Technical articles

Why is d90 a key parameter for the particle size distribution of silver paste

2025-04-10

Why are d10, d50, and d90 key parameters used to describe the particle size distribution characteristics of particles in slurries (such as silver slurries). Here is a specific explanation:


1. Definition d90: Refers to the particle size distribution where 90% of particles have a diameter less than or equal to this value. For example, if the d90 of a certain slurry is 3.1 μ m, it means that 90% of the particles in the slurry have a diameter ≤ 3.1 μ m, and the remaining 10% have a larger diameter.

d10: 10% of particles have a diameter ≤ this value (reflecting the minimum particle range).

d50: 50% of the particles have a diameter ≤ this value (the median value reflecting the overall particle size).

2. The measurement method is carried out using a laser diffraction particle size analyzer (such as the Malvern Panalytical Masterstar 3000 Hydro MV mentioned in the literature), which can draw a particle size distribution curve and extract parameters such as d10, d50, d90 from it.

3. The importance of aperture adaptability in ultra-fine line printing: When the template aperture width is extremely small (such as 5-10 μ m), the larger the d90 value in the slurry (such as d90=3.1 μ m for Paste A), the easier it is for large particles to block the aperture, leading to printing defects. Nano sized slurries with smaller d90 values (such as d90=1.9 μ m for Paste B) have smaller particles, better flowability, and can smoothly pass through narrow pore sizes, reducing the risk of blockage.

(2) Contact finger performance: Large particles (high d90) may cause rough contact finger surfaces and uneven resistance (as shown on the left in the figure). Small particles (low d90) help form a uniform and dense conductive layer, improving electrical performance (as shown on the right in the figure).

silver paste


Paste A(d90=3.1 μm): Suitable for conventional screen printing (such as 20 μ m line width), but due to its large particle size, it cannot be used for glass template printing with a nominal aperture of 5 μ m.

Paste B(d90=1.9 μm): Nanoscale particles significantly improved the uniformity of printing ultra-fine lines (9.7 ± 0.6 μ m) and increased the aspect ratio (ARopt=0.45)


D90 is a key parameter for measuring the upper limit of slurry particle size, which directly affects the feasibility and quality of ultra-fine line printing. Choosing a slurry with a d ₉ value that adapts to the template aperture is the core factor in avoiding blockages and achieving high-precision metallization.



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