Low temp. thermo-compression bonded conductive sheet

Thin, Flexible Electrode Connections from Transparent Conductive Films.
Low-Temperature Thermocompression-Bonding Conductive Sheet TKS Series

A low-temperature thermocompression-bonding conductive sheet developed for transparent conductive films (ITO films) used in applications such as transparent heaters and smart films. It enables low-temperature connection, thinner designs, flexibility, and lower resistance, which are difficult to achieve with conventional soldering or anisotropic conductive film (ACF).

Inquiries About Catalogs, Technical Documents, and Evaluation Samples

What Is a Conductive Sheet?

A conductive sheet is a sheet-shaped material with an electrically conductive layer.
Conductive sheets are used for a wide variety of applications, including electrode connections, noise suppression, and grounding. In recent years, they have also been adopted for extracting electrodes from transparent conductive films and flexible devices. There are various types of conductive sheets, including conductive tapes, anisotropic conductive films (ACFs), and thermocompression-bonding conductive sheets, and the appropriate type must be selected according to the application.

What Is a Conductive Film?

A conductive film is a functional film in which a conductive layer such as ITO, silver nanowires, or copper mesh is formed on a film substrate such as PET or PEN.
It is used in applications such as smart films, transparent heaters, transparent antennas, touch panels, and film-type solar cells. Although conductive films are thin and flexible, extracting electrodes from them can present a challenge.

Features Challenges Applications How to Use
Comparison Properties Q&A

Features of the TKS Series Conductive Sheets

01

Conductive Connection by Low-Temperature Thermocompression Bonding at 100 to 120°C

The TKS Series is a conductive sheet that can be thermocompression-bonded at low temperatures of 100 to 120°C. It is suitable for electrode connections to heat-sensitive materials such as transparent conductive films and PET films, enabling conductive connections to film devices that are difficult to achieve with conventional soldering.

02

Excellent Flexibility to Accommodate Bending and Forming

A specially designed conductive layer maintains flexibility even after connection. It is well suited for film devices and components for wearable equipment that are subject to bending or stretching, contributing to thin and flexible product designs.

03

Direct Electrode Extraction from Transparent Conductive Films

Electrodes can be extracted directly from transparent conductive films such as ITO films and transparent heaters. Compared with ACF and soldering, thinner designs and fewer process steps can be expected, enabling designs that make full use of the performance of transparent film devices.

Difference Between Conductive Sheets and Conductive Adhesives

The TKS Series conductive sheets are thermocompression-bonding conductive sheets developed for transparent conductive films. By combining our proprietary specially shaped silver powder with a thermoplastic resin, they achieve both flexibility and electrical conductivity, which can be difficult with conventional conductive adhesives.

Why the TKS Series Resists Bending and Maintains Stable Conductivity

The TKS Series is a low-temperature thermocompression-bonding conductive sheet developed for transparent conductive films. Its performance is supported by KAKEN TECH's proprietary specially shaped TK Silver Powder.

With conventional conductive adhesives, bending or deformation of a film can reduce contact between silver particles, causing electrical resistance to increase. To achieve both flexibility and conductivity, KAKEN TECH developed a large, thin, specially shaped TK Silver Powder optimized for transparent conductive film applications. Thanks to this proprietary technology, the TKS Series maintains stable conductivity even in environments where bending or deformation occurs.

【Conventional Conductive Adhesives】
When a conductive adhesive applied to a film is bent, it is stretched laterally. As contact between silver particles within the conductive layer decreases, electrical resistance increases and conductivity decreases.
Conventional silver powder Conventional silver powder under normal conditions Conventional silver powder when stretched
【TKS Series】
By using large, thin, specially shaped TK Silver Powder, contact between silver particles is maintained even when the film is bent. This enables conductive connections that combine flexibility with stable electrical conductivity.
Specially shaped TK Silver Powder TK Silver Powder under normal conditions TK Silver Powder when stretched

Are You Facing Any of These Challenges with Conductive Connections on Transparent Conductive Films?

  • Thermal Deformation of Films Caused by Soldering
    Transparent conductive films such as PET and PEN have low heat resistance and may deform or shrink due to the high temperatures involved in soldering. You need an electrode connection method that avoids heat-induced performance degradation and appearance defects.
  • Increased Resistance and Heat Generation with ACF Connections
    In transparent heaters and large film devices, high resistance at the connection can cause voltage drops and heat generation. You want to achieve a lower-resistance, more stable conductive connection to improve device performance.
  • Increased Thickness When Using Conductive Tape
    Conductive tape offers good workability, but it can increase the thickness of the connection and hinder efforts to make devices thinner. You are looking for a smarter electrode connection method that preserves the advantages of film devices.
  • Connection Breakage Caused by Bending or Forming
    Applications such as wearable devices and smart films may require bending or forming. Conventional connection methods may crack or break, creating a need for materials that combine flexibility with electrical conductivity.

