Stanlee India, A Reputed SMT PCB Assembly Manufacturer & Service Provider in India
With the advancement in technology as well as an increase in the number of industries using electrical products, there has been a significant increase in need of PCBs. To meet the demands of varied industries and reduce the costs, Surface Mount Technology (SMT) was developed and has been a great success since then. SMT PCB Assembly helps in the effective usage of the PCBs as well as reduces the overall manufacturing cost. Moreover, with SMT, building relatively more complex electric systems has become easier and more convenient.
What is Surface Mount Technology?
To describe it simply, Surface Mount Technology (SMT) is a method in which the company produces electric circuits by mounting the electrical components directly onto Printed Circuit Board’s (PCB’s) surface. Hence, by this method, the company generates a Surface Mount Device (SMD). When SMT came into existence, the traditional method was slowly replaced. In the traditional method such as through-hole technology method, the electric components were fitted onto the PCBs directly using wire leads for the holes in the PCBs.
Advantages of SMT PCB Assembly
There are a number of advantages of using SMT PCB Assembly techniques in today’s progressive industries. The most significant advantages are:
- The number of components that a PCB can support the increase. That is, there is an enhancement in the component density in SMT.
- One can utilize both sides of the PCBs for placing the electrical components.
- In the case of vibrations or shock conditions, SMT PCB Assembly works better than the traditional one.
- Minute errors in the placement of components, if any, automatically get corrected. This is so because the surface tension built because of the molten solder automatically pulls the components in proper alignment.
- The performance is way better and the unwanted RF signals that the process produces are also way lesser.
- More cost-effective and time-saving manufacturing.
- The initial cost of setup as well as overall manufacturing is lesser in comparison to traditional PCB Assembly methods.
- The radiation loop area is quite small. Therefore, EMC performance is better in the case of SMT.
Types of SMT PCB assembly services provided by STANLEE INDIA
BGA (Ball Grid Array)
Ball Grid Array (BGA) is a type of SMT PCB assembly that one generally utilizes in integrated circuits. There are a number of advantages to using BGA. The most prominent ones include effective space saving, better electrical performance, enhancement in manufacturing yields and reduction in the size of package thickness.
QFN (Quad Flat No-leads)
One utilizes the Quad Flat No-leads (QFN) package when micro-controllers are being utilized in the IC packages. Manufacturers often choose QFN over BGA, as BGA is the more complex one in this case. This is because escaping traces is difficult in the case of BGA. QFN allows easy routing as all the pins are exposed to the outer edge. However, because there is a need for X-ray inspection in QFN, this alternative is a little expensive as compared to the other types of SMT PCB assemblies.
SOIC (Small Outline Integrated Circuit)
Small Outline Integrated Circuit (SOIC) is the type of SMT IC that has an area occupancy of a total of 30%-50% lesser than that of Dual In-line Package (DIP). Also, the thickness is 70% lesser too. There are a number of SOIC types available such as narrow SOIC, wide SOIC, mini SOIC, etc.
POP (Part on Part) Technology)
In Part on Part (POP) technology, in the electric components, there is stacking of components one on top of the other. OPO is capable of providing miniaturization when required. The parts utilized in POP are relatively more complex. The manufacturer needs to perform screening of the solder paste.
QFP ( Quad Flat Package)
One also utilizes Quad Flat Package (QFP) when microcontrollers are a part of the circuits. To verify the solder joints’ QFP parts require X-ray Inspection after the PCB Assembly. QFP, along with QFN is a smarter choice as they reduce fabrication costs as well.
UBGA (Ultra-fine Ball Grid Array)
Ultra-fine Ball Grid Array (UBGA) is a type of BGA that is based on Pitched BGA (or PBGA). Manufacturers utilize this package as well for the manufacture of integrated circuits.
SMT Assembly Process flow
Solder Paste Inspection
Most of the errors or defects usually arise in the printing process itself. Hence, to make it better, before placing any component on the PCB, the stencils are first verified. The manufacturer performs this verification using SPI Machine that checks solder thickness, speed, aperture as well as coating. The data is recorded on the SPI Machine after the check can be further utilized to investigate and analyze the issues if any.
