What is conductive adhesive?

Conductive adhesive is one of the most useful materials that is used today to connect electronic components and is produced by loading organic resins with small inorganic filler particles that generally include metals and metal nitrides.

What is electrical conduction and thermal conduction?

In order to get more familiar with the concept of electrical conductivity or conductor, it is good to know that we call any material that passes electric current well as an electrical conductor, and the main reason that some materials are conductors is that their electrons They can be easily separated from the atom and move. Metals such as silver, gold, copper and aluminum are the most common electrical conductors; Because they have free electrons in the metal bond. And because of this property, they are widely used in making conductive adhesives. In the definition of heat conduction, we can say the transfer of heat energy from inside the material, which is the basis of the production and manufacture of electrical adhesives.
Electrostatic adhesives are materials that have been chosen as a suitable alternative to leaded solders, and they are being added and becoming better quality day by day.

Application of conductive adhesive

As we mentioned, conductive adhesives are used to make connections in electronic components. However, the application of these types of adhesives is not limited to the electronics industry and is also in industries such as air and space, medical supplies and equipment, telecommunications, etc.
In the electronics industry, electrically conductive adhesives are primarily used to assemble electronic boards. These adhesives are excellent for electrical bonding as well as thermal and structural bonding applications. and provide more reliability and functionality in electronic systems. Electrically conductive adhesives help protect sensitive electronic components without compromising the performance of the electronic component assembly.

Classification of conductive adhesives

Electrically conductive adhesives, which are often made of silver, copper, gold, and aluminum, are divided into the following two categories based on the conduction path.

•  Isotropic conductive adhesives
•  Anisotropic conductive adhesives

The main application of isotropic conductive adhesives is in the field of electronic components. Based on the studies conducted in the field of electrically conductive adhesives, it has been determined that these adhesives have advantages such as lower processing temperature, high flexibility, better environmental performance and easier processability compared to the traditional and old technology of solder connection. . Also, in an isotropic electrical conductor, in order to achieve electrical conductivity, the volume component of the electrical conductor filler must be equal to or greater than the critical volume component.

The importance of electrically conductive glue

Since the heat produced by soldering causes problems during the production of electronic products. And high soldering temperatures may preclude the use of temperature-sensitive materials. The demand for all types of electrically conductive adhesives has increased. This increase in demand has led to new and advanced design to obtain materials with high properties for use in various fields of biomedicine as well as various medical applications.
Among the main reasons for using conductive adhesives and replacing them with tin/lead soldering, we can point out corrosion, low resistance of seams, fatigue of the soldering joint and cracking due to stress in the connection.

Advantages of conductive adhesive

Electrically conductive adhesives are often used as an alternative to soldering in cases where the connected components are sensitive to temperature; Because they have higher efficiency and durability. In addition, electrically conductive adhesives have their own advantages.
These adhesives have the ability to help us find easier ways to conduct electricity to best suit the use, applications and needs of society.

Why is using conductive glue better than soldering?

The reasons that make electrically conductive adhesives a better and more suitable option for other methods of connection and adhesion as well as soldering are:

•  Lower cooking temperature of electrically conductive adhesives than soldering temperature
•  More flexible than solder
•  Higher resistance to vibration
•  And not using any lead or solvent in their structure.

Commonly used types of conductive adhesives and their advantages

Among the types of conductive adhesives, we can mention: epoxy adhesives, electrically conductive silicone adhesives, thermal paste or thermal grease, and autoclave conductive adhesives.

■ Epoxy adhesives

In processes where there is a risk of mechanical cracking and high heat, electrically conductive epoxies are ideal for use. Electrically conductive epoxies are in the form of glue and consist of one or two parts. One-part epoxies are typically heated. And for this reason, care must be taken in choosing a treatment program so that sensitive electronic components do not suffer from danger and problems. Two-part epoxies contain a resin and a hardener, and when filled with silver, they are a useful and effective alternative to soldering.
Of course, one-part epoxies can also be used as an alternative to soldering.

Advantage and application of epoxy glue

Using electrically conductive epoxy glue or electrically conductive paste as an alternative to soldering has many advantages. Including:
• Lower costs
• Better performance and efficiency
• Faster production times
Electrically conductive epoxy adhesives are often used to bond components in automotive camera and radar systems.

