Electronics Manufacturing & Production Handbook 2024 Published by Dataweek
• AOI; X-ray • Component counters • Component storage • Conveyors • Device programming • Dot dispensing and conformal coating • ESD consumables • In-circuit testers • Jet printers • Low pressure injection moulding • PCB washing machines • Pick-and-place machines • Reflow ovens; vapour phase ovens • Rework and soldering stations • Selective wave soldering; wave soldering • Solder wire and solder paste • SPI • Stencil printers +27 11 869 0049 | [email protected] | www.mykaytronics.co.za Bridging the gap in your production MyKay Tronics We efficiently supply and support a total turnkey solution to the South African electronics market Supply Efficiency Support
EMP Handbook 2024 1 www.dataweek.co.za Opinions & insights AI is revolutionising electronics manufacturing ...................................................................................................... 4 Modern vision systems in manufacturing.................................................................................................................. 5 Designing and manufacturing robust enclosures for extreme environments ............................................. 6 Maximising soldering iron tip life.................................................................................................................................. 8 Technical articles White residues on the assembly ..................................................................................................................................11 Reducing solder paste spatter during reflow.......................................................................................................... 12 Issues surrounding foam when cleaning.................................................................................................................. 15 Equipment selection guide .............................................................................................. 17 Consumables, tools & accessories selection guide ............................................ 23 EMP 2024 Handbook Directory ..................................................................................... 27 contents Electronics Manufacturing & Production Handbook 2024
2 EMP Handbook 2024 www.dataweek.co.za From the editor’s desk Disclaimer While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements, inserts and company contact details are printed as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material. Gauteng Tracy Wolter, Tel: +27 11 543 5800, [email protected] KwaZulu-Natal Jane van der Spuy, Tel: +27 83 234 5412, [email protected] Western Cape Contact Durban or Jhb numbers for details Advertising: Print and Online Sales Manager: Malckey Tehini [email protected] Editor: Peter Howells, B.Tech (Electronic Engineering), [email protected] Subscription services For address changes, subscriptions, renewal status or missing issues call +27 11 543 5800 or [email protected] or WRITE TO: Technews Publishing (Pty) Ltd, Box 385, Pinegowrie 2123 Subscribe online: www.technews.co.za All rights reserved. No part of this publication may be reproduced, adapted, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of Technews Publishing (PTY) Ltd. Reg No. 2005/034598/07 ISSN 0256-8934 Published by: Technews Publishing (Pty) Ltd Wild Fig Business Park, Block B, Unit 21, 1494 Cranberry Street, Honeydew Tel: +27 11 543 5800 [email protected] A Dataweek Handbook Electronics Manufacturing & Production Handbook 2024 Exciting time ahead Another year has begun, and what a start it has been for some! As I sit here and jot my thoughts down into my trusty PC, my mind keeps racing back to Saturday night when I was ankle deep in mud and water after a flash flood that wreaked havoc in the northern suburbs of Durban. Within the space of one and a half hours, 103 mm of rain was dumped onto the unsuspecting residents of Durban North, causing widespread damage to property and taking the lives of a few unfortunate souls. Frightening as Saturday night was, the resilience of residents was amazing to behold. People turned up to help neighbours rescue possessions that were being damaged, and to help with the cleanup thereafter. A day later and I was poring through weather apps on my phone to see what was in store for us for the rest of the week. Another storm was to hit on the Wednesday, prompting the Department of Education to close schools early that day, trying to make sure that nobody needed to be out in the inclement weather conditions. It is quite undeniable that the recent weather conditions have worsened over the last few years. The average global temperature has increased year-on-year, and the storms seem to have become worse, dumping more rain in a shorter period, with the associated wind being more fierce. Whether this is solely caused by what is known as global warming is up for debate. I, however, certainly believe that it does have a large influence on the destructive weather patterns we are experiencing. Why am I bringing this up? Mainly because I am quite excited by the ongoing worldwide march towards renewable energy, which will hopefully see us burning fewer fossil fuels to generate the energy we require. South Africa is ideally situated to harness many forms of renewable energy and could become a world leader in the transition away from its reliance on fossil fuels. One such example of a successful renewable energy project is the Kenhardt hybrid solar and battery facility in the Northern Cape, which started feeding electricity to the national grid in midDecember. The facility, one of the world’s first and largest hybrid generation and storage facilities, has a combined installed solar capacity of 540 MW from its three plants, and its attached battery system can output 225 MW of power. With a 1140 MWh capacity, the battery can deliver 150 MW of power consistently between the peak times of 05:00 to 21:30 throughout the year. To put this into perspective, this output is about 30 MW more than the last unit that was producing power at Komati Power Station before it was decommissioned in October 2022. For the first time, we have a large facility that can reliably deliver power in low sunlight conditions. And best of all; the entire plant was constructed in 18 months. Here’s hoping that the government sees the value in this project, and commissions more like it. In closing, I would like to take this opportunity to wish all our readers of both Electronic Manufacturing & Production (EMP) and Dataweek magazines the best for this new year. We all have it within ourselves to make it a great year. Bill Vaughan said it best when he penned, “An optimist stays up until midnight to welcome the new year in. A pessimist stays up to make sure the old year leaves.” This year, let’s be the optimist! P er