Depending on the type of PCB Assembly that you require as well as the components that one needs to manufacture and mount, the time per cycle of manufacture differs. Again, the support placements used for each are also different.
Oven & Heating Technology
The PCB assembly manufacturer can optimize and create customized profiles for each electronic product into consideration. The manufacturer needs to select an ideal oven temperature for the optimum heating process of the electronic component. The experts at STANLEE INDIA look into the peak temperature to liquid solder, soak time as well as cooling time to decide the final oven temperature for best results.
Automated Optical Inspection
Apart from the error checks performed, the manufacturer inspects all the SMT products through and Automated Optical Inspection (AOI) that verifies the quality of the solder that the manufacturer used, pad placement, part markings as well as solder joints. This ensures that the final SMT products are in the best of quality.
Component Storage Solution
There is an additional storage space to house the manufactured SMT products. Hence, the manufacturing firm registers the requirements for specific orders and caters to them by looking into the storage first.
SMT MAKES REWORK EASIER
In case of any defective components that might get mounted, repair/ rework for them is possible using a soldering iron in case of SMT. Or, the firm uses a non-rework system in some cases. Reworking is responsible for the correction of the machine as well as human-generated error. Here are the basic steps one follows:
- Melting of solder and removal of electrical components
- Removing the residual solder
- Printing new solder paste onto the PCB. One can do this directly or by using a dispenser.
- Placing a new component and reflow.
However, in case one detects the error too late into the process, rework becomes really tough to handle and might also require exclusive operations to cater to the issue. The two main methods used for extensive rework include infrared and hot gas method.
STANLEE INDIA: Firm excelling at providing SMT Assembly services
Having an experience of over two decades, STANLEE INDIA stands tall as a provider of SMT PCB assembly services today. The employees at STANLEE INDIA are complete electrical enthusiasts and have the required skills and knowledge when it comes to anything to do with PCB Assembly.
SMD – Surface Mount Device
Surface-mount Device (SMD) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In the industry, it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board.
Both technologies can be used on the same board for components not suited to surface mounting such as large transformers and heat-sinked power semiconductors.
An SMD component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls (BGA), or terminations on the body of the component.
Increase Quality And Density While Saving Time And Money
In addition to THT assembly, our electronics manufacturing also uses modern assembly machines for PCB assembly with surface-mounted device (SMD) components featuring component sizes of 01005 and higher.
SMD Assembly Enables:
The higher component density in the SMD assembly allows for greater miniaturisation of circuits and assemblies and thereby helps to reduce costs.
Cost Benefits Of SMD Manufacturing:
The SMD components are attached onto the substrate by way of reflow or wave soldering.The PCB assembly then undergoes an AOI (automatic optical inspection) test and/or an AXI (automatic X-ray inspection) test.
PCB Wave Soldering Services
Wave soldering is a large-scale soldering process by which electronic components are soldered to a printed circuit board (PCB) to form an electronic assembly. The name is derived from the use of waves of molten solder to attach metal components to the PCB. The process uses a tank to hold a quantity of molten solder; the components are inserted into or placed on the PCB and the loaded PCB is passed across a pumped wave or waterfall of solder. The solder wets the exposed metallic areas of the board (those not protected with solder mask, a protective coating that prevents the solder from bridging between connections), creating a reliable mechanical and electrical connection. The process is much faster and can create a higher quality product than manual soldering of components.
Wave soldering is used for both through-hole printed circuit assemblies, and surface mount. In the latter case, the components are glued by the placement equipment onto the printed circuit board surface before being run through the molten solder wave.
Comparison between Wave Soldering and Reflow Soldering
As contemporary electronics embraces light weight, high speed and increasing efficiency, each link of manufacturing thereafter conforms to such philosophy, which is open to Printed Circuit Board Assembly as well. Soldering has been playing an essential role in determining the success of electronic products since electrical connection achievement derives from precise soldering. Compared with hand soldering that’s still preferred by some electronics hobbyists, automatic soldering has been widely selected due to its merits of high accuracy and speed and demands of large volume and high cost-effectiveness. As the leading soldering technologies for assembly, wave soldering and reflow soldering have been most widely applied to contribute to high-quality assembly. Nevertheless, they are always being mixed up and differences between them tend to confuse many and when to use them is even vague.
