same isn’t possible in a conventional through hole mechanism as once the leads are drawn through the holes, the components are fully aligned and cannot move laterally out of alignment.
  • Under Stress Performance: Due to lower mass and lesser cantilevering, the SMT designed PCBs have shown better mechanical performance under stress situations like in case of a shock or vibrations.
  • EMC Performance: The smaller radiation loop and lesser lead inductance results in lower radiated emissions, therefore better EMC Performance.
  • Efficient Solution: In comparison to a through hole mechanism, the SMT proves more efficient in terms of costing and time consumption. It is an automated process so is a simpler and faster technique.

Disadvantages

The SMT might prove effective in many terms but it has its own set of disadvantages. With the smaller sizes and lead spacings of the SMT devised PCBs, manual prototype assembly or component-level repair can be a costly affair requiring skilled operators and more expensive tools. Also, this puts the reliability of solder joints to question. The compact size leaves no space for markings, due to which the marked ID codes or the component values need to be more cryptic and smaller that are impossible to read normally and require magnification.

The SMT might have its own set of disadvantages but overall, the introduction of this technology has revolutionised the PCB designing process, giving way to building highly complex electronic circuits with compact assemblies and good repeatability due to the higher level of automation at a lesser cost.

Why are Prototype Circuit Boards Needed?

02May
by Admin  
0

A prototype is an early sample of the product built to evaluate the intended design. It helps in testing the concept of the product intended, checking the processes involved and analysing the functionality of the product. Before manufacturing a PCB, it is always suggested to build a prototype circuit board to examine the functionality of the intended final PCB (Printed Circuit Board). It is always better to check the functionality of the final PCB before making it available in the market for the customers, therefore, keeping in mind the application of the printed circuit boards and the applicable benefits, build a prototype before getting into the actual manufacturing stage.

Let’s discuss the added benefits of building a prototype before manufacturing the intended product.

  • Simplifies and Fastens the Manufacturing Process: A prototype gives you the exact idea of the processes involved and the material needed. It is already tried and tested, making the manufacturing process simple and swift. Once you are well aware and already trained for the involved steps, it won’t take much time for you to construct the original PCB.
  • Helps in Better Understanding of the Circuit Board: A prototype helps you understand the functionality, operational abilities, risks, limitations, and scope of application of the end product. It also gives you a clear picture of how the circuit would work. A better understanding of circuit boards is beneficial for the manufacturers, dealers and customers.
  • Leaves Room for Improvements: Helps the customers or the manufacturers to detect or identify any loopholes at an early stage. It is also ideal for running tests and analysing its functionality which leaves enough room for including improvisations.
  • Cost-effective: At times, the customer isn’t satisfied with the final product, making changes and deviations in the final product can be quite expensive and time-consuming. Improvisations made on the prototype can be included in the final product but if the product is created, there is no scope for any improvisation or changes. The problems double if a large volume of production is involved. Thus, it is imperative for the customers to approve the prototype PCB before opting for the production of the final PCB units. Creating a prototype can save you from such losses.
  • Convenience for both Buyer & Manufacturer: It is always an ideal situation when both manufacturer and the customer are sure of the end product. Prototypes help in better understanding of the product and open the opportunity for improvisation which can be convenient for customers as they can analyse the functionality and improvise the design based on their needs without the manufacturer having to bear any losses. It creates a win-win situation for the parties.

Everyone expects to purchase and supply products with perfect functional value and exacting features with efficient performance. In order to achieve this end, it is imperative to analyze the quality, efficiency, and performance, of the final PCB. This cannot be served by assessing the circuit diagram of the PCB. A prototype is created from the diagram wherein the functionality is assessed, further developments are included and improvements are analyzed. Enabling 100% design satisfaction.

But always be sure to contact trusted brands like Gelco EMS when it comes to designing or manufactering a prototype or even the final Printer Circuit Board.

Tools for PCB Designing: Keep it handy!

03Mar
by Admin  
0

As discussed in our earlier blogs, Printed Circuit Board Designing is quite a process. In today’s section, we are going to discuss some basic tools that would be needed to design your PCB. When we refer to tools, they aren’t the usual tools that one might find in a hardware shop but are software and programs especially designed to assist you while designing a PCB. They are electronic software that supports your Gerber file, Excellon file and CAD software. Also, the Internet for finding the right avenues to source your components from. We also require physical tools such as stencils and soldering tools.

