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.

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.

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.

Things To Consider When Choosing Low Temperature Lead-Free Solders

The new age has ushered in new technology and materials in the electronics industry which are set to revolutionize traditional methods. Lead-free solders are a part of this revolution, and have proved to be better and more versatile than the materials used earlier for soldering. There are many specialized jobs that lead-free solders can achieve which were earlier not possible with leaded solders. If you have some specialized soldering jobs lined up, here are things to consider when choosing low temperature lead-free solders.

First off, assess the temperature you are going to be working at while soldering. If there are components and materials involved that are likely to melt or get damaged at normal soldering temperatures, it is time to go for a low temperature lead-free solder.

Secondly, think of the application of the soldering job. Certain specialized applications require low temperature solders, like thermometers used in food preparation and fire detection devices. Also, in reflow processes where temperatures are likely to harm the assembly, low temperature lead-free solder can be used in applications such as:

• Flex circuitry in cell phones, smartwatches and other smart devices

• Components that are temperature sensitive

• Step soldering process where sequential soldering is to be done without damaging the previous one

• Large area devices in order to avoid common faults like head-in-pillow and non-wet open.

If any of the above situation corresponds to your soldering job, you should buy a low temperature lead free solder.

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.

PV Ribbon Wire: How Are They Used And Where To Get Them

PV is the acronym for Photovoltaic. A photovoltaic material contains molecules that are capable of producing electricity from photons of light, thus the name. These materials are extensively used in solar powered applications in the form of ‘solar cells’. To convey the electricity produced in the material to the DC wires installed in solar-powered applications, many mini-connections are required to be made internally between the solar cells – which is where the photovoltaic ribbon wires are used. In this blog post, you will learn about PV ribbon wire.

How are photovoltaic ribbon wires used?

A photovoltaic ribbon is a flattened wire made of tinned copper which is installed in solar applications to collect the current produced by solar cells and deliver it to the consequent cables. The solar cell is a wafer-thin material made of mostly silicon, layered with other metals in between. Photovoltaic ribbon wire is directly soldered onto each solar cell, and interconnected with the next photovoltaic ribbon…and so on. When all the cells in a solar panel row relate to photovoltaic ribbon wire, the endpoints are then soldered to a bus bar, which accumulates all the current of that row and sends it further.

Where to find photovoltaic ribbon wires?

Photovoltaic ribbon wires are widely available on online stores these days. Many brands manufacture photovoltaic ribbons of different compositions and properties, which you can cherry-pick from as per suitability for various applications.

Solar PV ribbon wires need to be thoroughly efficient in doing their job because solar cell efficiency is still in its growing stage. A good solder bond will ensure there is no wastage in the conveyance of the energy produced. 

Important Industrial Solder Alloys and Their Uses

Knowing the right solder alloy to use for your application is critical to the success of any project. If the proper solder alloy isn’t chosen and correct plating requirements aren’t defined or flowed, it could result in rework and excessive scrap, or worse the failure of your application. There are many different types of solder alloys and concentrations used for all kinds of applications, but it is important to first have a general understanding of solder and how it works.

Solder is basically a metal wire that has a low melting point (or low enough for melting using a soldering iron). For electronics, solder is usually made from a combination of lead and tin. Tin has a much lower melting point than Lead, which means that higher tin concentrations means a lower solder melting point. Typically, you would find 60Sn/40Pb lead-based solders at gadget stores, although other minor variations are also sold. For industrial purposes, however, you would typically find two major categories of solder alloys, namely, flux cores, and lead-free.

Flux cores further comes in two common forms, such as Acid and Rosin. Acid flux core solder alloys are ideal for plumbing use and cannot/should not be used in electronics as it will likely erode your boards and components. For electronics purposes, choose rosin core. Lead-free alloys are what industry regulations and standards are leaning more towards. Because the EU is now requiring pretty much every commercially available electronics to use lead-free parts and components, this also means more demand for lead-free solders. Lead-free solders pretty much work exactly like lead-based solders, only they are more environmentally friendly. Lead is believed to be a very toxic material, which is why safer metals are now being used in its place. Lead-free solders, however are a lot harder to work with, as replacement metal alloys behave differently and don’t flow as well as lead.