Applications

The TKS Series conductive sheets are low-temperature thermocompression-bonding conductive sheets developed for extracting electrodes from transparent conductive films and flexible devices. They are expected to be used in next-generation devices that require thinness and flexibility, including smart films, transparent heaters, and film-type solar cells.

  • Electrode extraction from smart films
  • Wiring connections for transparent heaters
  • Feed electrodes for transparent antennas
  • Wiring connections to ITO films
  • Electrode formation for touch panels
  • External electrodes for film-type perovskite solar cells
  • Conductive connections for flexible printed circuits
  • Electrode formation for wearable devices

Electrode Extraction for Liquid Crystal Smart Films

With conventional methods, silver paste and soldering must be used together to connect the ITO surface to copper tape, resulting in increased connection thickness and additional process steps. By using the TKS Series conductive sheets, electrode terminals can be thermocompression-bonded directly to transparent conductive films, enabling both thinner designs and fewer process steps.

Electrode extraction using solder
Electrode extraction using a thermocompression-bonding conductive sheet

Wiring Connections for Transparent Heaters

Because the sheet can be thermocompression-bonded directly to heater circuits formed on transparent conductive films, it is expected to reduce the risk of increased resistance and localized heat generation associated with ACF connections. Stable conductive connections make it possible to fully utilize the performance of transparent heaters.

Thermocompression-bonding sheet used on a transparent heaterThermographic image of a transparent heater using a thermocompression-bonding conductive sheet

How to Use

  1. Screen-print onto the substrate to be thermocompression-bonded and dry at the specified temperature and time. (Paste type)
  2. Align the thermocompression-bonding silver paste layer with the conductive surface to be bonded, and perform thermocompression bonding.
    If the conductive surface is uneven or thermocompression bonding is not applied uniformly, sufficient bonding strength may not be obtained.
    If sufficient bonding strength is not obtained, adjust the temperature, time, and pressure.
  3. Connect wiring or other components to the bonded electrode.

Comparison of Electrode Extraction Methods for Transparent Conductive Films

Various methods are available for extracting electrodes from transparent conductive films, including conductive adhesives, anisotropic conductive films (ACFs), and soldering. However, each method has challenges related to thermal deformation, resistance, flexibility, and other factors. By providing conductive connections through low-temperature thermocompression bonding, the TKS Series conductive sheets enable thin, low-resistance, highly flexible designs that take advantage of the characteristics of transparent conductive films.

Comparison Item TKS Series
Conductive Sheet		 Conductive
Adhesive		 ACF Soldering Eyelet
Risk of Thermal Deformation○△～○××○
Flexibility○×△××
Electrical Conductivity○○△◎△
Thin Profile○○○××
Number of Process Steps○×△～○△△

＜Comparison of Electrode Extraction Methods for Transparent Conductive Films＞

Product Specifications and Typical Properties

Available as a screen-printable paste type or as a pre-printed sheet type.

　 Low-Temperature Thermocompression-Bonding Conductive Adhesive
TK PASTE TKS-240
FormPaste TypeSheet Type
Main ComponentsSilver, Thermoplastic Resin
Base Layer-Rolled Copper Foil
(C1020 50um)
Printed Area Size-75mm×75mm
(Pre-cut width: 5mm or 3mm)
Paste Application MethodScreen Printing-
Paste Drying Conditions60℃×40 min~100℃×20 min-
Bonding ConditionsBonding Temperature100~120℃
Bonding Time60~120 sec
Pressure0.5~2.0MPa
Volume Resistivity2×10-4Ω・cm
Storage TemperatureFrozen (-10℃ or below)Room Temperature
Catalog Download

