Español
Français
Português
The core difference between dual conductive copper foil tape and single conductive tape is that the adhesive surface is also conductive. The characteristic of "double-sided conductivity" makes many engineers intuitively choose double conductivity when they need to cross ground or shield continuous grounding, thinking that as long as it is attached, the current can pass through the adhesive layer from the copper foil surface to the metal surface to be attached.
However, a recurring phenomenon during on-site testing is that the multimeter indicates that there is continuity between the adhesive surface and the copper foil surface, and the reading is normal; After the whole machine was installed, the ESD test still failed, and the grounding resistance was much higher than expected. The problem is not whether the tape is double conductive, but the essence of Z-axis conductivity - it is not a metallurgical connection like soldering, but a pressure contact between particles.
Z-axis conduction relies on particles being "pressed together" rather than "growing together"
The structure of double conductive copper foil tape consists of only three layers: high-purity electrolytic copper foil, conductive acrylic pressure-sensitive adhesive layer, and release layer. The conductivity of the adhesive surface comes from conductive particles such as nickel particles filled in the adhesive layer. When the tape is pressed between the surfaces of two conductors, the adhesive layer is compressed and the nickel particles approach each other; Only when the pressure is sufficient to overcome the elastic resistance of the adhesive layer, physical contact is formed between particles, and the Z-axis conductive path is truly established.
This mechanism determines that the Z-axis resistance is not a fixed material constant, but a state variable that varies with mounting pressure, adhesive layer thickness, and particle distribution density. When the pressure is insufficient or the adhesive layer is not fully compressed, the particles only "approach" rather than "contact", and the vertical resistance can be several orders of magnitude higher than the specification value. The vertical resistance marked on the specification sheet as<0.05 Ω· cm ² is the result measured under sufficient compression conditions, not the guaranteed value under "light adhesion" conditions.
The "multimeter test on" and "low impedance grounding" are two different things
The on/off range of a multimeter can only determine whether there is power, and cannot reflect the magnitude of contact resistance. In the adhesive layer of double conductive tape, even if the particles are not in sufficient contact, there may still be a weak conductive path that causes the multimeter to display "on", but the resistance of this path may be much higher than the low impedance level required for high-frequency reflux and ESD discharge.
A more reliable verification method is to measure the vertical volume resistance: clamp the tape between two gold-plated metal plates and measure the resistance penetrating the adhesive layer. The conventional qualification requirement for double conductive tape is<0.05 Ω/1cm ². Another method that can be used on site is to stick adhesive tape between two independent metal pieces and measure the conductivity resistance between the metal pieces, rather than directly gluing the surface with a probe. If the impedance requirement of the grounding path is high, the DC on-off test can only be used as a preliminary screening and cannot replace low resistance verification.
Where does the pressure come from: Rolling is not an "optional process", it is a prerequisite for conductivity
The dependence of the Z-axis conductivity of the double conductive tape on pressure means that the mounting process itself is a part of the electrical performance. Manual light pasting and finger smoothing often result in insufficient actual pressure transmitted to the adhesive metal interface to ensure stable contact between particles. In engineering practice, after installation, it is necessary to compact with rollers, and important workstations should sample and measure the Z-axis grounding resistance to confirm conductivity.
If there are oil stains, fingerprints, release agents, or dust on the mounting surface, these residues will isolate the particles from contact with the metal surface, and even if the pressure is sufficient, the conductive path will be blocked by the insulation layer. The conductive particles of double conductive tape cannot "pierce" the contaminated layer like solder, and interface cleaning is another prerequisite besides pressure.
Z-axis conduction cannot carry high current: physical upper limit of particle contact
The Z-axis path of the double conductive tape is a point contact between particles, with a small contact area. Although the contact resistance can be low, it is not designed to carry high currents. Using double conductive copper foil tape to apply high current can cause heating, impedance drift, and even adhesive failure. Its reasonable positioning is for electrostatic discharge, weak signal grounding, and equipotential connection of shielding chambers, rather than as a carrier for power return or power current. High current circuits require metal wires or copper bars and cannot rely on the Z-axis path of adhesive tape.
