High Thermal Conductivity Aluminum Substrate Based On Interface Assembly Technology

The development of high-density,integrated power products,so that the circuit substrate thermal problems have become an important factor limiting product performance and life.Aluminum-based copper laminate is the most widely used class of metal-based thermal substrates,the core technology is to improve the thermal conductivity of the insulation layer,the insulating layer of polymer filled with high thermal conductivity particles to form a thermally conductive network is the most common method,but high particle filling will make the polymer bonding performance,insulation performance degradation,and thus can not meet the substrate requirements.Compared with the filled polymer insulating layer,the anodized aluminum film has better thermal conductivity and insulation,and there is no filling bottleneck problem,but the anodized aluminum film contains anodic holes,and the holes will cause the film thermal conductivity and insulation performance is impaired,which leads to the limited application of the anodized aluminum plate to prepare aluminum-based copper-clad plates.In order to solve the insulating thermal conductivity problem caused by the holes in the anodic oxide layer,this paper proposes an adhesive-anodic oxide layer interface assembly method,using the adhesive and anodic holes to form a mosaic structure to improve the insulating thermal conductivity of the anodic oxide layer,so as to prepare a widely used high thermal conductivity aluminum-based copper clad plate.The main studies are shown below:(1)Finite element simulation study of interface assembly insulation layer.Using finite element simulation method to study the influence of adhesive inlay depth and thickness on the thermal conductivity of the assembled insulation layer,it is found that the thermal conductivity of the assembled insulation layer tends to rise with the increase of inlay depth,and the rise decreases with the increase of inlay depth.With the increase of adhesive thickness,the thermal conductivity tends to decrease,and the decrease is gradually slowed down,and finally tends to the thermal conductivity of the adhesive itself.(2)Preparation and performance study of interfacial assembly adhesive.Phenolic epoxy resin and bisphenol S type epoxy resin with small epoxy value were selected as the base,polyurethane modified epoxy resin was used instead of long molecular chain rubber as toughening agent,and submicron grade alumina and silica were selected as fillers.The adhesives were prepared according to different amounts of polyurethane modified epoxy,and the best overall performance was selected as the base formulation for interfacial assembly by comparing the properties of adhesives such as thermal stability,glass transition temperature and thermal stress.The study showed that the adhesive performance was optimized when the content of polyurethane modified epoxy resin was 15%,at which the 5%weight loss temperature was 369°C,the glass transition temperature was 178°C,and the ultimate drifting tin time was 782 s at 288°C.(3)Preparation and performance study of interfacially assembled insulating layers.The selected basic formulation was used as a template,and the basic formulation was modified with different forms of nano-modification,and the modified adhesive was used to assemble with the anode aluminum plate at the interface,and the anode aluminum plate was tested for thermal conductivity and pressure resistance before and after the assembly.The experimental results showed that the thermal conductivity of the assembled anode aluminum plate was 2.6 W/(m·K)with 10%nano-alumina modified adhesive containing resin,which was 43.65%higher than that before the assembly,and the breakdown voltage was 2.6 k V,which was 1 times higher than that before the assembly,and this result confirmed the feasibility of the insulating layer assembly scheme at the interface between the adhesive and the anode oxide layer.The effect of adhesive thickness on the performance of the assembled insulating layer was found that the thermal conductivity of the assembled insulating layer decreased and the voltage resistance increased with the increase of the adhesive thickness,and the comprehensive performance of both was optimal at the adhesive thickness of 10μm.Among the different nano-modified adhesives at 10μm adhesive thickness,the 10%nano-alumina modified adhesive assembled insulating layer had the best comprehensive performance with a thermal conductivity of The thermal conductivity was 2.25W/(m·K)and the breakdown voltage was 4 k V.The thermal conductivity of the high thermal conductivity aluminum substrate prepared by the interface assembly modification technology is 2.6 W/(m·K),breakdown voltage is 2.6 k V,and increasing the thickness of the adhesive to 10μm,the thermal conductivity is up to 2.25 W/(m·K),breakdown voltage is 4 k V.(about 0.2～0.3 K-cm~2/W)is small,and the thermal conductivity and heat dissipation performance is strong.Compared with the direct preparation of aluminum substrates from anodic aluminum plates,this technology can overcome the insulation problems caused by uneven oxide insulation layer and anodic holes,and expand its application scope.