■ Silicone glue

Among the most common uses of silicone adhesives, we can mention the following:
1. Antistatic systems of electric charge (spark arrester)
Antistatic systems are used to eliminate static electricity on the goods.
2. Electrically conductive silicone adhesives
With the advancement of the hardware industry and processors becoming more powerful, the heat produced also increases. Therefore, in order to increase the life, efficiency and performance of hardware parts, laptops, computers and televisions, we must take the heat control of the parts seriously. Because the main cause of wear and tear of hardware parts is heat. Silicone adhesives are also produced for this purpose. For use in tools that require high flexibility and high conductivity. These adhesives are used to install small parts to various types of interconnected substrates and are often used in the automotive industry as a connection for cameras and radars. The medical, telecommunications and aerospace industries are among the other areas where electrically conductive silicone adhesives are used.

■ Thermal paste or thermal grease

Thermal adhesive is a type of pasty material that is made of polymer and its composition is mostly composed of silicon and oxide. Of course, in some more expensive pastes, first-class conductors of heat and heat, such as silver and ceramics, are also used. This type of heat-conducting adhesive is placed between parts that have high heat or heat transfer parts, such as between the processor (system brain or cpu). In fact, the function of this thermal paste is to help transfer the heat flow as quickly and easily as possible and make it easier to cool the hardware parts.
And high and better heat transfer is one of the main advantages of thermal pastes. Thermal paste is usually present by default on some systems. But for productivity and performance as much as possible, it is necessary to replace it. And the point that we need to mention about thermal adhesives is that in our country, heat conducting materials that are placed between hardware parts are known as silicone paste, which is a completely wrong idea.

Types of thermal pastes

There are different types of thermal pastes such as silicone thermal paste, metal thermal paste and ceramic thermal paste in the market. Normally, the upper limit of a quality dough is up to 150 degrees Celsius. Of course, we must consider that the performance of all these materials is not the same.

1. Thermal pastes based on silicon or silicone pastes

As we mentioned, the materials used as heat conductors in hardware are called thermal pastes or thermal greases. And silicone paste is only one type of thermal paste. These pastes usually have a very low price and using this category of pastes is very easy and fast. But they do not have high efficiency.

What does thermal silicone paste do?

Silicone paste is a heat conductor and the job of this paste is to transfer heat as much and faster as possible and cools the processor. This paste is placed in the form of a thin layer between the processor (cpu or GPU) of the computer and laptop and the heatsink (heat sink) and since air is a very weak conductor for heat and is placed in the empty spaces between the processors. has it. By placing the silicone paste, all the microscopic empty spaces on the processor or heatsink are covered, thus preventing inefficient heat transfer and poor performance of the cooling system.

2. Thermal pastes based on metal

These pastes are one of the best types of pastes and also one of the most expensive types. Metal-based pastes have high conductivity and transfer heat in the best way. Normally, metal-based pastes are very expensive because they are made of expensive metals such as aluminum and silver, and because they are electrically conductive, we must be careful and careful when installing them, and as much as possible, avoid anyone who is involved in this He has a specialized field, let’s get help.

3. Thermal pastes based on ceramics

Metal is not used in making these pastes. But this does not mean that they do not conduct heat. Pastes or oils that are based on ceramics have a more reasonable price and have a higher performance and are suitable for professional users.

Type of thermal pastes

Thermal pastes are usually produced in zinc oxide, ceramic, aluminum, copper, silver, graphite, silicon oil, carbon nanoparticles and various anti-oxidation materials.

The difference between thermal pastes and thermal pads

Heat-conducting adhesives, which are heat-conducting materials, are generally produced and marketed in two forms: thermal pastes or thermal greases and thermal pads. Although these materials have different shapes and separate from each other, in the end, their purpose and application are completely the same, and the biggest difference they have is in how they are installed on the parts.

Installation of thermal pastes and thermal pads

Since installing thermal pastes is more difficult, an expert and experienced person should do this work. Also, when we want to install metal-based thermal pastes, due to the conductive material, we must be careful not to cause problems in the motherboard.
But on the other hand, unlike thermal pastes, installing thermal pads is very easy and they also have a lower price. There are different ways to install thermal paste on the processor. But in any case, before starting, we must carefully clean the surface of the processor, and we usually do this with a high percentage of alcohol and a clean tissue or ear cleaner.

What thermal paste should we buy?

Zalman thermal paste model ZM_ STG2

An excellent paste with a relatively high price, which has a metal base and weighs 3.5 grams and is available in the market.
These pastes are suitable for professional users who are worried about the high temperature of their processor.
Zalman thermal paste with its volume can be used up to four times.
And it is one of the best thermal pastes whose composition contains 40% silver oxide and 50% iron oxide.
The temperature that can be tolerated by this paste is from minus 40 to 150 degrees Celsius, which makes it a suitable choice for powerful systems.