4 EMP Handbook 2024 www.dataweek.co.za OPINIONS & INSIGHTS The manufacturing industry has been one of the most receptive sectors to artificial intelligence and machine learning, especially in electronics manufacturing. There is no denying that the electronics sector has a long history of invention. The sector has frequently shown itself to be at the forefront of technology adoption. Electronics industry experts have identified and highlighted a significant change driven by artificial intelligence in the industry which reveals that using AI in electronic manufacturing has many advantages. According to a report, by 2030, AI will have a value of about $22,6 billion, at a CAGR of 48,2% in the manufacturing sector. It indicates that AI is essential to the future of electronics manufacturing, and early adopters will benefit from process optimisation, reduced costs, improved product quality, and the generation of fresh ideas that AI offers. Application of AI to improve the manufacturing process AI in the electronics manufacturing sector can be utilised in almost all processes. For example, AI can help automate the design process by analysing the schematic, and generating a layout that is optimised for performance and manufacturability. AI can also assist in identifying and removing faulty components before they consume further resources. Listed are three ways in which AI can benefit a manufacturing process: 1. Quality control Quality control is a significant use of AI in the manufacturing of electronics. It involves analysing images and other data from production processes to identify defects AI is revolutionising electronics manufacturing By Wellerpcb, www.wellerpcb.com and other issues that can impact product quality. Early detection of problems allows manufacturers to limit the quantity of substandard goods that reach the market. Due to its role in ensuring that goods satisfy the high standards of quality that customers want, quality control is crucial to the electronics manufacturing sector. 2. Predictive maintenance Predictive maintenance is an application of AI that uses data from sensors and other sources to forecast when a machine is likely to break down. Predictive maintenance plans repairs or maintenance before a machine breaks down, thereby minimising downtime and enhancing product quality. This is a crucial component of electronics manufacturing, as it helps avoid costly downtime and repairs that can result from equipment failures. 3. Production process optimisation One of the most significant benefits of AI in electronics manufacturing is the ability to optimise production processes. By analysing data from machines and other sources, AI algorithms can identify areas where production can be improved, such as by modifying machine settings or changing the order of production steps. In the very competitive electronics manufacturing sector, cost reduction and increased productivity can both be achieved with the help of AI for optimisation. Challenges of AI in electronic manufacturing AI is one of the most impressive human achievements that offers endless opportunities in the electronics manufacturing industry. However, certain barriers impeding digital transformation and AI initiatives in this industry need to be overcome. Lack of skilled workers: Developing and implementing AI systems requires specialised skills and knowledge, which may be in short supply in some organisations. Although AI is often associated with the rise of robotic automation systems, machine learning technologies are constantly advancing. If an inhouse team lacks skilled data scientists, it may be beneficial to seek out AI professionals with the relevant experience. Data quality: The quality of data used to train AI models is critical to the model’s success. Electronic manufacturing can generate a large amount of complex data, and ensuring its accuracy and completeness can be challenging. Integration: Integrating AI systems with existing manufacturing processes and systems can be difficult, as it could require significant changes to the organisation’s infrastructure. Cost: Implementing AI systems can be initially expensive, as it requires significant investment in hardware, software, and personnel. Regulatory compliance: Electronic manufacturing is subject to a range of regulations and standards, and ensuring that AI systems comply with these regulations can be challenging. Security: AI systems used in electronic manufacturing may be vulnerable to cyber-attacks, and ensuring their security is critical, to avoid losing critical data or system uptime. Ethical considerations: The use of AI in electronic manufacturing raises ethical considerations, such as privacy and transparency, which must be addressed. Overall, these challenges need to be carefully considered and addressed for the successful implementation. As the industry becomes more competitive, manufacturers need new ways to reduce costs, improve efficiency, and maintain high product quality. AI technologies provide a way to achieve these goals and stay ahead of the competition. Predictive maintenance, quality control, and production optimisation are just a few examples of the applications of AI in electronics manufacturing.
EMP Handbook 2024 5 www.dataweek.co.za OPINIONS & INSIGHTS The development of autonomous cars has caught the headlines, and the use of visual systems will play a key role in their future success. Embedded vision, combined with other sensors, provides guidance for the vehicle. Systems such as lidar (light direction and ranging) measures distance, and the embedded vision systems then provide object recognition. With this technology, the vehicle is able to identify potential obstacles and react accordingly. The automotive industry, with its headline-grabbing developments, represents the most public example of embedded vision systems for collision avoidance. However, the same technology has a range of applications in the industrial world. As operators are employing more autonomous robots in the factory environment, the need for collision avoidance grows. Embedded vision systems Modern vision systems in manufacturing By David Pike, Samtec. allow factory robots to identify potential hazards and act in the most appropriate way. This keeps the factory safe, while maintaining the best possible efficiency. Embedded vision systems also have applications within the area of machine safety. The task of providing safe working areas continues to grow in complexity as manufacturing plants become more flexible. Not only do machines have to detect possible hazards, but it is also vital for them to understand the nature of the hazard in real time, so that the right action can be taken to prevent accidents. It is only with the sophistication of modern embedded vision systems that this has become truly possible. Embedded vision systems also bring benefits to an efficient production line. On any production line, one of the key tasks is quality control. If the only source of quality control is manual inspection, manufacturers are forced to choose between random sampling or 100% inspection. The first method tries to predict the quality of the entire batch based upon a random selection of products. This process introduces fewer delays, but can risk the release of faulty products if the sample is too small. The alternative, 100% inspection, is Figure 1. Modern visual inspection system. Continued on page 6 Embedded vision systems are becoming part of everyday life.