PCB Wave Soldering Process
Wave soldering process is composed by four steps: flux spraying, pre-heating, wave soldering and cooling.
Step one: Flux Spraying. Cleanliness of metal surface is the basic element ensuring soldering performance, depending on functions of solder flux. Solder flux plays a crucial role in smooth implementation of soldering. Leading functions of solder flux include:
Step two: Pre-heating. In a pallet along a chain similar to conveyor belt, PCBs travel through a heat tunnel to carry out pre-heating and activate flux.
Step three: Wave Soldering. As temperature constantly rises, solder paste becomes liquid with a wave formed from whose edge boards will travel above and components can be solidly bonded on boards.
Step four: Cooling. Wave soldering profile conforms to a temperature curve. As temperature reaches the peak in wave soldering stage, its reduction comes, which is called a cooling zone. After being cooled to room temperature, board will be successfully assembled.
Step four: Cooling. Wave soldering profile conforms to a temperature curve. As temperature reaches the peak in wave soldering stage, its reduction comes, which is called a cooling zone. After being cooled to room temperature, board will be successfully assembled.
As circuit boards are placed on pallet ready to go through wave soldering, time and temperature are closely associated with soldering performance. As far as time and temperature are concerned, a professional wave soldering machine is of much necessity while PCB Assembler’s expertise and experience are seldom easy to obtain since they depend on years’ accumulation, application of up-to-date technologies and business focus.
If temperature is set to be too low, flux won’t be melted so that it won’t maintain activity, reaction capability and capabilities to dissolve oxide and dirt on the surface of metal. In addition, alloy won’t be generated by flux and metal if temperature is not sufficiently high. Furthermore, other factors such as speed of band carrier, wave contact time etc. should be taken into considerations and calculation.
Generally speaking, even though the same wave soldering equipment is applied, different Assemblers possibly feature different manufacturing efficiency due to different operation methods and extent of understanding on soldering machine. For example, Stanlee (India) Enterprises Pvt Ltd (a India-based full turnkey PCB Assembly service supplier) engineers take advantage of fixture to fix THT components prior to wave soldering so that all parts can be accurately mounted on boards with soldering defects dramatically decreased.
PCB Conformal Coating Services
A PCB Conformal coating is a protective chemical coating or polymer film 25-75µm thick (50µm typical) that ‘conforms’ to the circuit board topology. Its purpose is to protect electronic circuits from harsh environments that may contain moisture and or chemical contaminants. By being electrically insulating, it maintains long-term surface insulation resistance (SIR) levels and thus ensures the operational integrity of the assembly. It also provides a barrier to air-borne contaminants from the operating environment, such as salt-spray, thus preventing corrosion.
Some typical application examples include high-reliability defence, automotive and aerospace, where coatings are used to protect against various combinations of moisture, aggressive chemicals and vapours, salt sprays, large temperature variations, mechanical vibration, and even organic attack (e.g. fungus). The protective nature of conformal coatings also means that they not only protect, but also serve to enhance product reliability and thereby reduce the potential cost and damaging effects of early field failures.
How do conformal coatings work?
A PCB conformal coating is a protective barrier that shields sensitive electronic components against harsh environmental conditions such as moisture, chemicals, and debris. They are not designed to be a total sealant. Conformal coatings are a breathable protective layer that will protect against the particular environment requirement but will also allow any moisture trapped in the circuit board to escape.
The particular advantages of conformal coatings can be summarized as follows:
Ideally, conformal coatings should exhibit the following characteristics:
How do I apply Conformal Coating
There are four main types of application method used for conformal coatings.
Products are available in bulk, aerosol, and small packaging sizes, therefore the correct method and conditions should be assessed for each application. Careful consideration of the advised humidity and temperature conditions for the selected coating should be taken for both application and curing stages.