Frequently Asked Questions

How is the TKS Series different from anisotropic conductive film (ACF)?
The TKS Series is a low-temperature thermocompression-bonding conductive sheet developed for extracting electrodes from transparent conductive films. Compared with ACF, it is easier to achieve lower resistance and is suitable for higher-current applications such as transparent heaters and transparent antennas. It also offers excellent flexibility, enabling designs that make use of the characteristics of film devices.
What types of film can it be used with?
It is designed for use with film substrates such as PET, PEN, PI, and polycarbonate. Actual adhesion and conductivity vary depending on the type and surface condition of the conductive layer, so prior evaluation is recommended.
What are the recommended bonding conditions?
Standard bonding conditions are 100 to 120°C, 60 to 120 seconds, and 0.5 to 2.0 MPa. Optimal conditions vary depending on the material being bonded and equipment conditions, so evaluation under the actual operating conditions is recommended.
Can conductivity be maintained after bending or forming?
The TKS Series uses specially shaped TK Silver Powder, with a structure designed to maintain contact between silver particles even when the film is bent or deformed. This makes it suitable for film device applications that require flexibility.
Are evaluation samples available?
Yes. Evaluation samples and technical documents are available. We can recommend an optimal connection method according to the film material and type of conductive layer. Please feel free to contact us.
Why is the TKS Series less likely to lose conductivity when bent?
This is because it uses KAKEN TECH's proprietary specially shaped TK Silver Powder. With conventional conductive adhesives, bending the film may reduce contact between silver particles and increase resistance. The TKS Series uses large, thin, specially shaped TK Silver Powder to help maintain conductive paths, achieving both flexibility and stable electrical conductivity.
Can it be thermocompression-bonded directly to ITO film?
Yes. The TKS Series conductive sheets were developed for extracting electrodes from transparent conductive films. They can be thermocompression-bonded directly to conductive layers such as ITO films and transparent heaters. Actual adhesion and electrical properties vary depending on the type of conductive layer, so prior evaluation is recommended.
What is a conductive sheet?
A conductive sheet is a sheet-shaped material with an electrically conductive layer. It is used in a wide range of applications, including electrode connections, wiring extraction, and grounding. In recent years, conductive sheets have increasingly been adopted for extracting electrodes from transparent conductive films such as ITO films, transparent heaters, transparent antennas, and film-type solar cells.
What is the difference between a conductive sheet and conductive tape?
Conductive tape provides electrical continuity through conductive metal foil or conductive adhesive. In contrast, thermocompression-bonding conductive sheets such as the TKS Series connect a conductive layer to the adherend through thermocompression bonding, so lower contact resistance can be expected. They are also suitable for applications requiring electrode extraction from transparent conductive films and thinner designs.
What is the difference between a conductive sheet and anisotropic conductive film (ACF)?
Anisotropic conductive film (ACF) is a connection material that conducts electricity only in the vertical direction and is widely used in liquid crystal displays and electronic component assembly. In contrast, the TKS Series is a thermocompression-bonding conductive sheet developed for extracting electrodes from transparent conductive films. For applications carrying relatively high current, such as transparent heaters and film-type devices, it offers the advantage of easier low-resistance connection. Its excellent flexibility also makes it suitable for applications involving bending.
Can conductive sheets be used in perovskite solar cells?
Yes. The TKS Series is also being evaluated for external electrode applications in film-type perovskite solar cells. Because it can connect to transparent conductive layers by low-temperature thermocompression bonding at approximately 100 to 120°C, electrodes can be formed while minimizing thermal effects on film substrates such as PET and PEN. Its excellent flexibility also makes it suitable for use with flexible perovskite solar cells.
Can conductive sheets be used with ITO films?
Yes. The TKS Series is a conductive sheet developed for transparent conductive films such as ITO films, transparent heaters, and transparent antennas. Electrodes can be extracted by thermocompression-bonding directly to the conductive layer, helping address issues such as thermal deformation caused by soldering and increased thickness caused by conductive tape. Since adhesion and electrical properties vary depending on the type and surface condition of the conductive layer, prior evaluation is recommended.
What is a conductive film?
A conductive film is a functional film in which conductive materials such as ITO (indium tin oxide) or silver nanowires are formed on a film substrate such as PET or PEN. Because it can provide both transparency and electrical conductivity, it is widely used in smart films, transparent heaters, transparent antennas, touch panels, and film-type solar cells. However, because of its thin and flexible structure, connecting wiring to the conductive layer and extracting electrodes can present challenges.
What is the difference between a conductive sheet and a conductive adhesive?
A conductive adhesive is a material that provides a conductive connection by applying an adhesive containing conductive particles. In contrast, thermocompression-bonding conductive sheets such as the TKS Series connect a pre-formed conductive layer by thermocompression bonding, making it easier to simplify the process. The TKS Series also uses proprietary specially shaped TK Silver Powder, helping maintain conductive paths even when bending or deformation occurs and achieving both flexibility and stable conductivity, which can be difficult with conventional conductive adhesives.

Request Evaluation Samples and Technical Documents

Are you looking to extract electrodes from transparent conductive films, concerned about resistance or heat generation with ACF, trying to avoid thermal deformation caused by soldering, considering connection methods for smart films or transparent heaters, or seeking thinner and more flexible electrode connections?
KAKEN TECH can recommend conductive connection methods suited to your film material, conductive layer type, and operating environment. Evaluation samples and technical documents are also available, so please feel free to contact us.

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