6 EMP Handbook 2024 www.dataweek.co.za OPINIONS & INSIGHTS considerably slower and therefore makes the process more expensive. Integration into the Smart Factory As a solution, the sophistication of modern embedded vision systems allows automated, 100% visual inspection. Each item can be imaged by a dedicated camera and compared to the standard in real time. The result is that faulty products can be identified immediately and discarded (or retained for further analysis). This immediate inspection also provides important data that can be used to understand maintenance needs and even predict future failures. This use of data is at the heart of the smart factory concept. For example, vision systems might identify a rising trend in faults from a moulding machine, which could suggest the need for corrective maintenance. This information can be correlated with other data collected from the same machine, including temperatures and energy consumption. By analysing all the associated data, the maintenance of the machine can be planned before a major failure occurs, which in turn minimises the disruption to production. Embedded vision systems are continually being developed to make them smaller, more cost effective and more capable. Their ease of use makes them an increasingly effective solution for a wide range of applications in the smart factory, from logistics to safety, forming part of the factory network and sharing data to increase the integration of all systems. The scenario A technology company developed an edge device tailored for monitoring various facets of agricultural equipment, from fuel consumption to engine management. They selected a robust off-the-shelf enclosure and subjected the enclosure to rigorous outdoor testing, confident that it was fit-for-purpose after being exposed to harsh weather elements. As the device was deployed in the field, a problem emerged. The supposedly robust enclosures faltered. Initially, the failure was attributed to UV exposure. However, after closer inspection the real problem was revealed – diesel splashes. The device was installed in the proximity of a fuel cap. Despite its high rating and considerable cost, the plastic polymer suffered from exposure to diesel, which resulted in cracks in the enclosure. Design decisions about the robustness of electronic enclosures often focus solely on weather conditions, leading to the perception that off-the-shelf IP-rated enclosures are adequate. The tendency to go for IP67 or IP68 casings further exacerbates the problem. No, or little, consideration is given to dust, vibration, temperature variation, and exposure to UV or chemicals. Designing and manufacturing robust enclosures for extreme environments Combined with artificial intelligence, vision systems have surged forward, reshaping the way manufacturing processes are conducted. These advanced systems combine modern computer vision with machine learning algorithms to analyse and interpret visual data, providing unparalleled efficiency, accuracy, and productivity on factory floors. AI vision systems can be used for quality control and inspection, defect detection and prevention, intelligent robotics and automation, inventory management and supply chain optimisation, and worker safety. They can detect and analyse potential safety hazards, such as equipment malfunctions, improper tool usage, or unsafe working conditions. Using an intelligent vision system provides a proactive approach, which helps prevent faulty products from reaching the market, thereby reducing customer complaints and minimising recall costs. For more information, visit www.samtec.com Figure 2. Samtec vision board utilising AcceleRate interconnects. Continued from page 5 The deployment of IoT devices has grown exponentially and is expected to continue growing. IoT and remote devices are increasingly deployed in challenging environments like mining, transport, marine, and agriculture. It is paramount for these devices to endure harsh conditions to ensure both data continuity and reliable control. IoT edge devices typically include sensing capabilities, a controller (a microcontroller or small compute module), and a communication module. The design of IoT edge devices requires an integrated approach between electronic, mechanical and enclosure design. Robust electronic design is essential to handle physical, EMI, and power challenges, especially for remote or mobile applications. Mechanical design considerations for the PCB and wiring should include heat, vibration, and corrosion. Added to this, the casing or enclosure of the device needs to be robust enough to protect
www.dataweek.co.za OPINIONS & INSIGHTS and prevent the electronics and mechanics from failure in extreme environments. Very often, chemical resistance is the culprit in severely damaging enclosures. In the transport industry, diesel and cleaning agents are known for weakening enclosures. In any environment, petroleum-based fuels, cleaning agents or greases can weaken polymer along stress concentrations. This failure mode is regularly overlooked. With regards to IP ratings, IP67 and IP68 are designed for underwater purposes, which poses challenges. While the benefit is easy testing – just hold it under water to check for leaks – the requirement for complete sealing becomes problematic during temperature fluctuations. This issue intensifies with larger enclosures, leading to water ingress over time, due to condensation. Experience indicates that even custom-designed enclosures with these IP ratings can experience water-related failures in as little as two weeks, making it a major concern for IoT and remote devices. Another significant problem for edge devices is insects. Despite receiving minimal attention, insects can quickly damage or disrupt the functioning of electronic devices. The mitigation of insect-related issues demands specialised design considerations. Solutions for creating rugged enclosures The lifecycle of robust edge devices starts with design. All aspects, including electronic components, packaging, shipping, installation, and servicing needs to be considered at the design stage to ensure that an edge device can operate in the environment it is intended for. Designing for IP67 or IP68 ratings typically increases cost from a sealing and connector aspect, but may also set up the product to fail as explained earlier. Designing only for IP65 