Although organosilicon thermal conductive adhesive materials have many advantages, they also have some disadvantages:
 I. Relatively High Cost
1. Raw Material Cost
- The production cost of organosilicon polymers themselves is relatively high. Compared with some common adhesive materials, the prices of their basic raw materials are rather expensive. Moreover, in order to achieve good thermal conductivity, it is necessary to add high-purity and high-performance thermal conductive fillers, such as boron nitride. The high prices of these fillers increase the overall raw material cost of organosilicon thermal conductive adhesive materials.
- During the production process, strict requirements are imposed on the quality control and purity of raw materials. For example, the impurity content in organosilicon raw materials needs to be strictly controlled at a very low level, which also increases the cost of obtaining raw materials. Meanwhile, more costs need to be invested in the selection and pretreatment of fillers to ensure that the fillers can be evenly dispersed in the organosilicon matrix and achieve the best thermal conductivity and adhesion effects.
2. Processing Cost
- The production process of organosilicon thermal conductive adhesive materials is relatively complex. Its processing requires precise control of multiple parameters such as temperature, pressure, and time to ensure the stability of the material's performance. For example, in the process of mixing thermal conductive fillers with organosilicon polymers, special mixing equipment and processes, such as high-speed stirring and vacuum defoaming, need to be adopted. The purchase and maintenance costs of these equipment are relatively high.
- There is also a certain degree of difficulty in forming processing. Since it is relatively sensitive to temperature and pressure, if the parameters are not properly controlled during the forming process, it is easy to cause a decline in material performance or the appearance of defects. In order to ensure product quality, it is necessary to finely adjust and optimize the forming process, which undoubtedly increases the processing cost.
II. Limited Mechanical Properties
1. Low Strength
- The mechanical strength of organosilicon thermal conductive adhesive materials is relatively low. Compared with some structural adhesive materials, it is prone to deformation or even fracture when subjected to relatively large tensile and shear forces. In application scenarios where relatively large external forces need to be withstood, it may not be able to meet the requirements. For example, in some mechanical equipment with high requirements for structural strength, when the connections between components need to bear relatively large dynamic loads, organosilicon thermal conductive adhesive materials may not be able to provide sufficient strength to maintain the stability of the connections.
2. Insufficient Hardness
- Its hardness is also relatively low. In some occasions where wear resistance or scratch resistance is required, organosilicon thermal conductive adhesive materials may be easily worn or scratched due to insufficient hardness. This will affect its application in some equipment with high requirements for surface quality. For example, in the bonding of the outer casings of electronic devices or the connection of the appearance parts of some precision instruments, if the surface of the material is scratched, it may affect the appearance and performance of the equipment.
III. Limitations in Specific Application Environments
1. Performance Changes in Certain High-Temperature Environments
- Although organosilicon thermal conductive adhesive materials have good temperature resistance, in some extreme high-temperature environments (higher than their tolerance upper limit), such as near some ultra-high-temperature industrial furnaces or during specific aerospace reentry stages, the materials may undergo performance degradation. After being exposed to such high-temperature environments for a long time, the organosilicon main chain may decompose or the bonding force between the fillers and the matrix may decline, resulting in a reduction in thermal conductivity and adhesion performance.
2. Sensitivity to Special Chemical Substances
- Although they have a certain resistance to common acids, alkalis and organic solvents, organosilicon thermal conductive adhesive materials may be relatively sensitive to certain special chemical substances or strong oxidants. For example, in some chemical industrial environments involving strongly oxidizing acids or special corrosive halides, the materials may be corroded, thereby affecting their normal thermal conductivity and adhesion functions.