No-Clean Solder Paste: What Does “No-Clean” Actually Mean?

You are likely to come across no-clean solder paste when choosing materials for your soldering and PCB assembly needs. Its purpose is to eliminate the need to clean the printed circuit boards after the soldering process, but with some products still requiring you to clean the board, you might be wondering what ‘no-clean’ actually means. In some cases, the no-clean variant will still require you to do some cleaning. A manufacturer may have adjusted their assembly lines to use this type of solder paste, then clean only the boards that require cleaning. So what does ‘no-clean’ mean then?

In a no-clean solder paste, ‘no-clean’ actually means solder paste with minimal residue. After reflow, flux will still leave a small amount of resinous but non-corrosive residue around or on the solder joints. The residue may vary in color, usually appearing amber or transparent, depending on the flux resin used and the reflow temperature. The amount of residue will depend on the amount of the activators, gelling agents, and the solid resins in the flux. So, the less solids content it has, the less flux residue on the board. Contemporary no-clean solder pastes contain around 50 to 70 percent of solids.

‘No-clean’ may also pertain to the solder paste leaving a clean look, making it as good as a water-soluble paste. But why remove residue from a no-clean solder paste from a PCB? One reason is to minimize problems during in-circuit testing, as the test pins are unable to go through the flux and establish and electrical connection with test pads. Moreover, residue could build up gradually on the pins and cause issues with test accuracy and maintenance. However, you do not have to worry about those problems when you use high-quality no-clean solder paste with recent formulations.

In-Depth Knowledge about PV Ribbon Wire

“PV” is an acronym for Photo Voltaic, meaning something that produces current when struck by a molecule of natural light. Solar photovoltaics is a booming technology these days, with so many environmental concerns being raised be conventional sources of energy. The genius combination of solar photovoltaic materials and harnessing energy has made it possible to convert sunlight into electricity on a large scale. The PV ribbon wire is a very important component of photovoltaics. This blog will give you in-depth knowledge about PV ribbon wire.

What is PV ribbon?

Typically, a photovoltaic ribbon is a thin strip of copper which is heat coated with tin. This is the wire which is used to connect solar cells together in a solar module. The photovoltaic ribbon is attached directly to the silicon substrate on a solar cell, which enables it to collect the electricity produced in the cell. These PV ribbons then connect to the PV bus bar. In this manner, the current generated in the solar cells connected with one PV ribbon is sent to the PV bus bar. PV bus bar is also a PV ribbon which is slightly bigger than the interconnect ribbon used with solar cells.

Technical details of PV ribbon

The PV ribbon used as bus bars are about 3 to 6mm wide and 0.2 to 0.5mm thick, while those used for interconnection of solar cells are 1 to 3mm wide and 0.08 to 0.2mm thick. If you went out to buy one, you would typically find spools weighing anywhere between 50kg to 600kg. They contain tin (100%) as the lead free solder option, and SnPb 60/40 as the leaded option. You can find these ribbons in low temperature versions as well with Bismuth in the alloy.

Above are the major points you need to know about PV ribbon.

The Benefits of Using Low Melting Point Solders

Soldering two surfaces or components together involves fusing the two surfaces together using a soldering alloy, by melting it and forming a connection between them. Since this activity consists in melting the solder, there is a very high temperature at the surfaces. Now if the components or the surfaces to be connected are not prepared to resist this heat of the molten alloy, there could be considerable damage to the elements. It is for this reason that low-temperature solder alloys are used for sensitive applications.  This blogpost will explore the benefits of using low melting point solders.

First, low-temperature solder alloys prevent any damage that could happen to the components and the printed circuit board. Since these alloys are never heated up to very high temperatures for melting, there is no burning of the circuit board or the components.

Secondly, using low temperature solder alloys directly translates into energy savings. The soldering iron does not need to be heated up to very high temperatures to melt the solder alloy. It thus consumes lesser electricity. In case of industrial manufacturing, these little savings convert into a massive amount of money saved in electricity bills.

Thirdly, low temperature alloys are known to perform better in thermal cycling tests, impact resistance and durability. These alloys also help in reducing the number of steps required to complete the surface mount technology process.