or IP66 is mostly not sufficient, as the ingress rating is not high enough. A solution is opting for IP69K. The automotive industry developed IP69K as a non-submersible rating with the intention to withstand washdown from high-pressure washers. If the energy from the water can be effectively managed within a good design, the enclosure, and the peripherals, like connectors, do not need higher IP ratings. Therefore, more affordable component choices can be made. Next, material choice is critical, with the favouring of low-volume or high-volume plastic manufacturing methods over exotic materials or aluminium, which are not feasible. Injection-moulded parts in suitable materials would often be the most cost-effective option. The benefit of IP69K is that it will not be an ordeal to fit injection-moulded parts to its rating, as opposed to IP67 or IP68. Heat management is a special consideration when high processing power is required by edge devices. Examples are the Jetson Nano or Xavier, or similar SoM devices where heat needs to be actively removed from the enclosure. The use of fans is a certain failure point, and forcing air over the electronics is a guarantee that there will be contamination. It is at this point where the enclosure designer and the PCB designer need to work closely together, as the heat management starts at the PCB, but does not end at the heatsink. Here, aluminium enclosures are beneficial if careful design is implemented for the heat path. Potting of electronics is an option with simple PCB designs, but has its own challenges. Proper potting materials should be used. Hard thermoset materials that exhibit high shrinkage, or materials with chemicals which have the potential to damage the PCB, must be avoided. There are still products going to market where silicone is used as either a sealant for the enclosure or worse, as potting material. Silicone sealer uses acetic acid as the curing agent which destroys tracks on PCBs. Conclusion The most expensive component of IoT or remote devices is installation and servicing. The cost of replacement or repair and the loss of data due to field failure far exceeds the win on the BoM choices on the robustness of the product. At SKEG the recommended approach is one that involves the concurrent design of the PCB, internals, and the enclosure, allowing these challenges from the project’s inception to be addressed. Typically, the environment in which enclosures will operate will be reviewed, but the solutions toolbox has matured to a point where we can design for the IP specification, address heat management, and select materials that will work in almost any extreme environment. These solutions can be manufactured in low volume, and when quantities justify it, scale to higher volume processes, retaining all design attributes. To ensure compliance and a robust product extensive testing is performed inhouse. For more information contact SKEG, +27 21 551 1441, [email protected], www.skeg.com
8 EMP Handbook 2024 www.dataweek.co.za Figure 1 – Soldering iron tip construction. OPINIONS & INSIGHTS During the soldering process, the soldering iron tip undergoes physical changes which are a normal part of the process. These changes, over time, affect the ability of the soldering iron tip to make quality solder connections, and can decrease an operator’s performance. The key to maximising soldering iron tip life is understanding these changes and how to minimise them. To understand the changes a soldering iron tip goes through during the soldering process, it is important to have a basic understanding of the construction of a soldering iron tip. Maximising soldering iron tip life As shown in figure 1, most soldering iron tips have a copper (Cu) core that conducts heat energy from the heating element to the application being soldered. This core is protected with iron (Fe) plating that prevents corrosion of the core from the various components of the solder and flux being used in the soldering process. Iron is used due to its ability to conduct heat, and its chemical compatibility with the components of solder which allows the solder to flow from the tip to the soldering joint. An additional plating of chromium (Cr) is added to the tip, excluding its working surface, which protects the iron plating from corrosion. There are two parts of this tip construction that are critical to the soldering iron tips life: • Copper core. • Iron plating. These two parts of a soldering iron tip are directly affected by the following variables of the soldering process: • Tip maintenance. • Tip temperature. • Solder. • Flux. The life of a soldering iron tip is a measure of how long the tip will continue to make quality solder connections without reducing the operator’s performance.
EMP Handbook 2024 9 www.dataweek.co.za OPINIONS & INSIGHTS Tel: +27 11 704 3020 | [email protected] | www.testerion.co.za WE NEVER STOP ACHIEVING We stock and supply: • Alpha solder pastes (leaded and lead-free) • Alpha solder wires (leaded, SAC305 and lead-free replacement SnCX Plus07) • Alpha and Kester fluxes (solar panel manufacturing, wave solder application, dipping) • Operator technique. • Soldering/rework application. Tip maintenance Maintenance of a soldering iron tip consists of regular cleaning, inspection, and the re-tinning of the tip’s working surface for protection. Proper tip maintenance is possibly the single largest contributor to extending tip life. A soldering iron tip should be cleaned regularly by removing any oxidised solder, flux residue and debris from the tip. This can be done with a damp sponge or non-abrasive tip cleaner. If a sponge is used, be sure to use only distilled water on the sponge. If distilled water is not available or is too costly, de-ionised water may be used. The use of distilled or de-ionised water minimises any mineral contamination on the surface of the tip. It is also important to be sure to regularly replace the sponge since it will collect debris and other contaminants over time, and doing so will reduce the likelihood of reintroducing contaminants or debris to the tip. A non-abrasive tip cleaner is an excellent alternative to using a damp sponge, since it minimises the thermal shock to the tip and does not remove all the solder from the end of the tip. This helps protect the plating of the tip from reacting with the surrounding air, which leads to oxidation of the