Temperature resistance and long-term reliability: The adhesive layer is the most fragile link in Z-axis conduction
The Z-axis conductivity of double conductive tape depends on the compression state of the adhesive layer. It is recommended that the long-term use temperature of conventional pressure-sensitive adhesives should not exceed 80 ℃; High temperature modified acrylic adhesive can adapt to short-term heating of 120-150 ℃, but it is still recommended to control the long-term continuous temperature within 120 ℃. After the temperature exceeds the tolerance range of the adhesive layer, the adhesive layer may soften or creep, the compression pressure may relax, the particle contact state will degrade, and the vertical resistance will increase accordingly.
For scenarios that require reflow soldering, high-temperature modified acrylic adhesive products should be selected, and temperature cycling verification should be completed in advance when the mounting position is close to the power pad or heating element to confirm that the adhesive layer is not softened or warped, and the copper foil is not displaced. In humid environments, oxidation of the copper foil surface occurs independently of the adhesive layer, and tin plated copper foil options should be prioritized for high humidity or long-term aging conditions.
Selection judgment based on pressure, interface, and current
Firstly, confirm whether the grounding path truly requires Z-axis conductivity
If the current only needs to enter the exposed copper area of the PCB from the copper foil surface, and the adhesive surface is attached to the insulation surface, single conductive tape is a matching choice, and the insulation adhesive layer can also avoid misleading the non target area under the adhesive. Dual conductivity is only necessary when the adhesive surface needs to form an electrical connection with the metal shielding cover, chassis, or grounding spring, and the current must pass through the adhesive layer. Do not default to using dual conductors just because they are more versatile, as the conductivity of the adhesive surface increases the risk of short circuits in non essential scenarios.
Secondly, consider the installation pressure and interface cleaning as part of the selection evaluation, rather than assuming that 'once it is applied, it will pass'
The Z-axis resistance of the double conductive tape is sensitive to pressure, and the supplier's specification value is measured under sufficient compression conditions. When selecting, the recommended minimum mounting pressure and rolling process should be confirmed with the supplier, and the vertical resistance or lap resistance should be measured according to the actual production line conditions during the sample stage, rather than just using a multimeter for on/off judgment. Interface cleaning (wiping with isopropanol, completely drying) should be part of the process specification, not optional.
Thirdly, distinguish between "static discharge" and "current carrying", and do not use double conductive tape as a wire
The Z-axis path of the double conductive tape is suitable for ESD discharge, shielding cavity equipotential connection, and weak signal grounding. If the grounding path needs to carry large DC or low-frequency currents, the current carrying capacity of the Z-axis path of the tape should be evaluated, and if necessary, metal wires or copper bars should be used instead. The cross-sectional area and particle contact area of the tape determine its upper limit of current, which is usually much lower than the intuitive judgment of "appearing wide enough".
Fourthly, in high temperature or long-life scenarios, the temperature resistance level of the adhesive layer and the vertical resistance change after high temperature are used as independent verification items
The long-term use temperature of conventional pressure-sensitive adhesives does not exceed 80 ℃, while high-temperature modified adhesives can adapt to short-term heating at 120-150 ℃. When selecting, the actual working temperature of the mounting position should be confirmed, and the supplier should be required to provide vertical resistance data after high-temperature storage or temperature cycling, rather than just based on the initial value at room temperature.
Advanced Institute (Shenzhen) Technology Co., LtdThe dual conductive copper foil tape product line adopts high-purity electrolytic copper foil substrate, and the adhesive layer is filled with conductive particles to achieve Z-axis conductivity. The vertical resistance can be controlled at the level of<0.05 Ω· cm ².
The product can provide conventional pressure-sensitive adhesive or high-temperature modified acrylic adhesive options according to the mounting process, supporting roll, sheet, and precision die-cutting. It is recommended that customers verify the lap resistance according to actual rolling conditions during the sample stage. Suitable for scenarios such as continuous grounding of shielding covers, gap bridging, and double-sided overlapping of metal structural components that require adhesive surfaces to participate in conductivity. For more technical information, please visithttp://www.avanzado.cn/.