Considerations for Choosing the Best PCB Cleaning Solvent

The printed circuit board (PCB) assembly process can result in residues from the solder and the flux, and these can cause current leakage without proper control and monitoring. In some cases, even a no-clean flux may need to be cleaned to prevent issues. You can save time and effort by using a specially formulated PCB cleaning solution, a solvent that will make the clean-up process easier and fuss-free. Here are some things to consider when choosing the right cleaning agent for your applications: 

• High-quality cleaning solvents are designed for electronic assembly manufacturing applications, such as PCB and stencil cleaning. However, you can also find a non-solvent-based PCB cleaner that is semi-aqueous or aqueous. 

• If you choose a solvent-based cleaner, be sure to look into its formulation. A good PCB board cleaner is made of organic solvents for non-aqueous applications. It effectively removes most kinds of uncured SMT adhesives and raw solder paste residues, and it is effective on organic contaminants and residues of post-soldering flux.

• Make sure that the PCB cleaning solution evaporates well and leaves no distinctive or strong odors. Likewise, consider a cleaning solvent that will not require you to rinse it off. That way, you can save time and move on to the next stage of your manufacturing process.

• Look for a PCB cleaner that is non-corrosive, so it will be compatible with most PWA and stencil materials. Moreover, consider a formulation that can minimize the build-up of solids, so you can reduce the need for equipment maintenance.

• Go for a PCB board cleaner that is non-flammable and non-hazardous. A good cleaner does not contain any glycol ethers or amines to keep your workers safe, and no VOCs, so you do not have to apply for relevant permits.

Is Solder Dross Recyclable?

Solder dross is made up of layers of impurities and oxidized metal that collect on the solder’s surface and it is typically produced during the selective or wave soldering process. It is technically leftover solder that still has over 90 percent of metal in it, with drossing rate dependent on agitation, alloy type, and temperature. Instead of letting all the remaining metal go to waste, smart electronic assembly companies turn to solder dross recycling, which refines the recycled material into a new solder bar.

Solder dross recycling services are safe and environmentally friendly, and they allow you to meet legislative and environmental requirements of your city or state. Moreover, they enable you to maximize returns on solder dross, paste waste, and scraps. Reputable manufacturers of solder dross offer these services as a part of their commitment to be responsible for the environment, with recycling facilities located in key areas around the world. With their help, metal waste streams are responsibly and efficiently recycled into highly pure raw materials, which can be reused once more. They serve a wide array of markets including computers, telecommunications, automotive, power supply, semiconductor packaging, IT, photovoltaic, medical and military, television and displays, and LED.

The benefits of solder dross recycling apply to your business, too. The process itself is simple, as you only need to get in touch with an appropriate solder manufacturer that offers the service and make arrangements for pick-up. So, it should not have to disrupt your daily operations. Some recycling companies offer flexible custom programs that will suit your unique requirements, too.

                

When considering solder dross recycling, be sure to pick a reputable and dependable company that has a good track record. Check if they have a minimum weight requirement for pickup. Some companies can recycle any amount of dross you may have generated for the time being. Also check if they can provide you with the vessels, and make sure that there are no additional fees.

Emerging Applications for Low Melting Point Solders

Electronic assembly requires the use of proper solders to establish electrical circuits and connections. Low melting point solders are fairly new and have the potential to be a low-cost way to establish reliable and strong joints. Low melting point solders are suitable for surface mount technology processes and they deliver high-quality joints while reducing operational costs, as they reduce the need for additional materials, labor, and energy. Using the material in through-hole steps can replace two critical SMT steps and the wave soldering process, resulting in more value for electronics manufacturers.

A lead-free alloy in a good solder material provides a lower melting point while exhibiting temperature resistance in advanced thermal cycling tests. Using low melting point solders can create value to your company and assembly process once it is established in your electronic assembly procedure. SAC alloys used to be the main alloys used in large-scale electronic manufacturing when lead-free standards were initially implemented. However, some manufacturers have begun looking into innovative alloy alternatives for their SMT processes, as lead-free soldering continues to thrive in the industry.

A low melting point of 138°C enables peak reflow temperatures between 170 to 180°C. The SnBiAg alloy system in the solder paste meets those parameters for reflow and melting point. Some lead-free alloys in certain products may have a lower melting point, but the resistance is good against accelerated thermal cycling tests in consumer electronics. This way, low temperature SMT processes help eliminate the wave soldering step, which is often a part of mixed technology assemblies.

Low melting point solders can be practical as you implement an SMT-only assembly process to ensure higher and streamlined throughput. It lets you switch to a low-temperature processing that can enhance secondary soldering, a process that will enable you to rework certain components, like RF shields that must be soldered separately. Low temperature alloys may also be used as an alternative to mercury in certain applications, so you can ensure the safety of your workers.

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.

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.

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.