working surface and corrosion. Most chemical tip cleaners, or ‘tip tinners’ should be avoided due to their aggressive cleaning properties, which is similar to highly active fluxes. These chemical tip cleaners may also leave residue that can build up, causing a blackening of tips and the oxidation of the plating. Gentle chemical tip cleaners, such as the Hakko FS-100 Tip Polish, may be used but only as supplemental cleaning aids. During the cleaning of the tip, the condition of the working surface of the tip should be visually inspected for any signs of shape change, pin hole, or other physical defect. These are indications that the tip life has been consumed, and the tip should be replaced. The final and most important part of tip maintenance is the application of solder to the tip’s working surface for protection, also known as ‘tinning the tip’. It is best to flood the entire working surface of the tip with solder immediately after cleaning. This process covers the working surface and protects it from reacting with the surrounding air which can lead to oxidation and corrosion. Tip temperature The selected temperature for a soldering iron tip affects tip life by accelerating the oxidation of the tip and the reaction of the solder and flux with the iron plating of the tip. Tip temperature also causes physical changes to the tip through the natural thermal expansion and contraction the metal undergoes during normal use. In many cases, a common reaction to difficulties encountered in the soldering process, such as switching from tin-lead solder to lead-free solder, is to raise the tip temperature. This increases the rate of oxidation buildup on the tip and accelerates the reaction between the tin in the solder and the iron plating, corroding the tip faster. The added heat also increases the amount of thermal stress the metal undergoes. Using a lower tip Continued on page 10
10 EMP Handbook 2024 www.dataweek.co.za OPINIONS & INSIGHTS temperature decreases the rate of oxidation, decreases the reaction between the tin in the solder and the iron plating, and lowers the thermal stress on the tip. The most common affect tip temperature has on tip life is the acceleration of the reactions of the plating on the working surface of the tip, with not only the solder and flux that come in contact with the tip, but also with the surrounding air. At higher tip temperatures, these chemical reactions happen faster than at lower tip temperatures. The plating undergoes a chemical reaction with the components of the solder, namely tin (Sn), which over time will cause plating to wear away. This can be seen on some tips as minor shape changes such as concave surfaces or smaller diameters when compared to new tips. The thickness, quality, and uniformity of this plating varies not only between tip manufacturers but in some cases, between tip shapes. Once the plating is worn thin enough, exposing the core of the tip directly to the solder, tip failure has occurred, and corrosion of the copper core happens rapidly. Using lower tip temperatures decreases the rate of this chemical reaction between the plating and the components of the solder. Most high-end soldering stations in the industry today recognise this, and as a result, have built into their soldering station design the ability for the soldering station to reduce the soldering iron temperature when it is not being used by the operator. This‘sleep’mode slows the reaction between the plating and the components of the solder that is on the tip, and slows the rate of oxidation buildup. These high-end soldering stations sometimes include a feature that will automatically turn off the soldering station if it has not been used over a period of time. Whether or not you have a high-end soldering station, you should always reduce tip temperature when the soldering station is idle, and turn it off if it is not going to be used for some time. Doing so will decrease the rate of the chemical reaction between the plating and the components of the solder, and reduce the buildup of oxidation on the working surface of the tip. The plating also undergoes a chemical reaction with the flux being used. This reaction is what you would expect from flux, but instead of cleaning the surfaces of the connection to be soldered, the flux is cleaning the working surface of the tip. This ‘cleaning’ also wears away the plating of the tip to a small degree. However, in this case, higher tip temperatures result in a faster burning of the flux, which results in deposits that are left on the surface of the tip. These deposits, if not cleaned off the surface of the tip, can build up over time, causing blackened tips and the exposure of the plating of the tip to the surrounding air, which leads to oxidation of the working surface and corrosion. This oxidation and corrosion is also accelerated by higher tip temperatures. Using a lower tip temperature reduces the buildup of deposits, the blackening of tips, and slows the reaction of any exposed iron plating with the surrounding air. In older-technology soldering stations, the tip is inserted over a heating element. Over time, the thermal expansion and contraction of the metal in the tip core can cause air gaps between the core of the tip and the heating element when the tip is installed. These air gaps decrease the tip’s ability to conduct heat energy away from the heating element, causing lower tip temperatures. The higher the selected tip temperature, the more thermal stress the metal undergoes, which can lead to the faster formation of air gaps between the tip core and heating element. Solder The composition of the solder being used affects tip life through the reactions between the plating of the tip and the components of the solder. Solders that have high levels of tin (Sn), and other components that react with the plating, will shorten tip life. A clear example of this can be found in the industry switch from tin-lead solder to lead-free solder. While the selection of solder being used likely cannot be changed as easily as selected temperature, it is important to understand that any change in solder composition can affect tip life. Flux The flux being used in the soldering process, either in the wire core, or applied separately, affects soldering iron tip life to a small degree through the reaction between the plating of the tip and the activators in the flux. Fluxes