Spherical Silicon Micropowder for Expoxy Mold Filling

Spherical Silicon Micropowder for Epoxy Mold Filling

Our spherical silicon micropowder is manufactured from premium fused quartz through a flame-jet melting and spheroidizing process. This high-strength, high-hardness, inert spherical particle features a SiO2 content exceeding 99.8%, with a whiteness of 92-98, density of 2.2, Mohs hardness of 6.0, and fineness ranging from 50μm to 2μm-0.2μm, offering a precisely adjustable particle size distribution.

High-quality spherical quartz powder for EMC exhibits superior dielectric properties, low thermal expansion coefficient, high thermal conductivity, excellent flowability, low oil absorption, easy dispersion, and low mixing viscosity. These advantages reduce the thermal expansion coefficient, water absorption rate, and molding shrinkage of epoxy molding compounds while lowering production costs. Additionally, it enhances heat resistance, mechanical strength, dielectric performance, and thermal conductivity.

II. Our company's product specifications:

3. Product Features of Spherical Silicon Micropowder for Epoxy Plastic Encapsulation:

1. High specific surface area: The surface is pore-free, resulting in extremely low moisture content;

2. 99.9% purity: High-purity raw materials and specialized processing ensure minimal impurity ions.

3. Sphericity up to 95%: true spherical particles with a size range of 30-2 microns;

4. Excellent insulation: low impurity content and superior electrochemical performance;

5. Low thermal expansion coefficient: Made of high purity special grade fused quartz, with low expansion coefficient;

6. Narrow and controllable particle size distribution: The distribution is highly concentrated, with customizable range to meet customer requirements.

7. Fluidity and dispersibility: No surface adhesion, smooth spheres with excellent fluidity, easy to disperse;

8. High filling ratio: A well-distributed particle size enhances the filling efficiency.

9. Smooth surface: Low friction coefficient reduces wear.

4. Basic performance parameters of spherical silicon micropowder:

Silicon micropowder can be classified by the following characteristics and customized to meet customer requirements:

5、Application Analysis of Spherical Silicon Micropowder in EMC Industry

Electronic components in electronic and electrical products are typically encapsulated with epoxy resin (EMC), while filler components such as silicon micropowder can enhance the cost-effectiveness of the epoxy resin.

Spherical silicon micropowder is extensively utilized in high-end semiconductor device packaging owing to its superior properties: high packing density, excellent flowability, minimal wear, and low stress. Particularly, precisely controlled spherical silicon micropowder with large particle sizes is ideal for narrow-gap packaging epoxy encapsulants. It also serves as a filler in liquid encapsulation resins such as underfiller and globetop, as well as in various resin-based substrates.

Moreover, with the miniaturization and increasing integration of electronic products, thermal management has become increasingly crucial. Materials such as rounded silicon micropowder can provide excellent thermal conductivity for fully encapsulated and high-thermal-conductivity epoxy plastic encapsulants.

6、The Role of Spherical Silicon Micropowder in Epoxy Mold Sealing Material

(1) Spherical silica powder exhibits excellent surface fluidity, ensuring uniform film formation when mixed with resin. With minimal resin addition, the powder achieves maximum filling capacity, reaching a mass ratio of 90.5%. Spherification consequently increases the filling rate of silica micro-powder. Higher filling rates result in lower thermal expansion coefficients and reduced thermal conductivity, closely approximating the thermal expansion coefficient of bulk silicon. This leads to superior performance in manufactured products.

(2) The stress concentration of the plastic encapsulation material is the least and the strength is the highest when the spherical powder is used. When the stress concentration of the plastic encapsulation material is 1, the stress of the spherical powder is only 0.6. Therefore, the yield of the spherical powder encapsulation material is high, and it is not easy to produce mechanical damage in the process of transportation, installation and use.

(3) Spherical powder exhibits a low friction coefficient, resulting in minimal mold wear. Compared to angular powder, this significantly doubles the mold's service life. Given the high cost of plastic encapsulation molds—some even requiring imports—this feature proves crucial for packaging manufacturers to reduce costs and enhance profitability. When used as a filler in epoxy resin systems, it can save up to 30% of epoxy resin usage, demonstrating vast market potential.

7、Application Analysis of Different Silicon Micropowders in Epoxy Plastic Encapsulation Materials

In epoxy molding compounds, inorganic fillers constitute the predominant component by weight. Among the available filler options, silicon dioxide (silica powder) is the most widely used. However, even within the category of silicon dioxide, there are several distinct types: these can be classified by shape into angular and spherical varieties; by internal crystalline structure into molten and crystalline forms; and by alpha-ray content into standard and low-uranium content variants.