The engineer requires these tools at different stages of designing and manufacturing a PCB. When all the required materials are allocated, the basic framework of the printed circuit board has been drawn, and a proper grid has been sketched to understand the working of the PCB; these stages of designing and manufacturing begins when we put to use the above-mentioned tools. Let’s discuss the usage of each.

Stencils:

Stainless foils used for applying solder paste onto the board are stencils. There are laser-cut openings on the stencil that are used to deposit solder paste on designated places on a bare PCB board. A solder mask is used to prevent any excess solder paste deposition on selected areas.

Soldering Machine:

Comprising of a lead or a tin solder, the machine helps in attaching all the electrical components onto the Printed Wiring Board.

CAD Software:

CAD or the Computer Aided Design software comes in handy for the engineer while transferring a design from paper to computer. The software is used to define the schematics, components, and connections within the PCB.

Gerber File

Gerber is a file format that contains information on each physical board layer of the PCB design. It comes in handy for the engineer while creating the artwork for circuit board imaging. Circuit board objects, like copper traces, vias, pads, solder masks and silkscreen images, are all represented by a flash or draw code and defined by a series of vector coordinates.

Excellon File

Excellon file or the drill file s a file format has all the information regarding drill tool number, hole size and quantity, and whether or not the holes are plated. It is used to govern the sizes and locations of finished holes on the printed circuit board.

Growing Trends in PCB Manufacturing & Fabrication

04Feb
by Admin  
0

Technical advancements call for innovation and more efficient solutions. Whether it is the compact size or increased endurance to withstand heat and other environmental parameters, the expectation and scope of betterment has no end. The same is the case when it comes to PCBs. More advanced technologies call for PCBs with better functionalities that are compact in size, mounting of several components, highly durable, flexible with high voltage, thin width and intricate designing. The demand for advanced PCBs has been a driving factor to introduce newer and better fabrication techniques. Below, we will discuss some of the growing trends experienced in the field of  Metal fabrication.

The increasing demand in high-end applications such as solar energy setups, electric vehicles, etc. requires high capacity batteries to help in providing long, undisrupted operation of devices. And the increase in demand is very recent, therefore over the past few years, we notice an increasing demand for high voltage batteries.

Secondly, even though customisation has its own benefits yet consumers have got fond of Commercially developed or ready-to-use (COTS) components. There is an increasing demand for such products as they are readily available and is a time saviour and are also pocket friendly.

As discussed above, even the PCBs, their fabrication and manufacturing, too, has been witnessing a lot of positive changes. But these have also paved the path for duplicacy and supply of counterfeit components. Steps have been taken to curb such issues but still, a lot needs to be done.

Not to miss the board types. Compact solutions are fast making their way into the industry. The modern, complex, small, and lightweight devices don’t have spaces for the traditional PCBs. This has led to an increase in demand for flexible PCBs and rigid-flex PCBs that now rule the market.

A growing trend is observed in modern-day applications such as medical, surveillance etc. is that the boards are mounted with high-resolution cameras for videos and pictures. The cameras are designed such that despite their small size, the quality of the image is of a high order. The mounting of delicate cameras surely lays some pressure on the fabrication and manufacturing of PCBs, therefore pushing further improvement and newer manufacturing and fabrication techniques.

Another widely growing trend observed is the usage of autorouters in PCBs to enhance automation and track the digital functions through the board.

The above-discussed trends might face some challenges but that also leaves scope for improvement and that is where new technologies are developed.

Understanding the Fabrication Process of a PCB

05Jan
by Admin  
0

Manufacturing a PCB is a complex task with several stages involved. From designing a PCB to assembling, one has to be critical about a number of things, such as the material being used, the design of PCB, fabrication techniques and the layering processes, and each stage needs to be properly documented. In this post, we shall discuss the details of the fabrication process. The fabrication process is quite critical and keeping in view the compact nature of modern devices, it has become even more complex.