Low temperature alloys are more versatile for use over different materials of printed circuit boards since they have the lesser potential to damage the surfaces they touch. Some special plastics that are used to make printed circuit boards usually don’t work well with high temperature solders, which is why low temperature solders are employed.

The Secret to Perfect Solder Lines

Soldering is a valuable and critical skill to learn in many electronics and assembly applications. Achieving professional quality soldering requires clean, smooth, and uniform solder lines. Perfect solder lines are not only a sign of quality and craftsmanship, but also of durability and value, which is why perfecting soldering techniques is a must, especially for professionals who want to improve the quality of their work. While there are no hard and fast rules for perfecting solder lines, these guidelines will help you enhance your skills, build your confidence, and increase your precision in soldering:

• The perfect soldering lines start with the right tools. Choose high quality soldering equipment and supplies to help you avoid common mistakes and difficulties in soldering perfect and precise lines. Soldering irons with ceramic heating element and temperature controller (built in or separate) are ideal along with solder with a 60-40 mixture of alloys. Non-smoking, odorless liquid flux is also preferred.

• To perfect your lines and increase your precision takes a lot of practice and requires an understanding of how your own equipment works. Spend time practicing your lines and discovering the perfect temperatures or temperature ranges that create more refined lines as you work. It helps using a wet sponge or an abrasive pad to wipe off your iron’s tip periodically to keep gunk and residue from building up. Slow, constant strokes are ideal for creating perfect soldering lines. It is also better to keep your solder at a manageable length to help you keep your strokes consistent.

• Avoiding common problems will also help with perfecting your technique. Pits or bubbles, for instance, are typically caused by too much flux, while too little flux results in uneven and uncovered portions. Lumpy lines could mean that your iron isn’t hot enough, while spits and sputters may likewise be caused by excessive flux. Flat lines mean that your iron is moving too quickly or that you are using insufficient amounts of solder. Bulges on the other hand, mean slow movements and excessive use of solder.

Features and Applications of Lead-Free Solder Bar

Going lead-free may be the best in certain applications where safety and reliability are prioritized, and when the assembly process can be compatible with it. The lead-free solder bar is one of the most flexible products, particularly if it is developed and formulated by an established and reputable company that provides soldering solutions. This way, you can be confident in using technologically advanced solder products that offer high throughput applications and high reliability. Here are some of the important things to learn about lead-free solder bars:

• The composition – Leading lead-free solder bar can be made of Sn95.5Ag4Cu0.5 or Sn96.5Ag3Cu0.5, with replenishment alloys being Sn96.5Ag3.5Cu0, Sn96Ag4Cu, and Sn97Ag3Cu0, all of which are lead-free alloys that are safe replacements for the Sn63 alloy. Replenishment alloys stabilize on the reduction of copper content during wave soldering, depending on the conditions of the process.
  
  
• It removes impurities – The alloying process in high-quality lead-free solder bars eliminate oxides and other impurities that can affect the quality of the joints. Alloy conditioning helps reduce dross generation, too.
  
  
• Increase yield – A good lead-free solder bar ensures the best in class yield that may surpass the quality of performance of Sn/Cu-based materials. Faster wetting helps speed up the manufacturing process and solderability for higher throughput and increased productivity. Excellent drainage minimizes the chances of bridging, unlike when you use certain types of Sn/Cu alloys. This way, it delivers dependable performance across various flux technologies.
  
  
• Helpful to electronic assemblers going lead-free – Lead-free solder bar works with lead-free surface mount and wave soldering applications.
  
  
• Recommended temperatures – You need to make sure that the solder pot temperature is within the range of 491 to 509° Fahrenheit (255° to 265° Celsius). The manufacturer should be able to provide a guide to help you select the right solder bar for your application.

Tips for Selecting Suitable Stencil Cleaner For Your Operations

Stencils have proven to be an advantage for the electronics industry as they have made accuracy and material savings possible when working with solder and fluxes. That being said, when solder pastes and fluxes are applied to stencils, some of the stuff sticks to the stencil and stays there. This leads to the requirement of cleaning the stencil because solder and flux cannot be removed that easily. Stencil cleaners are now available in the market which achieves perfect and spotless cleaning of stencils like it was never used before. Here are some tips for selecting suitable stencil cleaner for your operations.

