Silver paste resistance is influenced by multiple factors, and in addition to the shape of silver powder, the following key factors also significantly affect its conductivity:

1、 Characteristics of silver powder itself
The particle size and distribution of silver powder directly affect the resistance. When the particle size of silver powder decreases from 5 μ m to 1 μ m, the specific surface area increases, the number of indirect contacts between particles increases, and the resistance can be reduced by 30% -40%. However, if the particle size is too small (<0.5 μ m), it is prone to agglomeration, which in turn leads to an increase in resistance. The purity of silver powder is also crucial. If it contains impurities such as copper and iron exceeding 0.1%, it will form electron scattering centers, increasing the resistance by more than 15%.

2、 Composition ratio of silver paste
Silver content is the core factor. When the proportion of silver powder increases from 70% to 90%, the conductive path becomes denser and the resistance can decrease by 50% -60%. However, excessive silver content will reduce the fluidity of the slurry. The proportion of glass powder needs to be precisely controlled. If it exceeds 5%, an insulation barrier layer will form, leading to a sudden increase in resistance; If it is less than 2%, it cannot guarantee good bonding between silver powder and substrate, and the contact resistance increases.

3、 Preparation and sintering process
The sintering temperature and time have a significant impact. In the range of 500-600 ℃, for every 50 ℃ increase in temperature, the silver particles fuse more fully, and the resistance can be reduced by 10% -15%. However, exceeding 650 ℃ may cause oxidation of the silver layer or damage to the substrate. The dispersion process determines the uniformity of silver powder. When the ultrasonic dispersion power is insufficient, the silver powder agglomeration rate exceeds 20%, and the local resistance will fluctuate by 2-3 times.

4、 Application environment and aging

An increase in temperature will cause a linear increase in the resistance of silver paste. Within the range of -40 ℃ to 85 ℃, the resistance increases by 2% -3% for every 10 ℃ increase in temperature. When the humidity exceeds 60%, the migration of silver ions accelerates, and the resistance can increase by 10% -20% after long-term use. Mechanical stress such as bending and vibration can damage the conductive network, causing a sudden increase in resistance, with an amplitude of up to 5% -15%.

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