Conformal Coating Method
This method as the name suggests uses a brush to apply the coating to the circuit board. The benefits of using this application method are primarily that it can be more cost effective for small scale production, and it is easy to select which areas to coat.
However, we generally advise against brush coating application as it is not always easy to apply an even coating. This can lead to either a lack of adequate protection if the coating is too thin, or if the coating is too thick, can lead to the coating cracking (especially under thermal cycling). Another disadvantage of this method is that you can only coat one side of the PCB at a time
With this method, the PCB is ‘dipped’ into the coating by machine, immersing the entire board and allowing the coating to easily get into gaps and under components otherwise hard to reach.
Most coatings can be used for this process, however, dipping generally requires higher viscosity/higher solids content materials and any coating which reacts to the environment such as moisture-curing coatings are difficult to use since the tank cannot be sealed from moisture contained on the boards that are being immersed.
Disadvantages of this method are:
Accurate masking is essential for connectors and other areas that must not be coated. Masking is often a labour intensive process and is 100% waste. The material (liquid or tape) must be applied, dried, and removed, and often the coating must be touched up if areas are damaged during demasking, and then the masking material must be thrown away. The use of custom made rubber masking boots, designed to form fit the components being masked, can save time but is still an added process and additional expense that is difficult to automate.
Selective Coating by Machine
Selective coating is a method by which you ‘select’ which part of the PCB you would like to coat. Usually, this method uses a machine which you program to coat only the areas which you want.
This method is suitable for all levels of manufacture and has the benefit over dip coating of needing minimum masking, and if the board is designed well for coating, masking can be avoided entirely. Being applied by machine also means you are guaranteed an even, uniform and repeatable coating applied to the recommended thickness. It can usually be applied more quickly and is suitable for in-line, one-piece flow production.
The downside to this method is that it requires a more sophisticated operator to run the machine, and it is not always easy to get penetration under components. Programming can also be time intensive and require machine downtime, which can limit the appeal of this method in low-volume, high-mix production environments. It also can also lead to ‘cobwebbing’ or blooming
Spray coating is, as the name suggests a method where the coating is sprayed onto the board, usually applied by hand in a spray booth or by aerosol, although it can be automated as in the selective coating process.
This is one of the most cost-effective and convenient ways to apply a coating as it can be done on the benchtop if necessary and is, therefore, a good choice for rework or repair items, or small scale projects.
Most coatings can be used for this application method, however, it requires a low viscosity, so solvent based coatings may need to be diluted to the required viscosity using the appropriate thinners.
Finally, when selecting the coating application method you should review the coatings curing instructions. As is mentioned above, some application methods are not suitable for certain curing types. More information on the types of cure
What else should I consider while applying a conformal coating?
There are several environmental factors which should be considered when applying coatings.
X ray Inspection System
Stanlee (India) Enterprises Pvt Ltd its position as industry leader with the IX Series – top-of-the-range X-ray inspection systems that can detect foreign bodies of the lowest densities, greatly outperforming more conventional models on the market.
The IX Series is unique in the industry for using STANLEE INDIA “Genetic Algorithms” (GA) in its image processing technology. Fully adaptable to your specific applications, GA will ensure a thorough inspection of your product for the full spectrum of foreign bodies at unrivalled sensitivity levels.
With the IX Series, we can guarantee:
Tips to select the right X-ray Inspection system
The decision to purchase X-ray inspection equipment can be daunting for food producers. After deciding what product the machine will handle and the function the machine will be responsible for, there are still a number of important factors to consider. Read on for a quick run-down of the top 10 considerations when choosing an X-ray inspection system.
Within an X-ray machine, the generator produces the X-rays that are transmitted through the product and foreign bodies. The higher its specifications, the better the machine’s performance – and the greater the quality of inspection.
While most machines just have one sensor, multiple sensors, provide greater contrasting images – this is useful in applications such as poultry, where there are low differences in density between the product and the foreign body.
Just as you get pixels in digital cameras, you’ll find them in line sensors. The more and smaller the pixels, the better the resolution.
The size and weight of your products, as well as how fast you want to make the inspection process, will factor into your decision. Either way, this mechanism is vital for getting rid of bad products.