Tip #1: How are you cleaning?

The method you are going to adopt for cleaning your stencils is going to have an impact on your choice of cleaner – for example, if you are going to use an automated cleaner, or if you are going to do it manually, or how often or seldom you are going to clean, etc. The chemical composition of your cleaner will vary according to these practices.

Tip #2: What are you cleaning?

It is not just the stencil you will be cleaning – the chemical composition of the flux sticking to it will also determine what chemicals are needed in the cleaner to remove it. Also, if you are going to be using different kinds of fluxes, then choosing a cleaner compatible with most will be a good idea.

Tip #3: How finely are you cleaning?

If your stencil has fine apertures for precision application, you may want to narrow your search down to cleaners that are thin enough to flow through them for effective cleaning.

Keep the above tips in mind to get cleaners that get the job done right.

Common Questions about Low Melting Point Solder

Almost all electronics used these days employ printed circuit boards (PCBs) in some way. Most of printed circuit boards require working at high temperatures because of the higher temperature needs of underlying soldering application. However, not all applications require or can work efficiently at such high temperatures – which is why low temperature solders were developed. These solders are alloys that melt at comparatively lower temperatures so that the components housed on the board do not suffer from heat damage. Here are answers to some of the common questions about the low melting point solder.

The most common question that comes up often is about the type of alloys used for low temperature soldering. Technically, these alloys have a comparatively lower melting point than other kinds of solder alloys. Therefore, they are employed extensively in step soldering processes. This is a process where different assemblies and sub-assemblies have to be soldered sequentially, without melting the previously soldered joint. This can be done by successively using solders of decreasing melting points for each subassembly.

The second most commonly asked question is about the conductivity of low melting point solders.  It has been observed that low melting point solders have a very good thermal and electrical conductivity. They are sometimes even used for heat exchange processes because of this very property.

The fact that these alloys are mostly liquid makes them highly desirable to work with because of their wetting properties. Low-temperature solder alloys are beginning to make their mark in the soldering industry.

What Makes Liquid Solder A Perfect Choice For Electrical Assemblies?

Assembling a printed circuit board is a complicated process, and it requires a lot of precision and patience. How good a solder joint turns out to be depends significantly on how well the preceding methods have been tackled, for example, fluxing. Fluxing is done to remove impurities from the surface of the printed circuit board, making it possible to achieve a homogeneous bond. The most important property of flux, thus, would be the wetting it achieves on the board. Here is what makes liquid solder a perfect choice for electrical assemblies.

Liquid solder is nothing but solder with liquid flux. The reason why liquid solder flux is so significant in electronics applications is that it can reach every space and corner on a circuit board and wet it. This ensures efficient cleaning before actual soldering can begin. Liquid solder fluxes are less active than most pasty fluxes, which assures that the components on your printed circuit board do not experience corrosion.

Liquid fluxes are usually water-based, but there are some alcohol-based liquid fluxes available in the market too that work on the principle of no-cleaning. These fluxes do not need to be cleaned after application because they leave very little or no residue.

Liquid soldering fluxes have enabled high heat processes to touch new heights in soldering. Many other fluxes burn in high temperatures, ultimately leading to failures in soldering – this issue can be tackled by using liquid soldering fluxes. Liquid soldering fluxes also enable high precision jobs where small components are to be wetted perfectly and evenly.

Top Three Benefits of Selective Soldering

Technology has been continuously evolving, and the same is true for soldering as well. The most popular type of soldering process these days is surface mount technology, wherein all the components are simultaneously soldered onto a printed circuit board. However, it may not allow for highly precise soldering applications. It is for this reason that many manufacturers have gone back to adopting selective, through-hole soldering. Here are top three benefits of selective soldering.

Benefit #1: Precision

Selective soldering allows forming a conductive bond on a printed circuit board at specific locations. It essentially means that while all other components can be wave soldered, some through-hole components at particular places can be selectively soldered, achieving high efficiency of joint and precision.