that are highly active have a more aggressive cleaning action and are more aggressive in wearing away the plating from the tip. Using mildly active fluxes and/or less flux in the soldering process will reduce the wear on the plating of the tip. Operator technique Soldering iron tip life is affected by the techniques an operator uses when making solder connections. Some of these techniques can increase the physical abrasion of, or otherwise damage, the plating of the tip. Included as part of the operator’s technique are the selection of the proper tip shape or size, and the application of the flux and/or solder. Selecting a proper tip shape or size provides for ample heat transfer to make a quality solder connection, without damaging components or boards. This also reduces the likelihood that an operator will be tempted to raise the tip temperature because they are having trouble making the connection at the present setting, or want to go faster. The application of flux and/or solder can also affect tip life if they are applied directly to the tip, and primarily to the same location on the tip. Never apply flux directly to a soldering iron tip. Only apply flux to the surfaces of the connection to be soldered. Also, you should try to avoid applying solder to the soldering iron tip and letting the solder flow onto the connection. If you must apply solder to the tip when making the connection, vary the surfaces that the solder is applied to. For example, if you are using a chisel-shaped tip, which looks like the end of a standard screwdriver, alternate between the two flat sides of the tip. Or, if you are using a conical shape tip, rotate the tip every few connections. This will spread the wear of the plating over a larger area, increasing tip life. Soldering/rework application The last variable of the soldering process is the soldering/rework application itself. Besides the obvious difference in the number of solder connections made, some applications may increase the amount of thermal cycling a tip experiences due to heavy ground planes. While you can’t necessarily pick and choose the applications you work with, it is important to consider the application when evaluating tip life, when making comparisons. Summary There are two main parts of the construction of soldering iron tips that are affected by six different variables in the soldering process. The ability to adjust any one, or a combination, of these six variables can increase soldering iron tip life. The most important variable in the soldering process affecting tip life is tip maintenance. The amount of tip life one can gain depends on the fundamental understanding of the tip’s construction and the affect the six variables have on tip life. Applying this understanding to a soldering process and implementing the adjustments appropriate to the situation will maximise the life of the soldering iron tips. For more information contact Vepac Electronics, +27 11 454 8053, [email protected], www.vepac.co.za Continued from page 9
EMP Handbook 2024 11 www.dataweek.co.za TECHNICAL ARTICLES 012 327 1729 [email protected] www.newelec.co.za Communication Protocols for the NewFeed Relay: PROFINET Modbus/TCP Soon to Release: IEC 61850 with Goose ANSI 50P / 51P Curves for Feeder Protection (ANSI 67 Directional) Curve Selection: IEC (NINV), (VINV), (LINV), (EINV), (MINV), (DT), (IT), (I2T), (I4T) THD Protection and Monitoring ANSI 46 (I2) Negative Sequence Bridge the gap between wind turbines, solar farms and the real grid with NewFeed Relay: ANSI 24 Volts / Hertz Overfluxing ANSI 81R Rate of freq change ANSI LOP Loss of Power Configurable Switch Gear Logic Free Configuration Software Simulator, 3 Phase Recorder ANSI 50G /51G (I0) Zero Sequence Locally Designed and Manufactured Motor and Feeder Protection Solutions Full Backup Memory Module Option Pluggable onto the T-Bus Facilitating easy NewCode or NewFeed Replacement by Maintenance Staff or Settings Editing by Off-Site Engineers newelecpretoriaptyltd When white residues suddenly appear on assemblies for unknown reasons, the customer is often confused – and the first idea is often the same: something must be wrong with the cleaner. However, this is only the cause in extremely rare cases. In the majority of cases, there are other causes – but these can be manifold. In many cases, changes in the assemblies are responsible. Cheaper materials, less development time, or simply a change of supplier can be the cause. A supposedly more favourable offer can also have disadvantages. If the new parts are not compatible with the previous cleaning process, problems arise – not infrequently in the form of white residues. If it is not possible to switch back to the old components, the only option is often process optimisation. Reasons for white residues Solder resist mask not completely cured: One reason that often causes white residues is that the solder mask is not completely cured. In this case, water from the cleaning process can accumulate in the material of the solder mask and condense there at room temperature. This can also lead to staining. A solution that is as practical as it is pragmatic: a hot hair dryer, held over the assembly for some time, quickly makes the milky, white residues disappear. Solder paste change: A change of solder paste is also often responsible for white residues. If the change is made without first consulting the manufacturer of the cleaning media, the cleaner may not be able to optimally remove the new solder paste with the same system settings. Again, if the cleaner is not to be changed, in most cases other parameters will have to be changed. White residues on the assembly In principle, however, there are a whole host of reasons why white residues can occur. Other causes include the quality or temperature of the rinse water. However, these problems can also be eliminated by adjusting the parameters or preparing the rinsing medium. If a cleaner has already been used too often, it is sometimes possible to achieve the desired result again by increasing the concentration. In general, it can be stated that in most cases where complications with white residues occur, good results can be achieved by optimising the process. If a solution to the problem cannot be found in this way, consultation with an experienced solution provider who can analyse each case individually should be the next port of call. A change of cleaner is usually only necessary in the rarest of cases. For more information contact Electronic Industry Supplies, +27 11 726 6758, [email protected], www.eispty.co.za