There is a case that a notification or a registration to government agency is required on importing or installing X-ray units. Guidelines depend on the country, please ask to Stanlee (India) Enterprises Pvt Ltd local office for details.
This has a huge impact on the internal adoption of X-ray technology. You should ask how easy the machine is to use and how quickly the pre-sets can be set up?
We’ve all seen those grainy X-ray images that might show a foreign object…possibly? When the density of the product and foreign body are close, machine hardware can struggle, however software can be then used to enhance images.
The results from X-ray inspection are dependent on the objects imaged. So, it’s important to work with an organisation that knows your sector, and can help you align your equipment to your application.
While X-ray systems are not complex to understand, training is essential to build the knowledge to use them safely and compliantly.
Cost of ownership
Ultimately, you get what you pay for. It’s important to assess which type of X-ray will suit your needs, along with the quality of the support, available training and the provision of ongoing service maintenance, before making a decision.
Classification of X-ray Inspection Devices
X-ray inspection systems for BGAs and CSPs are mainly classified into two categories: 2D (two dimensional) system and 3D (three dimensional) system. All the devices can be operated off line and are capable of making panel inspection and sampling inspection. Off line devices make it convenient to inspect PCBs at any stage in the assembly line and easy to be back to the assembly line again. Some X-ray devices are used on-line so that most of these devices are put after reflow oven. Whether to use on-line or off-line devices relies on the application and inspection amount. Generally speaking, online devices are suitable for applications with large quantity, complexity and few type changes based on the extra cost and safety elements. However, on-line X-ray inspection systems are basically the slowest part in the assembly line, making fabrication line capacity become low. So even if in the application with high capacity, off-line devices can be used to make panel inspection with cost taken into consideration.
A 2D X-ray system is capable of displaying simultaneously the 2D images of all the components from both sides of PCB just like the medical application used to inspect the bone fracture conditions. A 3D X-ray system is capable of generating the images of cross sections by rebuilding a series of 2D images just like the medical application, CT. Besides its cross section inspection, 3D system has another method which is Laminographic. The inspection process is carried out by combining the image of a cross section and eliminating the images from other cross sections to rebuild the image of a certain cross section. 2D systems can be operated on line or off line. So can X-ray laminographic. However, the on line method usually costs more time. The X-ray inspection system with CT function is accomplished off line because many 2D images and complicated algorithm are needed so that a couple of minutes have to be cost. Therefore, X-ray inspection system in CT type is only used in the less important professional research analysis application. Other 2D and 3D systems must be instructed with a privilege of the least time and the best image so as to reduce the cost of inspection.
X-ray Tube is the Heart of X-ray Inspection Device
For all kinds of X-ray inspection devices, X-ray tube is the most essential part. Nowadays, X-ray tubes can be classified into two categories: open tube and closed tube. The feature comparison between the two types of tubes is shown in Table 1.
- X-ray tube type: open tube or closed tube. This type is correlated with the resolution and lifespan of inspection devices. The higher the resolution is, the more intricate and delicate details users will see. If the target inspected is at a large scale, then it won’t matter when you choose the device with a relatively low resolution. However, as far as BGAs and CSPs are concerned, the resolution of 2μm or smaller is required.
- Target type: penetrating or reflective. The target type plays a role in influencing the distance between the sample and X-ray tube focus that will eventually influence the magnifying times of inspection devices.
- X-ray voltage and power. The penetration capability of X-ray tube is proportional to the voltage. When voltage is large, objects with higher density and thickness can be inspected. When the inspected target is single-sided boards, devices with low voltage can be chosen. However, when the inspected target is multi-layer boards, high voltage is required. As for the certain voltage, the image definition is proportional to X-ray tube power.
All in all, X-ray inspection technology has brought new reforms to SMT inspection methods, and it can be regarded as the best alternative for PCBA manufacturer to further increase the fabrication craft and product quality.
Stanlee (India) Enterprises Pvt Ltd offers X-ray inspection on our assembled circuit boards to test their quality. We promise to ship out only qualified boards. Interested in getting a quick quotation for your custom PCB Assembly project? Click the following button to submit RFQ. We will give the pcb assembly price and lead time within 1-2 working days.