Before initiating the fabrication, an appropriate PCB design needs to be well in place as it may impact the outcome in terms of tolerances, the level of Coefficient of Thermal Expansion, and structural reliability. The design should include details regarding drilling, layering, copper-coated layers, apertures, components, etc. A flawless design can make the work of the fabrication team much easier. Using the design specification, the actual physical board of the PCB is formed.

The process of fabrication, in itself, involves a number of techniques and processes. Firstly, layouts are made on copper-coated laminates using images as references. Excess copper is scraped off by the etching technique so that the traces and pads are clearly visible. Holes are drilled for the purpose of component mounting. Following the process, the boards are either soldered or extra protective layers are added. Markings such as logos, company name etc. are also added during the fabrication process. Then, the copper-coated surface is fine-tuned, for a perfect finishing. 

These are some basic steps involved in the process of fabrication. However, the ongoing advancements in the field of science and technology pave way for further innovations that deliver more effective techniques, delivering boards with better functionality and capabilities. In addition to addressing the basic needs of a PCB, the modern PCBs are more flexible and compact in nature and have high resistance to heat and hold the capacity to withstand any environmental parameters.

Properties to Consider While Selecting Pcb Laminate Material

06Dec
by Admin  
0

PCB Laminate is an essential component as it holds the different layers of a PCB together. Traditionally, a PCB has multiple layers of substrate, copper, solder mask, and silkscreen. These layers are sandwiched between the laminate sheets that are then heated and pressurized to create the final piece of uniform thickness; the process is called lamination.

There is various material available for lamination like FR-4, Polyimide, Teflon etc. It is essential to choose the appropriate material for lamination as it forms the base for the PCB. The selection of appropriate material is a technical process as it requires due consideration of the thermal, electrical, chemical and mechanical properties of the material.

Do consider the following points while selecting application-centric PCB laminate material:

Mechanical Properties:
  • High Peel Strength for lesser chances of de-lamination. The peel strength is the bonding force between the lamination and the copper layers.
  • High Flexural Strength to avoid any cracks or breaks. Flexural strength is the ability of the material to withstand physical stress without causing any cracks or damage to the material.
  • Delayed De-Lamination Time for higher durability. The delamination time defines the duration, a PCB laminate can withstand exposure to high temperatures before it starts to unravel. 
Thermal Properties:
  • Optimal Glass Transition Temperature (Tg). The glass transition temperature defines the sensitive temperature range of the substrate, exposure to which can cause the substrate to harden or soften.
  • Lower Thermal Expansion to avoid any changes in the dimension or other stress on the PCB. This is possible if the substrate has higher CTE i.e. Coefficient of Thermal Expansion. CTE is the expansion rate of a PCB.
  • Higher Thermal Conductivity (k) to allow adequate heat distribution. It is directly linked to the heat transfer capability of the board. A lower k may result in uneven distribution of heat across the board which might result in overheating of certain layers.
  • Higher Decomposition Temperature (Td). If exposed to a higher temperature, the substrate starts to decompose, which needs to be avoided in any case. It is essential to ensure that the Td of the material is higher than that of the board.
Chemical Properties:
  • Non-Flammable Material. When exposed to heat, if the material is combustible, there are chances of the circuit board catching fire. 
  • Moisture Absorption Value of Substrate ranging from 0.01% to 0.20%. The moisture absorption value directly affects the substrate’s thermal and electrical properties. It also increases the rate of delamination, making it water-resistant.
Electrical Properties:
  • Dielectric Constant (Er) ranging between 3.5 to 5.5 Er. The electrical resistance and signal integrity of the substrate defines the Er. The dielectric constant and dielectric loss tangent of the material needs to be maintained at a stable range to avoid electric shocks.
  • Dielectric Loss Tangent ranging between 0.02 to 0.001 to not let the material lose its strength. Though, one must be very careful of the Loss tangent in the case of analogue signals. 
  • Higher Electrical Strength ranging between 800V/mil to 1500V/mil to withstand any electrical breakdown.
  • Also, one must ensure the optimal Volume Resistivity (p) and Surface Resistivity (pS) of the substrate.

The above-mentioned properties play a crucial role in defining the efficiency of your circuit board. The safety and smooth functioning of your electric device is major concern, and one must never ignore that. Only seek a trusted name like Gelco when it comes to electric solutions like these.

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