Benefit #2: Workability

Selective soldering is preferred by many manufacturers, even though it has to be done manually because this technology is not very costly. The through-hole pins and paraphernalia are also not as sensitive as its more famous counterpart – the surface mount technology.

Benefit #3: Process optimization

Because selective soldering allows the technicians to target specific regions or areas on a printed circuit board, it induces repeatability into the process and leads to higher throughput and fewer defects. The best thing is that it can be automated, allowing for the elimination of human errors.

The reasons listed above demonstrate that selective soldering is ideal for through-hole applications.

Three Reasons Why SMT Is the Preferred PCB Assembly Technique

PCB or Printed Circuit Board, on which the electronic components are mounted or assembled, forms the base foundation to an electric machine. The process of soldering or assembling the electronic components to the PCB is known as Printed Circuit Board Assembly (PCBA), and this can be accomplished by following any of the two techniques. The first technique is the traditional Thru-Hole Technology and the second is the latest Surface Mount Technology (SMT). Though SMT is a newer concept, it has quickly become the most sought-after PCBA technique. Thus, here are the main three reasons why SMT is the preferred PCB assembly technique.

Improved Usability

Thru-Hole technology is the process of plugging the extra lead or wire into the holes in the PCB board. This, in turn, occupies a larger surface area, hence increase in size. The SMT process enables the mounting of SMT components that are smaller in size due to the absence of extra lead or wire. Nowadays, all electronic gadgets are shrinking in size with remarkable improvement in efficiency. SMT securely assembles the number of components to a small PCB board, thus promoting complexity, smaller size and high component density.

Faster Production

SMT technique can be easily carried out through automation, as it requires only surface mounting of the components. This is not the same with Thru-hole technique where problems may arise when plugging of the components is done through automation. There are chances of the lead or wire not fitting into the hole in the PCB or lose connection. It is estimated that the SMT components can be assembled at the rate of more than thousands to even ten thousand per hour while the thru-hole process can only mount less than a thousand components.

Cost Efficient

Most of the SMT components cost less when compared to its Thru-Hole counterparts. Apart from this, SMT can be carried out by automation process, cutting down the manufacturing time and labor effort. In total, SMT reduces the assembly production cost to a greater extent when compared to the traditional technique.

The above-mentioned factors are some of the reasons behind the fast growth of Surface Mount Technology in the field of PCB Assembly.

Enabling High-Performance Operations with Robotic Soldering

Modern day technology is enabling more and more automation because the lesser the presence of human interference in a process, the more accurate the process will be. In the soldering industry as well, robotic soldering is being implemented with increased preference and demand. How is robotic soldering so much in demand? This blogpost will talk about how robotic soldering enables high-performance operations.

Robotic soldering is nothing but automation of the steps involved in the soldering process – for example, stenciling – you simply need to feed the designed printed circuit board into a computer, and robotic arms will cut out a stencil as per the design. All the subsequent steps will be taken care of by the same automated setup – application of flux, solder, cleaning and everything. Automating any process brings efficiency into the system. Read further to find out the benefits of automating soldering processes and manufacturing high-performance units.

• Precision – robotic soldering ensures precision in application of fluxes and solder. Wastage is effectively prevented, thus amounting to considerable savings.

• Consistency in production – robotic soldering displays high consistency in finished products. There is almost never any deviation in patterns and design, resulting in uniformity in produced goods.

• Manpower requirement and errors – Manpower required to carry out any process is reduced or eliminated altogether through automation of processes. Errors associated with human handling of things is also eliminated.

• Speed – Production speed and volume is also consequently increased with automation.

Given all of the factors listed above, high-performance printed circuit boards can be manufactured without much hassle through robotic soldering.

Understanding the Concept of Electrical Reliability

Soldering is a process that establishes an electrical connection between two components on a printed circuit board. How effective this connection is ultimately depends on the quality of solder and the soldering process. A good solder joint has a good electrical reliability that does not give out even if the application is subjected to situational extremes. This blogpost will help you in understanding the concept of electrical reliability.