TECHNICAL ARTICLES Dedicated professional customer service Quick turnaround • Country-wide delivery • Solder paste stencils • Laser cutting services • Pneumatic stencil frames • Prototype stencil printer • Stepped stencils • SAWA ultrasonic stencil cleaners • Precision metal parts • Stencil storage systems • Polyimide high temperature labels • Personal protective equipment (PPE) +27 11 793 1318 • [email protected] • www.lstec.co.za There is a certain similarity between solder balls and spatters. However, the industry defining two kinds of defects is mainly due to the generation of solder balls and the solderability of tin powder. There is a great correlation with cleanliness of printing wipes. When the bottom of the stencil is not completely wiped, a single or a few tin powder particles adhere to the bottom of the stencil and are transferred to the PCB to form a solder ball during PCB printing. If to simply distinguish the solder ball and spatter, the cleanliness of the surface under the magnifying glass can be checked after printing on the PCB. If the surface of the PCB is very clean before going through the oven, then the solder ball can be defined as the spatter produced during reflow. Splash is mainly caused by the influence of moisture in the environment leading to water molecules entering the solder paste. During reflow, the solvent and water molecules in the solder paste volatilise too quickly to form an explosive vapourisation phenomenon due to rapid temperature rise. Therefore, when the solder paste is placed in a humid environment, or a more hygroscopic solder paste is used, splashing is more likely to occur. A typical example is that the solder ball is more likely to be produced with water-soluble solder paste than no-clean solder paste. The generation of spatter may also be caused by the coagulation of solder paste. During the preheating process, the flux removes the oxide on the surface of the solder powder, and numerous tin powder particles melt and fuse together as a whole, while the flux adhering to the surface of the solder powder is squeezed out. The faster the wetting rate, the stronger the cohesion of the solder powder is, resulting in the easier production of spatter. Figure 1 shows an example of solder spatter. Based on these principles, two sets of experiments were designed to study the effect of optimising the reflow profile on spatter. Reducing solder paste spatter during reflow By Leon Rao, Wisdom Qu, Jonas Sigfrid Sjoberg, Indium Corporation. We usually think of solder balls when talking about spatter. Experiment 1 Four mainstream lead-free, halogen-free solder pastes were selected to compare the effects of different types of solder paste, flux ratio, and temperature ramp on spatter. These solder pastes were identified using generic names of paste A, B, C and D respectively. Solder paste B was matched with two different metal loads, 88,25% and 88,75%, respectively, to observe the effect of different flux content on the splash. For the reflow profile, two linear temperature profiles Figure 1. Example of solder spatter. Figure 2. Wetting test set-up.
TECHNICAL ARTICLES with temperature ramps of 1,9°C/s and 1,2°C/s, respectively, were selected, as shown in Table 1. Experimental steps: 1. According to the IPC-TM-650 2.4.45 wetting test, a round copper sheet, a three-hole stencil with a thickness of 0,254 mm, and a circular opening of 6,35 mm was used to print the solder paste, as shown in Figure 2. 2. The copper sheet was placed on a 4 x 4-inch ceramic square. 3. This was placed in an oven for reflow, and spatter from the solder paste on the copper sheet onto the ceramic sheet was observed with a microscope and marked with a red marker. Experiment results Figure 3 shows the results of this experiment. Solder Paste A showed the least amount of splash; Solder Paste C had the most spatter with about 200 splash points appearing on the ceramic wafer; and the performance of Solder Pastes B and D were found to be relatively close. Therefore, different types of flux will bring about a significant difference in solder paste splash. It was observed in the Solder Paste B experiment that adjusting the metal load, 11,75% and 11,25% of flux content, did not significantly improve the reduction of splash. Under different reflow profile, with the slow temperature ramp and 50 s extension of the soak temperature of 25 to 217°C, the amount of spatter was relatively reduced by about 30%. Experiment 2 This experiment took place on a production line of a car electronics customer. The PCB was the actual product of the customer, and Solder Paste B (metal load 88,25%, SAC305) was used. The reflow profile was adjusted to observe the amount of spatter. Project Profile P5 Profile P6 Temperature ramp 1,15°C/s 1,3°C/s Soak temperature time 200 to 210°C 25 s 40 s Reflow time >217°C 70 s 65 s Peak temperature 247°C 240°C Cooling slope -3°C/s -3°C/s Project Profile P1 Profile P2 Temperature ramp 25 to 217°C 1,9°C/s 1,2°C/s Soak temperature time 25 to 217°C 175 s 225 s Reflow time >217°C 75 s 57 s Peak temperature 241°C 234°C Cooling slope -5°C/s -4°C/s Project Profile P3 Profile P4 (SAC305 profile) Temperature ramp 1,25°C/s 1,25°C/s Soak temperature time 200 to 210°C 35 s 9 s Reflow time >217°C 0 s 50 s Peak temperature 205°C 245°C Cooling slope -3°C/s -3,5°C/s Table 1. Linear temperature profiles used in the experiment. Table 2. Reflow profiles. Table 3. Reflow profiles. Step 1: The solder paste was printed on the PCB using reflow profile P3, as shown in Table 2. The maximum temperature was 205°C, lower than the melting point of the SAC305 alloy, to determine whether the spatter is generated by the moisture absorbed by the solder paste in the air. Through experiments, no spatter on the PCB surface was found. This indicated that the spatter was not caused by the moisture absorbed by the solder paste, or that the surface tension of the solder paste is very low before the solder paste reaches a liquid state. The flux was easily volatilised from the solder powder, and did not form a sharp vapourisation explosion. Step 2: The peak temperature was increased to 245°C, with a reflow time of 50 seconds, as shown in profile P4 in Table 2. The printing paste passed through the oven, and a large amount of spatter was generated on the surface of the PCB after going through the oven, as shown in Figure 4. It was determined that the spatter was generated after the liquefaction of the solder paste. This is due to the vapourisation explosion caused by the rapid extrusion of the flux, which had not been volatilised under the coagulation of solder powder. Therefore, a large amount of splash was generated. Continued on page 14
