The Pressure-Sensitive Adhesive Tape: Thermal Conductive Sealant

The technology is developing massively and in such a time, electronic devices have brought new design challenges with an emphasis on mechanical strength and thermal management capability. The sizes of every technology are shrinking these days and operating environments have become more rugged. Thus, integrated product design must overcome the challenge of dissipating heat while maintaining shock resistance.

Thermally conductive sealant is a category of TIM or Thermal Interface Materials which provides combination of low thermal resistance and high bond strength. These are designed to conform to surface irregularities, eliminate air gaps and improve heat flow which includes grease, compounds, gels, pads, phase change materials (PCMs), metallic solders and tapes. Using this process, heat energy is passed through a solid, liquid or gas from molecule to molecule in a material.

You can find a pressure-sensitive adhesive tape in the market under thermal conductive sealant comprising of pressure-sensitive adhesive layer. It has a thickness exceeding 0.2 mm and essentially made of a polymeric pressure-sensitive adhesive matrix and glass microbubbles of specific gravity not exceeding 1.0 dispersed throughout the matrix. The microbubbles of the product have an average diameter of 10 to 200 micrometers and comprising 20 to 65 volume percent of the pressure-sensitive adhesive layer.

Properties of Pressure-Sensitive Adhesive Tape:

• The glass microbubbles used in the tape have a specific gravity of less than 0.2 and are ultraviolet-transparent.
• It has the thickness of the tape is 0.2 to 1.0 mm which exceeds seven times the average diameter of the microbubbles.
• The average diameter of the microbubbles used in the tape is 20 to 80 micrometers.
• It includes of a backing sheet having a low-adhesion surface permitting it to be peeled away from the pressure-sensitive adhesive layer and discarded.
• The glass microbubbles used in the product comprises of 45 to 55 volume percent of said pressure-sensitive adhesive layer.
• An unfilled pressure-sensitive adhesive layer is laminated on one face of the microbubble-filled layer and the other exposed face of the laminated unfilled layer has a root-mean-square surface roughness of less than 5 micrometers.
• The Shore 00 hardness of the microbubble-filled is tested at an adhesive thickness of 3 mm is at least 50 at one second and at most 30 at 30 minutes.
• The pressure-sensitive adhesive of all three layers is an acrylic copolymer.
• The microbubble filled in this thermal conductive sealant is fairly elastic which stresses but has low elasticity after stress is maintained for a period of time.

With typical thermal resistance of Kcm^2/W: 0.15 - 1.0, thermally conductive adhesives requires a robust manufacturing process. Thermosetting polymers provide substantial long-term strength across the bond interface, and 2nd to only soldering in ultimate heat transfer capabilities. Thermally conductive tapes are similar to thermal pads but provide more substantial adhesion across the interface. Thermal resistance they provide is Kcm^2/W: 1.0 - 4.0.

Best insulation materials should have the lowest thermal conductivity to reduce the total coefficient of heat transmission.