AOI - Automatic optical inspection systems
Automatic or automated optical inspection, AOI, is a key technique used in the manufacture and test of electronics printed circuit boards, PCBs. Automatic optical inspection, AOI enables fast and accurate inspection of electronics assemblies and in particular, PCBs to ensure that the quality of product leaving the production line is high and the items are built correctly and without manufacturing faults.
It’s almost impossible for current electronic devices to work without a circuit board. A printed circuit board plays a critical role in electrical connection between components such as integrated circuits (ICs) that are assembled on bare boards applied in different electronic devices ranging from relatively simple equipment such as electronic watches, calculators, handheld computers, electronic communication equipment to advanced electronic devices like military, medical or aerospace products.
Need for AOI, automatic optical inspection
Despite the major improvements that have been made, modern circuits are far more complicated than boards were even a few years ago. The introduction of surface mount technology and the subsequent further reductions in size mean that boards are particularly compact. Even relatively average boards have thousands of soldered joints, and these are where the majority of problems are found.
This increase in the complexity of boards also means that manual inspection is not a viable option these days. Even when it was an acceptable approach, it was realized that it was not particularly effective as inspectors soon tired and poor and incorrect construction was easily missed. With the marketplace now requiring high volume, high-quality products to be brought to market very quickly very reliable and fast methods are needed to ensure that product quality remains high. AOI, automatic optical inspection is an essential tool in an integrated electronics test strategy that ensures costs are kept as low as possible by detecting faults early in the production line.
One of the solutions to this is to use automated or automatic optical inspection systems. Automated optical inspection systems can be placed into the production line just after the soldering process. In this way, they can be used to catch problems early in the production process. This has a number of advantages. With faults costing more to fix the further along the production process they are found, this is obviously the optimum place to find faults. Additionally, process problems in the solder and assembly area can be seen early in the production process and information used to feedback quickly to earlier stages. In this way, a rapid response can ensure that problems are recognized quickly and rectified before too many boards are built with the same problem.
Attributes and Capabilities of AOI Test
Depending on visual methods, AOI test can be applied to detect a lot of surface defects including scratches, nodules, stains, opens, shorts, insufficient or excessive solder, incorrect components, missing components, the incorrect polarity of components etc. As a matter of fact, these defects AOI is capable of going through belong to items of manual visual inspection that was mainly applied prior to the popularity of AOI test which is, however, capable of performing them quickly and accurately.
Multiple inspection objects – Automated Optical Inspection test works perfectly for both bare PCBs and PCBAs. For PCB inspection, defects are checked such as shorts, opens and insufficient solder. For PCBA inspection, issues are inspected including component soldering, polarity, and values.
Flexibility – Automated Optical Inspection can be arranged in any stage of the manufacturing line in accordance with customers’ needs and cost tolerance capacity. In order to increase inspection efficiency and reduce the corresponding cost, it’s optimal to place it after reflow soldering because most defects result from nonconformance occurring during the soldering process. The flexibility attribute of AOI test leads to a reduction of cost since it is an in-process test and as soon as issues are discovered, manufacturing or assembly parameters can be instantly modified so that later products will be correctly produced. As a result, more products won’t be rejected during a functional test or final inspection.
Low cost – Compared with Automated/Automatic X-ray Inspection (AXI), post-reflow AOI is less expensive when it comes to the solder joint defects inspection including bridges, broken joints, dry joints etc.
Working Principle of AOI Test
AOI test achieves its inspection process by scanning board surface. Depending on one or more high-definition cameras, this equipment can capture images of PCB surface with the help of numerous light sources including fluorescent lighting, LED lighting or infra-red or ultra-violet lighting. Then, a comparison will be made between the captured image and board parameters that have been input into computer in advance so that differences, abnormalities or even errors can be clearly indicated by its built-in processing software. The whole process can be monitored at any second.
The analysis of whether a board is perfect or features issues can be drawn by different algorithms applied by Automated Optical Inspection. When it comes to simple applications inspection, pixel-counting algorithm is used containing the following methods.