-Arsenic thermal paste model MX_4_2019

This type of thermal paste is one of the best and highest quality pastes available in the market.
Arsenic thermal paste in the weight of 3 grams is available in the market, which can be used several times and has a useful performance of 8 years.
This paste is composed of carbon microparticles and does not contain metal or silicone materials in its composition.
And unlike copper and silver materials, it does not damage the parts.
Arsenic paste, despite its high efficiency and performance, has a reasonable price and can be used for different types of processors of laptops and computers.

– E2 ESSENTIAL model cooler master silicone paste

This paste is a quality product and comes in a 1.5ml volume that can be used multiple times and is a good choice for professional users who are concerned about the high temperature of their CPU.
Cooler Master silicone paste is available in 3.5 gram packages in the market and it does not contain metal materials and its base is silicone.

Autoclave conductive glue

Autoclave conductive adhesive is an adhesive tape that discolors upon exposure to heat commonly used in the sterilization process. The range of this temperature is usually 121 degrees Celsius in a steam autoclave, but we can increase the temperature to 134 degrees in some autoclaves; Because they can bear it. In steam autoclave, autoclave glue is used as a marker. And by changing the color, we know that the sterile process has been done. The design of autoclave adhesive is pressure-sensitive and adhesive. Autoclave adhesive adheres to all types of coatings and remains secure throughout the sterilization process. This adhesive has a chemical indicator that confirms that this tape has been sterilized. And its black diagonal lines appear after 2 minutes at 134°C or after 10 minutes at 121°C.

Autoclave glue has a class one indicator. And it is made of high quality material with good adhesion and resistant to physical and chemical changes. As we know, the indicator or Autoclave Class 1 test is used to distinguish the equipment that has been subjected to sterilization from the equipment that has not been sterilized. And by observing the change in the color of the test, can you understand whether the equipment and tools have entered the sterile process or not?
It should be explained that this test never shows the correctness and accuracy of the sterile process and is actually a confirmation for performing the sterile process.

Why is class 1 autoclave test important?

Since this test is used to determine which of the packs and parts have been placed in the sterile process, it is necessary to perform it.

How to use autoclave class 1 test?

Autoclave 1 test has a strong adhesion to fabric, paper and plastic, and the colored strips on it change color after the sterile process, which indicates the presence of a pack in the sterilization process.

What are the characteristics of Autoclave conductive tape or adhesive?

• It is a resistant paper tape covered with a strong adhesive surface.
• Autoclave glue is available in 3 widths of 12 mm, 19 mm and 25 mm with a length of 50 meters in the market.
• Autoclave conductive glue is lead-free.
• The marker ink on the adhesive appears in the form of black diagonal lines when the autoclave sterilization process is completed.
• It has the property of easy separation without leaving any sticky effect on the equipment.
• The pressure-sensitive adhesive coating does not separate from the autoclave adhesive surface at high temperature and pressure.

How to use autoclave label 1

We stick the label on the equipment we want to sterilize and place it in sterile conditions. If the sterilization process has been carried out, the label will change color and we will make sure that the sterilization operation has actually been carried out.

Application of autoclave glue

Among the uses of autoclave glue, we can mention:

• Food and drug manufacturing industries
• Labs

Other types of conductive adhesives

• Arsine silver conductive adhesive (conductive adhesive)
• Can be used in physical and chemical electrodes
• Can be used in nano layers
• Use in conventional and SMD boards

Nickel conductive adhesive

It is a very good alternative to conductive silver or carbon adhesives . It is a strong acrylic hot glue with high adhesion properties, good conductivity and reasonable price in the market.

Application of nickel conductive adhesive

• Use in electron microscope, ion beam, electron micro probe and all devices that have a scanning probe.
• Repair of connections and lines in circuits
• Prototyping
• Conductive lubrication
• Electrochemical coating
Features of nickel conductive adhesive
• This adhesive dries quickly depending on the thickness and shows good thermal conductivity in dry state.
• The solvent is acetone. (This solution contains almost 50% nickel and acrylic binder.)

Conductive carbon tape with 99.98% purity

This adhesive tape has high electrical conductivity and is sensitive with acrylic adhesive.

Features of conductive carbon tape

• It has high adhesion to metals, plastics, wafers, ceramics, rubber, wood, glass, paper and small particles and fibers.
• Its sticky side is covered with silicone paper.
• It has a long life.
• Can be kept in the freezer.
• Very suitable for use in EDS.
• It has lower electrical conductivity than double-sided copper adhesives.
• And the solvent is acetone. (The solution contains about 15% graphite and carbon black powder plus acrylic adhesive.)

Application of conductive carbon tape

For use in electron microscopes, ion beams, electron micro probes and all devices that have scanning probes.