Thermal Conductive Adhesive Research Articles

Double-Sided Transferred Carbon Nanotube Arrays for Improved Thermal Interface Materials

Recently, much attention has been given to reducing the thermal resistance attributed to thermal interface materials (TIMs) in electronic devices, which contribute significantly to the overall package thermal resistance. Thermal transport measured experimentally through several vertically aligned carbon nanotube (VACNT) array TIMs anchored to copper and silicon substrates is considered. A steady-state infrared (IR) microscopy experimental setup was designed and utilized to measure the cross-plane total thermal resistance of VACNT TIMs. Overall thermal resistance for the anchored arrays ranged from 4 to 50 mm2 KW-1. These values are comparable to the best current TIMs used for microelectronic packaging. Furthermore, thermal stability after prolonged exposure to a high-temperature environment and thermal cycling tests shows limited deterioration for an array anchored using a silver-loaded thermal conductive adhesive (TCA).

Surface iodination: A simple and efficient protocol to improve the isotropically thermal conductivity of silver-epoxy pastes

Abstract Heat dissipation is a critical issue in many areas such as the high-performance electronic devices. The present work gives a detailed investigation regarding a simple and efficient surface modification method, which can remarkably improve the thermal conductivity of the isotropically thermally conductive adhesives (TCAs). Herein we demonstrate that the thermal conductivity of TCAs based on micron-sized silver fillers can be improved to near eightfold merely through simple surface chemistry treatment of the fillers, without changing the conventional epoxy resin (adhesive) processing conditions. Experimental results show that the thermal conductivity of a TCA sample with iodine modified silver fillers (85 wt%, size 1–2 μm, near-spherical particles) achieved 13.5 Wm−1 K−1 when cured at 150 °C. Compared to the unmodified silver-based TCAs, only 1.7 Wm−1 K−1 was achieved when cured in the same condition. This work suggests that through modulating the filler interface of a TCA, the thermal conductivity of a TCA can be drastically improved. These TCAs with superior isotropic thermal conductivity may find many heat dissipation applications e.g. surface mounted devices (SMDs) and high power (printed circuit) motherboards.

Study on the bimodal filler influence on the effective thermal conductivity of thermal conductive adhesive

The thermal management for electronics systems becomes more crucial to the overall system performance as the packaging density becomes much higher and the IC power increases at the same time. Thermal conductive adhesives (TCAs) have been widely adopted in electronics systems. As an epoxy matrix with conductive fillers, it is essential to figure out the effective thermal conductivity of this composite material. In the present paper, a parameterized cubic cell model (CCM) is developed and then implemented by the finite element method to investigate the effects of the bimodal fillers on the effective thermal conductivity. In addition, a series of bimodal TCA samples are prepared and the thermal conductivities in the in-plane and vertical directions are measured experimentally. An obvious anisotropy with respect to the thermal conductivities has been observed for the bimodal filler loading under consideration. A good agreement between the numerical results and the experimental data is obtained.

Influence of matrix viscoelastic properties on thermal conductivity of TCA – Numerical approach

Thermally conductive adhesives (TCA) and electrically conductive adhesives (ECA) are one of the major concerns of the contemporary micro-electronics. They are especially important in application where, e.g. effective heat dissipation is the key factor for reliability issues. Currently there is a lot of ongoing research in order to improve the basic thermal property of adhesives, which is mainly heat conductance. According to the literature data the heat conductance can vary from 0.1 up to 60 W/m K. It depends not only on the filler material, its content and configuration but also on thermo-mechanical properties of matrix. On the other hand numerical simulation becomes nowadays an inevitable tool for rapid non-destructive and low-cost experiments. The basic problem of numerical experiments is accuracy. Nevertheless the accuracy can be improved by combining the numerical and traditional experiments. This can be achieved by means of partial validation of numerical results by traditional experiments or by precise and appropriate material properties measurement. In fact, the above approach was applied in current work in order to simulate the influence of curing temperature and time on the thermal conductance of polymers. Thermally conductive adhesives belong to polymer based materials. In order to apply numerical simulation it is required to have an appropriate description of the thermal and mechanical behavior of polymers. Most often polymers are described by cure dependent or independent linear viscoelastic model [3,5]. Having this model, which parameters in fact can be measured experimentally, it is possible to simulate the stress and strain field caused by polymer curing and shrinkage phenomena and finally assess the thermal conductance accordingly. Current paper focuses on a problem of numerical simulation of TCA in order to recognize the trend dependence of thermal conductivity due to viscoelastic model of polymers and filler particles contact area.

Attaching Planar Waveguide Dies to Aluminum Using Low-Stress Thermal Conductive Adhesives

We analyzed stress and heat transfer in attached planar waveguides. Die attaching adhesives were known to be the key to avoiding stress buildup in and dissipating heat from waveguides. When adhesives have a shear modulus of less than 1 MPa and a thermal conductivity of 2 w/mk, a 0.1–0.2-mm-thick layer of adhesive can eliminate stress-related effects and efficiently dissipate 30–50 mW/mm2 of heat, even if aluminum is used as a substrate. Supersoft thermal conductive adhesives were thus developed and used to attach 60-mm-long AWG dies to aluminum with excellent results.