What to expect from solder joints?

Solder joints are designed to last long. In sensitive applications like computers and surveillance systems, solder joints must outlast the life of the device in order to make sure the device keeps working until the last moment. The electrical reliability of a good solder joint enables:

• Good conductivity of current across the joint

• Homogeneity of the joint to offer less resistance to current flow

• Durability and endurance for long life and optimal performance

Joint reliability – tests performed to understand it

Solder joints need to perform on certain parameters if they are to be considered reliable. The thermal cycle test is performed on a solder joint to determine its reliability based on fatigue. In this test, a transition rate of 20°C per minute or less is applied to a solder joint to assess failure. When 63% failure has occurred in the solder joint, graphs are plotted to understand the patterns.

In moving applications of printed circuit boards, it is necessary that electrical conductivity of a joint be maintained with full integrity even if the board experiences vibration loads, which typically happens in automobiles, avionics and other transportation PCBs. Solder joints also need to have certain mechanical strength in order to save the connection in case the device experiences mechanical shock.

Electrical reliability of a solder joint determines how well current passes through the joint, which impacts the overall functioning of the device.

The Reliability and Solderability Factors of Lead-Free Soldering Bar

Soldering bars are bars of metal alloys used for soldering. Normally, for home soldering purposes, people prefer to purchase wires instead of bars. The reason is simple – domestic applications may not need as much alloy as a bar has to provide. Bars contain more metal, while a wire does not. In this sense, lead-free soldering bars are a convenient option for those who are looking at high volume soldering applications.

Lead-free soldering bars have this amazing convenience – they are available in weight ranges from anywhere from a few hundred grams to almost two kilograms. If there is a process which needs lead-free soldering alloy in high volumes, bars would be the best option. A wave soldering process, for example, requires molten solder alloy to work with – which automatically makes it a high solder volume procedure. If you are going to be undertaking wave soldering, purchasing lead-free soldering bars would be a good choice.

Lead-free soldering alloy bars are highly reliable as they have lower working temperatures. As compared to standard metal alloys used for soldering, lead-free soldering bars melt at relatively lower temperatures. There is lesser danger of burning the components while soldering them, which makes these bars highly reliable. This establishes a property of good solderability to lead-free soldering bars. Lead-free soldering bars also give a matte finish to the bond, which is highly desired for the cosmetics of the soldered joint.

Owing to such high environmental hazards that lead, as a metal, has displayed, lead-free soldering bars are becoming more and more popular as the safer and more environmentally responsible choice for soldering processes.

If you are still working with standard soldering alloys, switch to lead-free soldering bars today.

Choosing High-Performance Lead-Free Solder Pastes for Electronics Assembly

Environmental concerns have led the electronics industry to migrate from using leaded solders to lead-free solders. Various directives and regulations have been notified which make it mandatory for some electronics assemblies to be free of lead – which leads the industry enthusiasts looking for good lead-free high-performance solders. Here is a blogpost on choosing high-performance lead-free solder pastes for electronics assembly.

Lead-free solder paste alternatives are still in their burgeoning stages of development, which means there are certain errors or defects associated with them if not used mindfully. The first thing you need to consider is printability of the solder paste. Printability of a lead-free solder paste determines the magnitude of the defects arising at the end of the process – which is why it is important to get a solder paste with good printability. Printability factors such as recovery, printing speeds and durability need to be as high as possible.

The ratio of paste-to-metal in lead-free solders is another important factor to choose a high-performance solder paste. This ratio affects the cold slump of solder at drastic levels, which, if ignored, can lead to bridging defects in the finished product.

The lead-free solder paste can function optimally and form a good bond only if it has good wetting properties. The solder paste should be able to achieve maximum contact between components to be soldered. Cleaning should be easy – there should be no residue left behind upon examination. It would also work to your benefit if you perform a solder-balling test on the lead-free solder paste, just to be sure. Solder balls can be an extremely difficult defect to deal with.

Keep the above points in mind to choose a lead-free solder paste that is meant to perform during demanding situations for your printed circuit board assembly.