Template matching – Template-matching method, also called the area-based method or correlation-like method, has been popular for a couple of decades. Based on the pixel-by-pixel method, a small template is applied to a large inspection image through sliding template window. Then, normalized cross-correlation (NCC) will be calculated between the template and inspection image. The larger the value of NCC is, the higher the matching between them will be.
Object recognition – Object recognition conforms to the same principle as view method in that difference is observed through comparison between an ideal image and the captured image of an object.
Blob analysis – Blob analysis refers to a process during which the object is separated from the background first. Then with a pixel-based image applied, a blob is generated through a grouping of object pixels to inspect issues of objects.
Owing to the progress of technologies and higher demand from market for efficiency and effectiveness, some new methods start to play a major role in PCB or PCBA inspection, among which vectoral imaging technology stands out.
As a pattern location search technology, vector imaging is based on geometric feature extraction instead of complete grey scale pixel values. Under such circumstances, the image analysis is not influenced by color changes or non-linear changes. Furthermore, vectoral imaging performs better in the reduction of false failures due to the attribute of background elimination.
Automated Optical Inspection Test from Stanlee (India) Enterprises Pvt Ltd
As a primary testing technique in PCB assembly, Automated Optical Inspection applies to fast and accurate inspection of errors or defects occurring in PCB assembly process so that high quality of PCB assemblies can be ensured with no defects after their leaving assembly line. AOI can be applied both to bare PCBs and PCB assembly. In Stanlee (India) Enterprises Pvt Ltd, however, it is mainly applied to inspect SMT (Surface Mount Technology) assembly line and for testing of bare circuit boards, a bed of nail and flying probe is used instead.
STANLEE INDIA provides both online and offline AOI test to meet clients’ different demands. Online Automated Optical Inspection test features a higher degree of automation with no need of manual operation whereas offline AOI test features a lower degree of automation with the need for manual operation. Nevertheless, both of them share the same inspection principles, inspection objects and inspection methods. Click below button to get PCB Assembly Quote within AOI option.
Stanlee (India) Enterprises Pvt Ltd has an extensive array of PCBA testing equipment and systems. These include Automatic Optical Inspection (AOI), X-Ray Examination (BGA’s), Functional Testing, In-Circuit Testing (ICT) and Framescan. Each of these test methods serves different functions.
AOI testing provides a scan of components for proper placement. X-Ray Examination insures that BGA’s are installed and soldered correctly and will detect any shorts or poor solder joints. Functional Testing provides a partial or 100% test of the finished product. Typically these functional testers are provided by our Customers or designed and manufactured by us with their cooperation. ICT is an electrical probe test on populated PCB’s, checking for shorts, opens, resistance, capacitance, and other basic parameters to demonstrate correct assembly. Framescan is a vector-less test technique used to detect open pins on component packages and connectors. Text fixtures, if required, for any of the testing systems are typically built on-site.
PCBA Testing System
A flow meter manufacturer needed a small, modular test platform for printed circuit board assembly (PCBA) acceptance test. The success of the project would be measured by the ability to accomplish this task accurately, cost-effectively and with minimal cycle time.
PCB Engineers specified a National Instruments PXI system as the basis for the test system because of the wide availability of modules, flexibility in configuration and small size due to the inclusion of a Windows-based controller. The Test-X MT-100 bed-of-nails fixture was specified due to its small size, modularity and ease customization. A separate fixture was developed for each Printed Circuit Board to be tested and a set of standardized connectors were included to facilitate quick change-over.
Test software was written in Lab View and sequenced using Test Stand, which enabled a host of advanced features, including reliability testing and insertion of test data into a database. Ultimately, eight PCBA Testing were implemented using the methodology above and an additional system test fixture designed for the final product configuration.
The modular approach presented herein allowed our customer to leverage their test equipment budget across multiple test fixtures, while at the same time facilitating future capacity increases through the purchase of additional PXI chassis’. This creativity and flexibility demonstrate TCB Engineers’ unique ability to provide complete solutions to complex problems.