中国胶粘剂

采用环氧树脂、环氧稀释剂、固化剂、固化促进剂、偶联剂、导电助剂以及3倍前述质量的银粉(不同片银/球银比例)，制备了导电胶(ECA)，并从流变性能、热物理性能、导电性能、导热性能、形貌以及粘接强度几个方面研究了微米片银/微米球银复配对ECA性能的影响。研究结果表明：(1)黏度和触变指数受球银的占比影响很大，球银占比越高，黏度越小，触变指数越小。片银对提高ECA触变性有明显影响，而球银能有效降低黏度。(2)随着球银比例增加，玻璃化转变温度(T_g)发生轻微变化，对T_g前的热膨胀系数(CTE-1)影响不大，对T_g后的热膨胀系数(CTE-2)则有明显的降低作用。(3)在银粉总含量不变的情况下，球银对体积电阻率的降低不利，但能明显提升ECA的热导率。(4)添加的银粉整体呈现出均匀分布的特征，且具有一定的随机性和无序性。随着球银含量的增加，其在片银平面方向的填充密度由疏松逐渐趋于致密，同时片银被球银遮蔽的程度也相应提高。随着球银比例的进一步增加，大量的球银填充于片银平面垂直方向的间隙中，有利于构建各向同性的高效导热网络。(5)球银相对片银具有更紧密的堆积效果，机械补强效果随着球银含量的提升而得到体现，并且在球银含量达到1/3时，出现最佳粘接强度。

An electrically conductive adhesive(ECA) was prepared by using epoxy resin,epoxy diluent,curing agent,curing accelerator,coupling agent,conductive additive,and three times of the aforementioned mass of silver powder(different ratios of flake silver/sphere silver).The influence of micro flake silver/micro sphere silver compounding on the performance of ECA was studied from several aspects of rheological properties,thermophysical properties,electrical conductivity,thermal conductivity,morphology,and bonding strength. The research results showed that,(1) The viscosity and thixotropy index were greatly affected by the proportion of sphere silver.The higher the proportion of sphere silver,the lower the viscosity and thixotropy index.Flake silver had a significant effect on improving ECA thixotropy,while sphere silver could effectively reduce viscosity.(2) As the proportion of sphere silver increased,the glass transition temperature(T_g) underwent a slight change,with little effect on the coefficient of thermal expansion(CTE-1) before T_g,but a significant decrease in the coefficient of thermal expansion(CTE-2) after T_g.(3) Under the condition of fixed total content of silver powder,sphere silver was not conducive to reducing the volume resistivity,but it could significantly improve the thermal conductivity of ECA.(4) The added silver powder exhibited a uniform distribution as a whole,and had a certain degree of randomness and disorder.As the content of sphere silver increased,its filling density in the direction of flake silver gradually became denser from loose,and the degree of shielding of flake silver by sphere silver also increased accordingly.As the proportion of sphere silver increased further,a large amount of sphere silver filled the gaps in the vertical direction of flake silver,which was beneficial for constructing an isotropic and efficient thermal conductivity network.(5) Sphere silver had a tighter stacking effect compared to flake silver,and the mechanical reinforcement effect was reflected with the increase of sphere silver content.The optimal bonding strength occurred when the sphere silver content reached 1/3.