14 EMP Handbook 2024 www.dataweek.co.za TECHNICAL ARTICLES It is well known that on the line, the rate of coalescence of solder powder is very fast, and the entire agglomeration reaction is completed in two to three seconds. That is to say, the vapourisation explosion of the flux occurs immediately after reaching the 220°C alloy solidus line. It is then almost impossible to reduce spatter by adjusting the liquidus area. The board that was blasted in Step 1 (that is, the solder paste that had not reached the melting point of the solder paste, equivalent to pre-baked board) was again blasted with profile P4. The surface of the PCB was observed to have no spatter. This indicated that a large amount of consumable flux of pre-bake helped reduce spatter. This was consistent with the results of the effect of the heating rate and the constant temperature on the spatter of Experiment 1. Since most of the fluxes are around 200°C, is it effective for the spatter to stretch the baking time near the liquidus area and try to let more flux volatilise. Based on this, step 3 of the experiment was carried out. Step 3: Two different soak temperature profiles were used, shown in Table 3, to print the solder paste and pass it through the oven. Baking time of profile P5 was changed to 25 seconds, and that of profile P6 to 40 seconds. Experiments showed a small amount of spatter on the PCB board using the P5 profile, and the spatter ratio was reduced by about 80% compared to the conventional SAC305 curve P4. The PCB spatter using the P6 profile was further reduced, and almost no splash was observed. Summary Splash is a problem that solder paste will inevitably encounter during the welding process. Distinguishing between spatter and solder ball is the first step to solve the problem. Different types of solder pastes have different effects on splashing, which may be related to the amount of hydrophilic molecules in the flux formulation or material. Water-soluble solder paste is more prone to splashing than the no-clean solder paste. Reducing the flux content of the solder paste does not significantly contribute to the generation of spatter. In this experiment, it was found that the spatter was produced after the liquefaction of the solder paste. Splashes were rapidly reduced as the baking temperature was increased and the baking time extended. Because the surface tension of the solder paste was very low before the liquidus, the flux was easily separated and evaporated from the solder powder particles, and more oxide was generated. This reduced the propelling force of the solder powder, making it harder for the flux to be squeezed out by coagulation. Taking into account the boiling point of the flux, increasing the baking time between 200 and 210°C quickly helped to fully consume the volatiles in the flux. Due to the thermal deformation of the component or PCB and the oxidation of the metal, the baking time of 200 to 210°C cannot be extended indefinitely, and the specific limit must be confirmed with the solder paste manufacturer. For more information contact Techmet, +27 11 824 1427, [email protected], www.techmet.co.za Figure 3. Results of the wetting test. Figure 4 . Large amounts of spatter observed. Continued from page 13
TECHNICAL ARTICLES Foam is a common issue in the cleaning world. If left unchecked, foam can cause the following symptoms: • Leaks. • Excessive rinsing. • Pump cavitation. • Pump seal failure. Fortunately, it is among the easiest problems to correct. There are several causes for foam. They include equipment parameters, flux selection, chemical selection, and process control. Each has its own unique solution. Cause A: • Liquid flux out of specification (solids content). • Inadequate preheat. Solution A: Most wave soldering machines are equipped with a foam or spray fluxer. A foam fluxer utilises an air-stone placed at the bottom of a liquid flux reservoir. A small volume of air is injected into the air-stone, causing the flux to develop a foam ‘head’. The flux develops the head of foam due to a foaming agent that is added to the flux during manufacturing. Issues surrounding foam when cleaning This foaming agent is designed to be burned off the board during the preheat and soldering process. If the foaming agents are not completely burned off, they will be carried into the cleaning system on the board’s surface. Foaming agents will foam when presented with high-pressure water sprays like those in a spray-in-air cleaning system. It needs to be ensured that the boards are preheated properly, and that the dwell time with the solder is sufficient. The specific gravity of the fluxes may also be checked. All fluxes have a solids content. The only way to maintain that solids content is to monitor and adjust the flux’s specific gravity at least twice per day. If the flux’s specific gravity is not maintained, the solids content will rise, increasing the likelihood of foam. If foam occurs in a water-soluble flux removal application using water only as a cleaning agent, the assemblies should be cleaned with a defluxing chemical additive. Most defluxing chemicals contain defoaming agents which will reduce or eliminate foam. Cause B: • Liquid flux added to the top side of an assembly (on wave solder applications). Continued on page 16 Contact us at [email protected] +27 11 473 2149 Priben – a full turnkey solution provider to the electronics manufacturing industry Some of the brands & services we provide are: ASMPT MacDermid Alpha products AOI (Automated Optical Inspection) equipment API (Advanced Paste Inspection) equipment PCBA handling equipment Full range of ESD consumables and equipment ESD ooring JBC soldering equipment PCB cleaning chemicals and equipment Microscopes IPC training & certi cation IPC manufacturing auditing Re ow ovens Drying cabinets Component baking ovens X-ray equipment Component counting equipment
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