While each type of silica exhibits distinct characteristics, they all share a common function as fillers: improving specific EMC parameters and properties. These include reducing shrinkage, enhancing toughness, improving wear resistance, decreasing water absorption, raising thermal deformation temperatures, increasing thermal conductivity, lowering thermal expansion coefficients, and reducing production costs. Beyond these shared traits, different silica types demonstrate unique characteristics. For instance, spherical silica micro-powder offers higher filling capacity and better flowability compared to angular silica micro-powder, while also exhibiting superior crack resistance. Melting-type silica demonstrates low thermal conductivity and low linear expansion coefficients, whereas crystalline silica exhibits higher thermal conductivity and greater linear expansion coefficients. Consequently, their application in epoxy molding compounds produces varying effects, as detailed below.

n Effect on viscosity

To enhance electromagnetic compatibility (EMC) performance, researchers have explored various methods to maximize filler content. However, increasing filler content simultaneously raises the viscosity of EMC, reduces formability, and adversely affects gold traces in integrated circuits, thereby compromising reliability. Therefore, appropriate filler content selection is crucial. Currently, the primary methods to increase filler content while maintaining stable viscosity involve adjusting particle size distribution, improving stacking density, adopting composite inorganic fillers (e.g., spherical or a combination of spherical and angular particles), and selecting low-viscosity resins. These approaches effectively achieve higher filler content without significantly increasing EMC viscosity. The optimal median particle size for formulated composite inorganic fillers ranges from 5 to 30 micrometers.

n Influence on the Coefficient of Thermal Expansion

The primary method to reduce the thermal expansion coefficient (TEC) of EMC is to increase the amount of inorganic filler. Epoxy resin has a TEC of approximately 100×10⁻⁶/°C, while silica exhibits a TEC of 0.5×10⁻⁶/°C, representing a difference of nearly 200 times. However, the addition of filler is limited, as excessive filler can increase the melt viscosity of EMC, leading to reduced fluidity and elevated E. Therefore, to primarily control the TEC, spherical molten silicon micropowder is typically used, which allows for a significant increase in filler content, reaching 75%–80%. Additionally, spherical powder helps mitigate stress concentration at filler tips and reduces wear of encapsulation materials in molds.

n Effect on thermal conductivity

Generally, the thermal conductivity of EMC increases with the filler content, and crystalline silica exhibits higher thermal conductivity than molten silica. To meet the thermal conductivity requirements of high-power discrete devices, high-heat devices, and especially fully encapsulated discrete devices for epoxy molding compounds, crystalline silica can be used as a high-thermal-conductivity filler.

n Effect of Packing Material on Water Absorption Rate of EMC

Since the filler material is neither hygroscopic nor permeable, increasing its content effectively reduces the moisture absorption rate of EMC, though this may lead to reduced fluidity. Currently, the primary approach involves adding surface-treated fillers to enhance the moisture resistance of EMC, thereby extending the distance water can penetrate into the chip. Generally, angular particle fillers demonstrate greater effectiveness than spherical ones in improving crack resistance during reflow soldering.

n Effect on overflow

During encapsulation molding, overflow is a common defect that affects solderability and appearance. One cause of overflow is low resin viscosity or improper filler particle size distribution. To address this, resin with higher viscosity can be selected within the allowable range, and the filler particle size distribution can be adjusted to increase filling volume, thereby improving the material's anti-overflow performance. Japanese researchers found that when spherical molten silica with a maximum particle size below 74 microns and molten silica with a maximum particle size below 40 microns are mixed, they can form a blended filler with a specific surface area of less than 3 m²/g at mass fractions of 55-95% and 45-5%, respectively. This blended filler can account for 40-90% of the total EMC material.

8、EMC's spherical silica product introduction:

At present, in the industry of electronic packaging materials, epoxy molding compounds (EMC), to meet the requirements of environmental protection, to achieve the index of environmental certification, increasing the filling amount of silicon powder in EMC is one of the effective ways, the highest filling rate of spherical silicon powder in EMC has reached more than 90% in the world.

Spherical silica powder is an amorphous quartz powder material with spherical particles, primarily composed of silicon dioxide. Our company produces this spherical silica powder through specialized manufacturing processes, featuring exceptional sphericity and spheroidization rates. It achieves electronic-grade purity, with particle sizes as small as sub-micron or nanometer, uniform distribution, and no agglomeration. As a filler, spherical silica micro-powder significantly enhances the rigidity, wear resistance, weather resistance, impact and compression resistance, tensile strength, flame resistance, arc insulation properties, and UV radiation resistance of electronic products.

In order to make spherical silicon powder can be applied to epoxy molding compound better, generally the spherical silicon powder product particle size distribution, chemical composition, conductivity, pH, spherization rate and whiteness and other performance parameters are tested, in order to control its quality.

The spheroidization rate indicates the proportion of spherical particles in the product. Higher spheroidization rates result in better filling performance of spherical silicon micropowder in epoxy molding compounds. When producing spherical silicon micropowder using the flame method, key factors affecting spheroidization rate include flame temperature and particle dispersion. Optimal flame temperature can be achieved by adjusting the flow rates of gas and oxygen. The dispersion of quartz particles is a critical process in manufacturing ultrafine spherical silicon micropowder. Due to their small particle size and large specific surface area, ultrafine powders are prone to agglomeration caused by electrostatic attraction and van der Waals forces. If agglomeration of angular silicon micropowder is not resolved before entering the spheroidizing furnace, multiple quartz particles may fuse and coalesce in the flame, forming oversized particles after spheroidization, which compromises product quality and yield. To address this, ultrafine powders can be atomized using high-pressure air and subsequently dispersed through ultrasonic treatment to disperse agglomerated particles, thereby improving the spheroidization rate of spherical silicon micropowder.